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1. Create amp manage test questions Generate amp print tests Figure 1 2 Test generation actions The scenario described above is used as a model for the application that makes up the main part of this work Before describing its implementation let us digress and look at an already released application that was tailored to very similar purpose 2 Code Examiner Before implementing an application it would be appropriate to look at already existing applications with the same goals and analyse their merits and faults However even extensive Internet search revealed no reference to such an application Fortunately there is a similar project developed right at the Faculty of Mathematics and Physics of Charles University in Prague MFF UK that has been released just recently Its name is Code Examiner CodEx and its properties are describe in full in 1 CodEx also deals with management of homework assignments but it is focused on programming courses and problems in programming courses form a very specific class of problems from the correction point of view Generally homework is simple there is one set of input data and the task is to find the corresponding output What is specific about programming problems is the fact that their input is a whole class of input data sets The solution of a programming problem is a program able to find the corresponding output for any input from the defined class While going over the solut
2. Ph D Department of Software Engineering Abstract The goal of this thesis is to implement a software system facilitating management of homework assignments and automated generation of tests From the teachers point of view homework management means creation of problems their assignment to students and correction and rating of solutions For students it means handing in solutions to assigned problems and solution rating overview The focus of this thesis is the description of implementation and utilization of the Assignment Manager web application Apart from the goals described above the application also enables the management of user groups sharing of problems among student groups within the scope of a single course and using external plug ins for automated correction of solutions Furthermore it is capable of automated generation of tests from saved sets of test questions The application was field tested during a single semester and it was extended based on the teachers and students suggestions The thesis includes a discussion of the differences between the original assumptions serving as the basis for the application s implementation and the demands of live deployment Keywords homework management automated correction of homework automated generation of tests generation of random tests Contents PRT OGUCUION 5c csksdiccvacesrsccelsngsceeiserecesteedivesteosseassesdeeesnsunesesbsatscsiuseuetseness 1 Management of
3. pencil action and edit the lecture description Edit a problem description or the configuration of the used plug in Go to Lecturer gt Problems use the edit problem pencil action and edit the problem Upload a new file for an existing attachment Go to Lecturer gt Attachments use the edit attachment pencil action and edit the attachment The name of the attachment cannot be changed Edit a question Go to Lecturer gt Questions use the edit question pencil action and edit the question Delete a lecture Go to Lecturer gt Lectures and use the remove lecture trash can action Deleting a lecture removes all data belonging to that lecture including problems groups assignments and solutions 73 KA lt lt lt lt lt Delete a problem Go to Lecturer gt Problems and use the remove problem trash can Deleting a problem deletes all assignments using that problem Delete an attachment Go to Lecturer gt Attachments and use the remove attachment trash can action Deleting an attachment removes all questions using that attachment Delete a question Go to Lecturer gt Questions and use the remove question trash can action Deleting a question removes all templates using that question Delete a test template Go to Lecturer gt Tests and use the remove test trash can action Cancel running test or remove completed test results Go to Lecturer gt Plugin tests and use
4. To keep the descriptions short this step is described as go to group gt page where group is the group name shown at a menu group header and page is the name of the menu item to be selected Other common steps include using the table action buttons or using the editor pattern Action buttons are labelled with icons and using them is described as use the action icon action where action is the action description visible on mouse 68 over and icon is the icon name See Figure 4 8 for a comprehensive list of icon names used below Editor pattern consists of using the Edit entity or Create entity action filling in the displayed form and submitting it to modify or create a particular entity e g user The act of filling in and submitting the form is described simply as edit entity or create entity thick plus calendar pencil tag trash can 2 person v check refresh cross amp print down arrow dialog uparrow contact paper D paper 2 Figure 4 8 Icon names The tasks described in this section are divided into five groups The first group includes all tasks not specific to any user role The rest is grouped based on the menu groups i e based on the user roles 4 6 1 Common Tasks Register a new user account 1 Instead of logging in click on the Register button on the login screen 2 Fill in the registration form and submit it Entering a working e mail address is ess
5. content Instead the UI keeps an active lookout for hash changes and reacts to them by rendering the content corresponding to the current hash value This makes it possible to use the browser buttons Back and Forward or to navigate the application directly using the browser address bar Using the hash for navigation has one caveat Unlike a static web page where the hash is simply an address of a point on the page the addressing in dynamic web application means in a sense and to some extent describing the state of the application Navigation complexity depends on the complexity of the address space Therefore ASM UI chooses to impose the following limits for its navigation and content 1 At any time there is exactly one content area in the whole display area a k a viewport and only the content in that area is addressed The left menu in user session layout is a slight exception to this as its selection reflects the current address even though it is not a part of the content area itself 2 An address consists of one or more parts separated by hash signs ordered from the left to the right by decreasing importance Each part but the leftmost is a further specification of the address formed by the parts to its left Address change handling is closely connected to the component hierarchy of the UI and it is described in the following section Display Components Invalid addresses are stripped of the invalid parts from the right until the
6. files and because PHP includes support for INI file parsing From the Core viewpoint the configuration file is read only AsM configuration consists of two parts public and private In the public part properties describe the external environment AsM administrator is encouraged to change them manually if necessary They include MySQL account data and adatabase name SMTP server account data and a From header value for outbound e mails paths to PHP CLI and Java interpreter an absolute path to Apache document root and a relative path to AsM deployment directory etc The private part is clearly separated from the public part and contains properties describing the inner structure of the application These properties serve only for development purposes and should not be changed manually by AsM administrators under any circumstances During the early development and even in the alpha version of AsM Core the manual modification of the configuration file was the only way to configure the application Later on an additional script AsM Installer was introduced to make AsM deployment simpler The Installer requests the initial configuration data from the administrator and it attempts to guess and verify some of the values e g paths to PHP and Java interpreters Section 3 6 contains more information on this subject 4 PHP Extension and Application Repository PEAR is a system for distribution of reusable PHP components see 24 It is use
7. with very little or no information technology IT background However the installation requires certain experience with IT It should not be performed without some basic knowledge of the Apache web server and the PHP server extended by PEAR 4 2 1 Requirements The requirements necessary for installing and running AsM are described below Apache web server accessible to all potential users either through the school s local network or over the internet running PHP version 5 3 or greater with PEAR The server needs to be correctly configured as described below MySQL server using MySQL version 5 0 1 or greater ASM needs a valid user account on the MySQL server with permissions to create a database and to fully manage it A standard compliant web browser such as Mozilla Firefox Opera or Google Chrome on a computer with the access to the web server mentioned above 4 2 2 Installation The installation or upgrade is partly manual and partly managed by the AsM Installer Use the following steps to install the application 1 Extract the application files and folders to a folder located inside the document root of your Apache web server see 16 2 Ensure that the web server is correctly configured htaccess files are allowed in the application folders and URL rewriting is enabled by adding the following configuration to the configuration file of the Apache server AccessFileName htaccess LoadModule rewrite_module
8. 1 2 Actors In the extended form the college course homework assignment scenario involves the following actors o Koca Lecturer Lecturer is the person designing the course and responsible for it He creates problems which are the same for all students attending the course He also manages the corrective plug ins to be used for correcting the problems Tutor Tutor is responsible for a single group He assigns homework problems created by the lecturer to his group and rates the solutions Student Student is a member of one or more groups He receives homework assignments and submits his solutions for correction and rating Administrator Administrator is a person responsible for installation and maintenance of the AMS and also for the management of AMS users and their privileges Of course this list of actors does not match every possible real world situation but it should be comprehensive for most cases The actors and the actions performed by them are shown in Figure 1 1 Manage plug ins Administrator Lecturer Manage users Test plug ins DO j Manage user types include K Student Subscribe to homework groups solutions Rate solutions Figure 1 1 Actors in a homework assignment scenario x Tutor 1 2 Automated Generation of Tests Automated generation of tests is mentioned in the Introduction separately because it is not directly related to the management of homework assignments I
9. 3 4 6 Model view controller Pattern cccccccccssssccceessscececsesseeecssesseeeceeeees 41 NCAT WV TO AE EEE AE E EA ea cdubodeeruaseeareneinneneaaotns 42 2A User SQSSION cesses ea r A a a E E E AAEN E ans 44 3 4 9 Navigation and Browser History ccsscccssssecessecessseceeeceeesssseeeeeeees 44 3 410 Display Components ennei ninar AEE E 46 3 4 11 Data Retrieval and Storage cccesscecssscecsseceesseceesseceeeseesseneeeeeeeeees 47 JAIS EVENT S iieiea a a a a ea a eei 48 3413 Error Rep porna desc sede odesesbcegd oes ee lala adel eaae a eea aa ETEA E E iaa 49 Foy A Teea a TA EA A E AAT 50 FRA Tasky 210086 theta a a a a a aa a a a ihe Sal ah has 51 3 5 2 Plug in Format sseesseessesssesssssessseosseessseessressoresssesssessseessressersssseessseessees 51 3 5 3 Communication Contract seseesesssssseseeeessssssesereessssssesseseeeessssssssssssso 52 3 5 4 PHP Plugin Framework ssseessssessseesseossresseresssessseesseeessssssssresssssssreeee 54 a6 Installert snae a E E A T a a 55 ile Install ese a Ai ENEY 56 3 6 2 Upgrade n i en aE STE bade sald E ER aS 56 37 DocumentatioM esenee e iaee eaan aTe E TEES ER S 57 4 How to Use he Assignment Manager ccsccscsscssssceccscescscescecesees 59 Aa User ROLES ae a R lpn EAT TTR ER 59 4 2 Installation and Configuration seessesesssssssesersseessessressessssseessessesseeessssrees 60 4 2 1 REQINTEMENIS soseer renet nen EEE NEE TEEKS 60 42D DO Tras balla T
10. College Course Homework and Tests 0000 1 1 Extended Homework Assignment Scenario cssceeeseceseceecceeeceeeeeeeeeeeeeeees 4 1 11 Basic Terminology 2cc cszcos acisvareasteeeceesenectivecconsesiescecnnec worse 4 1 1 2 ATOT 35 5638 ss sesk ences abs ok e50h hb waa gcc e Sa 55th 5a bs Aad an ncudsb a Ravan ah ak Beeb aban aE eee 5 1 2 Automated Generation Of Tests scssccssscssrsesrsssnssssssscaseesesnrseeseereesseres 6 lt Code EXaminel scscsesicccccacnsccdcascsessenewscecese cdsevdeesd a T Ee ass Esos esses 9 2 1 Lecturer amp Tutor vs Group Wier ssseesssssssesssssessssseesssseessssteeeeeeesseeeeeessessssss 9 2 2 Fully Automated Correction ssesessssessesereseessessesseessessseseeessssessseressssereseees 10 3 Notable SIMAT OS 42356 n aee A e ANE 10 Inside the Assignment Manager sesesssescscscesesesoesocesessesseseesseseeoee 11 3 1 Used Technologies sessseeseessesssesesssessesseessesssesecsseessesseessesseesseteesssetesseeesesseee 11 3 2 System Breakdown and Interaction se ssssssssessseseessessseseesssesersseesseserssresssseee 12 BPs E 0 k EAEI AAA A E AAN E ETET 13 ea Pa B E E E E E A E aeeaies 13 323 9 User SESSION an a a a eee ee 14 9 9 8 User ACCO e aa E A aa 15 2 2 A User Permissions euros hetee eiee rn Ee Se Easa i neiaie es 15 3 3 5 Courses Groups Problems and Assignments ccccssccesscecesesereeeees 17 3 3 6 Solutions and Their Correction cccccccc
11. The database contains both the various entities and the connections between them Base data are stored in simple tables Each table has a special ID column with numeric IDs of table rows The connection of the tables is arranged using views which are predefined SELECT queries stored in the database which can be used as sources for other queries just like normal tables The views created as a part of ASM join the tables by connecting ID references with the respective IDs As an example the database contains tables users and usertypes The first table contains columns for properties such as user s full name his e mail address username and password It also has a type column which contains references to row IDs in the second table Apart from the obligatory ID column the second table contains columns for the usertype name and the set of user permissions A view usersWithPermissions also included in the database joins these two tables by extending the user table rows with the usertype name and the privileges corresponding to the user type referenced by the type column 3 3 16 Requirements AsM Core code is written in PHP 5 3 and takes full advantage of its features such as namespaces or class constants therefore it is incompatible with the earlier versions of PHP A great deal of effort was put into making its object oriented code as clean 29 as possible Type hinting PHP 5 feature is used to substitute strong typing missing in older
12. WWW lt http www ecma international org publications files ECMA ST Ecma 262 pdf gt 5 jQuery The Write Less Do More JavaScript Library online 2010 cit 6 7 8 9 2011 11 20 jQuery The Write Less Do More JavaScript Library Available from WWW lt http jquery com gt PHP Hypertext Processor online 2001 last updated Nov 2011 cit 2011 11 20 Type Hinting Available from WWW lt http cz php net manual en language oop5 typehinting php gt Apache HTTP Server version 2 2 online 2011 cit 2011 11 20 Apache Module mod_rewrite Available from WWW lt http httpd apache org docs 2 2 mod mod_rewrite html gt EDWARDS Dean A Base Class for JavaScript Inheritance online 2006 cit 2011 11 20 A Base Class for JavaScript Inheritance Available from WWW lt hittp dean edwards name weblog 2006 03 base gt WELIE Martin van Welie com Patterns in Interaction Design online 2008 cit 2011 11 20 Accordion Available from WWW lt http www welie com patterns showPattern php patternID accordion gt 10 Wikipedia the free encyclopedia online 2003 last updated Nov 2011 cit 2011 11 20 Model view controller Available from WWW lt http en wikipedia org wiki Model view controller gt 11 Architecture of the World Wide Web Volume One online 2004 cit 2011 11 20 Fragment identifiers Available from WWW lt http www w3 org TR w
13. While it may seem that gaining points to pass the course requirements is the point of submitting homework the main point is actually learning from mistakes in the submitted solutions AsM needs to facilitate this goal by allowing tutors to describe found mistakes in detail Allow forgotten password recovery Automated password recovery is one of the features necessary for reducing ASM maintenance It would be sufficient to generate a new random password on demand and send it to the user s e mail address Limit the number of uploads for a single assignment Correcting large amounts of solutions could become resource demanding Discouraging the students from uploading too many incorrect solutions could be achieved by limiting the number possible uploads of solutions for a single assignment Improve the model of table display to support scaling Another oversight in the design is the lack of focus on data volume scaling This is most apparent in the implementation of the table element which renders all its contents and performs pagination sorting and filtering only by hiding certain parts Consequently large amounts of data cause a long rendering of the table This could be remedied by performing selection functions on raw data and rendering only the current selection Allow server side filtering An extension to the previous enhancement would be to move data selection functions to the server and to make the selection commands part of the Core
14. a tree structure used for event hierarchy as well it is possible to catch errors originating in a specific part of the UI by observing its root component Catching and logging of errors and possibly their display is a task for error manager classes Design of the error managers and error wrappers to certain extent is based on the following requirements 49 1 Errors should be displayed close to their source Therefore it should be possible to handle the display of errors originating in different parts of UI separately 2 Asingle error should not be displayed repeatedly 3 There should be a way to view all errors that occurred in the UI on demand regardless of their point of origin Based on the above requirements error managers contain different logic for logging and displaying of errors added to caught by them Additionally error wrappers contain a reported flag which helps to ensure that each error is displayed just once Stopping the event s propagation could be used for the same purpose but using a separate flag allows simple creation of a log containing all errors by catching errors at the root of the component tree AsM UI makes use of this technique and allows viewing of the error log on a separate page The default behaviour of an error manager is to observe its assigned component to log all observed errors to display those of them which are not yet flagged as reported and to flag them as reported The base erro
15. always in one of the following states Disabled A disabled field has no value and cannot be edited A field may be disabled for example when its value would not make sense in the context of another field s value e g field plug in configuration makes no sense if there is no plug in selected in the plug in field The state of the disabled field is indicated by the input elements being greyed out and unselectable and the interaction cues being hidden 35 KA lt Read only The only difference between a disabled and a read only field is that a read only field contains a value This makes sense for fields that must not be edited for some reason e g the username and user type of admin user which cannot be modified There is not difference in visual properties Untouched A field is untouched when it is enabled i e not disabled or read lt only and its value has not been edited yet An initial hint is shown while the field is in this state lt Focused A field is focused when one of its input elements is focused The focused input element is always highlighted while the rest of field s visual properties depend on its previous state If a field becomes focused after being invalid it retains the visual cues of the invalid state Otherwise the initial hint is displayed lt Valid Valid field is an enabled field that is not focused containing a value that has been edited and that is valid A check mark
16. created by students in that group as well as every student s total rating Subscription requests page is a table with pending subscription requests which can be used to allow or deny other users requests to subscribe to a private group owned by the user Lectures page is an editor allowing the management of courses a k a lectures Problems page is an editor for the management of problems Plugins page is another editor for the creation and removal of plug ins Plugin tests page allows testing plug ins by running them with custom arguments on the supplied input The page contains two tables with running and completed tests respectively and a form for starting a new test The tables provide means for test removal and in case of completed tests the download of plug in output Questions page contains an editor for the management of questions and a form for the creation of templates The latter is hidden while a question is being created or edited The form is closely connected to the table because it uses the table for the selection of questions Table filters can be used to constrain the set of questions included in the template Additionally table row selection can be used to choose the mandatory questions Attachments page is an editor for the management of attachments Tests page is a table of templates It enables generating new tests from the templates printing the generated tests and removing the templates System log pa
17. filter a Pagination 5j Add filter form Figure 4 4 Table Perform table specific actions A table can contain global and or row action buttons which provide the main method of interaction They are labelled only with icons to avoid taking too much space but hovering with a mouse cursor over an action button displays the action s description Clicking the button performs the described action Row action buttons are used to perform actions on the respective rows e g delete a user in the table of users Global action buttons perform actions related to the table but not actions related to a specific row e g create a new user Collapse expand table The whole table can be collapsed or expanded by clicking on its header An empty table is automatically collapsed and cannot be expanded Expand collapse cell content If a cell contains an overlong text only the beginning of the text is shown The rest can be shown or hidden by clicking a small plus or minus sign in square brackets appended aside the value All cells in a single row can be expanded or collapsed at once by double clicking the row Show table as multiple pages with X rows To prevent tables from using too much space there is a row limit page size set for each table If a table exceeds that limit its rows are divided into pages User can navigate pages using pagination controls on the bottom of the table which allow moving one or five pages forward or
18. groups he is subscribed to Figure 3 1 Course management entities and their relationships 3 3 6 Solutions and Their Correction The format of a solution may vary a lot depending on the problem it is supposed to solve These differences have no meaning from the Core viewpoint so a unified format is imposed to hide them and make the solution handling more convenient Before handing in the data of every solution have to be packed into a single ZIP archive This is convenient because ZIP archives are supported on all major operating systems and compression makes uploading solutions to the server faster and helps save space After a solution is successfully uploaded to the server it is annotated with date and time and becomes a submission During its life cycle in Core a submission is always in one of the following states new corrected confirmed and rated The sequence of the states is linear and their changes are irreversible Every submission starts as new If there is a plug in set up to correct it it is launched and the uploaded solution is handed to it When the correction is finished the plug in returns the results of all performed checks The results are added to the ZIP is a common file format allowing to compress multiple files into a single archive 18 submission as well as the percentage of the overall success If there is no plug in associated with the problem this step is skipped In both cases the submissio
19. in AsM UI is not just restricted to using navigation menu or a few of the action buttons in select tables ASM UI is a web application running in a web browser which means that its users may well expect it to act like a static web page 44 and respond to browser controls Back and Forward In other words it should be possible to navigate it using the browser history or through the address bar The address bar navigation is trivial for regular web pages that are served by the web server depending on the URL entered into the address bar In contrast a JavaScript web application such as AsM UI is served just once by the server After that its interaction with the server even content retrieval takes place in the background hidden from the user While the application is running sending a new URL to the server using the address bar would stop the application and load new content into the browser window tab However there is an optional part of URL called fragment identifier or hash which is not sent to the server with the rest and which can therefore be changed without triggering a server request see 11 Fragment identifiers are used by regular web pages to point the user to a specific part of the currently loaded page e g chapter section picture ASM UI uses them in a similar fashion only in this case the page content is dynamic making it impossible to just let the browser point the user to the appropriate part of the
20. it makes all smaller changes much more difficult Adding a new feature almost always requires changes on multiple levels separated from each other and extensions of interfaces between them For example enabling to add a note to a solution when rating it would require extending the database layout applying this change in the abstract database layout in the Core changing or adding a database request changing or adding a core request and extending the UI to reflect this change So it became apparent that the modularity should have been applied deliberately and only where really necessary By default the implementation should have been as simple as possible Instead of aiming to create absolutely robust code the focus should have been put on other aspects like the application s reliability And again keeping it simple would be much easier using an iterative development pattern rather than specifying everything in advance The arguments against modularity discussed above can be similarly applied to the complexity of the scenario used as a model for AsM s functionality Expanding the scope of the model scenario to cover the homework management of a whole college added a lot of complexity that was not really necessary In this case it is the application design that should have been kept as simple as possible at the beginning and extended iteratively Unfortunately due to the author s lack of experience or lack of formal schooling in application des
21. libraries written in Java JavaScript Object Notation an open standard for text representation of simple data structures see 23 Faculty of Mathematics and Physics of Charles University in Prague model view controller a software architecture pattern used to separate the application logic from the display logic see 91 PEAR PHP PHP CGI PHP CLI PHPDoc POST SMTP UI URL XHTML XML ZIP 10 PHP Extension and Application Repository a system for distribution of reusable PHP components see 24 PHP Hypertext Preprocessor programming language see 3 the PHP preprocessor of content returned by a web server in response to a HTTP request a PHP preprocessor that can be used directly from the command line independently on a web browser PHP documentation standard see 14 the POST method supported by the HTTP protocol used for sending data to the web server as part of the request Simple Mail Transfer Protocol a standard concerned with e mail communication see 25 user interface in general or AsM User Interface specifically Uniform Resource Locator a format for addressing an internet resource see 27 Extensible HyperText Markup Language an application of XML offering functionality similar to that of HTML see 22 Extensible Markup Language a set of rules for creating documents with added logical structure see 19 ZIP file format used for data compression and arch
22. not surprised with new concepts on every page The elements are carefully extended to provide tools required by the users while remaining intuitive and easy to use The list of used elements follows the details of the most important two of them are provided in the following sections Table Element and Form Element See section Widgets for implementation details o Form Form fields provide hints about value restrictions as well as visual focus cues and an instant validation feedback Forms are designed to be fully validating so that instead of sending the data and hoping for the best the users are sure that they are sending the correct data Table Enhanced tables serve as the principal means of data presentation and interactivity They include both static enhancements concerned just with data display such as pagination sorting and filtering and interactivity enhancements provided by action buttons Editor Editor is not a single visual element like a form or a table but rather a design pattern which combines a table with a form for the creation and or modification of table rows Editor pattern as defined in AsM unifies the look and descriptions of the action buttons used for the creation modification and removal of rows and how the two used elements interact In its initial state an editor is just a table with rows that can be created modified or removed When a user decides to either create or modify a row the table
23. path to mod_rewrite so lt Directory application folder path relative to document root gt 60 AllowOverride FileInfo lt Directory gt 3 Ensure that the correct default time zone is set for both PHP CGI and CLI see Runtime Configuration section of 6 date timezone Europe Prague use your time zone set the same values for CGI and CLI 4 Install the PEAR modules Mail and Net_SMTP if they are not already installed 5 Ensure that the Apache server can create files and sub folders in files create files in core and write to htaccess where all the paths are relative to the root folder of the extracted files 6 Access the AsM Installer from your web browser by entering the following address http WEB_SERVER_ADDRESS APPLICATION_LOCATION where WEB_SERVER_ADDRESS is the address IP or domain name of your web server and APPLICATION_LOCATION is the path to the folder where you extracted the application relative to the document root 7 Follow the Installer wizard and fill in the appropriate data The entered data are saved to the configuration file and it is possible to modify them later The configuration file is described below 8 Wait for the AsM UI to launch after the Installer has successfully finished 9 Log in as administrator username admin password admin and change your administrator password 4 2 3 Configuration AsM is configured using a special configuration file core config ini whi
24. plug in development is the access to utility classes and functions implemented as a part of the AsM Core These include various convenient methods not included in PHP itself such as simplified custom array sorting filtering and mapping or ZIP de compression of whole directories For the full list of available utility enhancements see the developer documentation on the attached CD 3 6 Installer The AsM Installer was not a part of the first version of the AsM project It was added as an afterthought and it is completely separated from the other parts It is a web based wizard which guides the administrator through the initial configuration of AsM or through an upgrade to a newer version There are two reasons for adding the Installer to the application First of them is an upgrade capability and the second one is usability Upgrading AsM without such a tool would be a very trying task as it may require for example a direct adjustment of the database If done incorrectly such adjustment could have catastrophic results The initial configuration of AsM Core could be done without the Installer by editing the configuration file manually but using the Installer for this task allows to add features like guessing and validation of certain configuration option values e g locations of PHP and Java command line interpreters The Installer is written in XHTML and PHP but its code base is not in any way connected with AsM Core It uses the r
25. regular DOM elements There are three kinds of extensions provided by widgets extensions of properties extensions of methods and visual enhancements Visual enhancements are usually a part of any widget Property extensions are far more common than method extensions Widgets implemented as a part of AsM UI depend only on jQuery jQuery UI and sometimes on other simpler widgets Therefore they are fully reusable in other projects The reason for implementing them separately is to thoroughly separate the display logic layer from the main application logic In other words widgets created as a part of the AsM UI help the display layer to function as required so that the rest of the code can really focus on what should be displayed 42 The list of selected widgets and the extensions they offer follows Note that some of them follow concepts described in the Presentation Elements section o Corner Corner widget extends an element with a corner style property reflecting when used on a box element which element corners are rounded The corner rounding in this context means the uniform corner rounding used throughout the application with a common radius Field The Field widget greatly extends a basic form field by making its type mutable adding several new field types e g check box set or date and adding a lot of other properties based on behaviour requirements of the form presentation element see Section 3 4 3 It binds a fi
26. remaining fragment is a valid address and then they are replaced with that fragment so they do not even remain in the browser history The addresses of content pages unavailable to the user because of insufficient user permissions are considered invalid 1 Uniform Resource Locator URL is an address of an Internet resource e g web page image or script see 27 45 AsM UI uses the hash navigation only in its simplest form Possible enhancements include assigning titles to the components so that the use of the application would leave a history that could be used for jumping directly to a certain content page This would also make creating bookmarks of a specific content page more convenient however that would require an accompanying mechanism for remembering the requested address through the login process Another possible enhancement would be the ability to lock the hash navigation while the access to other navigation controls i e menu action buttons is disabled e g while showing a modal dialog window 3 4 10 Display Components The main application logic of the AsM UI consists of the communication with the Core and generation and display of the UI content In the context of the whole AsM project AsM UI is the front end and AsM Core is the back end The same distinction can be made in the AsM UI context with content generation and display being the front end and data retrieval and storage being the back end The front end
27. requests However such a modification would be very costly while there are only a few requests that could really benefit from it e g system log retrieval Allow adding attachments to a problem Problem descriptions could be enhanced by allowing to add attachments to them similarly to adding attachments to test questions The attachments could be either downloadable or they could be displayed together with the problem description Allow online solving of tests Allowing the students to solve the tests online would be quite a large enhancement but a highly useful one as well Creating an application for sophisticated test generation and for online testing could be a goal for a thesis of its own Enhance correction results returned by the plug ins AsM project includes six correction plug ins which are not discussed in this work as a result of being specific to the problems they correct These plug ins use various external libraries to cope with parsing of XML DTD XSLT and other XML related formats and they finally pass the error messages that were received 82 from the library validation functions on to the users Unfortunately live testing showed that such error messages are not always very user friendly Additional analysis would be necessary to determine whether it is possible to improve error intelligibility in those cases It is important to note that even though using external libraries is a necessity they may not always be err
28. results This is accomplished by detaching plug ins from the request handling process into a separate background process This requires the following two steps 1 Detaching the environment If plug ins were allowed to call the Core with the correction results directly it would result in great increase of complexity In that case the channels of communication between the Core and the plug ins would have to be defined To ensure security a plug in session would have to be established based on the user session that caused the plug in to be launched AsM uses a much simpler alternative When a plug in needs to be detached the Core dynamically creates a script which is able to initialize a partial copy of the current PHP environment and then launch the plug in and retrieve its results The created script is then launched in a separate process 2 Detaching the process Launching the script in a separate process is unfortunately an OS dependent task not covered by the native PHP functions AsM contains methods for detaching a background process on both Unix based operating systems and Microsoft Windows These methods belong to one of the standalone utility modules implemented as a part of AsM and they are very convenient for any application in need of performing asynchronous tasks on the server Plug ins themselves are launched and handled in a manner depending on their type Executables and JAR archives are simply launched and requested to return
29. the application has already been deployed is much more difficult Additionally testing manually while creating hot fixes for an already deployed application puts even more strain on the developer because it is essential to avoid creating new bugs in the hot fixes themselves On the other hand even the best unit and integration tests cannot be 100 sure to reveal all problems either Therefore it would be the best to also test the application on real users This would need both an iterative development pattern allowing to release and to gather feedback after each development cycle as well as the set of willing application testers Automated testing is only one of the bases of application reliability One of the other important but often overlooked elements is the data safety Any application that is a sole owner and manager of valuable data should have backup capability to prevent complete data loss in case of unforeseen circumstances e g server failure Adding the backup capability to ASM would require more than only saving the current state of the database Certain files at least plug ins and confirmed but not yet rated solutions would have to be saved as well 5 4 Dependencies and Maintenance During its development the AsM had been tested on a private local web server Having a web server fully dedicated to the application made it possible to make use of its various features and add a few libraries which made certain tasks unrelated to
30. the form switches to the page with uploaded solutions Confirm a solution Go to Student gt Submissions and use the confirm submission check action Only a corrected solution can be confirmed Confirming a solution marks it as ready for rating and prevents confirmation of another solution to the same assignment View solution rating Go to Student gt Submissions and check the Confirmed submissions table If the solution does not have a rating it has not been rated by the tutor yet Unsubscribe from a homework group Go to Student gt Subscriptions and use the cancel subscription cross action in Active and requested subscriptions table Download plug in output based on an uploaded solution Go to Student gt Submissions and use the download output down arrow action Delete uploaded solution Go to Student gt Submissions and use the remove submission trash can action Confirmed solutions cannot be deleted 4 6 3 Tutor Create a homework group Go to Tutor gt Groups use the add group thick plus action and create the group Before a group can be created its parent course has to exist Marking a group as public means that any student will be able to subscribe to it directly Otherwise students will have to request permission to subscribe to the group Allow or deny a request to subscribe to your private group Go to Tutor gt Subscription requests to view all pending requests Use the allow subscription check o
31. the most important it would be quite restrictive e g cross referencing between parts would become a problem Additionally using different tools for each part would require spending additional time studying how to use those tools Instead a decision was made to use a single tool for generating documentation for the whole project providing that there is one which meets the following requirements PHP documentation format should resemble PHPDoc format so that the IDEs could understand it as such There should be little or no difference between the JavaScript and PHP code documentation formatting Modification of the tool for this purpose should be less costly i e time consuming than creation and maintenance of documentation in two different formats The tool selected on the basis of these requirements Doxygen is the most widely used source code documentation tool nowadays It supports a wide range of programming languages and it is highly customizable Doxygen formatting can be customized to resemble PHPDoc formatting enough to pass for one see 15 Unfortunately JavaScript is not supported by Doxygen because in general the JavaScript code has very loose structure To remedy this the AsM project includes a 21 Integrated Development Environment IDE is an application providing a comprehensive set of tools for software developers including a source code editor a compiler and a debugger Commonly used IDEs include N
32. the remove test trash can action 4 6 5 System KA lt lt lt lt lt lt Create a user type Go to System gt User types use the add user type thick plus action and create the user type by specifying the set of permissions Create a user Go to System gt Users use the add user thick plus action and create the user View system log Go to System gt System log and peruse the log table Note that the System log table may take long time to render Edit or delete a user type Go to System gt User types Use the edit user type pencil action and edit the user type or use the remove user type trash can action Deleting a user type causes all users of that type to be assigned the default user type STUDENT Base user types STUDENT and ADMIN cannot be deleted and the ADMIN type cannot be edited Edit or delete a user Go to System gt Users Use the edit user pencil action and edit the user or use the remove user trash can action Deleting a user does not delete the entities owned by that user e g lectures groups However it is currently impossible to set a new owner for them The user account with the username admin cannot be deleted and cannot have its user type changed Give a particular user certain permissions Users cannot be given permissions on individual basis their permissions are determined by their assigned user type To change the user type of a particular user edit
33. the top bar and find a link to the documentation in the last but one panel at the bottom If neither of these options work try entering the following URL into the address bar of your web browser http hon2a wz cz asm docs Access the dashboard Click the application name on the top bar to show the Home page It shows some of the following information based on user role solution rating totals for subscribed groups student number of pending assignments student number of uploaded solutions that are corrected but not yet confirmed student number of solutions waiting to be rated tutor number of incoming subscription requests tutor and number of new errors in the system log since previous login administrator Find out what needs to be done next See Access the dashboard above Go to a previously visited page Use the browser buttons Back and Forward browser buttons 4 6 2 Student Subscribe to a homework group Go to Student gt Subscriptions and use the add request subscription add action in the Available subscriptions table Open an assignment Go to Student gt Assignments and use the open assignment paper action to view the assignment details 70 Submit a solution Open an assignment see above It is possible to upload the solution file using the form at the bottom of the page providing that no other solution has been confirmed already and it is not past the deadline Submitting
34. thus increase code re usability The impulse for the development of such model is a simple realization that even with an inventive use of arguments the code of a plug in can never be really reusable because it needs to be specialized for a very specific problem or a set of problems at best While the correction is connected to a specific problem most of the solution processing could be reusable if it was separated correctly This idea led to the creation of the test model The first concept of plug in tests had been to have a lot of small separate tests for all processing tasks that need to be done However it soon became apparent that the processing tasks tend to form groups based on common prerequisites e g parsing of the same input file This led to the emergence of a more complex test concept A test as implemented in the Test class of the PHP Plugin Framework is a set of goals which can be reached or failed It is run with a set of parameters containing at least the paths of files to be processed Using tests to group the tasks related implementation wise while using plug ins to group the tasks related problem wise is a good way to separate the problem specific code and keep the rest as reusable as possible The Test class included in PHP Plugin Framework is useful by providing 54 goal management precision error reporting tools and a few other convenience enhancements The last advantage of choosing PHP as a platform for
35. to create an interface that is clean and clutter less while feeling fresh and up to date A big emphasis is put on clarity of the UI To accomplish these goals in a limited time frame and without having any visual design experience the author relied heavily on the jQuery UI theme framework jQuery UI theme framework is a CSS framework with capabilities extending far beyond styling of widgets that come with the jQuery UI library itself It defines a handful of logical types of elements and allows the definition of visual styles appropriate for each of the element types A set of visual style definitions for all defined element types plus a few common style properties is called a theme DOM elements can then be flagged as belonging to a particular type using classes to have the appropriate style applied to them when a theme is used This allows using well defined visual cues consistently throughout the application to ensure the clarity Additional feature of jQuery UI theme framework is that every theme contains an extensive set of simplistic single color icons which is rendered in multiple colors one for each element type Using these icons is as simple as adding an appropriate 18 Cascading Style Sheets CSS is a style sheet language used to describe the look and formatting of a document written in a markup language such as HTML or XHTML see 26 40 icon class to a DOM element which then becomes an icon Icons are always dis
36. versions of PHP Furthermore the Core requires Apache to run and takes advantage of some very convenient features including but not limited to the usage of its rewrite module documented in 7 to prevent access to AsM source configuration files and stored data This is not a large restriction because Apache runs on all major operating systems This concludes the section dealing with the AsM Core For more insight into the implementation please see the developer documentation on the attached CD The next section describes another large part of the project the AsM User Interface 3 4 User Interface User Interface UI of the AsM is a JavaScript application that runs in a web browser and provides access to the tasks performed by the AsM Core It communicates with the Core using POST and GET HTTP requests see previous section for more details To provide access to the Core tasks and present retrieved data the UI uses just a few basic elements e g form or table with extended functionality The AsM UI is written in JavaScript It utilizes a tiny framework Base js which enhances regular JavaScript with some syntactic sugar that enables the use of the classical inheritance pattern instead of the default prototypal inheritance see 8 Another much larger framework jQuery is used as the sole means of DOM manipulation and AJAX communication jQuery was chosen because it is simple to use and provides an extensive ar
37. 94 cit 2011 11 29 Uniform Resource Locators URL Available from WWW lt http www ietf org rfc rfc1738 txt gt 89 90 List of Abbreviations AJAX AMS CodEx CSS DOM GET HTML HTTP ID IDE INI IT JAR JSON MFF UK MVC Asynchronous JavaScript and XML a set of technologies used to create asynchronous web applications assignment manager software fitting the role described in Section 1 1 1 Assignment Manager application implemented as a part of this work Code Examiner application see 1 Cascading Style Sheets a style sheet language used to describe the look and formatting of a document written in a markup language such as HTML or XHTML see 26 Document Object Model a representation of objects in XHTML documents used by scripting languages to access and manipulate those objects see 21 the GET method supported by the HTTP protocol used for retrieving data from the web server HyperText Markup Language used for creating web pages Hypertext Transfer Protocol a networking protocol used for communication between a web server and a web browser see 20 identification number integrated development environment an application providing a comprehensive set of tools for software developers INI file format a standard for simple configuration files see 17 information technology Java Archive a file format extended from ZIP used for distribution of applications
38. Charles University in Prague Faculty of Mathematics and Physics BACHELOR THESIS Jan Konopasek Syst m pro spr vu kol a test Department of Software Engineering Supervisor of the bachelor thesis RNDr Irena Ml nkov Ph D Study programme Computer Science Specialization General Computer Science Prague 2011 I would like to thank my supervisor RNDr Irena Mlynkova Ph D who bore with me throughout the whole time it took me to finish this project I offer my sincere gratitude to my parents for both the wanted and the needed advice Finally I thank you Misha for keeping me going I declare that I carried out this bachelor thesis independently and only with the cited sources literature and other professional sources I understand that my work relates to the rights and obligations under the Act No 121 2000 Coll the Copyright Act as amended in particular the fact that the Charles University in Prague has the right to conclude a license agreement on the use of this work as a school work pursuant to Section 60 paragraph 1 of the Copyright Act l ha EEEREN AE date sseeseessessee Jan Konop sek N zev pr ce Syst m pro spr vu kol a test Autor Jan Konop sek Katedra Katedra softwarov ho in en rstv Vedouc bakal sk pr ce RNDr Irena Ml nkov Ph D Katedra softwarov ho in en rstv Abstrakt C lem t to pr ce je implementace softwarov ho syst mu usnad uj c ho spr v
39. Use the edit assignment pencil action and edit the assignment or use the remove assignment trash can action Deleting an assignment deletes all solutions submitted for this assignment 4 6 4 Lecturer lt lt lt KA lt Create a lecture course Go to Lecturer gt Lectures use the add group thick plus action and create the lecture Install a plug in for automated correction Go to Lecturer gt Plugins use the add plugin thick plus action and use the displayed form to upload the plug in It is essential to test the plug in before using it because plug ins cannot be upgraded Test a plug in Go to Lecturer gt Plugin tests Use the form on the bottom of the page to upload the test input and start the test Use the tables above the form to keep track of the test and view results after the test is completed Use the download test input up arrow and download test output down arrow actions to download the test input and plug in output files respectively Create a problem Go to Lecturer gt Problems use the add problem thick plus action and create the problem Before a problem can be created its parent lecture has to exist If a problem is supposed to use a plug in for automated correction then the plug in has to be installed as well 72 Upload an attachment Go to Lecturer gt Problems use the add attachment thick plus action and create the attachment Before an attachment can be create
40. WWW lt http www w3 org TR 2008 REC xml 20081126 gt 20 Hypertext Transfer Protocol HTTP 1 1 online 1999 cit 2011 11 29 Hypertext Transfer Protocol HTTP 1 1 Available from WWW lt http www w3 org Protocols rfc2616 rfc2616 html gt 21 Document Object Model DOM online 1995 last updated 2005 cit 2011 11 29 Document Object Model DOM Available from WWW lt http www w3 org DOM gt 22 XHTML 1 0 The Extensible HyperText Markup Language Second Edition online 2000 last updated Aug 2002 cit 2011 11 29 XHTML 1 0 The Extensible HyperText Markup Language Second Edition Available from WWW lt http www w3 org TR xhtml1 gt 23 Introducing JSON online 2006 cit 2011 11 29 Introducing JSON Available from WWW lt http www json org gt 24 PEAR PHP Extension and Application Repository online 2011 cit 2011 11 29 PEAR Manual Available from WWW lt http pear php net manual en gt 88 25 KLENSIN J Simple Mail Transfer Protocol online 2008 cit 2011 11 29 Simple Mail Transfer Protocol Available from WWW lt http tools ietf org html rfe5321 gt 26 Cascading Style Sheets Level 2 Revision 1 CSS 2 1 Specification online 2011 cit 2011 11 29 Cascading Style Sheets Level 2 Revision 1 CSS 2 1 Specification Available from WWW lt http www w3 org TR CSS21 gt 27 Berners Lee T Uniform Resource Locators URL online 19
41. a nice extension but it is not part of the original design Originally ASM was designed to enforce maximum fairness and transparency to the point of being very unforgiving to tutors mistakes when rating Modifications such as adding the permission to change the rating of an already rated solution have been made as the results of live testing 3 3 5 Courses Groups Problems and Assignments From the Core viewpoint a course is a named group of problems owned by a single user A problem consists of a problem description and optionally of plug in configuration which comprises of plug in selection and the arguments required to make it usable for this specific problem if the plug in accepts arguments Unlike CodEx where problems can exist in public domain every problem in AsM belongs to a single course It is possible to view each course as a namespace encapsulating CodEx like environment A group is a named set of assignments bound to a single course and owned by a single user The group can be owned by a different user than its parent course An assignment consists of a problem from the parent course and a deadline A group can be either public or private Public groups are visible to all users with the subscribe public permission and these users can freely subscribe to any of them To subscribe to a private group a user needs to request consent from the group s owner This mechanism allows tutors to make sure that only stud
42. action buttons are displayed at the left side of each row and they are used to add actions which are connected specifically to the entities represented by the table 33 rows e g for editing a user account cancelling a subscription downloading a solution or viewing problems belonging to a specific course Global action buttons are located on the column header row above the row action buttons and they are used for actions not directly connected to any specific entity displayed in the table but rather to the whole group of entities represented by that table e g for adding a new user course problem group Action buttons represent the main method of interacting with AsM UI Collapsibility A table has an option to be collapsed as a whole by clicking the table header while another click expands the table again This feature is useful when there are more tables on a single content page Additionally a table can be flagged as auto collapsing so that it is automatically collapsed KA lt when empty Collapsing an empty table means hiding its column headers and bottom controls which saves space and also significantly decreases page clutter An empty auto collapsed table has empty label appended to the header and it cannot be manually expanded 3 4 3 Form Element A form consists of one or more field sets and a submit button and optionally some additional custom buttons Each field set contains one or more fields Figure 3 5 sho
43. an be unbound again Eventful mix in is a practical implementation of the Observer design pattern described in 12 and allows to wire together model view and controller parts of the AsM UI while avoiding pitfalls of the tight coupling 3 4 13 Error Reporting Error reporting constitutes a small separate part of AsM UI It is divided into four parts error wrapping management display and logging To enforce common error structure a wrapper class is provided and it or its descendants are used to wrap all errors Error wrapper structure does not reflect AsM Core error structure because the UI has very different needs where errors are concerned Every error in UI consists of error message severity time stamp a reported flag and optionally a list of additional details providing implicit extensibility Specialized error wrapper descendants are provided for most commonly encountered errors namely connection errors and Core errors The Core errors are transformed by having their cause effect and details squeezed into a single string with unified formatting and their severity mapped onto a less granular UI error severity scale Regardless of their real source errors in AsM UI take the form of error events originating in a UI component Error event triggering mechanism is common to all components it is implemented in their common ancestor and it includes wrapping of those errors that are not wrapped already Because UI components create
44. and their deadlines to allow students to post their solutions and to let the teachers retrieve them and post the grades To meet the expectations outlined in the first chapter we need to expand the scenario described above by a few important elements The most important of them is making the software capable of semi automated correction of students solutions This makes the software a discernible entity instead of a mere transparent interface between the teacher and the students However it should still be possible to use the software as a simple manager Adding the automated correction means splitting the grading process into two parts further called correction and rating where the former is performed by the software and the latter by the teacher Other important expansion follows the usual structure of a college course In large college courses students are divided into smaller groups for exercise or experimental sessions which can only accommodate limited amount of people at a time These exercise groups have their assigned tutors who supervise the exercise sessions assign homework to students and rate their solutions In this case homework assignment needs to be split into two separate parts problem creation and problem assignment Thus all students attending the same course can be assigned the same problems but the deadlines can be specific for each exercise group to fit its schedule and pace Lastly a typical coll
45. as developed during the years 2009 2011 The development time was longer than expected both due to misjudging the complexity of the project and the time constraints of the author It was deployed live in the spring of 2011 and tested on the XML Technologies course at MFF UK This chapter broadly describes ASM implementation and discusses the choices made For more implementation details please see the developer documentation on the attached CD or see 2 3 1 Used Technologies A web based application is the obvious choice for this project with no real drawbacks and a lot of benefits the foremost among them being portability Particular technologies chosen for this project include PHP for the server side and dynamic HTML XHTML and JavaScript with jQuery framework for the client side which is a common choice for web applications This selection of technologies offers the least restrictions and makes use of author s previous experience Selecting PHP for the application s server side imposes a restriction upon it and that is the passive application logic PHP in its most common form is designed just to respond to client requests PHP scripts are invoked upon receiving a client request and return a result upon completion There are different possibilities as well but this one is prevalent This model suits the proposed scenario because AMS is just supposed to help the actors perform their tasks easily All actions performed b
46. ate a new group lt Manage group own Modify or remove owned group and create modify or remove assignments bound to it lt Manage group any Modify or remove any group and create modify or remove assignments bound to it Create course Create a new course lt lt Manage course own Modify or remove owned course and create modify or remove problems attachments questions and templates bound to it lt Manage course any Modify or remove any course and create modify or remove problems attachments questions and templates bound to it lt Rate solution Rate a solution uploaded by a student in one of the owned groups lt View author See real names of solution authors while rating the solutions lt Modify rating Modify rating of an already rated solution View log Retrieve the system log contents As it is apparent from above descriptions there are actions that require more than just a specific permission Few of them require ownership of the action s object as 16 well In most cases there are stronger override permissions allowing to bypass the ownership requirement but there are a few cases where that is not possible e g the rating of solutions Object ownership is established at the time of its creation and cannot be changed later An option to pass object ownership from the original creator to another user as seen in CodEx could be
47. ater than starting ending with or containing a specific value all of these can be inverted as well Filters of the start end with or contain type cannot be used on columns flagged for numeric sorting Multiple filters can be applied at once for more complex filtering Filter controls are at the bottom of the table as well next to and below the pagination controls By default only the Filter overview button is displayed showing the numbers of currently enabled filters and all created filters as well as a button for removing all filters at once Clicking the Filter overview button toggles visibility of the whole filter control pane underneath containing array of filters and a simple tool for the creation of additional filters Individual filters consist of a button showing the filtering rule and an adjoined button for removing the filter It is possible to disable a filter temporarily by clicking its button and then enable it again by another click The filtering not only is convenient for users in certain cases e g for an administrator trying to find only users of a certain type but it is also used by the application itself as e g linking to problems belonging to a certain course right from the table of courses Action buttons Adding action buttons transforms a table from a static display element to a highly useful interactive element Action buttons fall into two categories row action buttons and global action buttons Row
48. ation parts and the interactions between them 3 2 System Breakdown and Interaction In the AsM implementation a lot of emphasis is placed on extensibility i e creating a modular and robust code which is a concept not directly related to its goals Simplicity vs extensibility is a choice to be made on every level of application structure In this case maximum extensibility had been chosen wherever possible even on the top level of the application This choice was based on the assumption that extensibility always saves time in the long run Unfortunately that assumption caused by the lack of author s previous experience with projects of comparable scope proved false The excessive focus on extensibility increased application s complexity dramatically For further discussion of this problem see Section 5 2 The AsM application is divided into three separate parts The following list provides just a brief overview of the parts and their interaction The rest of this chapter provides more detail Core Core is an alias for the application s server side It is written exclusively in PHP and it uses MySQL database for data storage It is open for communication with the client side using HTTP requests with specifically formatted contents This type of communication is initiated exclusively by the client side Other venue of communication is the communication between the Core and the checker plug ins when the Core launches the plug ins a
49. backward or moving directly to the first or to the last page Page size can be changed at the bottom of the table as well Sort rows by column Clicking a column header will sort the table by the values in that column in ascending order Clicking the same header again reverses the order The latest sorting is indicated by a little triangle icon shown inside the column header pointed upwards or downwards to indicate ascending or descending sorting Filter rows A table can be filtered to show only the rows satisfying certain conditions A filtering condition restricts values in a certain column by 65 comparing them to a specified value Possible restrictions are equal to greater than gt less than lt starting with ending with and containing where the last three cannot be used with numeric columns All of the restrictions can be inverted Filtering is accomplished by creating a filter for each condition A filter is created as active and it is immediately applied but it can be deactivated again without being destroyed Filtering controls are located at the bottom of the table Only two buttons are visible by default Filter overview and Remove all filters The first button shows the current number of active filters and the current number of all filters respectively Clicking on it shows or hides the rest of the controls i e a list of filters and a filter creation tool A filter is created
50. button Fields Field labels Figure 4 5 Form Value hints When entering a form most of the fields have hints displayed next to them Hints provide the information needed to fill in the correct values Instant validation After a form field is edited and abandoned the user moves to the next field its value is checked immediately and a feedback is provided in one of the two possible forms If the field is correctly filled in a check mark is displayed next to it If the value is incorrect the whole field is highlighted as an error and a validation hint is displayed in place of the value hint describing how to correct the current value Smart submit button Form submit button is disabled as long as the value of any field is invalid Therefore the user cannot submit incorrect data by mistake The described enhancements empower users to fill in the appropriate data quickly and correctly before submitting a form 4 5 Error Reporting Any errors that occur during the application run are displayed either in error panels or in error dialog windows depending on their importance and the current layout While in the pre login layout see Section 4 3 all errors are displayed in dialog windows regardless of their importance In the main layout only the fatal errors are displayed in dialog windows see Figure 4 6 non fatal errors are displayed in panels see Figure 4 7 Both styles of error reporting also include highlightin
51. ch can be opened and edited in any text editor It is an INI file with sections as described in 17 Only the property values should be edited while property names and section names should never be changed Neither the properties nor the sections should be moved or added Values should be enclosed in quotes and any quotes inside the values should be escaped with backslash The description of the individual sections and properties follows database MySQL server properties host server address user username pass password 61 lt KA lt lt lt db database name mail SMTP server configuration host SMTP server address user username leave blank for no authentication pass password optional from value of the From e mail header Some SMTP servers require this to be at least syntactically valid e mail address to accept outgoing e mails bin paths to used external programs phpCli path to PHP interpreter for running PHP scripts from command line java path to the Java interpreter for running Java plug ins defaults submissionFileName default name suggested when downloading a submitted solution file pluginTestFileName default name suggested when downloading a test input file for a plug in pluginOutputFileName default name suggested when downloading a plug in output file roots web absolute path of the web server document root with trailing s
52. ckup all error data on the server for later perusal Using a database for this purpose would be unwise because errors can easily occur during the communication with the database In contrast to writing into a database writing directly to a file is very simple and therefore much easier to keep error free For this reason AsM logs all errors directly into log files Additionally should AsM ever break down completely having errors logged in simple text files makes it easy for the system administrator to look them over without AsM s assistance Logging in AsM is managed by a stand alone logging class independent on the rest of the application Its functionality is based on the fact that all errors occur in certain context and that multiple errors may have the same context In AsM s case every error s context consists of a Core request IP address issuing the request etc Therefore AsM logger enables logging of entries each one consisting of a header context and variable number of lines events Entry header always contains a time stamp and it can optionally contain any other data as well Each entry line may contain any number of data items When using the logger this abstract structure has to be concretized by supplying strings for separating individual log entities The separators are stripped from all consequently logged items to avoid corrupting the log Care should be taken to select separators that make the log files human readable an
53. d its parent lecture has to exist Create a question Go to Lecturer gt Questions use the add question thick plus action and create the question Before a question can be created its parent lecture has to exist If a question is supposed to use attachments the attachments have to be already uploaded as well Create a test template Go to Lecturer gt Questions Use the table filtering and row selection to select the optional and mandatory questions respectively Then fill in the test description and number of questions in the form below the table and submit the form Submitting the form switches to the page with test templates Note that the test description is used as a heading when printing the generated tests Generate a test Go to Lecturer gt Tests Use the re generate test refresh action to generate a new test from a particular template Note that the first test is generated automatically when a template is created Print a test Go to Lecturer gt Tests and use the print test print action to print the test View problems questions attachments templates belonging to a certain lecture Go to Lecturer gt Lectures and use the show problems questions attachments tests for this lecture paper dialog contact paper 2 actions to view the tables of problems questions attachments templates filtered to show only the appropriate entities respectively Edit lecture description Go to Lecturer gt Lectures use the edit lecture
54. d ready for installation as well as the source files It also contains six plug ins for automated correction of homework problems belonging to the XML Technologies course at MFF UK Additionally it contains the AsM project documentation generated by Doxygen including the User Manual The included documentation has been generated from the current version of source files AsM 0 6 2 but the User Manual section covers only the features included in the version deployed on MFF UK AsM 0 5 5 See the following sections of this thesis for descriptions of the automated test generation feature added in AsM 0 6 Section 3 3 7 Section 3 4 4 and Section 4 6 4 Finally the CD contains the digital version of this thesis The descriptions of the most important files and folders follow asm 6 2 zip the full AsM application ready for installation asm 6 2 lite zip the AsM application without the documentation ready for installation docs index html the index file of the AsM project documentation open in a web browser to access the full documentation plugins correction plugins for the homework assigned at the XML Technologies course each ZIP archive is a valid plug in accepted by the AsM application src AsM source files src core AsM Core source files src docs the source files of the documentation framework and the special documentation pages the User Manual etc src install AsM Installer source files src web AsM UI source files the
55. d so that the Installer could automatically apply the necessary changes in the correct order The upgrade is irreversible because making it reversible would require substantial amount of programming unrelated to the main AsM functionality 56 3 7 Documentation Any source code that should be easily modifiable extensible needs to be documented For a project as large as AsM the code documentation is not sufficient more accessible documentation has to be available as well A common way to provide such documentation is to automatically generate the developer documentation from a specifically formatted code documentation However every programming language is different therefore many of them have their own formatting rules and documentation tools This section describes the tools used by the AsM project to generate common developer documentation for the whole project AsM project is composed of parts written in different programming languages mostly in PHP and JavaScript PHP has a formal code documentation standard PHPDoc which is described in 14 It not only allows to generate a separate documentation using external tools such as phpDocumentor but it also lets IDEs provide various convenient features e g code completion JavaScript being a very different programming language altogether has no such standard While it would be possible to generate separate documentation for each part of the AsM project the Core and the UI being
56. d that are not needed inside the logged entries The log files themselves do not contain information about their structure so it is possible to read a log file using two differently configured loggers To avoid swamping the file system with overly large logs log files have configurable maximum size and they are automatically rotated This means that a single log consists of a whole sequence of files When an entry would make a log file exceed its size limit it is logged to the next file in the sequence instead Maximum number of files in the sequence is customizable Then when the number of log files in the sequence reaches a given limit the oldest file is always deleted before a new one is created Log rotation is a mechanism commonly implemented on Unix operating systems However using this implementation would mean a substantial restriction for ASM deployment so the log rotation is implemented as part of the AsM logger instead 3 3 11 Plug in Launching Launching of plug ins is AsM s only deviation from the conventional model of passive PHP application The automated correction can be time consuming 23 therefore the handler of a Core request that leads to plug in launch cannot wait for the plug in to finish before returning request results Consequently plug ins need to be able to run outside the passive model of Core request handling Additionally when a plug in stops running AsM database needs to be updated with the correction
57. d to add the component modules directly to the web server 15 Simple Mail Transfer Protocol SMTP is a standard defining e mail communication over IP networks e g the Internet see 25 PHP Command Line Interface CLI is an interface of PHP usable from command line as opposed to the PHP CGI used for web server scripting 26 3 3 15 Database The Core uses a database to store all data apart from the configuration and from error logs The access to the database is managed by a special database framework which is implemented as a part of AsM The framework provides the following abstraction layers over the used database implementation the database request layer the abstract query layer and the database adapter layer 3 3 15 1 Database Request Layer The database request layer is the only layer accessible to the rest of the Core It provides a set of database requests i e addProblem cofirmSubscriptionBylId or getGroupsVisibleByUserId Each of them has a name and a specific set of required arguments The layer s purpose is to restrict the access to the database to a set of predefined actions and thus ensure the consistency of contained data with the application data model Ensuring database consistency is much easier when the Core uses abstract requests based on application logic instead of accessing the database directly In the former case the mistakes are much more easily spotted On the other hand transforming raw database r
58. e a lecture to be able to create problems or to generate tests for that lecture Problems as well as plug ins needed by them can be added at any time before they are to be assigned to the students For test generation a lecturer has to create the test questions and optionally upload attachments to be used by some of them Only then can he create a test template and generate and print tests based on that template There are no repeated tasks that would require handling by lecturers 75 4 7 4 Administrator An administrator has to create user accounts for lecturers and tutors or just edit their user accounts if they registered themselves He may periodically check the dashboard for a notification about new system errors and view their details in the system log if necessary 76 5 Assignment Manager in the Wild Based on very broad specifications the implementation of Assignment Manager took more than 1 5 years Then it was released and tested for one semester on a single course XML Technologies at MFF UK During the development quite a few assumptions were made which seemed perfectly obvious at the time from the theoretical point of view This chapter focuses on the differences between those assumptions and the reality and on other information gathered during the live testing 5 1 Design for Reality AsM development was heavily impacted by the fact that the main purpose of the AsM project was to act as a school project and a basis f
59. e in conflict with the purpose of automatic expiration ASM UI uses a third approach it keeps automatically refreshing the session as long as it is actively used This basically means extending the refresh session on every successful action principle present in the Core to the UI as well A UI action is either a mouse movement or a keyboard key press while the application is focused Access restrictions in the UI have to reflect the possibility of having user types with various combinations of user permissions based on the deployment context Retaining such modularity makes it impossible to hand craft the UI layout and content specifically for every possible user role which is otherwise a feasible option for systems with just a few distinct user roles Also it is necessary to disable interaction with UI parts connected with unavailable tasks namely to disable navigation items leading to inaccessible pages or to hide these parts entirely Both approaches have their benefits Disabling keeps users informed about the full application functionality even if they cannot access some of it at the time while hiding reduces the clutter Because the AsM user base will always consist mostly of students i e users with very few permissions hiding is the obvious choice in this case Hiding permeates both levels of navigation the navigation group header is hidden if all of the items in that group are hidden 3 4 9 Navigation and Browser History Navigation
60. ebarch fragid gt 87 12 Object Oriented Design online cit 2011 11 20 Observer pattern Available from WWW lt http www oodesign com observer pattern html gt 13 ASM Plugin Framework Project online 2010 cit 2011 11 20 ASM Plugin Framework Project Available from WWW lt http hon2a wz cz asm docs java gt 14 phpDocumentor Manual online 2000 cit 2011 11 20 phpDocumentor Tutorial Available from WWW lt http manual phpdoc org HTMLframesConverter default gt 15 Doxygen online 1997 last updated Aug 2011 cit 2011 11 20 Documenting the code Available from WWW lt http www stack nl dimitri doxygen gt 16 Apache HTTP Server version 2 2 online 2011 cit 2011 11 20 Apache Core Features Available from WWW lt http httpd apache org docs current mod core html gt 17 Cloanto Implementation of INI File Format online 2009 last updated Jun 2010 cit 2011 11 20 Cloanto Implementation of INI File Format Available from WWW lt http www cloanto com specs ini gt 18 MLYNKOVA Irena Technologie XML PRGO36 cvi en LS 2011 online 2011 cit 2011 11 20 Technologie XML PRGO36 cvi en LS 2011 Available from WWW lt http www ksi mff cuni cz mlynkova prgo36 indexCV htmlI gt 19 Extensible Markup Language XML 1 0 Fifth Edition online 2008 cit 2011 11 29 Extensible Markup Language XML 1 0 Fifth Edition Available from
61. ected by the user and it could already be uploaded by the time the user sends the rest of the data along resulting in shorter waiting times The mechanism for pre uploading files had been implemented as a part of the AsM Core but it was abandoned after testing because the benefits were not substantial enough to warrant the increased complexity of the system Furthermore there are just a few requests making use of file upload and the single one that is used frequently solution upload does not accompany the file with any additional data The handling of uploaded files depends on their purpose Uploaded attachment files are stored with unique names based on the id of the lecture they belong to and their assigned name Solutions input data for plug in testing and plug in output data are stored as ZIP archives with unique names based on the date and time of the upload creation and other context variables Solutions are passed to plug ins still as ZIP archives and the plug ins themselves are responsible for their temporary unpacking Plugin files are unpacked right after their upload and they are stored unpacked to be ready for repeated execution Downloading a file stored by the AsM Core is not only a simple matter of knowing the file s location and requesting it from the server In such model enforcing restrictions based on the ownership and user permissions would be very difficult not to mention that the file storage folder structure and fi
62. ed on users permissions lt User management Creation modification and removal of user accounts and user types lt Plugin management Receiving uploads testing and removing the plug ins lt Course management Creation modification and removal of courses and their associated problems attachments questions and templates lt Group management Creation modification and removal of student groups Assignment of problems to students in those groups and rating of students solutions lt Solution hand in Receiving solution uploads and correction of solutions using plug ins Removal of solutions or their confirmation for rating 3 3 2 User Session Before performing any other tasks the Core requires the user to be authenticated The only exception to this rule are the tasks that assist the user with getting authenticated After the user successfully logs in using active user account credentials a user session is started which allows the user to perform required tasks while being restricted by the permissions associated with his account The user session makes use of PHP session to store data Particular behaviour of the PHP session depends on the web server configuration The session remains active only for a certain period of time but can be refreshed which resets the timer The session is refreshed by any successful core request that requires authentication but it can also be refr
63. ed to concern themselves with the output formatting at all Plug ins of other types need to return a XML string with one of the following structures depending on the nature of the response If a plug in finishes successfully it needs to use the following response structure lt xml version 1 0 standalone yes gt lt plug in reply gt lt output gt lt file gt OUTPUT_FILE_PATH lt file gt lt output gt lt criterion name CRITERION_NAME gt lt passed gt PASSED lt passed gt lt fulfillment gt FULFILLMENT lt fulfillment gt lt details gt DETAILS lt details gt lt criterion gt lt more criteria gt lt plug in reply gt where the lt output gt tag is optional CRITERION_NAME is unique in context of the response PASSED is either true or false FULFILLMENT is a number from o to 100 and DETAILS is a string of arbitrary length If a plug in finishes with an error it needs to use a simpler response structure lt xml version 1 0 standalone yes gt lt plug in reply gt lt error gt ERROR lt error gt lt plug in reply gt where ERROR is a string containing the detailed error message 53 3 5 4 PHP Plugin Framework PHP Plugin Framework is a set of PHP classes distributed together with the AsM Core which provides a solid base for the development of AsM plug ins in PHP The benefits provided by it can be divided into three parts the implementation of the common plug in logic a test model ai
64. edirection module of the Apache server to present itself in place of the AsM UI as long as the initial configuration is not successfully finished and every time when the administrator attempts to upgrade AsM The same redirection module is used to hide the Installer after it has finished and to provide access to the UI and Core instead It is not possible to switch between the AsM UI and the Installer on demand This section briefly describes the implementation of the install and upgrade procedures in AsM The implementation of the Installer itself is trivial it is only a set of web pages using PHP as the server side scripting language therefore it is not explored further 2 A wizard in this context means a sequence of steps pages forms shown one at a time to help the user complete a certain complicated task 55 3 6 1 Install The AsM install procedure is not as sophisticated as the procedures employed by many other contemporary software products because its enhancements are not cost effective i e they do not impact main application functionality The installation of AsM on a web server consists of copying the folder with the source files into an accessible location slightly altering the web server configuration if necessary and installing a set of PHP library modules see Section 4 2 for details The implemented Installer is not a real installer concerned with the procedure described above It is just a tool designed to
65. eee t esc shate nS 80 5 4 Dependencies and Maintenance csssccsssccesseccesssecesssssnncceeccsssesseneees 80 5 5 Proposed Enhancements sicicsssacsccorcescsnasseenssoennssdentevgncsaasaneersonssevsseasaeovecdensers 81 CONCLUSION 1 05 2e655553cescsccccecsclessececeestevs aeree oE EEE O Eoi ses aeie 85 Bibliography csere ca caleeain este wince a oss co onus woes aoa das ps os pea aaa 87 List Of Abbreviations s ccesesscccecccceccscoscvencsecceecsoevseucvowevadsvestecdsesuecesesesses 91 LAST OF Figures cocccsscvecensapescencavewcsswsvevsgicurncayensenctvsnaeuns uname tearestewsssucetneds 93 Attachments s c2cccscssiscetecsssoscesSsscecsoseccsesencecocsne cassetn S o assaia 95 As Tist Of PUGS erenn e E E E N 95 Introduction The need for homework assignments is a thing that almost all college lectures have in common For teachers and their assistants the management of homework submission and correction is a waste of precious time which could be better used on research Nowadays basic management of homework assignment usually entails setting up a web page containing descriptions of assigned problems and their deadlines as well as tables with students results Teachers with little or no background in IT may find it daunting therefore they might greatly benefit from a solution suited specifically to this task Also correction of students homework takes more time with ever increasing number of students which could be often remedied by part
66. ege course contains multiple homework assignments of unequal importance Therefore the homework assignment scenario should support separate weighted ratings of individual assignments which could be combined into a single comprehensive rating of the whole coursework While extending the scenario the following considerations should be taken into account Firstly the project presented here is to be the work of a single developer over a limited period of time so the scope of the project needs to be reasonably limited Additionally it is the author s opinion that any software should not only help users accomplish their tasks but also promote good practices In the context of homework correction and grading these are namely transparency and fairness 1 1 Extended Homework Assignment Scenario Before we continue with the description of the extended homework assignment scenario we need to define some terms All terms defined below are commonly used words with broad meaning e g course group problem For the purpose of this work their meaning is constrained They are sorted in logical not alphabetical order 1 1 1 Basic Terminology KA lt Assignment manager software AMS AMS stands for the focus of this work an application facilitating simple management of homework assignments and semi automated correction of solutions It is used to refer to such software in general rather than to the particular implementation described in t
67. eld with its label visually enhances it and adds mechanisms for value hinting and validation Other extensions include an option to make the field read only and an option to use an alternate fancy display mode for some field types e g a check box can be displayed as a button switch Fields are grouped together using the Fieldset and Form widgets Icon Icon widget turns an element into an icon and extends it with an icon type property specifying which icon it is Stateful The Stateful widget extends an element to support mouse clicking The element can be enhanced visually based on its state and handlers can be assigned to its activation and deactivation events It can also be assigned a group of other stateful elements together with a group behaviour style e g single which means that only one element of the group can be active at a time Table The Table widget greatly extends a basic table both visually and by adding sorting filtering and pagination capabilities as well as an option to add action buttons to its rows and to the table as a whole A part of the action button specifications is a handler function which is launched when the button is clicked and which is supplied with the respective row data Table widget is an extension of a static table Sorting filtering and pagination make use of showing only certain rows and hiding the rest so they are as fast as possible However it means that all rows have to be initialized w
68. enance tasks required from the AsM administrator 5 5 Proposed Enhancements The previous sections discuss some of the possible general enhancements for the AsM This section completes the chapter with an outline of a few potential specific enhancements features that could also benefit AsM in its present state while being smaller in scope Some of the following enhancements were proposed by the ASM users during the live deployment Add submission date to the list of corrected solutions Currently the corrected solutions can be distinguished only by their success ratio and correction results This requires that users actively keep the number of corrected solutions manageable by deleting the unsatisfactory ones Adding the date of submission would allow easy identification of solutions even when there is a lot of them Allow user based column hiding in tables This is an extension of the previous enhancement Instead of always providing users just with the data that the author considered the most useful ASM Core could provide all data relevant to the query and the UI could let the users choose themselves which data to display and which to hide The current selection would remain as the default 81 lt lt lt lt lt lt lt lt Allow adding notes when rating a solution The fact that rating of a solution is restricted to the number of awarded points is an oversight in ASM design
69. ential 3 Check your mailbox corresponding to the e mail address you entered When you receive the activation e mail continue by activating the user account Activate a user account 1 Instead of logging in click on Activate button on the login screen 2 Enter the activation code received in the activation e mail see above and submit the form 3 Registered user account is now active and it can be used to log in Log out Click the Logout button in the top right corner of the screen If there is no Logout button there you are not logged in Change the properties of your user account full name e mail address or password Go to Settings gt Account settings make the required changes and submit the form The password is changed only if a new password is entered 69 Change the appearance of the application Go to Settings gt User interface and select one of the available application themes The theme is changed instantly without a need to submit the form However this preference is bound to the currently used web browser on the currently used computer not to the user account so it will persist if accessing AsM from a different browser or computer View errors that occured during the current session Go to System gt UI error log and peruse the Error log table Find the AsM project documentation If not logged in click the link in the upper right corner of the screen Otherwise click the application name on
70. ents belonging to their homework group in reality are subscribed to it in AsM thus keeping the groups well arranged Students subscribed to a group can access the problems assigned to that group and submit their solutions The entities described above cannot outlive the entity they belong to Therefore a great care needs to be taken when removing objects like courses groups problems and assignments or when cancelling subscriptions Removing an assignment removes all respective solutions Removing a group removes all assignments in that group while removing a problem removes all assignments based on that problem Removing a course removes all problems and groups belonging to that course effectively removing any trace of it from the system Removing a user causes his groups to become owner less and thus practically unusable This mechanism was chosen for its simplicity and heavily relies on the responsibility of more empowered 17 users Associated risks may be lowered by not giving users permissions to remove higher level objects or by adding safeguards to the user interface Relations between the objects described above are shown in Figure 3 1 belongs to belongs to relationship is transitive 1 1 belongsto 0 belongs to Assignment Subscription must be permitted by the group s owner if the group is private is subscribed to 0 D The user can submit solutions to problems assigned to the
71. equests into the abstract logical requests without adding unnecessary restrictions to the Core requires a lot of additional code Another function of the database request layer is to provide high level validation of database query data so that any error messages refer to data in application terms instead of revealing details about the internal database structure At this level the data that are potentially harmful to the database are rejected or erased so the lower layers may expect all input passed to them to be clean and sensible To fully function as a buffer between the database and the rest of the Core the database request layer needs to perform one additional role to translate the internal database representation of stored data into the application data model This is accomplished by translating property names of application entities i e user problem group into field names of database entries This approach allows to use the same name for a certain property of a certain entity regardless of the possible differences in its naming on lower levels Again this feature makes the rest of the Core code cleaner and easier to maintain but it requires additional code 3 3 15 2 Abstract Query Layer The abstract query layer basically makes it possible to avoid using a particular database query language altogether by providing an object oriented query framework It uses an extensive hierarchy of abstract expressions to cover basic database que
72. eshed manually by a special request The main reason for automatic expiration of the session is security Leaving the session open forever would increase the risk of session hijacking if the user left an open session on a public computer For increased security users can also terminate session manually by logging out The inherent part of user session data are user s permissions which are loaded from a database on the session start They are used to determine which of the requested tasks are permitted to the user See Section 3 3 4 for more detail The PHP session is bound to the web browser so multiple user sessions can be opened from the same computer only by using multiple browsers In that case each session is completely separated from the others There is no limit on the number of concurrently open user sessions apart from the limits of the PHP server itself 14 3 3 38 User Account Before a user can log in i e start a user session he first needs to own an active user account User account consists of login information username and password associated user type see the next subsection and other miscellaneous data User account can be created in two ways each suited to a different situation One way is very simple a user with appropriate permissions can directly create a new active user account of any kind This is useful for creating user accounts for lecturers and tutors as they need specific permissions However creati
73. essary for requests concerned with actions rather than data retrieval Those actions are preformed directly by the controller Controller and view parts of ASM UI are reasonably well decoupled even though the decoupling was not done with the MVC pattern in mind Their separation is clear even in the source code because each of them is written using a very different approach View code is completely separated from the rest of ASM UI code base because it consists of external library jQuery UI and an extension of it through its widget factory see the Widgets section for details Controller on the other hand uses classical hierarchy enabled by Base js library the same as the model For details on controller implementation see Section 3 4 10 Wiring of the three parts together is facilitated by events which are further discussed in the Events section 3 4 7 Widgets AsM UI implementation uses a combination of two different approaches Most of it is implemented using purely a classical hierarchy model and uses jQuery which does not follow such model at all just as a DOM access layer and a communication layer In a similar fashion jQuery UI is used as an extension to DOM element functionality However part of AsM UI code falls into another category which directly extends jQuery UI using its widget factory Widgets created this way are not regular stand alone classes but rather direct functional and visual extensions for
74. esssscecceesssceceesssseeecsseeesseeeees 18 3 3 7 Attachments Questions Templates and Tests ccsssscccccceessseeees 19 3 3 8 Core Request Handling s ssssssssesssssessseesseseesssesersseessessessssessseresssseeeseeee 21 SO ETTOLS crite ana E O A a E E A ean aan 22 3 3 104 Error Logging snsnersein noii e e eV este e imine 23 3 3 11 Pl g in Launching o enea raa r ies sections A eE EEEE EE eek aes 23 2312 Pile Management insanos r R R oaee eee 24 3o i9 Sende MAIS setia A R ns 25 3 3 14 Configuration sesssssesssessseesseesseessssessseosseessseessressereeeeesserreeessssssseeessss 26 9 Database Naenae e a a a AT 27 3 3 15 1 Database Request Layer csscccsssscsssecssssccsssecesssecceeeessesensees 27 3 3 15 2 Abstract Query Layer acicssccoseesevqaesanak cass cararteadevedeoced Sree troesea eres 27 3 3 15 3 Database Adapter Layer vac ccadsced csaeckachsaaccnsachenestnanescaatensteteces 28 SPAR A Data Struct e ei aeee aie inea wdes codes cs noes wesedestands SE AEE aN E aS 29 9 39 16 Reqg irementS ennonn dica eniai S E E Ghee oi 29 zA User Interface eieae ei aeae a Ea aas Ee Aaa ER E EaR 30 3 4 1 Presentation Elements cccccssccccssssececeessececeecssaececssssececeessaeaaeeeees 31 JA able Element Speenreseeie snien ea EEEE EENE EEEE 32 e E e Horii lE NE ah E AAE E E A ian seansenascaatuaains 34 SAA Layoutand Contento uns ee ee mE wees 36 BiASG Visual CSI STi ias n na aaa arcane ase a a RR a RS 40
75. etBeans Microsoft Visual Studio or Eclipse 57 script for turning both the classical JavaScript code and widget factory code see Section 3 4 for details to a pseudo C code understood by Doxygen Formatting accepted by this pre processing script is identical to the PHP code documentation formatting except for a few details e g tparam is used for adding types to the method arguments instead of param Having a common documentation for the whole project could quickly make it incomprehensible with the increasing project size To prevent this a combination of two mechanisms is used On the top level the documentation is separated into modules Doxygen constructs Each module has its own documentation page explaining its purpose and basic functionality Entities such as namespaces or classes can be linked to modules The second mechanism is a coordinated use of namespaces across the whole project A common namespace asm is used for the whole project except for widgets and the second namespace level is used to distinguish parts of the project and link them to modules By virtue of Doxygen s extensive set of features the main page with project description is a part of the documentation as well as the whole User manual This makes it possible to publish all project documentation together and to maintain it very easily 58 4 How to Use he Assignment Manager Assignment Manager UI is focused on establishing high standard of usabil
76. ey have been clicked in case of button like elements or as long as they are active in case of tabs accordion headers and other switch like elements Highlight Used to highlight focused input elements in forms and warning messages Error Used to highlight form fields with invalid values and error messages AsM UI uses the jQuery UI theme framework as the base for visual theme definition apart from base layout constraints This keeps the UI looking fresh while behaving consistently and therefore predictably As a bonus jQuery UI web page contains both a large selection of already completed themes and a tool for easy creation of new ones All of the completed themes are included in AsM UI and the user can switch between them on the UI Settings page 3 4 6 Model view controller Pattern AsM UI implementation is loosely based on the model view controller MVC design pattern described in 10 It is not a matter of conscious choice because at the time 41 of AsM implementation the author was not familiar with MVC pattern yet nonetheless it emerged in the code due to an ever present effort to reduce the complexity and to keep the code modular and extensible A part of AsM UI acting as the model or back end is in fact just a layer providing direct access to data retrieved from server and masking the retrieval process see Section 3 4 11 for more details It does not have exclusive access to the server because it is not nec
77. for the dynamic content The right side of the top bar allows the user to log out leading him back to the login screen in the pre login layout Logo amp application name User s real name Logout button Assignment Manager 0 5 2 Jan Konopasek v Student Hello Jan Konop sek welcome to Assignment Manager z Your last previous login was 2010 11 29 13 57 34 Assignments Submissions Current group ratings A Subscriptions gt System Assignment Manager is a modular management system for homework assignment submission and semi or fully automatic correction See the Z project documentation for more details gt Settings 2009 2010 Jan Konopasek Content area Figure 4 2 Main application layout The left menu consists of navigation links divided into groups A menu group is expanded by clicking its header Only one group can be expanded at a time Other groups are collapsed showing only their headers Menu groups reflect the user roles see Section 4 1 so that each one contains the pages useful for a particular user role 63 There are two exceptions to this rule The first exception is the UI error log page in the System group which is accessible by all users regardless of their role The second exception is the last group Settings which also contains pages useful for all users See Figure 4 3 for an overview v Student Selected header Assignments Submissions A Subscriptions gt Sy
78. g of errors and adding icons to errors reflecting their importance 67 Error Runtime error Cannot connect to MySQL database ed mirt matah tha narr Figure 4 6 Error dialog Message Pin unpin Hide error Hello system root welcome to Assignment Manager Your last previous login was 2010 11 29 17 12 00 a Iser type hasn t been modified cannot change user type of root user _ a eS Root user cannot be deleted Notice Warning Error Figure 4 7 Error panels Dialog windows are displayed in the center of the screen They are modal preventing the access to the rest of the UI until they are closed Error panels are shown in the content area of the main layout above all other content They are set to fade away fifteen seconds after they appear which can be either prevented by pinning the error to the screen or hastened by closing the error manually Pinning the error to the screen does not suspend the timer so if the error is unpinned again it is usually hidden immediately A log of all the errors that appeared during a single user session can be accessed at any time to help with troubleshooting see below 4 6 Howto This section describes how to perform all basic tasks available in AsM UI All tasks require the user to be logged in first if not specifically told otherwise After logging in the user usually needs to find the appropriate content page using the menu or the top header
79. ge allows viewing of the Core error log in a table While this is not the best way to view long log entries it is very convenient for sorting and filtering of entries which is often used while trying to fix a particular error 39 UI error log page is a table with errors that occurred during the currently open user session Unlike system log this page is accessible for all users and it exists solely for the purpose of remote troubleshooting Not only does it contain error messages received from the AsM Core but it also contains UI errors and notices which do not appear in the system log at all Data contained in the user log are available only while the user session is open because the user log is cleared upon logout UI error log page is one of the two pages that exist independently on Core tasks KA lt Users page is an editor for the management of user accounts lt User types page is an editor for the management of user types lt User account settings page lets users change properties of their own user account i e their full name e mail address and password using a simple form lt UI settings page is the second page with no connection to the Core It allows changing of UI properties Unfortunately the personalisation of the UI is very low on AsM project priority list therefore the page currently allows only the visual theme selection 3 4 5 Visual Design The goal of the AsM UI visual design is
80. he proposed scenario Two of the predefined user types are special The first of them is the ADMIN type which has all permissions and cannot be modified or removed AsM contains a single non removable user of this type to ensure that there is always a user capable of managing it The second is the STUDENT type mentioned above which cannot be removed either It serves as the default user type Follows the list of all user permissions Create user Create a new active user account 15 lt Modify user Modify any user account lt Remove user Remove any user account lt Browse users Retrieve user account data of all users except passwords lt Manage user types Create modify remove or view any user type lt Create plug in Upload new plug in and add it to the application lt Modify plug in Modify data of any plug in lt Browse plug ins Retrieve data of all plug ins lt Remove plug in Remove plug in from the application lt Test plug in Test run any plug in with custom arguments and input lt Submit solution Upload solution to assigned problem lt Subscribe public Subscribe to a public group lt Subscribe private Subscribe to a private group without requesting consent from the group s owner lt Request private Request owner s consent to subscribe to his private group lt Create group Cre
81. he rest of this work lt Course lecture Course stands for a single college course as well as a set of problems related to the course topic lt Group Group stands for a group of students belonging to certain course created for the purpose of exercise sessions and homework assignments lt Problem Problem stands for the description of a homework problem KA lt Assignment Assignment stands for a problem bundled with its deadline as well as for the act of passing such a bundle to all students in a single homework group lt Solution Solution is a set of data created to solve certain problem lt Submission Submission stands for a solution successfully uploaded to the server plus all the data bound to it during its life cycle inside the application e g the results of automated correction or rating lt Correction Correction stands for the automated correction performed by AMS during which the solution is checked for adherence to some or all problem specifications Checker plug in Checker plug in or just plugin in is a separate executable or script added to the AMS to extend it with a capability of automated correction of solutions of certain problems Rating Rating noun stands for the points received by a student for a specific solution Rating verb is the act of assigning a rating to that solution The remaining special terms are defined in the following section 1
82. he user a general idea what might be the cause of the problem The user should be able to differentiate between errors caused by his incorrect use of the application and other errors 2 To inform the user about the immediate effects of the error related to the action he was trying to perform 3 To provide a detailed error description helpful for the person trying to fix the problem Additionally using code numbers for known causes serves two different purposes First not to confuse users with different error messages in different instances of the same error cause Second to allow the client UI to define specific reactions to certain error causes e g insufficient permissions without binding them to specific error message strings As a side effect the described expansion of the error structure emphasises the need of being aware of the relation of created errors to the user while writing the code This helps preventing a frequent mistake of software developers creating errors that are incomprehensible for users because they describe the error in a completely alien context 3 JavaScript Object Notation JSON is an open standard for text representation of simple data structures see 23 22 3 3 10 Error Logging To fix errors encountered by users the administrator needs to have access to all details of these errors Since the users often fail to remember or write down the encountered error messages it is necessary to ba
83. help with the initial configuration of the AsM which requires the configuration to function properly see Section 3 3 14 for details Its purpose is to gather the initial configuration values from the user and to use them to create the configuration file and to initialize the database Apart from being used to store the configuration the configuration file serves as an indicator of that the application is is not properly initialized After the initialization is completed the Installer moves on to the upgrade procedure described below 3 6 2 Upgrade Upgrading AsM is similar to its installation but it is far less complicated An upgrade is started simply by copying a new set of the source files over the old ones This rewrites the file with redirection rules and thus puts the application into the install mode again i e it starts showing the Installer instead of the UI If the application is already initialized the Installer skips the initialization procedure described above and continues directly to the upgrade The upgrade process consists in the application of patches A patch is a set of changes that need to be performed on the application parts except for the source files in order to reflect the source file changes Most commonly this means a change or extension of the database structure A patch can either be a set of MySQL queries that perform the changes of the database or it can be a full fledged patch script Patches are versione
84. hen the table is created which is a severe drawback for large tables Moreover all rows also have to be initialized every time the table is updated with new data in case of dynamic tables The Table widget could possibly be upgraded to enhance only the currently displayed rows For very large tables partial data retrieval could also come into play but that would mean adding filtering and sorting capabilities to the Core 43 Text cutter Text cutter enhances an element containing formatted text with the capability to show only its beginning and to show hide the rest by clicking a special mark added after the text 3 4 8 User Session The Core uses user sessions as the way to provide secure access to its features To assure this the UI has not only to provide login logout option but also to handle other user session aspects namely its automatic expiration and the access restrictions based on permissions associated with the user account Automatic expiration of a user session decreases security risks but it is not very practical for users because the session may expire while users are performing some of the more time demanding tasks e g writing a full description of a more complex problem Additional mechanisms would have to be implemented for letting a user re log without losing unfinished work and even then it would not be very convenient Other extreme would be refreshing the session automatically before it expires which would b
85. iO e e e aces sdeas ate red lected acusabid esnhas aaa aaa 60 ADS COMMS UTA LONG 441s aer e eee i a E AE E TES 61 4 3 User Interface Lay OWE e csatactstosnssereciacecontsopeureaia noe hameesd ona see ea a aa eo nants 62 44 Control Elem ENS e e vad vivnnes wissnwcss A a a i 64 BA A Table perege R A A R E 64 AA 2 EO paaa a a a a a a e ae A a a an 66 4 5 Error Reporting eseesesesesssssseesssseessssreessseeessseseesssseessssseressseeeesseeeesssseesssseess 67 AO HH OW NO nss feesess sesanceantatwoasesscicetin tauwesbeseeivcata Ee EET SEEE E EED TNR 68 7a Comino TASKS E T AA A A ee cece seas can 69 amp 6 2 Student e p a A E A E E R 70 4 0 3 TUOT en e a aea a aeee aa a Trees 71 40 4 LECCE 81 2 iE E OERE EEEE RE A A ETATS 72 4 05 SYSUCIN eaea cock a s a E EEE E E OES TEE OSEAS 74 4 7 Common Task Sequences ccsssccssssccssssccssscecsencecseneecseecesessecesseecesscesseees 75 47a Student enen RR EEA EENEN 75 4 7 2 TUO sinnn a a a a a A ia aat 75 AF Di NCUUIT OT notre a E a A E E Aa EE 75 ATA PAI ISIE ALOR oenina a a 76 5 Assignment Manager in the Wild cccsscecscscscscscsssssscccscscscees 77 Bed Design for Reality sasiore renere ssar nienean TEE NE ESSEK EEGA 77 5 1 1 Users Real and lmiaeitiatya 43 nchinndies cies a a D tae ere 77 5 2 Cost of Modularity and Complexity 200 0 ceeeeseeseceeeceeececeeeceeeceeeneeeeeseaeees 79 5 3 Testing and Reliability saxciseceteettedecideattehamtantaettt Secedeat ha tetacth i
86. ial or full automation of the correction process But again creating a correction tool complete with user interface etc is a big time investment with uncertain results Another necessity common to all lectures is the creation of tests To keep up with the students posting test solutions on the Internet teachers need to create a special set of questions for every exam One way to aproach this problem is to generate a large pool of test questions from which the tests could be randomly generated Again teachers would benefit from a simple solution that would let them enter questions and generate tests on demand This thesis is concerned with the implementation of a web based software system allowing teachers to set up problems to assign them to students as homework and to set up systems of partially or fully automated correction of solutions and allowing students to hand in their solutions and see the results all in one place The objective is to create a modular solution that works as a tool for the management of homework assignments on its own but is easily extensible to allow automated correction as well In addition the system should let lecturers create pools of test questions and generate tests on demand The deployment of the application with some specific homework correction plugins in a real world use case scenario is discussed as well The initial chapter Management of College Course Homework and Tests analyses the problem and pre
87. icating that the restriction is only temporary It does so by putting up a semi transparent screen over the restricted area with a small panel in the middle containing an animated icon indicating activity and a short explanatory message Text cutter In certain cases only a beginning of a long block of text should be displayed by default to avoid cluttering the screen e g when displaying long text inside a table cell Text cutter provides a smart way to cut text exceeding a certain length and to hide the rest even in HTML content It is optimized to either display just the first line of text or at least to cut at spaces A click able tool for showing hiding the remaining text is appended after the text 3 4 2 Table Element Figure 3 4 shows a mock up of a simple table element and points out all areas of interest An enhanced table is built on a standard table with a caption a row of column headers and multiple rows of data Below there are the descriptions of the additional features that make the table truly useful as the main presentation element Most of these extensions are similarly used by many modern web applications 1 Global action s 2 Row actions 3 Pagination Table caption First column Second column Third column 4 Active filters 5 Add filter form er rr 6 Column headers 7 Sort indicator MOD CH Show fier Figure 3 4 Table element mock up Pagination If the table is to be
88. ign at the time of AsM creation this was an understandable mistake as well as a very expensive way to learn to keep the design simple 79 5 3 Testing and Reliability The previous section explained why focusing on modularity was a bad idea altogether Its main results is that focusing on modularity made the author overlook other aspects of the implementation which later turned out to be significant With hindsight the most notable of those were testing and reliability Developing software on one s own and without regular contact with users does not force the developer to devote time to the creation of tests As all the application code is written by the same person changes are made with full insight and a very accurate notion of consequences That makes it seem possible with just a few rules and a little discipline to maintain application integrity by manually testing it after each set of changes is made However as the project grows larger the manual testing gets progressively more difficult which clearly shows a need for automated testing Automated testing would not only need time that was spent elsewhere as discussed above but it would also need more detailed analysis and specifications so that the units to be tested would have well defined stable interfaces Live deployment showed that the need for more extensive testing is paramount because it is impossible to detect all bugs by manual testing and because fixing the bugs after
89. in and it provides a welcome screen with a dashboard and a link to the AsM project documentation which contains the AsM User Manual The dashboard shows an overview of tasks related to the used user account Its content depends on permissions associated with that user account It may include information about point totals for subscribed groups pending assignments unconfirmed solutions solutions pending for rating system errors and others things Assignments page contains two tables one with the pending assignments from subscribed groups and one with the past assignments Assignments can be selected to view their details in a well arranged format and to allow the upload of solutions Submissions page contains three tables with new corrected and confirmed submissions respectively Submissions can be confirmed or removed depending on their state 38 Subscriptions page displays two tables 1 groups available for subscription and 2 groups already subscribed to User may subscribe or request subscription to the former and unsubscribe from the latter Assignments page in the Tutor section is an editor allowing the management creation modification and removal of assignments Groups page is an editor for the management of groups Submissions page in the Tutor section contains a table with solutions ready to be rated User ratings page contains a table for every owned group Each table shows ratings awarded to solutions
90. ion of a simple problem should provide an accurate notion whether it is correct or not programming problem solutions usually need to be tested i e run on multiple sets of input data prepared with potential solution flaws in mind Automation of testing is the main focus of CodEx There are many similarities between CodEx and the proposed AMS CodEx is an application that allows teachers to post homework problems set up correction mechanisms and assign problems to students with specific deadlines Also it allows students to hand in their solutions and have them automatically corrected But in spite of the similarities the focus of AMS is quite different from the focus of CodEx The differences between the model scenario used by CodEx and the scenario used by AMS further referred to as the proposed scenario are described below 2 1 Lecturer amp Tutor vs Group Owner The first notable difference is the fact that CodEx recognizes only a single unified group owner instead of the proposed two tiered teacher hierarchy lecturer tutor In CodEx problems are created by group owners as either public or private where the public ones can be used by any group owner while the private ones can be used only by their creator This scenario is simpler which is obviously beneficial On the other hand its drawback is the lack of support for multiple parallel courses each containing multiple groups of students As a consequence it is impos
91. ionship 2 is transitive 0 belongs to uy 1 1 1 1 belongs to 1 1 belongs to Lecturer os belongs to The last test generated from each template is saved with that template belongs to uses to allow repeated download and printing Figure 3 2 Entities used for test generation and their relationships 3 3 8 Core Request Handling The tasks described above are performed by the Core upon receiving a request This section describes the nature and handling of these requests A list of all supported requests and their arguments and requirements is in the developer documentation on the attached CD A Core request is a POST or GET HTTP request containing key value pairs in the format appropriate for the request type These are further called properties where property A stands for a key value pair with key A All requests have to contain the property action with the Core request name All other properties are the arguments for the specified core request A Core request can have both mandatory and optional arguments Sending a request without all its mandatory arguments results in an error Other requirements have to be met to run most of the requests often based on specific user permissions AsM Core has a single entry point a script handling all the received requests A special address core where the working directory is the one where AsM is POST and GET are the most common HTTP req
92. is clearly separated from the back end and it uses its global data stores to get the needed data regardless of how they got there see Section 3 4 11 for more details This section broadly describes the implementation of AsM UI front end The AsM UI front end consists predominantly of components Components are classes with common ancestor Panel that take over a certain DOM element and using it as a container for the content managed by them There are two distinct types of components containers and content components which can be visualized as the inner nodes and the leaves of the component hierarchy tree respectively The containers cannot manage any content directly but instead they contain children components and manage sharing of their assigned display space between those children The content components as their name suggest contain the real UI content All components share a handful of common properties and behavior patterns defined by their common ancestor They are eventful a k a observable see Section 3 4 12 for details and use their hierarchy as the event hierarchy They have two layers of configuration the base configuration supplied to the constructor and additional display parameters passed to content display adjustment methods Most importantly they share a common two part display model which separates content showing and adjusting Content showing is the creation of the base content independent on dis
93. is hidden and a form is shown instead When the form is successfully submitted it is hidden again and the table is brought back The resulting effect is different from having a table with editable cells because when using the editor pattern the rows are the base entities instead of the cells Panel AsM UI does not have open space for random content Most content has a tabular character and it is therefore displayed using the table element or form element when showing a single item Panel provides a consistent way to enclose content with different structure Apart from visually setting off the content it provides a unified way to add an icon to it or to highlight it to increase clarity Accordion Accordion is a common design pattern described in 9 which is used in AsM UI only for a single element the navigation menu It provides a natural way to merge the two navigation levels into a single visual element that displays the lower level of navigation only for the currently selected item in the 31 upper level thus showing all information needed while avoiding unnecessary clutter Loading overlay Sometimes the user should not be able to access a particular content area because its content is being loaded or submitted and touching it would only lead to inconsistencies The loading overlay provides a unified method to prevent access to content in such cases while clearly presenting the user with the reason of access denial and ind
94. is shown to inform the user about the field s validity Invalid Invalid field is an enabled unfocused field with a value that has been lt edited and that is now invalid In this case the whole field not just the input elements has a background and border indicating an error and a validation hint is displayed These visual properties are retained even after an invalid field becomes focused While a form contains one or more invalid fields its submit button is disabled to prevent submission of invalid data The field state transitions described above ensure instant feedback and empower the user to fill the form correctly before submitting it This ensures that the user feels completely in control of the consequences of his actions in contrast to the server side validation model and thus leads to higher user satisfaction Custom form buttons are not directly related to the form functionality They just provide a way to add additional exit points to the form apart from the submit button For example a simple Go back exit point may be convenient for users not familiar with using the browser history 3 4 4 Layout and Content AsM UI uses one of two simple layouts depending on the displayed content The three special pages that do not require login Registration Activation and Login have the content displayed in the middle of the screen because each of them consists just of a single form Figure 3 6 shows the layout used by the re
95. ity while staying flexible and extensible This chapter starts with the User Roles section which describes how these conflicting goals are achieved The next section Installation and Configuration deals with the deployment of the AsM Finally the rest of the chapter describes how to use the AsM UI to perform the tasks provided by the AsM AsM UL uses powerful tools to achieve high usability simplicity and uniformity It uses just a few control and presentation elements to provide all of its functionality The level of the uniformity is so high that learning to use AsM UI requires first of all that the user should cope with these few control elements Therefore it is more reasonable to describe how to use the control elements and then to add a few details that are particular to individual tasks rather than to describe all tasks in full detail For this reason the sections concerned with using AsM UI were divided into two groups The first group describes the UI in general It consists of the following sections User Interface Layout Control Elements and Error Reporting The former two are particularly important and using the UI after reading those two sections should be very intuitive The second group consists of just one section How to containing all details useful for the users who are still unsure about a certain task 4 1 User Roles Accessing any AsM feature requires a user account Every user account has a set of permissions bou
96. iving 92 List of Figures 1 1 Actors in a homework assignment scenario ceesseeeseceeeceecceesceeeeceeeeeeeeeeneeees 6 1 2 POSE SENET ALIOM ACLIONS kineta e eeta e aae E ar anA SaaS 7 3 1 Course management entities and their relationships e sssssessesssssesssesssressees 18 3 2 Entities used for test generation and their relationships ceesseeeeeeeeeees 21 3 3 Interaction between database layers during a database request 005 29 3 4 Table element mock up essesssesssssessseesseosseessseesssesssessseesseesseessssessssssssreesssssne 32 35 Form element MOCKUP s sieren iia E ea EE E a i rsr a 35 3 6 Main ULlayo t serres ieena a ae a ena ee Etes ASE ERE ESEN EERS 37 3 7 Content page grouping sesiis ren eena vasa nes a Ee eSEE AaS REAR ANa 38 As Prelogin layout sinen nieistnienie EE V AE REE 63 4 2 Main application layout esessesesessesssssressessssressessesseessesseeseeessesersseesseserssseesseeee 63 4 3 Navigation Men noei eneee enia aaier re r ateiti e ia deaa Aik 64 AA Tabler e a a eae E E A e E 65 ALR HOLM EET E A A A E TA T NT 67 4 6 Err r dialog eane A EAEE RE E EE Ol whi eee 68 ASP Error panels aone hinien e eane a a a aa a a titania aa ar aaas 68 4 8 ICOM NAMES c sssssesescscscscscscscncscscscssscscnssessscsesssescsesescseceuaaseecccnanaseseeuanens 69 93 94 Attachments A List of Files The attached CD contains the Assignment Manager application built an
97. lash app path to the application root folder relative to the document root without leading slash with trailing slash Only forward slashes should be used in paths independently on the used operating system Editing the properties below the comment DO NOT CHANGE PROPERTIES BELOW is discouraged because it can have unexpected results including severe data loss 4 3 User Interface Layout AsM UI uses two layouts the pre login and the post login layout The pre login layout is used just by the three content pages which do not require login and each of which consists of a single form Figure 4 1 shows these three pages as well as navigation between them A successful login leads to the post login main layout 62 Login Activate account Username Activation code Password Pe 6 Back v Activate Register x Activate Login l T Access the rest of the application amp Register new account Full name your first name and surname separated by space Email valid address is required for account activation Username alphanumeric 5 to 15 characters Password 6 to 20 characters do not use common words Retype password must match the password above 6 Back 4 Register Figure 4 1 Pre login layout The main layout is shown in Figure 4 2 It consists of a top bar a left menu and a content area The top bar and the left menu take up just a little space on the edges of the screen and the rest is reserved
98. le the choice and multi types of questions require selecting one and any number of options respectively Therefore a question with the choice or multi type must be supplemented by a set of options answers Additionally a question can use one or multiple attachments A template is created by selecting a set of questions and the number of questions the generated tests should contain The selected questions are further divided into two categories mandatory and optional The template can be used to generate a test that contains all the mandatory questions and as many of the optional questions as necessary to reach the required question total For increased convenience a test is generated right when the template is created and the Core stores the last generated test for every template to allow downloading and printing the test multiple times The generated tests are downloaded as HTML files each containing first the selected questions and second the attachments if there are any Both the questions and the attachments are numbered Questions with choice and multi types are followed by the description of their type and a list of available answers Every attachment is included only once even if it is used by multiple questions and each question that uses attachments is followed by the list of the attachment numbers it uses The relationships between the entities described in this section are shown in Figure 3 2 20 Belongs to relat
99. lenames are private implementation details Instead files are requested in the same way as all other data using a Core request If the request is granted the requested file is returned directly as the result This is the only case where the result of a Core request is not a JSON encoded object If an error occurs during the handling of such request the usual error result is returned instead Therefore the sender of the request needs to adjust the handling of the result based on its type 3 3 13 Sending E mails Sending e mail alerts and digests is a feature not included in AsM due to time constraints However the e mail sending mechanism itself is implemented and it is used during the user account registration process The implementation of the mailing mechanism is modular The mailer class is decoupled from the rest of the application to be easily exchangeable for a different 25 implementation of the mailer interface defined by AsM The currently used mailer is just an adapter for the PEAR class Mail used with SMTP back end SMTP server set up is a part of the AsM Core configuration 3 3 14 Configuration To be deployed successfully ASM Core needs some specific information about the environment it is supposed to interact with This information is supplied using the AsM configuration file which is an INI file with sections as described in 17 The INI format has been chosen both because it is a standard format for configuration
100. medtheat decoupling the input processing from the correction and the set of utility functions The part of the PHP Plugin Framework implementing the common plug in logic is not only a asset but it is also a restriction because its use is compulsory for all PHP plug ins This allows for close integration of PHP plug ins into the AsM Core without a need for an additional interface layer Since the common logic is quite straightforward and it would have to be implemented by every plug in anyway this restriction is not of any importance The benefits of the framework on the other hand are unquestionable because the framework allows the individual plug ins to focus on implementing their main correction logic without being distracted by the unrelated tasks of technical nature A PHP plug in just needs to implement its correction logic as an override of a particular abstract method and to use the criterion handling output saving and error reporting methods of its ancestor to save the results Everything else including the unpacking of the solution archive error handling output packing clean up and returning well formatted results is taken care of See the developer documentation on the attached CD for more implementation details There is a second part of the PHP Plugin Framework which is not compulsory for plug in developers It establishes a specific model of solution processing and correction which allows to keep these two tasks separated and
101. ment Manager at the MFF UK during a single semester The application s performance was satisfactory and the deployment provided valuable feedback and commentary on decisions made during the implementation The comparison of the live deployment feedback with the original assumptions is discussed in this work as well and forms an important part of it Assignment Manager is designed with high degree of modularity which makes several parts independent on the main application Therefore these parts can be used or published separately as for example the presentation elements used in ASM User Interface Moreover this work also deals with the problem of documenting a project that uses multiple programming languages The solution presented here can be applied elsewhere as well 85 86 Bibliography 1 2 3 4 CodEx The Code Examiner online 2008 cit 2011 11 20 CodEx Design Manual Available from WWW lt http codex2 ms mff cuni cz project doc manual pdf gt Assignment Manager Home online 2009 last updated 2010 cit 2011 11 20 Assignment Manager Documentation Available from WWW lt http hon2a wz cz asm docs gt PHP Hypertext Processor online 2001 last updated Sun Nov 20 15 02 56 2011 UTC cit 2011 11 20 PHP Documentation Available from WWW lt http www php net docs php gt Ecma International online 2011 cit 2011 11 20 ECMAScript Language Specification Available from
102. mework It is distributed separately from the AsM and therefore it is not further discussed in this paper it is fully documented in 13 50 It is however built on the same basic principles as the PHP Plugin Framework discussed at the end of this section 3 5 1 Tasks Each AsM plug in needs to do the following tasks during its every run Unpack a ZIP archive with the solution files to be able to access those files Set up the criteria to be used for judging the solution For every criterion check the files of interest in the supplied solution and determine how much they fulfill the criterion Optionally process some of the input files to produce other files a k a plug in output Pack the output files into a single ZIP archive Clean up all temporary files unpacked solution files output files Return a response with information about the fulfilment of the plug in criteria including descriptions of all found mistakes If an error occurred during the plug in run return the error info instead As described above every plug in must have a set of criteria which reflect the requirements imposed on the solutions Adherence to each of the criteria must be judged and reported separately Judging of each criterion results in the following information an indication of whether the criterion is passed a fulfilment percentage and the details The first two properties are not automatically bound t
103. n becomes corrected The corrected submission is still fully under its author s control The author of the submission can view the correction results if present and decide whether to confirm the submission for rating which makes it confirmed The only alternative apart from leaving the solution in corrected state is the removal of the submission which can be done at any point before the confirmation Once a submission is confirmed it becomes the author s official solution and can be viewed and rated by its associated tutor It can no longer be removed and no other submission for the same assignment can be confirmed Submission stays in this state until the tutor reviews and rates it Then it becomes rated There are two key points in the solution handling procedure described in this section One of them is the possibility to cancel the submission based on the correction results before handing it over for rating The main motivation for this is the assumption that the tutors time is much more valuable than computing time It is also assumed that the main point of any homework is an exercise not testing While the latter holds true for the AsM s original deployment environment it is not true for every possible case To remedy this a limit could be put on the number of solutions that a single user can upload for a single assignment Another key point in the solution handling procedure is the lack of an option to return the solution to it
104. nd receives specifically formatted results lt User Interface User Interface is the application s client side and provides the only access point to the application for users It is written mainly in MySQL is an open source database widely used by modern web applications 7 Hypertext Transfer Protocol HTTP is a networking protocol used as the base means of communication between a web browser and a web server see 20 12 JavaScript and it makes use of jQuery framework for extended cross browser capabilities of DOM manipulation and AJAX communication Plug ins Checker plug ins are not an inherent part of the application but they are closely tied to it Each of them belongs to one of the three possible types PHP script Java JAR archive or a native executable All of them have to conform to the AsM plug in specifications which differ quite a bit between PHP script and the other types A framework for PHP plug in creation is part of the AsM itself Apart from correction results plug ins can also produce other arbitrary output so they can be used for solution preprocessing as well as correction There are other parts belonging to the AsM project than just the AsM application The most costly one is a complete set of checker plug ins for a single college course XML Technologies Another part closely tied to the AsM is the AsM Installer which helps with the initial configuration and upgrades Last significant part i
105. nd to it which defines the features available while using that account The sets of permissions are called user types and they are defined separately to make it easier to manage permissions of whole groups of users To retain maximum possible flexibility AsM allows combining permissions into custom sets However such flexibility alone would make it very difficult to start using the application right away so the AsM also provides a set of predefined user types which reflect the actors described in Section 1 1 2 They are administrator lecturer tutor and STUDENT These four user types altogether provide access to all application functionality but each of them provides an access only to the tasks necessary for the respective role see Figure 1 1 and Figure 1 2 for an overview of task distribution between user roles User roles reflected by predefined user types do not only provide a way to let users start using the application quickly and easily They also provide a very intuitive 59 distribution of tasks into distinct groups The same grouping of the tasks is used in the last section of this chapter to help the reader to find any particular task very quickly 4 2 Installation and Configuration AsM is a web based application which means that it needs to be installed on a web server Once installed properly it is accessed over the local network or over the Internet using a web browser Using the application is quite simple even for users
106. ng all students accounts this way would mean a lot of work for the person in charge of creating the accounts Another way to create an account is to register it Registering a new user account does not require login so it can be done by the students themselves User account created this way has two important properties First right after its creation the user account is inactive and cannot be used to log in To become active it needs to be activated by a code sent to the e mail address entered during the registration process This security measure prevents automated user account creation by bot scripts Second users cannot choose their permissions when registering new user account Instead they are assigned the default user type STUDENT User type of any user account can be changed by a user with appropriate permissions Users cannot remove user accounts without appropriate permissions not even their own account 3 3 4 User Permissions The proposed scenario describes several actors and the actions they need to be able to perform This is a simplification for the sake of an easy use case analysis In reality different situations call for slightly different solutions so having a fixed set of actors would not be a good idea Instead every task performed by the Core has an associated permission and these permissions are grouped into sets called user types ASM comes with several predefined user types corresponding to the actors of t
107. ng the management of homework assignments This scenario used idealized actors performing tasks at their level of responsibility and the implementation reflected this by restricting users access to the application accordingly Additional restrictions were added to promote fairness and transparency e g the authors of solutions to be 77 rated were hidden and solution rating could not be changed While this seemed sensible during the specification and implementation phases it proved objectionable after the deployment The most important lesson resulting from the deployment of AsM is the discovery that the users priorities in the real world are different from their priorities in the idealized scenario Namely the main drive behind the users behavior seems to be convenience While the separation of the lecturer and the tutor reflects how creation and assignment of homework problems work in reality it proved to be meaningless during the testing In the observed case it turned out to be most convenient for the lecturer not to interact with the application at all but delegate this task to the tutors and interact with them instead In addition the tutors were given user accounts with full privileges again for the sake of convenience so there was no need of the special administrator role Over the testing period even more restrictions had to be removed for the sake of convenience Rating solutions as anonymous turned out to be the most contro
108. of simple database queries That is a task markedly diverging from the scope of AsM Core As a result the part of ASM Core dealing with the database management became so large that it does not correspond to its importance with respect to the project Due to time limitations some of the more complex features of the framework notably complex queries joining multiple tables could not be included and workarounds have to be used instead 3 3 15 38 Database Adapter Layer Database adapter layer is the bottom layer and it manages the transformation of abstract queries into a native query language of the used database MySQL was selected as a database of choice for AsM therefore the only adapter implemented is the MySQL adapter Database adapter layer logic is implemented as part of abstract query functionality therefore an abstract query just needs a set of database dependent tokens to be transformed into a native query string Figure 3 3 shows the interaction between the layers during a single database request 28 Database Abstract Database ore request query adapter nin layer layer layer request requestid arguments query mysqlQuery result typeof result boolean parseResult j result typeof rqsult boolean translateResulf result translatedResult T 1 Figure 3 3 Interaction between database layers during a database request 3 3 15 4 Data Structure
109. of the required input files etc the lt arguments gt tag is optional and ARGUMENT_DESCRIPTION is a short argument description Arguments must be listed in the order in which they are accepted by the plug in A plugin type is based on the type of the main plug in file the one that is able to be run by the AsM Core The Core accepts three plug in types php java and exe which stand for PHP Java and native executable plug ins respectively At the first glance the last type is the least restrictive because there are many ways to create a native executable However it is not a cross OS solution which may impact re usability of the plug in Both PHP and Java plug ins use their specific programming language but they are interpreted independently on the OS therefore they are more portable While the Java plug ins and the native executables are launched from the command line and act like stand alone programs PHP plug ins use a different approach The main file of a PHP plug in must contain a class descended from the Plugin class included in the PHP Plugin Framework see Section 3 5 4 The Plugin class implements all the technical tasks required from every plug in so the individual plug ins only need to contain the main correction logic 3 5 3 Communication Contract Every plug in s contract i e the accepted input and the returned output needs to adhere to the specifications described in this section so that it could be properly la
110. ogether i e a criterion may be flagged as passed even when it is not fulfilled completely If the criterion is not fulfilled completely all found mistakes must be accurately described in the details 3 5 2 Plug in Format An AsM plug in needs to have a very specific format to be accepted by the AsM Core All of the plug in files need to be packed in a single ZIP archive together with a special manifest file see below A plug in is unpacked with the folder structure being preserved as soon as it is added to the Core and the information contained in the manifest is used to determine how to use it A plug in cannot be added to the application if its manifest file is not well formed or if it does not contain the required data A plug in manifest is a XML file manifest xm1 which is located in the plug in root folder i e the root folder of the ZIP archive It uses the following format lt xml version 1 0 standalone yes gt 51 lt plug in manifest gt lt mainFile gt MAIN_FILE_PATH lt mainFile gt lt type gt TYPE lt type gt lt description gt DESCRIPTION lt description gt lt arguments gt lt argument gt ARGUMENT_DESCRIPTION lt argument gt lt more arguments gt lt arguments gt lt plug in manifest gt where TYPE is a plug in type see below MAIN_FILE_PATH is a path to the main plug in file relative to the plug in root folder DESCRIPTION is a plug in description the names and specifications
111. or free themselves Adding work arounds for known library bugs or at least reporting them as plug in runtime errors instead of correction results is essential if the plug ins are to be really useful 83 84 Conclusion The objective of this work was to create an application that would serve as an online platform for the management of homework assignments Specifically it was required to provide means for the creation and assignment of homework problems for handing in solutions for automated correction of solutions and for their manual rating Additionally it was required to facilitate the automated generation of tests from prepared sets of test questions These objectives are met by the Assignment Manager application implemented as a part of this work The Assignment Manager is a web based application that can be deployed on any Apache web server after appropriate server configuration It is split into two parts the Core and User Interface which were developed using different technologies namely PHP and JavaScript It is controlled solely through the user interface which can be accessed using any standard compliant web browser All required features are included in the core functionality with the exception of automated correction which can be added using external plug ins The automated correction is completely optional as proposed in the Introduction Meeting of the described objectives was verified by live deployment of the Assign
112. or this work The purpose of a school project is to provide students with experience in developing a full fledged software product which they may not have had previously as it was in the author s case There are certain requirements imposed on the school projects to help the students learn how to approach the development of such software product The most prominent requirement is the complete separation of the specification and implementation phases which should teach the student to perform an analysis and to create specifications before starting the implementation However enforcing such complete separation has certain drawbacks as well There is an important distinction between separating the specification phase in the context of a single development cycle and separating it for the whole project The latter works under the assumption that the whole application can be correctly designed beforehand and then implemented based on the completed design This assumption is not a problem as such but it becomes a problem when the project development is supposed to be done by a single inexperienced developer In this particular case the created specifications turned out to be both not specific enough allowing wide range of implementations and too extensive specifying much more features than necessary Especially the latter had a large impact on the project 5 1 1 Users Real and Imaginary AsM implementation was based on a generalized scenario describi
113. perties should follow especially established naming conventions so that the risk of overwriting other classes properties would be minimal Its purpose is not to be instantiated directly but to be mixed into other classes instead thus extending them with a specific behaviour Mix in concept is very useful for implementing behaviour patterns common to multiple classes without needing them to descend from a class with that 48 behaviour pattern implementation This enables to include multiple behaviour patterns in a single class independently which is impossible in the classical inheritance model A mix in most widely used throughout the AsM UI is the Eventful class which extends classes with an ability to trigger events similar to those used by DOM elements Events can be observed and acted upon in a similar fashion event handlers are bound to the class instance and event name to be automatically run when an event with that name is triggered by the instance Events can be triggered with arguments which specify the nature of the event and which are passed to all event handlers Instances of eventful classes may be assigned a parent in event hierarchy to make all events bubble up to that parent Events bubble up to the parent only after being handled by the immediate instance handlers which have the option to stop event propagation much as it is possible with DOM events Multiple handlers can be bound to the same event and the bound handlers c
114. play parameters while content adjusting is the modification of the base content to reflect the display parameters This helps to separate building of the static and dynamic parts of the content and thus to avoid repetitive building of the same static content e g forms do not need to be rebuilt every time they are to be filled with new values 46 The Container class extends the functionality described above not only with its signature ability to have children but also with common handling of display parameters which makes it possible to control the component hierarchy with the hash navigation see Navigation and Browser History The base container is designed to be completely transparent It passes commands and display parameters directly to its children The navigation is really connected to the component hierarchy in its descendant ContentSwitcher which uses the first of its display parameters to select one of its children to be displayed and passes the rest of the parameters to that child The ContentPanel class base for the content components extends the base component functionality by going one step further and separating content building from its display and adding an option to cache the content so that it does not need to be rebuilt when being repeatedly hidden and shown It also provides a way to disable access to the content see the Loading overlay in Section 3 4 1 which can be used while the content is being built Its descendan
115. played in color combinations appropriate to their context the element type of their container allowing them to be used to complement or replace text wherever needed That is a very powerful tool for UI simplification and it increases the clarity even more Each jQuery theme is comprised of the used font only a single font face is used the corner radius of rounded corners overlay and shadow definitions and color schemes for various types of elements Every color scheme consists of a background color and texture and the border text and icon colors A texture is a pattern displayed over the background in white color with customizable transparency The list of defined element types and their use in AsM UI follows Header toolbar Used for application header bar and headers of some jQuery UI widgets e g dialog windows date picker Content Partially used as a base style for the whole application and fully used for bodies of jQuery widgets as well as AsM UI widgets e g table form panel dialog window Click able default state Used for interactive UI elements those that can be clicked Also used for headers in a few cases where using header styles would be confusing field set headers table column headers Click able hover state Used for interactive UI elements when a mouse cursor is hovering over them to indicate their ability to be clicked Click able active state Used for interactive UI elements just after th
116. proach to the problem definition The authors of CodEx asked How do we automate the correction of programming homework and they ended up with a solution allowing basic homework management as well We approach the problem from the opposite direction The question behind the proposed scenario is How do we make homework management easier or even How do we make course management easier and the ability to correct solutions automatically or to generate simple tests is just an additional requirement 2 3 Notable Similarities Despite the differences some of which were discussed above several parts of CodEx design fit the proposed scenario well namely the system of groups private and public to which the students subscribe to receive assignments Other similarities include 1 the setting of a maximum rating to each assignment and awarding points for the respective solutions 2 having predefined user roles but supporting different configurations and 3 having a special role for system administrator These elements can serve as a possible source of inspiration when implementing the AMS The following chapter describes the implementation of the application designed to make handling proposed homework assignment scenario easier 10 3 Inside the Assignment Manager Assignment Manager AsM is a software system designed to fulfill the expectations outlined in the first two chapters Its concept was first proposed in the spring of 2008 and it w
117. r deny subscription cross to allow or deny the request respectively Assign a problem to a homework group Go to Tutor gt Assignments use the add assignment thick plus action and create the assignment The problem to be assigned is selected from the problems belonging to the homework group s parent course Rate a solution Go to Tutor gt Submissions use the rate solution tag action select a rating and submit the form 71 KA lt lt lt lt lt View student s ratings Go to Tutor gt User ratings Ratings are shown in a separate table for every homework group with students as rows and problems as columns Each table contains an additional column with the total rating View assignments for a certain homework group Go to Tutor gt Groups and use the show assignments for this group calendar action to view the table of assignments filtered to show only the assignments belonging to that group View ratings of students in a certain homework group Go to Tutor gt Groups and use the show ratings of users in this group person action to view the page with user ratings where all tables are collapsed except for the table belonging to that group Edit or delete a group Go to Tutor gt Groups Use the edit group pencil action and edit the group or use the remove group trash can action Deleting a group deletes all its assignments Edit or delete an assignment Go to Tutor gt Assignments
118. r manager class does not implement error display at all just a notion of having a set of currently displayed errors to which all new errors to be displayed are added Descendant classes implement their own methods of error display and hiding ASM UI contains two such descendants PanelErrorManager and DialogErrorManager which use a set of panels and a sequence of dialogs respectively to report errors While using dialogs for error reporting is quite straightforward it is also very disruptive to user s work Therefore the use of panels is preferred throughout the application The panels have additional features such as auto hiding after certain time supplemented by the ability to be pinned to the screen preventing auto hiding or to be closed manually Both panels and dialog windows can be highlighted to indicate error severity 3 5 Plug ins Plug ins for the correction of solutions make up the third part of the AsM application The AsM project contains six full fledged plug ins but they are not interesting with regard to this paper because they are narrowly focused on the correction of some very specific problems see 18 Rather than describing the individual plug ins this section is concerned with the AsM plug in specifications communication between the Core and plug ins and the PHP Plugin Framework included in AsM The author s work also includes a project concerned with facilitating Java plug in creation called ASM Plugin Fra
119. ray of DOM access and manipulation functions Its functionality bridges the gap between the implementation of standards in web browsers and the usability requirements of a modern web application Another reason for choosing jQuery as the base framework was its extension jQuery UI It extends the severely outdated HTML model by using various widgets like date picker dialog window and progress bar together with the animation effects for element transitions jQuery UI also provides a widget factory that can be used to create additional widgets The widgets created by this factory represent an exception to the class based model used throughout the rest of the AsM UI code Instead of being part of the class hierarchy they follow the jQuery model of immediate extension of DOM element selection This section consists of two distinct parts The first part up to Visual Design deals with the used presentation elements and the UI contents The rest of the section describes the key aspects of internal UI functionality 17 Apache HTTP server Apache is an open source web server 30 3 4 1 Presentation Elements To fulfill its purpose the AsM UI has to be usable by users with very little or no technical background This requires maximum possible clarity which is achieved by simplicity and consistency of the UI Only a handful of presentation and interaction elements is used throughout the application Thus the users are
120. re manually bypasses the caching completely and causes an immediate data reload The store refresh method can be used in the same manner as the common data retrieval method in cases where no caching is required Flagging the store as expired does not have any immediate consequences but it causes the store to be refreshed the next time anyone tries to retrieve data from it 47 Stores are designed to be used as read only to avoid code duplication and possible inconsistencies When a certain action e g entity removal impacts the validity of the data contained in a certain store a proper course of action is to flag that store as expired Stores are eventful see Section 3 4 12 so their updates and or expiration can be observed and acted upon For example when a store used by a currently displayed UI component expires that component may refresh the store and subsequently itself right away to keep the display up to date Last feature of stores is their ability to refresh automatically upon expiration cache time out as well as manual expiration The automatic refresh is very useful when a store is being used by a currently active UI component However frequent component rebuilds based on store reloads would not be very convenient for users especially when the store refresh does not necessarily mean data change For that reason stores contain an additional mechanism called revisions A store contains a numeric property revision that is inc
121. reased only when the newly loaded data actually differs from previously stored data A store triggers a change event only when its revision number increases which makes it possible to refresh the store often possibly automatically and at the same time to rebuild the UI only when it is really necessary 3 4 12 Events Event driven interaction between classes is an important part of AsM UI implementation The idea of events is based on DOM events which constitute the means of binding JavaScript handlers to user interaction with a web page jQuery further enhances these events by adding more convenient ways of their handling as well as an option to create completely new custom events However jQuery custom events are still bound to DOM elements and bubble up the DOM tree Events in ASM UI further called just events take this concept and apply it to any JavaScript class see the beginning of this chapter for details on how classical hierarchy is added to JavaScript Before describing how the event model works an excursion needs to be made about a concept called mix ins which is used in the AsM UI implementation but which does not fit into a classical hierarchy model Mix ins allow a partial multiple class inheritance While full multiple inheritance is not feasible a class can have only a single constructor etc it can be used with some restrictions for impressive results A mix in class must not have a constructor and its pro
122. results as specifically constrained XML PHP plug ins are more closely integrated with the Core They are executed inside the parent environment and are given access to the PHP Plugin Framework classes released with AsM They are requested to return results directly in order to avoid XML creation and parsing See the Section 3 5 for detailed description of how the plug ins work and how they are integrated into the Core 3 3 12 File Management AsM Core needs to deal with files on a regular basis These files include attachments plug ins assignment solutions input data for plug in testing and plug in output files They are uploaded to the server as property values of certain Core requests The POST method needs to be used for these requests because the GET method does not support file transfer Sending files attached to regular requests has a significant drawback Request handlers accepting files need to wait for the whole files to be uploaded before doing 24 anything else Waiting for a response to such a request may therefore take quite a long time A possible way to improve this situation is to add a special file upload request that temporarily saves the file and returns its storage ID Request making use of that file would then include just the file ID not the file itself The user interface could use it when a user needs to enter additional data that are to be sent with the file The file in question could be sent as soon as it is sel
123. ry functionality and bring its strong typing over into the PHP code using type hinting feature of PHP described in 6 27 The abstract query framework contains wrappers for all expressions required in the basic database queries The complex expression constructors have strongly typed arguments which ensures semantic correctness of all expressions The expression wrappers include expressions that yield a value e g Literal predicates that yield a boolean value e g Conjunction Negation statements e g Query and special re typing wrappers e g QuerySource Creating database queries in this manner is much more verbose than using a native database query language To overcome this disadvantage AsM contains various factory methods that make creating simple database queries as easy as supplying sets of values Another drawback is that abstracting database management logic requires keeping track of the whole database layout inside the application code Such data duplication lowers extensibility by increasing modification costs Main purpose behind the creation of the abstract query framework was an effort to write code that clearly shows the application logic and that is independent on the particular database type chosen The framework is a feature that proved to be insufficiently analysed and much more costly than previously expected Its implementation required creation of a class hierarchy that sufficiently reflects the semantics
124. s a code documentation framework that allows to document both the PHP and JavaScript code using similar formatting and to generate single common external documentation The following sections describe the individual parts in greater detail 3 3 Core AsM Core performs various tasks upon receiving requests from the client AsM User Interface a k a UI Apart from that the Core is passive there are no Core processes running on the server other than those handling the client requests The first part of this section up to the Section 3 3 6 describes the tasks performed by the Core and the logical entities the tasks are performed on The rest is dedicated to implementation details 3 3 1 Tasks Follows the list of tasks performed by the Core 8 Document Object Model DOM is a cross platform representation of objects in XHTML documents used by JavaScript and other scripting languages to manipulate those objects see 21 Asynchronous JavaScript and XML AJAX is a set of technologies used to create asynchronous web applications Asynchronous web application is a web page that communicates with the server in the background which enables it to behave like a single application entity rather than a set of interlinked pages Java Archive JAR is an archive file format used for distribution of applications or libraries written in Java programming language 13 lt Authentication Login and logout Access restrictions bas
125. s author for modifications once the solution has been confirmed This restriction was imposed not just because of the complications associated with the implementation of such an option but also to promote fairness If it was possible to return confirmed solutions additional safeguards would have to be put in place to ensure that the users are kept informed about their returned solutions and that they have enough time to submit new solutions before the deadline 3 3 7 Attachments Questions Templates and Tests Attachments questions and templates are all connected to a particular course therefore they are all managed by that course s owner The attachments are mentioned as separate entities because they are managed separately which allows reusing the same attachment for multiple questions It could also allow binding the attachments to homework problems if necessary Apart from the attachment file itself the attachment entity created by the Core contains the attachment s name and type The name is used to easily identify the file when binding it to a question The 19 type can be one of the following three types text code and image and it is used to render the attachment correctly when including it in a test to be printed A question can have one of multiple types as well In this case the types are text choice and multi and they indicate the style of the answer A question with the text type requires a complete text answer whi
126. s own was not mandatory and it appeared to be another step in the wrong direction Instead the first step of the design process should have been to poll the potential users for opinions on what they would require and or expect from such application as AsM It is essential for the developer to recognize that he sees the application with different eyes than the potential user and to have it in mind when he is asked to both design and develop the application 78 5 2 Cost of Modularity and Complexity Even during late phase of AsM development it became clear that the internal design of AsM should have been focused on completely different features Deploying AsM for testing only further exposed this problem The implementation of AsM had been focused on modularity on separating various application parts as much as possible to allow extending or completely changing the individual parts While this had seemed like a good approach and the author had made a point of it both as an exercise and out of misplaced perfectionism quite the opposite proved true Since the AsM is ultimately only a school project which is not very likely to ever reach a wide audience and even less likely to be extended by other developers the benefits of modularity are doubtful On the other hand the cost of modularity turned out to be very high While the modularity enables to perform certain substantial changes e g switching to a different database type without much hassle
127. sents a broad outline of the proposed solution The following chapter Code Examiner looks at the application with a similar focus and discusses its bearing on the problem Chapter three Inside the Assignment Manager contains a detailed description of the implemented software The user manual is included in the next chapter How to Use he Assignment Manager The last chapter Assignment Manager in the Wild describes the experience with the deployment of the application in the real world and suggests several changes and extensions of the application based on that experience The implemented application itself as well as the extensive code documentation is located on the attached CD see Attachment A 1 Management of College Course Homework and Tests Before we start creating software for the management of homework assignments we need to define its expected properties Let us do this by defining a simple homework assignment scenario and then expanding it to cover the requirements outlined in the previous chapter Our simple homework assignment scenario has two actors a teacher and a student The teacher creates homework problems and assigns them to the student with a specific deadline Then the student creates a solution of assigned problem and hands it in In the end the teacher grades the solution The role of the assignment manager software in such scenario would be just to provide teachers with a place to post the homework problems
128. sible to share problems between the groups inside a single course while not exposing them to other courses This drawback can be bypassed by having a separate instance of CodEx for each course which requires more administration or by re creating the problems separately for each group which means more work for group owners Proposed scenario eliminates these shortcomings Moreover it adds additional options such as the possibility for the lecturer to check on his students results while delegating the rating process to his subordinate tutors 2 2 Fully Automated Correction What is really different between the CodEx design from proposed scenario is the premise that the correction of all solutions can be fully automated While this premise makes sense in the context of programming courses it cannot work for the assignment management in general because for many homework problems automated correction would be either very difficult or it would not make sense at all The authors of CodEx obviously realized this shortcoming and added a mechanism for awarding bonus points manually Still the model used in AMS based on manual correction with an option of adding automated one is more intuitive and transparent than the model used by CodEx The question of full automation with bonus points vs manual correction with the possibility of automation is just a technical detail What makes the key difference between our project and CodEx is the different ap
129. sis pdf this thesis 95
130. st of the application It consists of three distinct areas the header the left menu and the content area The header contains the AsM logo which is in fact just a place holder 26 icon the application name and version on the left and the user s username and the Logout button on the right The left menu contains the UI navigation divided into two levels by separating pages by the role of their typical user The content area is designated for the content of each content page where a content page is a set of content belonging to a particular navigation item Application name lt J gt x aS http somedomain net path to application Qe Es Application name version Username Menu item 1 Menu item 2 Menu header 2 Menu header 3 Menu header 4 Content area Figure 3 6 Main UI layout Figure 3 7 shows the grouping of content pages and the connections between them The descriptions of the individual content pages and the tasks managed by them follow See the Core section for task details as the UI only provides an access to the tasks performed by the Core 37 Registration User account settings UI settings Figure 3 7 Content page grouping Registration page allows the registration of a new inactive user account Activation page allows the activation of a previously registered user account Login page lets the user log in using an active user account data Home page is the first page displayed after log
131. stem Section headers gt Settings Current page Figure 4 3 Navigation menu The content area is filled with content depending on the selected item in the left menu There is one additional page not accessible from the menu namely the one that is shown right after the login It is a minimalistic dashboard showing important information related to current user s account e g number of pending assignments or point totals for subscribed groups as well as a link to the AsM project documentation The dashboard can be accessed at any time by clicking the application name on the top bar 4 4 Control Elements AsM UL is controlled by using just two control elements apart from the left menu described in the previous section table and form These two elements are extended to provide all necessary functionality as described below 4 4 1 Table The table element is used for data presentation In addition to data perusal it is possible to interact with the table in the following ways see Figure 4 4 for the positions of all interaction elements mentioned below 64 Row actions Expand collapse Table header cell content Arguments qq o So maximum depth min i Selected rows element fan out min Filters XPath expressions min Remove filter s _ ecks number and validity of supplied XPath Page size 1 name XML DOM id gt 5 all filters Active
132. t DynamicContentPanel the ancestor of almost all of the content components used throughout the application goes even further by introducing an additional step called initializaton into the content showing process In this context initialization means the retrieval of needed data from the UI back end and generation of the content based on that data Disabling access to the content is stretched to cover the initialization period as well 3 4 11 Data Retrieval and Storage AsM UI back end manages the retrieval of data from the Core using jQuery as a cross browser connection layer Retrieved data are stored in stores which are global instances of classes with a common ancestor Store UI front end interacts solely with the stores leaving the underlying data management to the back end Apart from data retrieval the front end also manages flagging stores as expired based on user s actions A store provides a way to store the results of a specific Core request and to decouple data retrieval from data usage It contains various features designed to prevent redundant requests or UI rebuilds It uses a timed caching mechanism implemented separately to refresh itself reload data only if the age of contained data exceeds certain threshold so parallel data retrieval by multiple UI components does not lead to redundant Core requests Caching can be influenced in two slightly different ways manual refresh and expiration flagging Refreshing a sto
133. t is however one of the goals of this project Namely the goal is to allow the lecturers to submit test questions related to the lecture s topic to let them create test constraints and to generate tests from the set of submitted questions based on these constraints The generated tests should be formatted for printing Additionally the lecturers should be able to supplement the test questions with text or image file attachments Let us define a few additional terms to be used in the rest of this work Question Question stands for a test question Attachment Attachment stands for a text or image file that can be attached to a question Template Template stands for a set of questions and a set of constraints usable as a basis for the test generation The constraints include the number of questions that the generated tests should contain Test Test stands for a set of questions and their attachments in a printable format Providing the test generation to the scenario described above requires only to add a few additional actions that could be performed by the lecturer He should be able to upload attachments to create questions and bind attachments to them to create 6 templates and to use the templates repeatedly to generate and print tests The additional actions are shown in Figure 1 2 Create test templates Create amp manage attachments extends Own amp manage lectures Lecturer
134. that user see above 74 4 7 Common Task Sequences This section describes common work flow patterns for all user roles 4 7 1 Student The first thing a student needs to do is to subscribe to a homework group After that the usual student s work flow is as follows 1 Check the dashboard after every login to see if there are any pending assignments 2 If there is a pending assignment find it in the table of assignments view its details and create a solution 3 Submit the solution and wait for its correction 4 If the correction results fail to fulfill the expectations delete the solution create another one and go to the previous step Otherwise confirm the solution 5 After some time check the rating of the submitted solution the tutor has to rate it first 4 7 2 Tutor A tutor needs to create a homework group that can be subscribed to by students Then it is possible to assign problems to students in that group either all at once or separately during the semester Apart from that the tutor needs to check the dashboard regularly to see whether there are any pending subscription requests or solutions to be handled Subscription requests should be handled as a priority so that the students would not miss any assignment deadlines The rating of the solutions does not have to be done immediately however all solutions should be rated by the end of the semester 4 7 38 Lecturer At first a lecturer has to creat
135. the main application functionality possible or easier e g sending e mails or parsing 80 XML The author s lack of experience with public projects led him to pay little attention to the impact of adding such dependencies An application designed for users with no IT background has to avoid having too many dependencies or to hide them with automated installation process AsM s installation process provides some help by partially guessing and or testing the configuration but it does not cover the necessary web server configuration and the installation of the required PEAR libraries Another area that could be improved to better support the expected user base is the maintenance of the application At the time of its deployment AsM needed active maintenance as the result of the lack of automated testing discussed in the previous section Since the application cannot be actively maintained by its author in multiple instances additional steps should be taken to completely remove the need for regular maintenance Attempting to remove or hide dependencies and the need for maintenance is not the only possible approach AsM is designed to be usable in large scenarios e g for the whole school at once which could give sufficient reason to have an IT specialist maintaining it Currently the user manual contains sufficient information for such a person to install the application Additional documentation would have to be created for all periodic maint
136. u dom c ch kol a automatick generov n test Spr vou dom c ch kol se z pohledu vyu uj c ch rozum vytv en loh a jejich zad v n student m a oprava a hodnocen p ijat ch e en Z pohledu student se pak jedn o odevzd v n e en k aktu ln zadan m loh m a o p ehled hodnocen vypracovan ch e en T i t m pr ce je popis implementace a zp sobu pou it webov aplikace Assignment Manager Sou st aplikace je krom v e uveden ch vlastnost tak spr va u ivatelsk ch skupin spr va studentsk ch skupin a sd len loh mezi skupinami v r mci p edn ky a mo nost ste n automatizace kontroly e en oce pomoc extern ch plugin Samostatnou st je schopnost generov n test z ulo en ch mno in testov ch ot zek Aplikace byla testov na ve zku ebn m provozu po dobu jednoho semestru a upravov na na z klad p ipom nek student i pedagog Pr ce obsahuje i diskuzi kontrastu mezi p vodn mi p edpoklady na jejich z klad byla aplikace navr ena a re ln mi po adavky p i nasazen aplikace v praxi Kl ov slova spr va dom c ch kol automatick opravov n dom c ch kol automatick generov n test generov n n hodn ch test Title Homework and Test Management System Author Jan Konop sek Department Department of Software Engineering Supervisor of the bachelor thesis RNDr Irena Ml nkov
137. uest methods used by web browsers to submit data to web servers and retrieve content from them respectively 21 deployed is used to redirect requests to the handler script instead of addressing it directly The handler script sets up the environment for request handling and launches the handling procedure Every request has an associated handler class which contains the logic specific to that request All handler classes are descended from a common parent which implements the base handling logic including error reporting and logging input validation handling of uploaded files and other common tasks Both this and the adjustments of the environment done by the entry point script ensure consistent request handling and error reporting behaviour In response to requests the Core returns either an output file in some special cases or a JSON encoded object with two properties A property data contains request specific result data or it may be empty in case of errors A property errors is set only if some error s occurred and contains an array of errors 3 3 9 Errors Generally most applications use a simple model for errors in which an error consists of an error message and optionally its severity ASM expands on this by splitting the error message into cause effect and details and adding code numbers to known error causes The errors should simultaneously serve all of the following purposes 1 To give t
138. unched by AsM Core The first restriction is that every plug in needs to accept a path to a solution archive as its first argument There are no restrictions placed on the other arguments accepted by plug ins but every accepted argument must have a corresponding entry in the plug in manifest Argument descriptions in the plug in manifest are necessary because the AsM Core needs to be able to inform its users about them The argument values supplied by users are guaranteed to be passed on to the plug in only for the arguments described 52 in the manifest Plugin arguments allow for greater flexibility through abstraction instead of creating a separate plug in for every problem The flexibility could be further enhanced by allowing the use of multiple plug ins for correction of a single solution but it would notably increase the complexity A similar result can be achieved by sufficient abstraction in the plug in code and by subsequent code reuse Unlike plug in arguments the plug in results i e the values returned by plug ins need to follow very strict formatting rules These rules are based on the criterion model see Section 3 5 1 but they differ largely based on the plug in type PHP plug ins need to return an instance of the PluginResponse class which is used as a plug in response parser and wrapper by the Core Fortunately the response management is implemented as a part of the base Plugin class so the PHP plug in developers do not ne
139. used as a main display element it needs to be capable of being limited to certain height Then it is possible to put multiple 32 tables on a single content page while keeping the layout well arranged This needs to be done without limiting the volume of table contents It is achieved by breaking the table into pages of similar size the number of rows and showing only one page at a time A control panel is added to the bottom of the table to allow changing pages and or changing the page size Page changing controls allow going one five pages forward backward or jumping to the first last page directly To avoid unnecessary clutter these controls are hidden while all rows fit on a single page Sortable columns Table columns can be flagged as sortable by the developer The headers of flagged columns are highlighted on mouse over and they are click able When a user clicks on a column header the values in table rows are sorted in ascending order Clicking on the same header again sorts the table in descending order The sorting is stable and it is possible to flag a column for the numeric sorting instead of the default lexical sorting Filters Tables containing large ammounts of data can be hard to navigate especially when a user is interested only in a specific subset of that data Filters provide a way to restrict the displayed data by placing restrictions on values in certain columns A filter may restrict values to those equal to less gre
140. versial feature because the tutors did not see any reason for it and wanted to be able to communicate with individual authors of solutions before rating the solutions Being unable to change the rating of the solution after it was rated was not appreaciated either and had to be removed by a hot fix because the tutors sometimes made a mistake when rating a solution and needed a way to amend it The problems described above and others not mentioned arose from two misconceptions First it was assumed that it was possible to design the application by observing how the homework management works without such application and attempting to simulate the same scenario within the application With hindsight the problem with this approach is that adding the application to the scenario changes the scenario completely Rather than simulating the previous scenario the application needs to create a new one that is more convenient for all actors Second it was assumed that it was possible to create the right design for the whole application in advance and on one s own Unfortunately creating the design in advance is unfortunately one of the constraints of a school project Without this constraint it would be much better to apply an agile approach and to implement the application iteratively based on user feedback On the other hand getting a meaningful and representative user feedback repeatedly would pose the challenges of its own Creating the design on one
141. with the filter creation tool by selecting a column optionally the inversion flag and a comparison type filling in the value for comparison and confirming the selection The created filter immediately shows up in the filter list Any filter in the list can be deactivated or activated by clicking it or removed by clicking the Remove filter button next to it lt Pin rows to screen Any table row can be selected by a single click Selected row is highlighted and pinned to the screen so that it is displayed even after moving to a different table page or after applying a filter that would otherwise hide it The selected row can be deselected by another single click Multiple rows can be selected at a time 4 4 2 Form The form element is mostly used for modification of application entities e g users assignments or creation of new ones but there are a few cases where it has a different purpose e g as login or user account activation The forms used in the AsM UI have the following enhancements see Figure 4 5 for details 66 Field set header amp Add Edit user Username superDuperUser STUDENT v Type What won t tell you my name must contain only letters and spaces Email Password Retype password Focused field field Field with invalid value Full name 6 to 20 characters do not use common words must match the password above v Submit Submit
142. ws a mock up of a sample form with multiple field sets various field types and with extended interaction cues Regardless of the field type all fields have the same visual structure and use the same interaction patterns described below 34 Field set name Aready edited feld v Another edited field incorrect vave validation error text hint Currently focused field optional hint text Select field Select value w optional hint text Checkbox field g Radio field selected option O other option O disabled option Another field set name Date field 03 11 2010 E 7 File upload field file path ext Custom button 1 Custom button 2 Figure 3 5 Form element mock up Every form field consists of three parts a field label one or more input elements and an interaction cue space Field parts are displayed from the left to the right in a row and aligned with the respective parts of other fields as seen in Figure 3 5 Interaction cue space contains one of the following interaction cues Initial hint Initial hint contains information about the value expected to be filled in It can be empty if the value restrictions are self enforced in case of a check box a radio button or a select box or self explanatory Check mark Check mark is an icon indicating that the field value is valid Validation hint Validation hint specifies the value restriction not satisfied by the current field value A field is
143. y the application are to be triggered by users with one notable exception The checker Extensible Markup Language XML is a set of rules for creating documents with added logical structure see 19 PHP is a programming language with syntax loosely based on C Java and Perl It is most often used for serving dynamic web pages and server side scripting in web applications see 3 for details 3 XHTML is a document type used for web pages based on XML see 22 4 JavaScript is a programming language most often used to add interactivity to web pages specified in 4 5 jQuery is a JavaScript library that simplifies access to XHTML elements and events and communication with the web server It radically changes the way of writing JavaScript code see 5 11 plug ins although being a part of the application should run on its own and trigger save correction results action This is achieved by launching the plug ins asynchronously in the background and binding handlers to their completion as described below Out of the selected programming languages only PHP is a full fledged language with file system access etc Being also the programming language the author was most familiar with at the time of ASM development PHP serves as the project s base programming language As such it is used not only for server side part of AsM but also for various utility scripts The next section explores the top level breakdown of applic

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