Topic 2 - Features of the SDP
Contents
1. implementation testing documentation evaluation maintenance HERIOT WATT UNIVERSITY 2 3 THE ANALYSIS STAGE 15 Analysis is an attempt to understand a given problem clearly and exacily in order to generate a solution The outcome will QUESTIONNAIRES N a va loz NN be a specification that is used as the basis OBSERVATION for all subsequent work i DOCUMENT pamm Analysis sometimes called systems ANALYSIS analysis is the job of a specialist person ay EXPERT SYSTEMS sys the systems analyst re ane Full systems analysis has three phases 1 collection of information 2 analysis of information collected 3 production of a problem specification or user requirements specification Sometimes this stage begins with a vague idea or rough outline of the problem On other rather more formal occasions it will start with a full requirements specification This will include hardware and software specifications notes on project issues such as objectives constraints costs and schedule It may also include a full functional specification which will describe exactly how the system is meant to behave The functional specification is what the development team will follow in creating the software system INTERVIEWS DISCUSSIONS OBSERVATIONS specification agreed beween client and developers HER2. A Managed software feverishly coding programmers development team Organisations creating software usually do so for profit Money time and people are involved The people involved have different points of view some are clients wanting to buy software some are developers concerned in creating software managers are concerned with efficiency and profit within their organisation In the development of software the three aspects which the developer must consider are data processes human computer interface In traditional structured design the primary tasks are to focus on the processes A process is the work that a program carries out on data or in response to certain inputs The software development process does not always start in the same place Sometimes there will only be an outline of the problem At other times a specification will be available The specification must be agreed with the clients Work on the problem and the solution is often carried out by a group of people called the development team The aim of the team is to produce a new software system that will solve the problem 2 2 The need for iteration The traditional software development process contains a sequence of stages The precise names of the stages and even the number of stages are not universally agreed They differ from book to book and from developer to developer Much depends on the aspects of software development that a b
3. One aspect of this is the use of meaningful variable names 2 5 2 Standard algorithms and module libraries Standard algorithms Most projects will use certain standard algorithms Programmers need to be familiar with these common algorithms Ones that you will become familiar with later include linear searching counting occurrences finding maxima and minima Module libraries It is often possible to use with or without alteration modules that have been previously written and have been retained in a module library A module library will include code for standard algorithms Most development environments come with a large library of modules Programmers can use these in the code they are developing These libraries will include mathematical functions modules for converting text to numbers etc HERIOT WATT UNIVERSITY 21 22 TOPIC 2 FEATURES OF SOFTWARE DEVELOPMENT PROCESS if eval _root drag1 _droptarget _root target1 _root drag1 _visible false _root target1 nextFrame _root target1 _name false __parent answer _parent answer 1 if _parent answer 12 _Pparent message01 Well done Each module in a module library is pre tested well documented so that it can be adapted and easily used The use of previously written modules reduces the time spent creating the final software and minimises the cost Designers will incorporate if possible modules from the m
4. of paper or a disc drive not being available for writing because it simply isn t there the user s forgotten to put in the CD or the user entering a number when asked for a letter Reliability A reliable program always produces the expected result when given the expected input It is designed correctly to do the task specified Characteristic of good software design On the Web is an interactivity You should now complete this task 2 8 2 Review questions Q19 Choose the correct response that describes the term robust within software development a The program is strong and hardy b The program may be ported to a different machine architecture c The program can cope with mistakes that the user might make HERIOT WATT UNIVERSITY 2 9 MAINTENANCE 31 d The program runs to specification Q20 Choose the correct response that describes the term reliable within software development The program is strong and hardy The program may be ported to a different machine architecture The program can cope with mistakes that the user might make The program runs to specification a b c d Q21 Using a module library can reduce software development time because choose one a Common programming modules can be used b Programmers do not need to write programs from scratch c Programmers can re use library code in their projects d All of the above 2 9 Maintenance Once the software is operating the users will nee
5. to certain key words in the chapters and search offers the facility to locate key terms within the guide HERIOT WATT UNIVERSITY 27 28 TOPIC 2 FEATURES OF SOFTWARE DEVELOPMENT PROCESS 2 7 2 Technical guide The technical guide will contain information about the hardware and software requirements of the program The hardware specification will include details of the processor type and speed RAM required RAM desired monitor resolution graphics and sound card specifications etc It will also contain instructions about configuring the program DOCUMENTATION Software designed to operate or run on networks can be very complicated and require a good deal of expertise Technical guides can be very large and cumbersome and difficult to navigate Sentence completion Documentation On the Web is an interactivity You should now complete this task HERIOT WATT UNIVERSITY 2 8 EVALUATION 29 2 8 Evaluation Evaluation is the formal monitoring of a system to ensure that it is performing its purpose accurately efficiently cost effectively and in a timely manner The performance of the system must be matched against a given set of criteria such as the initial project specification Evaluations of various kinds are an important aspect of the software development industry Evaluations are used to determine if systems are usable cost effective conforming to performance criteria etc Evaluation is based on observation
6. 20 21 21 23 23 24 25 25 26 26 27 28 29 30 30 31 32 33 33 10 TOPIC 2 FEATURES OF SOFTWARE DEVELOPMENT PROCESS Prerequisite knowledge Before studying this topic you should be able to describe the following stages of the software development process analysis design implementation testing documentation evaluation maintenance describe and be able to use test data normal extreme and exceptional describe the features of a user guide and a technical guide evaluate software in terms of fitness for purpose user interface and readability Learning Objectives After studying this topic you should be able to understand the iterative nature of the software development process describe each stage of the software development process explain the purpose of the software specification and its status as a legal contract understand and be able to describe corrective adaptive and perfective maintenance explain the need for documentation at each stage of the software development process HERIOT WATT UNIVERSITY 2 1 INTRODUCTION 11 Revision 9 Q1 The software development process consists of seven stages Three of the stages are analysis testing and maintenance Which one of the following statements correctly identifies the missing stages in order a Design documentation evaluation implementation b Design evaluation documentation implementation c Design implem
7. IOT WATT UNIVERSITY 16 TOPIC 2 FEATURES OF SOFTWARE DEVELOPMENT PROCESS Questions to be asked at this stage would include What are the new system requirements What are the costs involved How long will it take to implement Details are gathered by a variety of methods such as interviews and questionnaires 2 4 The Design Stage analysis The product of the analysis stage is the completed specification During the design stage the specification of the problem is used as the basis for a planned solution implementation testing documentation evaluation maintenance The work on the design is carried out by a Jf designer this might be same person as Lu xil did the analysis or it may be a member of A pee the programming team Most analysts gt program and many programmers can carry out analysis People who can do both are Software Design stage Structure diagrams described as analyst programmers Specification pseudocode flowcharts data flow diagrams The design process is methodical using techniques such as structure charts and pseudo code The problem is approached by breaking it down into a collection of relatively small and simple tasks This approach is known as top down design with stepwise refinement The development team will attempt to make the design of the program both
8. Topic 2 Features of Software Development Process Contents 2 1 Introduction 2 2 The need for iteration 2 2 1 Review questions 2 3 Analysis Stage 2 4 The Design Stage 2 4 1 Review questions 2 4 2 Designing the human computer interface 2 4 3 Designing Data Structures 2 4 4 Other design choices 2 5 Implementation Stage 2 5 1 Debugging 2 5 2 Standard algorithms and module libraries 2 5 3 Review questions 2 6 Testing 2 6 1 Test data preparation 262 Alpha testing sae a he We a a de te dada Gee 2 6 3 Betatesting s aed are doe oy 2 6 4 Review questions 2 7 The Documentation Stage 2 7 1 User guide 2 7 2 Technical guide 2 8 Evaluation 2 8 1 Robustness and reliability 2 8 2 Review questions 2 9 Maintenance 2 10 Weaknesses of the software development process 2 11 Summary 2 12 End of topic test 11 12 13 14 16 17 17 18 19
9. Y 2 11 SUMMARY 4 Developers work in isolation from the clients often for months only for the clients to be disappointed with the results Many developers value feedback from clients as the project progresses 5 Errors arising from incorrect requirements will not be obvious until late in the cycle by which time they will be difficult and expensive to fix There is nothing so depressing as delivering months sometimes years of work to the customer only to be greeted with the response That s not what wanted at all 2 11 Summary The following summary points are related to the learning objectives in the topic introduction the software development process has 7 stages analysis design implementation testing documentation evaluation maintenance e the process is iterative and involves a continual revision and evaluation at each phase of the process 2 12 End of topic test An online assessment is provided to help you review this topic HERIOT WATT UNIVERSITY 33 34 TOPIC 2 FEATURES OF SOFTWARE DEVELOPMENT PROCESS HERIOT WATT UNIVERSITY
10. an also help with debugging Sometimes problems that arise at the implementation stage will call for a return to an earlier stage of the development process For example it might turn out that an HERIOT WATT UNIVERSITY 2 5 THE IMPLEMENTATION STAGE algorithm runs too slowly to be useful and that the designer will have to develop a faster algorithm Or it might be that the slowness of operation is due not to a poor algorithm but to the hardware capability In such a case the development team might have to return to the analysis stage and reconsider the hardware specification At the end of the implementation stage a structured listing is produced complete with internal documentation This will be checked against the design and against the original specification to ensure that the project remains on target 2 5 1 Debugging At this stage the programming team will make use of test data This data is designed to check that the program works properly and that it is reliable and robust Testing is often confused with the debugging of a program but these are not the same though they are very closely related testing discovers any faults a computer program debugging is the finding and correcting of these faults Maintainable software should include internal documentation This is commentary within the program to explain the various stages and to record any changes that might be implemented in the coding during debugging
11. aspects of the program normal operation data that the program has essentially been built to process all outputs should be satisfactory extreme boundary testing data to test that the program functions properly with data at the extremes of its operation for example if a number entered is meant to be limited the program s performance is tested just within the limit on the limit and just beyond the limit as another example if a table is supposed to have a maximum number of elements the program is tested to see if it can cope with exactly the maximum and if it can cope when an attempt is made to exceed the maximum exceptions testing data that lie beyond the extremes of the program s normal operation these should include a selection of what might be called silly data to test the program s robustness that a user might enter in a moment of confusion or mischief Matching definitions Testing On the Web is a interactivity You should now complete this task Faults that become evident during testing are known as bugs If bugs are identified the program is sent back with the test logs to the programming team for debugging This process is likely to be iterative testing finds bugs they get fixed the program s tested again more bugs are found and so on It may be that bugs reveal flaws that were introduced at an earlier stage of the process at the design or even at the analysis stage If this is the case the docum
12. at the software must do the hardware used to run the software the nature of the problem to be solved a b c d an outline of the problem solution 2 4 2 Designing the human computer interface The human computer interface is all that a user sees of a program A program s viability often relies the quality of the HCI A good interface makes things easier for the user A bad interface can introduce mistakes and cause irritation Modern HCls are often designed as Graphical User Interfaces GUIs which provide a WIMP environment WIMP stands for Windows Icons Menus Pointers although some HERIOT WATT UNIVERSITY 18 TOPIC 2 FEATURES OF SOFTWARE DEVELOPMENT PROCESS textbooks refer to Windows Icons Mouse Pulldown menus A GUI provides a set of Windows which contain Icons and Menus The user controls the program by means of a Pointer which reflects movement of a mouse trackerball or other input device The WIMP environment My computer X View Help Open Browse with Pro 5 Paint Explore Find 4 9 Scan for Viruses Add to Zip Menu Create Shortcut ins Delete Ravens briefcase Properties Ico n A Window Close Pointer The HCI must allow easy navigation Users should be able to move from one screen to another in a straightforward manner and to leave screens when they wish Some sites on the Internet for examp
13. d support In the case of a bespoke system the development team or the organisation it works for may offer training in the use of the new system Creators of software systems often establish help desks so users can obtain advice about the software Software does not wear out in any physical sense but the presence of errors or omissions will give rise to the need for maintenance This doesn t appear to be working HERIOT WATT UNIVERSITY 32 TOPIC 2 FEATURES OF SOFTWARE DEVELOPMENT PROCESS Software maintenance always involves a change in the software with the accompanying probability that additional errors may be introduced It is essential to ensure that adequate quality control is in place There are three types of software maintenance corrective adaptive perfective Corrective maintenance is concerned with errors that escaped detection during testing but which occur during actual use of the program Users are encouraged to complete an error report stating the inputs that seemed to provoke the problem and any messages that the program might have displayed These error reports are invaluable to the development team who will attempt to replicate the errors and provide a improved solution Adaptive maintenance is necessary when the program s environment changes allows the authors to provide a program which responds to changes in the operating environment For example a change of operati
14. d when it has been converted into code which can be used by the computer system eme Design Implementation Working program Documents which fulfils the specification The code is written in a high level language such as Pascal C or Java and converted into code which the computer understands A high level language is one that people find relatively easy to understand The code written at this stage is called source code The machine can understand machine code a translation of the source code into binary instructions This code because it can be executed by a computer is also known as executable code The translation from source code into machine code is carried out by a program called a compiler The resultant machine code is portable to machines of the same type running under the same kind of operating system Compiling and debugging large programs can take a lot of time Another form of translation that can reduce development time is an interpreter When an error is encountered the interpreter immediately feeds back information on the type of error and stops interpreting the code This allows the programmer to see instantly the nature of the error and where it has occurred He or she can then make the necessary changes to the source code and have it re interpreted As the interpreter is also executing each line of code one at a time the programmer is able to see the results of the program immediately which c
15. e devised against the specification so that you can see whether or not the program does what it is supposed to do In the full software development process test data should be prepared before implementation That is before you have invested time and effort in writing the code All too often there is a temptation especially at classroom level to start coding a program as soon as possible without having produced adequate test data But experience shows that this is a mistake Once you have written the code you will tend to go easy on it and let the program s behaviour shape what you expect of it You are going to be too kind to it MURPHY s LAW 1 MURPHY s LAW 2 The quicker program coding is started the Murphy s Law 1 is correct longer the project will take Testing follows a test plan or strategy Testing should be systematic That means testing is planned everything is tested a logical order the results of testing are recorded With most software projects the usual strategy is to test the software twice The methods are called alpha testing where the software is tested within the organisation beta testing where the software is tested by personnel outside the organisation or by certain members of the public This is sometimes called acceptance testing HERIOT WATT UNIVERSITY 2 6 TESTING 2 6 2 Alpha testing Test data is based on the specification Data will be designed to test three
16. entation documentation evaluation d Design documentation implementation evaluation Q2 Which one of the following is an essential item of documentation that should be produced during the software development process a Design notation b Test data c User interface d User and Technical Guides Q3 Which one of the following is NOT an aspect of the user interface of a program a Program listing b Help screens c Instruction screens d Screen layout 2 1 Introduction This topic considers the software development process From the initial client specification to the production of a working program can take considerable time and effort by the development team The process involves constant revision and evaluation at every phase which makes it an iterative process This ensures quality and efficiency in the final product Various models are introduced that aid the software development process but you will find that the perfect solution does not exist An individual may write a program for personal use If it does not work then it can be changed If more features or facilities are required then the individual can make amendments to their program This ad hoc method is not satisfactory in commercial environments where the goal is the creation of large scale software A more structured approach is necessary HERIOT WATT UNIVERSITY 12 TOPIC 2 FEATURES OF SOFTWARE DEVELOPMENT PROCESS The sole programmer Many unmanaged
17. entation for each stage of the development process will need to be corrected 2 6 3 Beta testing Otherwise known as acceptance testing it takes place after alpha testing The idea is to subject a completed program to testing under actual working conditions If a program has been developed for use by particular clients it is installed on their site The clients use the program for a given period and then report back to the development team The process might be iterative with the development team making adjustments to the software When the clients regard the program s operation as acceptable the testing stage is complete If a program is being developed by a software house for sale to a market rather than an individual client the developers will provide an alpha tested version to a select group of expert users such as computer journalists and authors and also makers of related computing products such as printers This group is known as an independent test group Alternatively they may use professional software testers This is of benefit to both parties the software house gets its product tested by people who are good at noticing faults and the writers get to know about products in advance which further benefits both parties when the final production software is released the HERIOT WATT UNIVERSITY 25 26 TOPIC 2 FEATURES OF SOFTWARE DEVELOPMENT PROCESS software house getting publicity and the writers receive credit for bei
18. interviews and questionnaires Additionally techniques such as automatic data logging are used Many organisations bring in consultants who design and carry out evaluations as the skills required to carry out effective evaluations are highly specialised The key criterion in evaluating a software product has to be whether it is fit for purpose i e does it meet the original specification and allow the client to carry out their tasks The evaluation is important for the user and the software author There are two reasons for conducting an evaluation does the software meet the users requirements how can the software house improve the product The performance of the system can be assessed in various ways how closely does it fit the system design how well does it meet the problem specification Questions may also be asked about matters such as e was the project within budget e was the project completed to schedule The development team will wish to review the project perhaps to learn from any mistakes to ensure they incorporate good points in future programmes Software houses aspire to produce new and better versions of their software They will study press reviews and note any contents and criticisms New or forthcoming changes in technology in operating environment and so on are also taken into account When the evaluation is complete work begins on the next version of the system For SQA assessment purpose
19. le include a site map to show the user how different forms are linked HCI must be consistent so that similar actions in different parts of the interface have similar responses throughout the program Prompts given to the user should be consistent Different screens should look as though they belong to the same software package The HCI should provide on line help offering intelligible prompts and send messages and warnings to the user about the consequences of choices made e g send a warning if a user chooses to delete data HCI design is based on an appreciation of what the user wishes to see The designer thinks in terms of the windows often called forms that are presented to the user Identifying characteristics of a good user interface On the Web is a interactivity You should now complete this task 2 4 3 Designing Data Structures A program must perform operations on the data supplied to it The data should be structured data The choice of data structure will affect the entire program When the amount of data is likely to be very large the designer must consider the HERIOT WATT UNIVERSITY 2 4 THE DESIGN STAGE physical capacity of the hardware For example a million records of a thousand bytes each will require about a gigabyte If the clients want these records ordered in different ways in different parts of the program even a modern PC may have insufficient memory Many large systems involve a database In ma
20. lysis design testing evaluation 0 9 HERIOT WATT UNIVERSITY 13 14 TOPIC 2 FEATURES OF SOFTWARE DEVELOPMENT PROCESS Q5 The software development process may involve iteration Which one of the following statements is true if iteration is used a The team may go back to an earlier stage to deal with a problem b The software is guaranteed to be error free c Each stage is carried out twice d Once all the stages have been completed the team go back and start again Q6 Software developers cannot get the software correct at the first attempt This is because Software systems can be very complex Unforeseen errors always creep in that take time to solve There could be problems with the client changing his her mind All of the above a b c d Q7 Regular feedback of information to members of the development team is important This is done in order to Speed up the development process Enable personnel to discuss progress Keep the team happy a b c d Lower the costs on a regular basis Sentence completion software development process On the Web is a sentence completion task on the software development process You should now complete this task 2 3 The Analysis Stage This stage is crucial to the entire cycle of events Any problems occurring at this stage will be propagated design through the system and will become increasingly costly to rectify when discovered
21. ng system could require changes in the program or a new printer might call for a new printer driver to be added to the program A change of computer system will require the program to be ported to the new system Perfective maintenance occurs in response to requests from the user to enhance the performance of the program This may be due to changes in the requirements or new legislation Such maintenance can involve revision of the entire system and can be expensive Matching definitions Maintenance On the Web is an interactivity You should now complete this task 2 10 Weaknesses of the software development process Problems are usually encountered when you use this model 1 Real projects rarely follow a linear sequential flow Apart from any software problems people change their minds and often there may be changes in legislation which mean that the program must be altered in order to comply with the new regulations No matter what the reason iteration always occurs and this creates problems because much of your work has to be re examined and revised 2 It is difficult for the customer to state all requirements explicitly at the start of developments The model depends on this and has difficulty incorporating customer uncertainty 3 Clients are frequently excluded from the development The working version of the program will not be available for the customer to see until late in the development cycle HERIOT WATT UNIVERSIT
22. ng up to date People involved in beta testing will send back error reports to the development team An error report is about a malfunction of the program and should contain details of the circumstances which lead to in the malfunction These error reports are used by the development team to find and correct the problem 2 6 4 Review questions Q16 Which one of the following statements describe alpha testing a Testing is done by the users b Testing is done within the organisation c Testing is done by specialist companies d Testing is done by the client Q17 Which of the following describes beta testing a The program is tested by the clients b The testing is more rigorous than alpha c The testing is for market research d The program is tested by specialist companies Q18 During alpha testing the program is usually subjected to exceptions testing This means a The input of unexpected data b The input of large numbers c The input of small numbers d All of these 2 7 The Documentation Stage Documentation is intended to describe a system and make it more easily understood Documentation will consist of 1 user guide 2 technical guide Some information may appear in both guides e g system specification Internal documentation such as remarks or comments in the code are for the benefit of the development team It will help if changes have to be made to the software in the future Other documentation fo
23. ny cases the data is held in different tables which are linked together These links are called relations and such a database is known as a relational database The fields that are to be in the tables and the relations between tables need to be defined at the design stage Object oriented design attempts to treat data and objects together An object brings together items of data and the operations that can be carried out on it For example a data item might be a customer s record the operations might include creating displaying editing and deleting 2 4 4 Other design choices The system specification and functional specification will form the basis for designing the program The design team must consider hardware specification choice of high level language e choice of operating system portability of the system Hardware aspects will include processor speed does the program require multiple processors for optimum performance as in networked database applications or maybe maximum memory for caching information on a regular basis How much external storage is required for say regular backing up procedures and on what medium This is an important issue especially on networked systems where users files are archived on a daily basis A high level language will be chosen that is best suited to the problem but also one which the programming team is conversant with and proficient in its use Modularity will be an im
24. odule library in the design For many software companies and programming departments one project will be similar to another Projects will have component parts which are similar for example many programs might require a sort routine to act on the contents of a database As time goes by a collection of modules is built up This collection is known as a module library Modules in the library can often be used over and over in new projects This saves time spent designing and coding If a module can be used without alteration there is the added advantage that it has been thoroughly tested and is reliable Use of unaltered modules reduces the time spent on the detection and correction of errors in the project as a whole Sometimes adjustments might be needed to a library module After the necessary work the module will require to undergo error and other testing Characteristics of module libraries On the Web is a interactivity You should now complete this task HERIOT WATT UNIVERSITY 2 6 TESTING 23 2 5 3 Review questions Q13 Which of the following is a quality of a good human computer interface It should be Windows based It can make a program execute faster It can make running a program a less irritable experience It should have lots of colour a b c d Q14 Which one of the following is not a high level language Visual Basic Pascal Assembler d C Q15 Which of these is not the result of c
25. ompilation a Executable code b Object code c Machine code d Source code 2 6 Testing Testing has several purposes It should check that e the software meets the specification design e itis robust e itis reliable testing documentation evaluation maintenance Commercial software is not exhaustively tested at the testing stage Software can be complicated and the available time is limited There must be a balance between creating a product for the market and exhaustive testing If errors become apparent after release the company will fix them and release an updated version Testing follows a test plan or strategy involving carefully selected test data with a view to ensuring that a reliable product has been constructed Important aspects would be what part of the program is being tested what is the expected output using suitable test data Testing is carried out at several stages during and after implementation HERIOT WATT UNIVERSITY 24 TOPIC 2 FEATURES OF SOFTWARE DEVELOPMENT PROCESS Unit Testing Module Testing Sub system Testing Integration Testing Acceptance Testing 2 6 1 Test data preparation Testing can never show that a program is correct Even with extensive testing it is almost certain that undetected errors exist Testing can only demonstrate the presence of errors it cannot demonstrate their absence Tests should b
26. ook wishes to emphasise or that a particular developer prefers HERIOT WATT UNIVERSITY 2 2 THE NEED FOR ITERATION In this course we will consider the following stages analysis documentation The idea here is that the development of the system flows down or cascades through the stages like water flowing down a fall As each stage is completed responsibility and control is passed down until the final section is completed The process as it stands represents an ideal world rather than reality Developers do not know everything the client will need at the start of a project they make wrong decisions possibly based on incomplete information The model can be improved significantly if it is made to be iterative Ideally you would start a process with the analysis and work through the stages in turn doing everything only once In practice this happens rarely People make mistakes faults become apparent that can only be corrected by going back to an earlier stage of the process An iterative development model There is an on line illustration of the need to use an iterative development model You should view this animation now 2 2 1 Review questions Q4 Which one of the following statements regarding the order of the stages in the software development process is correct Design implementation testing documentation Analysis testing implementation design Design testing evaluation implementation Ana
27. portant issue where the team can share the workload by compiling modules independently thereby reducing the overall development time Module libraries can be a source of standard algorithms to be used in software projects of many types Choice of operating system will relate to the functionality and feel of the HCI Windows might offer much in the way of colourful screens interactive help and dialogue boxes etc It must also affect how the program runs and behaves is the OS software stable enough for the developed program to behave normally without crashing or does the OS offer a true multi tasking environment as in UNIX with the added benefits of in built security Nowadays Linux is being seen as a viable operating system which is both stable and not difficult to use If the developed software can be moved to different machine architecture and still run to specification then it will be deemed to be portable In some cases this might not be required but it is a characteristic that good software should possess HERIOT WATT UNIVERSITY 20 TOPIC 2 FEATURES OF SOFTWARE DEVELOPMENT PROCESS 2 5 The Implementation Stage If the design has been thorough the implementation should be straightforward It should be a matter of design translating the pseudo code into code line by line implementation testing documentation evaluation maintenance 2 a lt The design is implemente
28. r the development team includes all the documents produced in the software development process requirements specification program design documents for the HCI and for the structure and logic of the underlying code a structured listing of the code and a test history HERIOT WATT UNIVERSITY 2 7 THE DOCUMENTATION STAGE 2 7 1 User guide The user guide contains information about how to install start and use software It should also contain a list of commands and how to use them Where there is a significant HCI the guide will show each form menu and icon and associated instructions about their use User guides may be supplied as paper manuals often with separate manuals for installation getting started and the user guide User manual Increasingly software vendors supply the manuals on disc or CD where they may be available in pdf or hypertext markup language HTML Paper manuals are costly to reproduce manufacturers frequently include electronic files which provide up to date amendments This lets the user read up to date information which could not be included in the original paper manual It is common for sample files to be included which complement the tutorial and provide the user with demonstration files The program should contain a help facility It is common for on line help to be presented in three tagged pages Contents Index and Search The contents present the help chapter by chapter the index refers
29. robust and reliable A reliable program is one that does not stop because of faults in its design A robust program is one that can cope with errors when it is running To put it another way an unreliable program is one that hangs or crashes for no apparent reason whereas a non robust program is one that cannot cope with events that the world HERIOT WATT UNIVERSITY 2 4 THE DESIGN STAGE 17 throws at it Identifying the characteristics of good software design On the Web is an interactivity You should now complete this task 2 4 1 Review questions Q8 Which one of the following processes describes breaking a complex system down into more manageable components top down design using pseudocode refined design prototyping Q9 Inthe software development process which of the following is a legal contract a functional specification b problem specification c requirements specification d software specification Q10 Which of the following are identified during the analysis stage of software development the main costs of the project time taken to complete the project hardware required to run the system d All of the above Q11 The completed software system should be able to cope with many errors while running This means that the software is choose one a Portable b Robust c Reliable d Stable Q12 Which of the following is included in the functional specification a description of wh
30. s you need to be able to evaluate software in terms of robustness reliability portability efficiency HERIOT WATT UNIVERSITY 30 La TOPIC 2 FEATURES OF SOFTWARE DEVELOPMENT PROCESS maintainability and from Int2 level readability fitness for purpose and quality of HCI Sentence completion Evaluation On the Web is an interactivity You should now complete this task Evaluation terminology On the Web is an interactivity You should now complete this task 2 8 1 Robustness and reliability There is often confusion between the terms robustness and reliability A program is robust if it can cope with problems that come from outside and are not of its own making e g corrupt input data Reliability is an internal matter A program is reliable if it runs well and is never brought to a halt by a design flaw When the program is complicated the distinction between the two terms is not always clear When a machine hangs it is not always obvious whether this is due to a failure in robustness or reliability Robustness The designer should try to ensure that the design is robust the resulting software should be able to cope with mistakes that users might make or unexpected conditions that might occur These should not lead to wrong results or cause the program to hang As examples of an unexpected condition we could take something going wrong with a printer it jams or it runs out
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