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HarAdmin: A Graphical Tool for Hyper G Server

1. amp Figure 6 15 Example Group Hierarchy for Deleting Group a In this example each group has two users named by group name e g group a has members al and a2 To delete group a select group a in the column Group s and press the Delete button in the Group Window Group and User Windows are updated and the Delete Dialog appears see Figure 6 17 Remember direct subgroups and direct users are highlighted The Group b and group c are direct subgroups and highlighted but as said before we want to delete group b and also the indirect group d Unselect group c by holding the shift key and clicking the left mouse button on group c select group d by holding the shift key and clicking the left mouse button on group d We also must select the direct users of group d dl and d2 otherwise group d can t be deleted and same for group b see Figure 6 18 Pressing the Ok button in the Delete Dialog all selected subgroups and users are deleted The new hierarchy after deleting groups a b and d is shown in Figure 6 19 0 9 EXample of Group Veletion 1 Group s Parent Groups No parent groups Description Example HarAdmin Figure 6 16 Displaying the Group Edit Delete Options 12 User s Hosts Passwords Groups No hosts i No passwords i No groups i Description Home Collection Account 0 E New Edt Delete Options Group 1 Group s Paren
2. update Windows User Group Search Resul Resu Search Haradmin HG CSP Hyper G Database Figure 7 1 The Three Main Classes of HarAdmin These three classes communicate with each other to send or retrieve messages including error messages to send or retrieve search requests and to retrieve a list of matching objects or a list of attributes of a certain group or user object Unapter i Lne Implementation or Haraadm n The classes User and Group manage the user interfaces and class Haradmin uses the Hyper G Client Server Protocol HG CSP to communicate with the Hyper G server To communicate with the Hyper G database an instance of the class HgStub is used 74 1 Class Haradmin The class Haradmin uses the previously discussed HG CSP messages for maintaining user accounts and user groups class Haradmin 1 Haradmin opens the connection to the Hyper G Server int getGroups RString amp filter RStringArray amp groups int getParSubDes RString amp filter RStringArray amp dpa RStringArray amp ipa RStringArray amp dsub RStringArray amp isub RString amp des int getLockedParentsDess RString filter RStringArray amp parents RStringArray amp dess int insEditGroup RString amp groupname RStringList pgrps RStringList ds int insNewGroup RString groupname RStringArray pgrps RStringArray ds int remGroup RString groupname void remSubGroups RStringArray amp subgrps RS
3. Geometry options Harmony Haradmin Harmony Haradmin Harmony Haradmin Harmony Haradmin Harmony Haradmin Harmony Haradmin Harmony Haradmin Harmony Haradmin Harmony Haradmin Harmony Haradmin Harmony Haradmin hghost hgiicm tu graz ac at hgport 418 Main geometry 300x115 10 5 Identify geometry 20 30 User geometry 680x375 10 160 NewUser geometry 720 180 EditUser geometry 720 160 User ptions geometry 720 160 Group geometry 680x360 10 580 NewGroup geometry 720 600 EditGroup geometry 720 580 Group0ptions geometry 720 600 DeleteDialog geometry 720 580 Options to enable or disable columns and lines in the User Window Harmony Haradmin Harmony Haradmin Harmony Haradmin Harmony Haradmin Harmony Haradmin Harmony Haradmin User ptions User ptions User ptions User ptions User ptions User ptions showhosts on showpasswds on showgroups on showdescription on showhome on showaccount on To show host by domain name domain or ip address ip or alias name alias Harmony Haradmin User ptions showhostby domain Options to enable or disable columns and lines in the Group Window Harmony Haradmin Group ptions showparents on Harmony Haradmin Group ptions showsubgroups on Harmony Haradmin Group ptions showdescription on 93 Appendix A DarAdm n A DEIAUults Appendix B HG CSP Commands used by HarAdmin The material in this sectio
4. groups with prefix i type or nothing and press Enter If you want see all and press Enter 4 1 hgaamun 29 Inserting a New Group Choose number 2 from the Main Screen enter the name of the new group and press Enter this leads to gt gt gt gt gt gt gt gt gt gt gt gt gt gt gt New Group lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt gt gt GroupName newGroup gt gt gt gt 1 Add to Parent Group gt gt 2 Add Description gt gt 3 Rem from Parent Group gt gt 4 Rem Description gt gt 5 Insert Group Object gt gt gt gt 12 qluit Commands of the New Group Screen e Add to Parent Group Choose this command to add a parent group to the new group to inherit the access rights Remember groups can be members of multiple groups which recursively leads to the collection hierarchy e Add Description Choose this to add a short description of the new group to the group object eg the meaning of the group DON T FORGET to use the command e Insert Group Object Try to insert the group object into the Hyper G data base Editing an Existing Group Choose number 4 from the Main Screen enter the group name and press Enter If you don t type any groupname you get a list of all existing groups If you type you get a list of all groups with prefix i This may lead to a screen similar to the following gt gt gt gt gt gt gt gt gt
5. uondioseq uiupyed oput ue utupVieH juaum2o q inu3 uonisog MOPUIM UIEN ullupVieH l L Jgou2uy uoneuns q aL se 1xo uonoejas asn A PEXO 66X0 uonsog AXODUIAA UIBJA XO uonduossag UWP YEH opp sMalA WOIl CI MOPU UIEN ultupvieH 5 uonduoseq uttupvieH s11 sioo1 gt s asn snowAuoue uon5 lloO tuoH unejeq WOII EI uon23 o2 tuoH s u3sIpulAA eipnej E suon29 oz euro sonr Buipnjour saasag uoneuuoju WOI EI 100g JadAH J EDRR Figure 5 10 Creating Links 993 vommunicating with Uther Users 9 0 79 00 00 68 10 00 89 10 00 17 10 00 87 00 00 20 20 00 S 20 00 28 00 00 28 20 00 65 80 00 22 10 00 10 10 00 22 70 00 tun lpi t0 90 SL LP S0 SL 2 S0 SL 81 50 SL 90 50 SL 85 70 SL 6P 70 SL bP70 SL 2p 0 SL 22 0 S1 L 0 SL L0 0 SL LS Z0 SL SUES sabessapy anes saBbessayy yenBurjyjnw 34e 3m yey S UBD PHOM Y ul jje OS ueuiac Ul YL ue 3A YUU iaysAs pUuIMd IH ua Boyd duinp uaaios e paau asne aq aDessaui e aw pues asea d 49494 IH ue Boxd 0 a essayy 1uas p34I3221 1X9 puag 0 x L 1 lBoyd 0 abessayy puss L LL SG L LL SG L LL SG L LL SG L LL SG L LL SG L LL SG L LL SG L LL SG uoissas jede zei ny Z0SSUIIIJ je se ze ny oul eoe ze ny zosswsny eoe zeJb ny oyu eoe zeJb ny zosswony jede ze n zosswioiy
6. Description Claudia Windisch gt gt Home collection cwind gt gt Additional groups ed95_part gt gt gt gt 1 Add Host gt gt 2 Add to Parent Group gt gt 3 Add Password gt gt 4 Add Password encrypted form gt gt 5 Add Description gt gt 6 Add Name of home collection gt gt 7 Rem Host gt gt 8 Rem from Parent Group gt gt 9 Rem Password gt gt 10 Rem Password encrypted form gt gt 11 Rem Description gt gt 12 Rem Name of home collection gt gt 13 Delete gt gt gt gt 14 qluit gt gt gt gt Enter your choice In this screen you see first all existing attributes of the user hosts displayed as Internet address and as domain name The listed groups are all direct parent groups the user is a member of and additional groups shows all indirect parent groups recursively iicm or system are subgroups of ed95 part Commands of the Edit User Screen e Add Rem entries Adding or removing an entry updates the database on each time Deleting an Existing User Choose number 3 from the Main Screen enter the name of the user and press Enter Select the number 13 from the Edit User Screen to delete the user If no error occurs like object locked from other users or permission denied the user is deleted from the Hyper G database 4 1 3 Managing Groups To see all existing groups on the current Hyper G host choose number 4 from the Main Screen then type
7. Document Full Text x nd on Wais im Z39 50 Hyper G EN TNT e Fe C FTP gt Legend x planned Figure 3 4 The Architecture of Hyper G On the left side of Figure 3 4 we see that e A Gopher client accessing the Hyper G server The Hyper G server maps the collection hierarchy into a Gopher menu tree Note that Gopher has no hyperlinks e A WWW client accessing the Hyper G server Each level of the collection hierarchy is converted to a HTML document containing a menu of links to the sub menus The menus are marked as searchable On the right side of Figure 3 4 we see that Hyper G clients can connect to Gopher WWW and WAIS servers to retrieve information from them stored on the Hyper G server as pointers to the remote objects e A Gopher server being accessed by a Hyper G client Gopher menus are trans formed into Hyper G collections e A WWW server being accessed by a Hyper G client WWW text documents are transformed into Hyper G text documents including also hyperlinks e A WAIS server accessed by a Hyper G client WAIS queries and responses are transformed into Hyper G queries and responses uhapter o Hyper ix e A FTP server accessed by a Hyper G client FTP directories are transformed into Hyper G collections Users and User Groups Other features supported by Hyper G and not found in comparable systems as Gopher and WWW include e User identification modes from an
8. G This makes it possible to insert manipulate and delete users and user groups 7 1 The Hyper G User Object The user object supports the attributes e UName The account name of the user e Group user is a member of at least one group e Passwd The password is in encrypted form There can be more than one Passwd entry for a user e Host The form user host is used for automatic identification e Home Name of the user s personal home collection e Descr Short description of user e g full name Account An amount of virtual money Not all attributes must be present for a user only UName and Passwd are neces sary for a user object for automatic identification Host is also needed 7 2 The Hyper G Group Object The group object supports the attributes e UGroup The Hyper G group name 17 Unapter i Lne Implementation or Haraadm n e Group parent group of the user group There can be more than one Group entry since a group can inherited from more than one parent group e Descr Short description of the group for example the purpose of the group Not all attributes are necessary for a group object only UGroup 7 3 The Hyper G Client Server Protocol The material in this section has been adapted from the technical report Hyper G Client Server Protocol HG CSP Version 7 05 written by Gerald Pani and Frank Kappe As mentioned at the beginning of this chapter Har Admin is based on the Hyper G Client Ser
9. Users may be organized into user groups User groups in Hyper G are hierarchically structured and a group can inherit from one or more parent groups The group hierarchy is like the collection hierarchy it is an acyclic directed graph As an example Figure 6 3 shows a possible group structure for a university 0 9 Managing User Groups Od university higher informatics mathematics d L hes 2 Se ower systems networks numerics Figure 6 3 A Group Hierarchy for a University Having an user that is member of the group numerics and informatics this user has all rights that are given to the groups university mathematics informatics and numerics but has no access rights of networks and systems In a group hierarchy exists direct and indirect parent groups and direct and indirect subgroups Direct and Indirect Parent Groups Direct parent groups are the nearest parents of a group For example group numerics has direct parent group group mathematics see Figure 6 3 An indirect parent group is a group with an higher hierarchical level than a direct parent group For example group numerics has indirect parent group group university Direct and Indirect Subgroups Direct subgroups are the nearest subgroups of a group For example group university has direct subgroups group informatics and group mathematics see Figure 4 1 An indirect subgroup is a
10. ciated mnemonic names and a short human readable description that could be output on a terminal for example Code Mnemonic Description 1 NOACCESS Access denied 2 NODOCS No documents 3 NONAME No collection name 4 NODOC Object is not a document 5 NOOBJ No object received 6 NOCOLLS No collections received 7 DBSTUBNG Connection to low level database failed 8 NOTFOUND Object not found 9 EXIST Collection already exists 10 FATHERDEL parent collection disappeared 11 FATHNOCOLL parent collection not a collection 12 NOTEMPTY Collection not empty 13 DESTNOCOLL Destination not a collection 14 SRCEQDEST Source equals destination 15 REQPEND Request pending 16 TIMEOUT Timeout 17 NAMENOTUNIQUE Name not unique 18 WRITESTOPPED Database now read only try again later 19 LOCKED Object locked try again later 20 CHANGEBASEFLD Change of base attribute 21 NOTREMOVED Attribute not removed 22 FLDEXISTS Attribute exists 23 CMDSYNTAX Syntax error in command 101 LUZ 24 25 26 27 28 29 30 31 32 33 34 35 36 37 NOLANGUAGE WRGTYPE WRGVERSION CONNECTION SYNC NOPATH WRGPATH PASSWD LC NO MORE USERS LC NO MORE DOCS RSERV NRESP Q OVERFLOW USR BREAK N_IMPL AppenalX Vo Hu Uor EITOT odes No or unknown language specified Wrong type in object Client version too old No connection to other server Synchronization error No path entry Wrong path entry Wrong password server to server server authentic
11. or hgtv Button Options Either by X Defaults or with the Option Window shown in Figure 6 12 you change e The look of the User Window by enabling or disabling certain columns and lines in the User Window e The display format for hosts options Users Show User 4 vf Hosts vf Passwords vf Groups vf Description vf Home Collection vf Account Host Alias Name P Address v Domain Name Ok Cancel L l Figure 6 12 The HarAdmin User Option Window 0 4 Manag ng Users 02 Button All ck This button changes the selection string User and Group field are set to and the User Window is automatically updated Button Show Group Selecting a group in the column Group s and pressing this button the Group Window is updated all attributes of the selected group are shown You also can double click with the left mouse button on the group in the column Group s to display the group in the Group Window Button Close Unmaps the User Window but does not destroy it If you press the User button in the Main Window again the old filters are reused to display all users of the current Hyper G server according to the selection string in the User Window 6 4 2 Creating a New User Only the system administrator and members of group system are allowed to create new users for users who are not members of the system group the New button in the User Window is disabled Pressing the New button in the User Windo
12. 5 Group Window Options Group Button All Changes the selection string to and displays all existing groups on the current Hyper G server in the Group Window Button Show Users Selecting a group in the column Group s and pressing the button Show User displays all direct and indirect users of the selected group in the User Window Unapter 0 HDarAdm n Lhe Harmony Administrator Button Close Closes the Group Window but does not destroy it If you press the Group button in the Main Window see Figure 6 1 the previous selection string is reused to display all groups according to the selection string 6 3 2 Creating a New Group Only the system administrator and members of group system are allowed to create new groups For users who are not members of the system group the New button in the Group Window is disabled Groups should be created before user accounts because users are members of at least one existing group A group comprises the following attributes Group unique name of the group and which must be a single word The group name is mapped to lower case letters on insertion Parent Name of the parent group This attribute is used to create a group hier archy To add additional attributes choose the corresponding one from the selection menu above the buttons Commit Clear Close The focus is set automatically Button Commit Sends the group object to the database for insertion The field valu
13. G is not a stand alone system it supports as much interoperability as possible with existing systems like Gopher WAIS and WWW Hyper G is one of the best Web servers AKM95b around and uses the Client Server Model with clients and servers connected over the Internet using TCP IP The Hyper G Client Server Protocol KP94 coordinates the communi cation between the Hyper G client and the Hyper G server The Hyper G server consists of three distinct servers The Link Server an object oriented database of objects and relations between such objects the Document Cache Server for caching documents and protocol and format converter and the Full Text Server for full text retrieval document clustering and automatic link generation The Harmony Client of Hyper G a X Windows based client provides naviga tional facilities and information feedback about the location of information The main part of Harmony is the Session Manager which communicates with the Hyper G server and coordinates all other activities Harmony supports several viewers and every document type has its own viewer text image audio film 3D scene postscript All viewers share a common user interface style If you know one you know all as well HarAdmin the Harmony Administrator for Hyper G Server Administration is a graphical X Windows based tool for maintaining user accounts and user groups The basic functionality is based on hgadmin a VT100 terminal based version
14. Ix Ez i BB 1 Figure 5 8 Inserting New Objects OL UOA JAAS SWOH Jap 1S WOII S9p weIs ssuoyeuuozuj seq u3I u 1sO ZeD JESJA uauosiuuoe Jap UPIN anau 94zjnjsabsazndwos pun BunyequiejeAsuonguuoju ing ynnsu ADI we aAsag 5 18d H uir unu qois uapuyaq ais 182 ze nyw oyu 3soH i ways s pumma wasn 1 WOII 244 0 SWM 15219ju jo suia C sa2ua13Ju05 LT eujsny jo saBeui E gt eu jS pue zeig ynogy DII m o auo2joM j 2u ps 49jnduio I si Alu jo jeuunor SONT P 5 19dAH 1noqy I JO 1 A4 sS BUOY y SI J9AI9S uoneunojul NOLI YL eugsny ABojouysa Jo Ay s aalun zeis jo eipajq man pamoddns wo aun mogy DI J jndwop pue Buissa2o4g uoneuuoju 10 Synyysu J9AIOS sui nogqy J WOII ay 1e Jaasas 5 18d H au Burssa22e mou Sue noA WON we uawwoyiim P WOII 8ul 0 awo M 7 WOII 24 0 awospa s asn snow uoue UON22 09 euo ynejed WI P gt uono lloO euroH s yas puly ephe gt suono SWOH Son Bulpniou 18A19S uoneuuojul WOI EI 1004 19d H cS Figure 5 9 The Multilingual Feature vommunlcati ng with Uther Users 9 0 ine Harmony Vient for Hyper uhapter o 94 00L b djaH ZGLXLZb ddI je oe ze16 nyuioirojur 3s0H waysAs pulmo asp 403e siumuipy AuouneH uoydussag ultupVvieH OpUIAA UIEN 34 SI uper jo ped uw ayy SI3AI9S y 19d H 104 001 uongajsiumupe jeaiudeJB e si unupYueH
15. all attributes of the selected group insNewUser void insNewUser It is called when the Commit button in the New User Window is pressed It stores all given attributes in arrays and sends the arrays and the user name to the class Haradmin for insertion insNewUser If an error occurs the method displays Unapter i Lne Implementation or Haraadm n the error in a message box and sets the focus to the line which contains the wrong value If no error occurs it calls the method userWindowUpdate to display the new user and the user s attributes in the User Window o deleteUsersFromGroup void deleteUsersFromGroup This command is called from the class Group when a group has members and therefore cannot be deleted It is used to update the UserWindow displays all direct and indirect users highlights all direct users and changes the user filter to the group filter to group and 7 4 3 Class Group The class Group manages all activities of the Group Window the New Group Win dow and the Edit Group Window It sends requests to classes Haradmin and User class Group public Group Haradmin User only initializes variables void groupMenu void usersForGroup private void showSubGroupO void showParentGroup void newGroupWindow void editGroupWindow void insNewGroup void insEditGroup void removeGroup void removeSubGroups void groupWindowUpdate void ggroupFilterAccept
16. and the Hyper G Client Server Protocol This thesis provides a user manual for HarAdmin and discusses the Hyper G Client Server Protocol commands used by HarAdmin The user manual describes in which way user or group objects can be inserted manipulated or deleted from the Hyper G database HarAdmin provides functions to navigate through the user group hierarchy for example to see the parent groups or subgroups of a certain group or the host accounts of a certain user This thesis gives a detailed example of deleting a group because deleting a group is more difficult than deleting multiple users Hyper G has a group hierarchy and the preconditions for deleting a group are all of the groups direct subgroups have to be deleted or unlinked and all direct members have to be deleted or unlinked Finally this thesis gives a short description of the Hyper G Client Server Pro tocol the message used by HarAdmin and the implementation of the three main C classes of HarAdmin Have fun using HarAdmin Chapter 2 Internet Information Systems The Internet Kro94 The95 LPJ 94 the worldwide network of networks is steady growing and supports several different information systems The Internet was born about 20 years ago to connect the ARPAnet Advanced Research Project Agency and various radio and satellite networks together The purpose of the ARPAnet was to build a network that could withstand unforeseen breakdowns of certain nodes durin
17. displayed with the Harmony VRweb 3D scene viewer see Figure 5 4 Users can view a model of a scene by moving themselves walk fly fly to headsup and manipulate an object translate rotate zoom Links can be attached to objects within a scene or groups of polygons within an object Harmony VRweb a D File Navigate Anchors Document Display Help F p Walk Fly Fly To Heads Up mm l BN Graz 3D Model SDF 8859 polygons Figure 5 4 The 3D Scene Viewer The PostScript Viewer displays documents in PostScript format and supports rectangular link anchors The documents are uncompressed locally by the viewer Harmony supports title keyword and full text search The user has the possi bility to restrict the search to the local server a particular collection or all Hyper G servers in the world The result of the search is an ordered list of matching objects as shown in Fig ure 5 5 By single clicking a certain object the Session Manager updates the collec tion hierarchy to display the path to the selected object The local map facility Figure 5 6 similar to the local map of Intermedia Mey86 It provides a kind of short range radar generating on request a map of the vicinity of a document The user has the possibility to double click on an uhapter o Lhe Harmony Vilent for Hyper kx Local Server Active Collections Selected Collection Result Search for User In fTitle o
18. erver 99 4 2 Netscape Commerce Server In October 1995 Netscape announced their new Netscape Commerce Server with special features It can support flexible user authorization HTTP 1 0 access autho rization and it can control access to individual files or directories using a username and a password domain name host name IP address or named group Netscape user groups are different to Hyper G groups because Netscape can not support a hierarchical structure of user groups After installing a Netscape Commerce Server NCS you have to create a new user database add users to the database and then apply access control 4 2 1 Managing Users The NCS uses HTML forms to manage users and user groups The main page of the Netscape Commerce Server administration tool is shown in Figure 4 2 Each underlined line points to forms which in turn have many links to each other vy User Databases User database creation destruction O Create a new database O Remove an existing database O Convert an NCSA database to DBM format O Modify a database s administrative password Database user manipulation O Add user s to a database O Add users from a text file O View the contents of a database Edit users in a database O Remove users from a database Vl Access Control and Dynamic Configuration Access Control O Restrict access to part of your server through authentication O Restrict access from certain addresses
19. gt gt gt gt gt gt Select Group lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt gt gt GroupName i gt gt gt gt 1 idg IDG Communications News Service gt gt 2 iicm IICM IHM Mitarbeiter gt gt gt gt 3 qluit Unapter 4 server Administration 10015 Now choose one of the displayed groups This may lead to gt gt gt gt gt gt gt gt gt gt gt gt gt gt gt Edit Group lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt gt gt GroupName Liicm gt gt BaseGroup Led95_part gt gt Description LIICM IHM Mitarbeiter gt gt gt gt 1 Add to Parent Group gt gt 2 Add Description gt gt 3 Rem from Parent Group gt gt 4 Rem Description gt gt 5 Show User gt gt 6 Delete gt gt gt gt 7 qluit gt gt gt gt Enter your choice In this screen you see first all existing attributes of the group The listed base groups are all direct parent groups the group is a member of and additional groups shows all indirect parent groups if exist Commands of the Edit Group Screen Add Rem entries Adding or removing an entry updates the database on each time Show User Shows all users within this group recursively Deleting an Existing Group Choose number 4 from the Main Screen enter the name of the group press Enter and choose the number 6 command Delete from the Edit Group Screen to delete a group 4 2 iwetscape Commerce
20. hghost yourhost hgport yourport or by setting the following X Resources Harmony Haradmin hghost your host Harmony Haradmin hgport your port e From within Harmony By setting up the X Attribute Harmony Session Collection tools haradmin Harmony Session Collection Tools haradmin commandline haradmin hghost host hgport port Harmony Session Collection Tools haradmin menuentry HarAdmin the user can start Har Admin from the File menu of Harmony HarAdmin has following commandline options haradmin options h help displays usage and defaults hghost name name of Hyper G server hgport port port number usually 418 The Main Window of HarAdmin After starting HarAdmin in one of the two above described ways the Main Window in Figure 6 1 appears The Main Window is the central point of HarAdmin and the three buttons each activate their own window The windows and their functionalities are described in the following sections HarAdmin uses automatic identification if configured and displays the user name and the current Hyper G host in the status line of the Main Window To exit the administration tool choose from the File menu of HarAdmin the command Exit Program 0 2 laentily ng LOUrsell to the perver If 1 Harmony Administrator RR File Help Identify Users Groups User cwind system Host info iicm tu graz ac at Figure 6 1 The HarAdmin Main Window Automatic Identification Having a user
21. map facility of Harmony HarAdmin is nevertheless a great step forward in maintaining user accounts and user groups under Hyper G Chapter 9 Concluding Remarks Simple and efficient access to information is the key to development Twenty years ago a great step was made The Internet the network of networks was born Be cause of the huge amount of information available on the Internet the user has difficulty gaining an overview and finding desired information Many different sys tems have been built to help the user to overcome these problems of disorientation Archie a directory server for locating files by name WAIS a search engine for full text searching Gopher the first system to provide browsing and full text searches and WWW the first generation hypermedia information system But they all to gether do not have the power to exploit the large information and communication resources available on the Internet Hyper G the first second generation hypermedia system was built to overcome some of the problems of distributed hypermedia systems It provides search naviga tional and orientational facilities structures its information in so called collections and builds a hierarchical structure called collection hierarchy It differs in many ways from previous systems it stores links in a separate database it supports links not only in text documents also MPEG video clips audio and 3D scenes Harmony the Unix client for Hyper
22. only in the local server the user has to identify to one server only e 5tatistics and user profile information can be gathered on a per session basis 9 9 Lne Hyper server Zl e Since every call passes through the local server billing can be performed The Hyper G server connects transparently to other servers on demand The architecture of Hyper G shown in Figure 3 4 consists of three distinct servers e Link Server e Document Cache Server e Full Text Server 3 3 2 Link Server hgserver As mentioned in the previous chapter Hyper G separates links from documents and stores them in a separate database as was pioneered by Intermedia One advan tages of this is that the user can attach links such as annotations to a document even when the document itself cannot be changed for example if the user has no access rights or the document 1s stored on a CD ROM Another feature of a centralized link store is that the system can support bidi rectional links The user has also the chance to go backwards Such links are preconditions for automatic link maintenance No dangling links can occur when a document is deleted or moved and for a local map which shows incoming and outgoing links of a certain document Links also may be assigned attributes such as access permission so links may be made visible only for a certain user or user groups A big difference to other systems is that Hyper G supports links in all kinds of documents s
23. or more users Before a group can be deleted two conditions have to be fulfilled e All direct users of the group have to be deleted e All direct subgroups of the group must be unlinked or deleted If at least one of the conditions is not fulfilled the Delete Dialog shown in Figure 6 10 appears Subgroups exist If one or more subgroups exists the column Subgroup s in the Group Window is filled and all direct subgroups are highlighted If the parent of the group is deleted and the group itself not than the group is simple unlinked from the parent Users exist Ve HANNS HD Ruh NM UNIS RARI MU New Edit Delete Options coa E HH 1 Group s Parent Groups Subgroups informatics university networks systems Description A Figure 6 9 Displaying the Group informatics All existing users are displayed in the column User s in the User Window Di rect users are also highlighted If at least one direct user is present the group cannot be deleted The user must either be selected for deletion or removed from the group using the Edit User Window delete the group attribute If all conditions are fulfilled the selected group is deleted the selection string is set to and all remaining groups are displayed in the Group Window Delete Group a vf Selected Users vf Selected Subgroups Figure 6 10 Group Window Delete Dialog Unapter 0 HDarAdm n Lhe Harmony Ad
24. the problem of seeing the same document again and again can occur Is this information the newest one If users found information about a certain topic they are not sure if that information is really the newest one Hyper G is a second generation hypermedia system which helps solve these problems by using tightly coupled structuring search and linking facilities and sophisticated user interface metaphors Chapter 3 Hyper G Hyper G is the first second generation hypermedia information system AKMS95 F1095 It is designed as a general purpose large scale distributed multi user sys tem and it is similar in scope to Xanadu Nel87 Intermedia Mey86 WAIS Gopher and WWW Hyper G AKM95a DH95 is under development at Graz University of Technology It is based on the Client Server Model across the Internet and provides as much interoperability as possible with similar existing tools and services Some primary design goals were to Provide orientational and navigational aids like local map and hyperlinks e Provide automatic structuring and maintenance e Reduce fragmentation across servers the consistency of data links etc is preserved eg no dangling links can occur when a document is deleted or moved e Support user identification and access control e Support multilinguality German English Spanish etc e Maintain interoperability with existing systems like Gopher WAIS and WWW 3 1 Special Facilities
25. to them Only identified users have the possibility to send messages ine Harmony VLLent for I1yper vix uhapter o 40 WOII 34 1noqy punoue sapou SOL 6881 ainyysuy ary jo uoyein neu uononpoaul WOI au inoqy m euia u1 suodeg jauuosiad DJ i faeiqr WOI 210022913 ET wing H Janey mj Has o LJ 9 19d H ynogy J 219 JO ALD Sul Ey N wayu WI DI 485 AH 1noqv EY 6881 aynyysuj y jo uoneanBneuy r u Jo sie quis J soBeui nogy red W 91 Jo uoisiH ER sa ew aul WO LI abeg awoH s yaneuusan s WOII 24 0 3w Z y U95SSIM seq uoyixa s III 34 inoqy 3 uouueH WOI we uw uonduosap japo uon wns yuawasu Aue g 7 jeusdui 2y jo jeesyunag au Jo jap unsse1dui gero Bunglaiyosag IPPON 35019 suondo e4 u29 W311 84 01 3wW0313M sioyouy 4 youras djaH dejds g juauinzoq sioyouy ajDieN lli Em 4A8malA JAL ajay suoydo wiajshg sioyouy mai ayebinen upz 3i cle Woll eur noqy EI 1 A4 S sit jnogy E WOII 24 0 Sulo2 9AA l s1 sn snow uoue uoaa uuoH Aneppa Wal E paloig osegied H I sz gae E 1 5 BB 1 Figure 5 6 The Local Map ad vormumunicating with Uther Users 9 0 10 N sa9uadajuo lt b c x u N 19110 zzer uy emm WaL OC TGWER Co W n o o aus E MER Y ys
26. 2 of the example for Document Anchor Relation and the circle is closed Objects and Relations Link Anchor Relation ObjectID 3000 Source Dest Link In a nivel 1235 2001 3000 ObjectID 1235 Type Anchor Position 100 230 Anch Position 521 623 1234 1235 ObjectlD 1234 2000 2001 ObjectID 2000 Type Document Lus Type Document Title Document A Title Document B Host otherhost Path otherpath ObjectID 2001 Type Anchor Doc Anchor Relation Host myhost Path mypath Figure 3 5 Some of the Link Server s Internal Objects and Relations Internally the link server comprises several components as shown in Figure 3 6 uhapter o Hyper ix e a low level database dbserver The dbserver knows about object and relations on a primitive level It is used to perform fast atomic functions e g locking an object and stores the link information of all documents e a full text server ftsever The ftserver is dedicated to full text retrieval document clustering and auto matic link generation e a number of high level database engines one per connected client hgserver Hgserver talks to the client using the Hyper G Client Server Protocol The hgserver knows about the user context and is a high level view of the database For example it knows what to do when an object is to be deleted The importa
27. 4 Deleting Existing Users 4 2 iwetscape Commerce erver o Viewing the Content of the Database A simple form shown in Figure 4 5 which shows the content of the previously selected database Only the usernames are displayed nothing more But you can easily switch to the froms for editing or removing an existing user amp L3 Choose a database The selector below should list all the user databases on your server Select one that you want to view and click View this database to view it Select a database cwinddb View this database Database cwinddb is a DBM database It has an administrative password Edit Remove admin Edit Remove cwindl i Figure 4 5 Viewing the Database Apply Access Control After added users to a database you have to apply access control As said before the Netscape Commerce Server supports user authorization and distinguishes between three different types of access as shown in Figure 4 2 e Restrict access to parts of the server Figure 4 6 e Restrict access to certain addresses Figure 4 7 You can restrict access to pages on your server by hostname and IP address e Restrict usage of file system links a file can be in two places without coping it Figure 4 8 Certain files are too important that every user can create links to such files such as system password files Unapter 4 server Administration 10015 L gt Which users Next you should tell the server which users from the
28. 6 7 Creating the Group networks university no parent group s Informatics parent group university mathematics parent group university systems parent group informatics networks parent groups informatics and mathematics numerics parent group mathematics The complete hierarchy in Figure 6 3 is shown in the window of Figure 6 8 by selecting the group university By selecting for example group informatics all columns are filled as illustrated in Figure 6 9 6 3 3 Editing an Existing Group Only members of group system are allowed to change the attributes of an existing group Select the group to be edited in the column Group s and press the Edit button Overwriting an existing attribute changes the attribute clearing the field Unapter 0 HDarAdmi n ihe Harmony Administrator New Edit Delete Options Group university 1 Group s Parent Groups Subgroups university No parent groups informatics mathematics networks numerics systems Description First Level All Show users Figure 6 8 Displaying the Group university I deletes the attribute Note that you cannot easily change the name of the group To change the name the group must be deleted and created new again 6 3 4 Deleting A Group In contrast to deleting users only one group can be selected in the column Group s The group hierarchy makes deleting a group much more complicated than deleting one
29. CSP command Change0bject and after all changes are made it sends back no error to the Group class The differences between insNewGroup and this message are it gets a list of parent groups instead of an array and it has to unlock the group object after changing it HG CSP UnLock Possible error codes 1 Database busy 2 ChangeObject failed void remGroup RString groupname It is used to remove one group from the Hyper G database If the object 1s not locked no subgroups and no members exist the group is deleted with the HG CSP message deleteObject and no error is sent back to the Group Window to be updated see groupWindowUpdate If members or subgroups exist the error code 3 1s returned to the Group class Possible error codes are a 4 Lhe Vor vUlass otructure of MarAdadmin o 1 Database busy 2 Object is already locked 3 DeleteObject failed subgroups or members exist remSubGroups void remSubGroups RStringArray amp subgrps RString amp groupname It is called after the Ok button in the Delete Dialog is pressed remSubGroups first recursively unlinks all subgroups from their parent groups if they should be deleted HG CSP ChangeObject Then it deletes all selected subgroups and the group selected in the column Group s in the Group Window HG CSP deleteObject o getSubGroupsAnd Users void getSubGroupsAndUsers RString groupfilter RStringArray amp dgrps RStringArray amp igrps RStringArra
30. FieldEditor31 char amp groupMenu void groupMenu It is used to build the Group Window If the Group Window already exists the Group Window is only mapped again At the beginning the group filter is set to These filters are used to search the database for existing groups getGroups To send the filters to the class Haradmin the method ggroupFilterAccept is used t NE U TT lass otructure Ol MarAdmin which builds the selection string sends it to Haradmin and after receiving the matching objects updates the Group Window o groupWindowUpdate void groupWindowUpdate It is activated when the user double clicks on a certain group in the column Group s to display all attributes of the selected group o showParentGroup showSubGroup void showParentGroup and void showSubGroup They are called when the user double clicks in the columns Parent Group s o Sub Group s to display all attributes of the selected group E newGroup Window void newGroupWindow It builds and initialize the lines in the New Group Window o edit Group Window void editGroupWindow It builds and initialize the lines in the Edit Group Window o usersForGroup void usersForGroup Is activated when the Show Users button in the Group Window is pressed It checks if a group is selected and then activates the method usersForGroup of the class User to display all users of the selected group in the User Window o insNe
31. G has structuring and retrieval facilities to provide nav igational and orientational facilities and information feedback about the location of information One of the most important differences is that Hyper G supports anonymous and identified access user accounts and a hierarchical scheme of user groups to grant or deny access rights to certain parts of the Hyper G information space HarAdmin the graphical administration tool for Hyper G servers was discussed in detail in this thesis Chapter 6 described in which ways user accounts and user groups can be inserted manipulated and deleted from the Hyper G data base Hyper G supports structures of groups and subgroups which form an acyclic directed graph Therefore deleting a group is complicated and certain preconditions must be fulfilled to delete a group HarAdmin has taken the place of the now more or less obsolete hgadmin administration tool which is terminal based and considerably less appealing to use 91 uhapter 7 vonciuding Memarks HarAdmin is based on the Hyper G Client Server Protocol The Hyper G Client Server protocol messages used by HarAdmin and the implementation of it are described in detail in this thesis for extending Har Admin in the future HarAd min is now the definitive administration tool for maintaining user accounts and user groups under Hyper G Appendix A HarAdmin X Defaults Default Hyper G host and port Harmony Haradmin Harmony Haradmin
32. G server on hghost Default is 418 or SHGPORT from environment updhelp Update Hyper G help entries 4 1 1 Using hgadmin Note that only the system administrator hgsystem and members of group system are allowed to insert edit and delete user accounts and user groups Other persons are only allowed to see all existing user accounts and user groups and they can only change their own attributes except adding themselves to a parent group After typing hgadmin in the commandline the user will see output similar to the following The material in this section has been adapted from the manpages for hgadmin written by Gerald Pani 4 1 hgaamun LI gt gt gt gt gt gt gt gt gt gt gt gt gt gt gt Hyper G Administration Tool lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt gt gt User cwind system gt gt gt gt gt gt 1 New User gt gt 2 New Group gt gt 3 Edit User gt gt 4 Edit Group gt gt 5 Identify gt gt 6 Update Help gt gt gt gt 7 qluit gt gt gt gt Enter your choice To choose a menu entry the user has to type in the corresponding number or the beginning of the description say 5 I Id for Identify In the first line of the Main Screen the identified user is displayed if this user is a system administrator or a member of group system it is displayed like in the above Main Screen eg cwind system Commands of the Main Scree
33. HarAdmin A Graphical Tool for Hyper G Server Administration Diplomarbeit der Technischen Mathematik TU Graz Claudia Windisch Technische Universit t Graz Institut f r Informationsverarbeitung und Computergest tzte neue Medien IICM Fertigstellung 30 November 1995 Begutachter o Univ Prof Dr phil Dr h c Hermann Maurer Betreuer Dipl Ing Keith Andrews Ich versichere diese Arbeit selbstst ndig verfa t andere als diese angegebenen Quellen und Hilfsmittel nicht benutzt und mich auch sonst keiner unerlaubten Hilfsmittel bedient zu haben Die Diplomarbeit ist in englischer Sprache Danksagungen Ich m chte mich beim Begutachter dieser Arbeit o Univ Prof Dr phil Dr h c Hermann Maurer und bei meinem Betreuer Dipl Ing Keith Andrews herzlich f r Ihre Unterst tzung bedanken Besonderer Dank gilt auch den anderen Mitarbeitern des Institutes im beson deren Dipl Ing Bernhard Marschall Dipl Ing Gerald Pani Dipl Ing Michael Pichler und J rgen Schipflinger die mir bei meiner Diplomarbeit stets mit Rat und Tat zur Seite standen Au erdem bedanke ich mich bei meiner Familie daf r da sie mir das Studium erm glichte Abstract This thesis gives a short overview of information systems available on the Inter net and a detailed description of Hyper G the first second generation hypermedia information system The biggest problem of distributed information systems is dis orientation Because of
34. LEINER B editor Proc INET 93 San Francisco California DCC 1 DCC 9 August 1993 Internet Society KAPPE F and PANI G Hyper G Client Server Protocol HG CSP Version 7 05 Technical report IICM Graz University of Technol ogy December 1994 Available at ftp ftp iicm tu graz ac at pub Hyper G papers HG CSP 7 05 ps gz KAPPE F PANI G and SCHNABEL F The Architecture of a Mas sively Distributed Hypermedia System Internet Research Electronic Networking Applications and Policy 3 1 10 24 Spring 1993 KROL E The Whole Internet User s Guide and Catalog O Reilly amp Associates second edition April 1994 LINTON M A CALDER P R and VLISSIDES J M The Design and Implementation of Inter Views In Proc USENIX C Workshop Santa Fe New Mexico November 1987 Liu C PEEK J JONES R Buus B and NYE A Managing Inter net Information Services World Wide Web Gopher FTP and more O Reilly amp Associates Sebastopol USA December 1994 LINTON M A VLISSIDES J M and CALDER P R Composing User Interfaces with InterViews IEEE Computer 22 2 8 22 Febru ary 1989 DIDLIVGNAL TAY LUO MA95 Mar95 Mau92 Mau96 Mey86 Nel87 Sch95 Ste91 Str91 The95 MCCAHILL M P and ANKLESARIA F X Evolution of Internet Gopher Journal of Universal Computer Science 1 4 235 246 April 1995 MARSHALL B Integration of Digital Vi
35. O Restrict usage of file system links Dynamic Configuration O Configure per directory configuration files Figure 4 2 The Main Page of The Netscape Commerce Server Insert Delete Edit Users The forms for adding deleting and editing shown in Figures 4 3 and 4 4 have a simple user interface A user object consists of an username and one password and there exists no group hierarchy like in Hyper G After having identified oneself as the system administrator you can insert edit and delete users Unapter 4 oerver Administration 10015 L Administrative password If this database currently has an administrative password you should enter it here You should consider turning off the administrative password if you are going to be adding a number of users then turning it back on again when you re done Administrative password amp L3 New username and password Next you should enter the username and password of the user you wish to add Remember that this is an HTTP user not an actual UNIX user The user will only be created for the server in the database you selected above Also you should not use colons in the username nor should you choose the username admin because they will cause problems with the way the databases are handled by the server Username Password Figure 4 3 Adding a New User EIS Username to delete Enter the username you want to remove Username to remove cwindl Figure 4
36. OLLER MANN B World Wide Web The Information Universe Electronic Networking Research Applications and Policy 2 1 52 58 Spring 1992 BERNERS LEE T CAILLIAU R LUOTONEN A NIELSEN H F and SECRET A The World Wide Web Communications of the ACM 37 8 76 82 August 1994 CAILLIAU R About WWW Journal of Universal Computer Sci ence 1 4 221 231 April 1995 103 104 DH95 DR94 ED92 Ey195 F1095 Kap93 KP94 KPS93 Kro94 LCV87 LPJ 94 LVC89 DIDLIU N BI AAT TAY DALITZ W and HEYER G Hyper G Das Internet Informationssystem der 2 Generation dpunkt October 1995 In German see http www dpunkt de DECEMBER J and RANDALL N The World Wide Web Unleashed Sams Publishing Indianapolis USA 1994 Available at http www rpt edu decemj works wwwu html EMTAGE A and DEUTSCH P archie An Electronic Directory Ser vice for the Internet In USENIX Winter 1992 Technical Conference Proceedings pages 93 110 San Francisco CA 1992 USENIX Associ ation Eyt M The Harmony Information Landscape Interactive Three Dimensional Navigation Through an Information Space Master s thesis University of Technology October 1995 Available at ftp ftp iicm tu graz ac at pub Hyper G doc eyl ps FLOHR U Hyper G Organizes the Web BYTE pages 59 64 No vember 1995 KAPPE F Hyper G A Distributed Hypermedia System In
37. The Hyper G Group Object 2 2 2 En nn nn 17 17 3 The Hyper G Client Server Protocol 2 22222 78 74 The C Class Structure of HarAdmin 0 0 000 79 74 1 Clas Haradmin 0 a 80 7 4 2 Class User 2 2 ee 84 1 4 8 Class Group rs 86 8 Future Work 89 9 Concluding Remarks 91 UUINLEUN LO D A HarAdmin X Defaults 93 B HG CSP Commands used by HarAdmin 95 C HG CSP Error Codes 101 UUINLEUN LO List of Figures 2 1 3 1 3 2 3 3 3 4 3 5 3 6 4 1 4 2 4 3 4 4 4 5 4 6 4 7 4 8 4 9 5 1 5 2 5 3 5 4 5 9 5 6 5 7 5 8 5 9 A Small Hypertext rs 12 The Hyper G Data Model 2 2 2 En 16 The Collection Hierarchy 2 2 2 CE Eon 17 Three Types of Collection 2 2 2 22 Emm nn 18 The Architecture of Hyper G 2n 19 Some of the Link Server s Internal Objects and Relations 23 Internals of Link Server 2 2 oo on nn 24 A Small Group Hierarchy 2 2 2 on Emmen 27 The Main Page of The Netscape Commerce Server 2 2 2 2 35 Adding a New User es 36 Deleting Existing Users 2 onen 36 Viewing the Database 3T Page for Access Control 1 Part of Server x llle 38 Page for Access Control 2 Certain Addresses 2 2 2222 38 Page for Access Control 3 File System Links les 39 Changing a Text File to DBM Format lens 40 The Architecture of Harmony lens 41 The Session Manager se 43 Viewers of Harmony Eon
38. above database should be allowed access Users should be chosen with a wildcard pattern For example if your database contained a list of your friends including Bob Fred Mary and Joe but you only wanted Bob and Joe access to this section you could use a wildcard pattern of Bob Joe as your allowed users Or if you leave this entry blank all users from the database will be allowed access You can view all the users in a given database with this form Users to allow cwindl cwind2 amp L3 Realm The realm is the name the server gives to the user so that they can identify which part of the server they are connecting to For example if you were restricting access to the current issue of your online magazine you might give the realm Current issue Reaim Current issue Figure 4 6 Page for Access Control 1 Part of Server Hostnames to allow IP addresses to allow Figure 4 7 Page for Access Control 2 Certain Addresses 4 2 iwetscape Commerce o erver DI gt Choose to disable enable links You should choose whether or not to allow links in the resource you have selected and what level of restriction you want I d like to enable the use of soft file system links I d like to disable the use of soft file system links entirely I d like to disable the use of soft links when the owners do not match I d like to enable the use of hard file system links I d like to disable the use of hard file system li
39. account with only username password home collection and groups implies that the user has to identify manually at the beginning of every Hyper G ses sion This can be disturbing especially when frequently using offline tools Hyper G uses automatic identification to prevent this For automatic identification the user name the machine names and the matching encrypted password of the users Unix account on the client machine are to be added to the user attributes 6 2 Identifying Yourself to the Server Hyper G distinguishes four user identification modes 1 anonymous user Such users have no account names and no passwords and have no chance to see anything about users or user groups on the current Hyper G server The User and the Group button are disabled 2 semi identified user The user uses a pseudonym nickname as username and only the system administrator knows the full identity of the user 3 fully identified user The user has an user account and a password and the identity of such users is generally known 4 anonymously identified user Have the same rights as an identified user The difference is that the system administrator also does not know the real identity of such an user But this mode is not really used in Hyper G yet Similar to the UNIX superuser root a Hyper G server has a system admin istrator called hgsystem All members of group system have the same rights as the system administrator they can insert m
40. ace of documents and links following the links is like navigating through this information space A link is displayed as a hot spot in the document by clicking on it the user comes to the destination of the link which can be a part of a document or the document itself Figure 2 1 A Small Hypertext Hypermedia Mau92 is multimedia with hyperlinks Documents may contain 2 2 First Generation Inlormalion oystems lo text and images audio film 3D scenes etc There exists two different kinds of systems In frame based systems like ToolBook each document must have the size of the computer s screen Large documents must be spilt over many nodes and the author has full control over information content and presentation In window based systems like Hyper G documents can have any size because a scrolling mechanism is used to scroll large documents In such systems the user has no control over the presentation but specifies the information content The WWW consists of three basic concepts e URL Uniform Resource Locator A URL is used to specify the location of a resource available electronically They link WWW pages together and have a specific format for example HTTP Hypertext Transfer Protocol with URL http Host port selectorstring Hyperg Hyper G protocol with URL hyperg Host port selectorstring ftp File Transfer Protocol with URL ftp host filename including path telnet Remote login wi
41. anipulate and delete users and user groups The group system and the user hgsystem are created when installing the Hyper G server Unapter 0 HarAdmi n Lhe Harmony Administrator Changing Identity with HarAdmin To change identity press the Identify button in the Main Window and type in the username and the password as shown in Figure 6 2 L Haraamin identity Login cwind Password Identify Cancel Figure 6 2 The HarAdmin Identify Window LL If you change the identity from a system administrator or a member of group system you have only to type in the username and no password is needed To change to an anonymously identified user type in anonymous or anon for short Users have different possibilities in HarAdmin according to their identification e Anonymous For an anonymous user only the Main Window is shown all other possibly open windows of HarAdmin are closed and only the Identify button is enabled e Identified and not a member of group system Such users have following privileges See all users and their attributes except passwords in the User Window See all groups and their attributes in the Group Window Can change their own attributes except adding to a group and changing the account value e Identified and a member of group system Such users have all privileges they can insert manipulate and delete other users and user groups 6 3 Managing User Groups
42. arayu jo sway 1s949ju Jo sway DNE j S99 UI suogdo WAS S main aebineN YPF itd Figure 5 7 The Information Landscape ine Harmony Ulent for I1yper Vr uhapter o OU pueg Psay Aypoyy PPY unqiau2sag uiupyep sb uondiuos q ultupyieH u won B Hd A pigu wea py BM ZPre8gL00x0 8066dLL8X0 S 000000X0 0P9 9000x090 Z2 2 2L EL LL S6 01 62 21 L LL S6 l L piom y SL siut Jouny PIOD wed PayIpopyauil p p ixa1 adAjjuawins0g wawnaog 2 000000X0 d 1 ampalgo sIoyauy Aejdsiq juoumoog siououy aebinen ap dan sudo wasAg siououy may JPPAEN YPJ oid uoissag uo INOpUIA Uey 3y SI ulupyer 40 ped uw au sISA19S j 1ad H 104 001 uongajsiunupe jes ydei e si urupyer uondioseq uiupyJeH yourag djay so yasay yesu xne ujew As yooq y Ays jsda By sapsey Ajs syapueyo xa Hdde xa dde pe oup uouueH D r sopeu Buisisauypurm3 s1asn snuaA Z1sn SWeN lld 2907 won B y Aap ey wesydy B AA s y y sap ey sp omAsy pumo J3UMO ppy ys Bu3 onduosaq uupyJeH HL se aueuaj4 sr J0yp3 oL MON waund OpulAA ue UIWPYAeH uonaajoo opui Hasuj voydussag ulupyieH E s11 sieo1 gt yas E sdasn snow uoue uon23 o2 3woH qnejed W2II EJ uono lloO tuoH s U3sIpu AA eipner gt SUuol12 9 oO SWOH E sonr Buipniour saAsag uoneuuoju WOI D 1004 1ed H J
43. archy after Deleting Groups a b and d 74 The Three Main Classes of HarAdmin 2 2 2 2 22 22 79 Figures 3 2 3 4 and 5 1 were created by Dipl Ing Keith Andrews Figures 3 4 and 3 6 were created by Dipl Ing Dr Frank Kappe Chapter 1 Introduction Since the beginning of the human race people want to communicate to other people and to get information about certain topics Many inventions were made to help people to do just that for example writing on stone slabs paper telephone and computers The Internet Kro94 The95 the network of networks built twenty years ago was a great step forward Nowadays computers can talk to millions of other computers over the Internet and can users can get almost any information they want Many different systems are available on the Internet LPJ 94 to help users lo cate information Archie ED92 developed at McGill University in Canada is a dictionary server to help locate files residing on FTP servers WAIS Ste91 Wide Area Information Server supports a powerful search engine for full text searching of large previously indexed databases and uses relevance feedback to refine the search for certain documents Gopher MA95 developed at University of Minnesota is the first information system that includes browsing and full text searches It struc tures its information as a hierarchy of menus WWW BLCGP92 Cai95 World Wide Web W3 or the Web developed at CERN in Gene
44. ation No more users for license No more documents for this session and license Remote server not responding Query overflow Break by user Not implemented Bibliography AAL 92 AK94 AKM95a AKM95b AKMS95 BLCGP92 BLCL 94 Cai95 ALBERTI B ANKLESARIA F LINDNER P MCCAHILL M and TORREY D The Internet Gopher Protocol A Distributed Document Search and Retrieval Protocol Available at ftp boombox micro umn edu pub gopher gopher protocol March 1992 ANDREWS K and KAPPE F Soaring Through Hyperspace A Snap shot of Hyper G and its Harmony Client In HERZNER W and KAPPE F editors Proc of Eurographics Symposium on Multime dia Hypermedia in Open Distributed Environments pages 181 191 Graz Austria June 1994 Springer ANDREWS K KAPPE F and MAURER H The Hyper G Net work Information System Journal of Universal Computer Sci ence 1 4 206 220 April 1995 Available at URL http hyperg iicm tu graz ac at jucs ANDREWS K KAPPE F and MAURER H Serving Information to the Web with Hyper G Computer Networks and ISDN Systems 27 6 919 926 April 1995 Proc Third International World Wide Web Conference WWW 95 Darmstadt Germany ANDREWS K KAPPE F MAURER H and SCHMARANZ K On Second Generation Network Hypermedia Systems In Proc of ED MEDIA 795 pages 75 80 Graz Austria June 1995 AACE BERNERS LEE T CAILLIAU R GROFF J F and P
45. d By default the user is identified as anonymous or automatically identified if con figured The name specifies the Hyper G user name while passwd is the password If encrypt is set to true the client supplies passwd in encrypted form according to modified DES same as UNIX passwords otherwise it is passed in clear text The server will return the object id of the users UserObject and the name of the user itself e g 0x0000000 anonymous if the identification failed Appendix D HAl m UDE Lommands used by HarAdm n No errors can occur o ChangeObject boolean Change bject ObjectID const RString amp command This command allows to remove add or modify individual attributes of an object record The object is specified by ObjectID commands adhere to the following syntax lt COMMAND gt lt REMCMD gt lt ADDCMD gt lt REMCMD gt NX lt ADDCMD gt lt REMCMD gt rem ATTRIBUTE VALUE lt ADDCMD gt add ATTRIBUTE VALUE Note that in order to delete or remove an attribute the object has to be locked GetAndLock and its old value has to be supplied some attributes are allowed more than once A command like rem Account oldvalue nadd Account newvalue allows to modify attributes in one operation here changes the value of the Account Attribute Errors If error is not zero an error has occurred e g NOACCESS No permission to modify objec
46. d name The implementation of changing the names with HarAdmin is too difficult because of the dependences of certain attributes of the objects For example if you would change a group name the name also would have to be changed in all subgroups parent groups direct users and access right fields e Deleting a group and direct members can also be extended If you do not want to delete some direct users you have to change the group object of each user using the Edit User Window Direct users are not unlinked automatically like direct subgroups This is deliberate so as to make sure that no users exist who do not belong to any group e It is maybe confusing that you can create user accounts and user groups but only can create a link to the home collection You have to create a home collection by using Hyper G clients such as Harmony Amadeus or hgtv e It can be tedious to create multiple users especially when you already have a list of users in a text file You do not have an opportunity to import such users like you have it in the Netscape Commerce Server e In this version only the system administrator and users of group system can create delete and manipulate other user accounts and user groups It would be useful to be able to delegate certain functions to subgroup administrators 89 unapter o Future vvork e If an organization has a complicated group hierarchy it might be useful to see the complete hierarchy like the local
47. deo into Distributed Hyper media Systems Master s thesis University of Technology March 1995 Available at ftp ftp iicm tu graz ac at pub Hyper G doc marschall ps MAURER H Why Hypermedia Systems are Important In Proc ICCAL 92 pages 1 15 LNCS 602 Springer Pub Co 1992 MAURER H Hyper G The Second Generation Web Solution Addison Wesley 1996 MEYROWITZ N K Intermedia The Architecture and Construction of an Object Oriented Hypertext Hypermedia System and Applications Framework In Proc OOPSLA 86 pages 186 201 Portland OR September October 1986 NELSON T H Literary Machines The Distributors South Bend IN 46618 USA 87 1 edition 1987 SCHMID A A Mail Archive Server on Top of Hyper G Master s thesis University of Technology November 1995 Available at ftp ftp iicm tu graz ac at pub Hyper G doc schmid ps STEIN R M Browsing Through Terabytes Wide area Information Servers Open a New Frontier in Personal and Corporate Information Services BYTE 16 5 157 164 May 1991 STROUSTRUP B The C Programming Language Addison Wesley Reading Massachusetts second edition 1991 The Internet Unleashed Sams net Publishing 2 edition May 1995
48. e Network News news With news you can easily find or get an answer to any kind of question you have There exist thousands of so called newsgroups to which you can talk to get a desired information Newsgroups can be compared with discussion groups or bulletin boards The newsgroups are hierarchically structured with the broadest grouping first in the name followed by an arbitrary number of subgroups separated by periods The USENET is a set of voluntary rules for passing and maintaining newsgroups There exists seven major news cat egories comp computer science news network news rec hobbies recre ational activities arts sci scientific research soc social issues talk de bating different topics and misc all other topics 2 2 First Generation Information Systems As mentioned at the beginning the Internet consists of different information systems but they all haven t enough functionality to provide the power to exploit the large information and communication resources available on the Internet Each of the existing information systems has its own special features but also weaknesses 2 2 First Generation Inlormalion oystems ll 2 2 1 Archie On the Internet many ftp servers exist and for users it is difficult to find the right one to get the information they are looking for Archie ED92 developed at McGill University in Canada is probably the first and most famous dictionary server to help locating files by na
49. em and they are useful for preparing hypermedia presentations of existing materials 18 uhapter o Hyper ix Collection Cluster x C 90 m A Tour Figure 3 3 Three Types of Collection Search Facilities Hyper G uses an object oriented database and every object is indexed automati cally on creation In Hyper G two different modes of searching exist e Boolean queries Every Hyper G object has a set of associated attributes like ti tle keywords author etc which can be searched for Typical queries might be Give me all documents with User accounts in the title or Give me all documents with author Claudia Windisch e Full text queries Text documents are automatically full text indexed on insertion The full text server supports fuzzy boolean queries WAIS like nearest neighbour searches based on the vector space model The result of the search is a ranked list 3 2 Interoperability Hyper G supports as much interoperability with other Internet information systems as is possible It can interact with Gopher WWW WAIS and FTP servers and 9 2 IHLETOPEeTaD lly 12 Gopher and WWW clients as shown in Figure 3 4 Gopher A Hyper G Server
50. equest for document 1234 1234 is the document ID to the server The client receives the document object 1234 and the anchor ob ject 1235 attached to this document look at the Document Anchor Object in Figure 3 5 9 9 Lne IiVper i server 49 2 The clients sends then the selector string containing the access information Host Port Protocol Path of the document object 1234 to receive the whole document and afterwards displays the document object and with the help of the Position information of the anchor object the client also can high light the attached anchor here 41235 Example For Link Anchor Relation 1 Having displayed the document with document ID 1234 and the attached link anchor 1235 assume the user clicks now on the link anchor 1235 The client sends the anchor ID 1235 to the Link Server to receive the cor responding destination document object 2 The Link Server looks at the link anchor relation for the source anchor 1235 and finds as destination anchor 2001 Also checks if the user has access rights remember links can be assigned with attributes such as access permis sion here 3000 3 Now the Link Server looks at the document anchor relation to find the docu ment with the source anchor 2001 and finds the destination document 2000 and sends the document object 2000 and the attached anchor objects to the client and we are at step
51. er name 6 4 3 Editing an Existing User Only members of group system are allowed to change the attributes of other users Select the user to be edited in the column User s and press the Edit button Adding attributes is done in the same way as in the New User Window Overwriting an attribute changes the value clearing the field deletes the attribute Note that you cannot easily change the name of a user as for all other Hyper G objects To change the name of the user the user must be deleted and created new again 6 4 4 Deleting Users To delete one or more users on the current Hyper G server one or more users have to be selected in the column User s in the User Window and afterwards the Delete button must be pressed By shift left clicking users multiple users can be selected and deselected for deletion 6 5 Example of Group Deletion Here is an example to show the way in which a group with members and subgroups is deleted Figure 6 15 shows a group hierarchy and Figure 6 16 the corresponding Group Window with selected group a Groups b and c are direct subgroups and groups d e f are indirect subgroups indicated by groupname Unapter 0 HDarAdmi n ihe Harmony Administrator Assume that we want to delete group a all direct members of group a direct subgroup b all direct members of group b indirect subgroup d all direct members of group d
52. erarchy The probability of becoming lost in hyperspace 9 1 opecial Fac litles Ol H1Vper Xx li university higher informatics mathematics d L hes 2 Se ower systems networks numerics Figure 3 2 The Collection Hierarchy is reduced because the collection hierarchy can be seen as a global map for showing where you are in the Hyperspace e Search Scope The user has the facility to restrict the search to particular collections by marking them active The scope of the search may be as narrow as one collection on a single server or as wide as all collections on all Hyper G servers worldwide e Access Rights The collection hierarchy is used to grant or deny Write permission to certain parts of the information structures to authors Read Access to certain users and user groups Currently three classes of collections exist as shown in Figure 3 3 collection displays a list of menu items when visited The list can be sorted by certain attributes title author cluster When a cluster is visited all its members are visited too In Hyper G a cluster is used to implement multimedia documents to support multilingual documents German English and version control tour is a collection that visits all its members in a certain order A special form is a guided tour Guided tours are paths through the information syst
53. es of the new group are not cleared except for the group name This is useful if you add multiple groups with same attributes If an error occurs a message box is displayed and the focus is set to the attribute which contains the wrong values Button Clear Clears all entries in the New Group Window Once a field has been edited the background colour of the field 1s changed to indicate an edited value Button Close Closes the New Window but does not destroy it If you create a new group again the old entries are displayed except the group name To create the structure shown in Figure 6 3 press the New button in the Group Window and type in the attributes shown in Figure 6 6 and Figure 6 7 Because the group university is the first in the hierarchy no parent group has to be entered After pressing the Commit button assuming no error occurs the group university is created on the current Hyper G server The newly created group is automatically selected as the current group and the group s attributes are displayed in the Group Window The remaining groups are created analogously 0 9 Managing User Groups 09 Group university Parent Group Description First Level Add Parent Group Commit Clear Close Zi Figure 6 6 Creating the Group university networks Parent Group mathematics informatics Description Add Parent Group Commit Clear Close Figure
54. g a nuclear attack The existing communication was only between a source and a destination computer but the idea was to build a network in which every computer could talk with any computer on the whole network The ARPAnet was extended with services like remote login telnet file transfer ftp and electronic mail email In 1983 the ARPAnet switched to TCP IP to connect diverse networks together and the name Internet was born TCP IP Transmission Control Protocol Internet Protocol The Internet is a packet switched network The Internet Protocol IP defines the addressing and routing mechanism puts the message data in envelopes also called packets with source and destination address Internet addresses are unique 32 bit numbers in four 8 bit parts for example 129 27 153 18 Names are easier to remember and gratefully the Internet uses a Domain Name System DNS which uses a name server to translate domain names into Internet addresses eg the domain name fiicmal01 tu graz ac at stands for the Internet address 129 27 153 18 If the packets are too large the Transmission Control Protocol TCP takes the packets breaks them into pieces and numbers them The numbers are useful to control the order of the received packets If one is missing or corrupted it is re transmitted The TCP data is placed in a TCP envelope which in turn is placed inside a IP envelope The IP packets are then routed through the Internet until they reached their des
55. g one way links so called dangling links can occur when a document is deleted or moved Like Gopher WWW servers generally have no integrated search facilities but can use WAIS for searching Altogether WWW should be considered a first generation networked hypermedia system 2 3 Second Generation Information Systems Second generation AKMS95 networked hypermedia information systems attempt to alleviate some of the previously mentioned weaknesses The largest problem is arguably that of disorientation also known as the Lost in Hyperspace syndrome When the user browses through the information space many questions arise Where am I The user sees only one current document at a time The document can contain hyperlinks and for users it is difficult to gain an overview They don t know which links from other documents point to the current document incoming links and to which other documents the hyperlinks in the current document point to outgoing links In the existing systems like Gopher WAIS and WWW to look backwards or using a map is not possible Hyper G uses a local map to show the relation of incoming and outgoing links of the current document to other documents How much information can I see about a certain topic It is difficult for a user to see how many documents and megabytes exist about a certain topic How much of the information have I already seen or is left Without so called footprints or checkmarks
56. group with an lower hierarchical level than a direct subgroup For example group university has indirect subgroup group systems group networks and group numerics To gather information about which groups exist or which attributes an existing group has press the Group button in the Main Window Figure 6 1 and the Group Window shown in Figure 6 4 appears 6 3 1 The Group Window of HarAdmin The function of the Group Window is to display several groups and the attributes of a selected group With the topmost button bar you can Unapter 0 HDarAdm n Lhe Harmony Administrator Create new groups Edit existing groups Delete existing groups Change the look of the Group Window The first time the Group Window appears the Group field is set to And after pressing Enter all groups of the current Hyper G server are displayed New Edit Delete Options Group 25 Group s Parent Groups Subgroups fbs_editors No group selected No group selected few_body_adm hardev hgteam hygen hypdoc hyperbase idg Description No group selected All Show users Figure 6 4 The HarAdmin Group Window Rows and Columns of the Group Window Only the field Group is editable and froms the selection string for searching the current Hyper G group database To change the selection the Group field is edited and after pressing Enter the new group s are displayed If only one group matches the group is se
57. he menus is like browsing through a big graphical tree In reality the user browses through a graph from one menu the user comes to the next sub menu and so on but sub menus can reside in many different places and a loop can be built The user has difficulty to come back to previous selected menus and after gets lost Most Gopher servers support no search facilities themselves but use WAIS as an add on search engine They also have no integrate hyperlinking facilities It is based on the Client Server Model servers accept connections from clients and return either documents collections of documents references of objects on other servers or perform searches of document collections 12 Unapter 2 internet information oystems 2 2 4 WWW The World Wide Web WWW W3 or The Web BLCGP92 BLCL 94 DR94 was developed at CERN in Geneva in 1989 as an information system for the particle physics community WWW was created by Tim Berners Lee and Robert Cailliau as a hypertext information system It is now a distributed hypermedia information retrieval system which provides access to a large universe of documents Merging the techniques of hypertext the user clicks with the mouse information retrieval and wide area networking produces the WWW model Hypertext is not a linear text one page after another it consists of pieces of text called nodes or documents which are connected by links shown in Figure 2 1 Hypertext forms a information sp
58. important for HarAdmin Atribute Parent group is used for automatic identification account name of the user Hyper G user group The syntax of indexQuery is as follows lt EXPR gt lt EXPR gt lt EXPR gt lt EXPR gt lt EXPR gt amp amp lt EXPR gt lt EXPR gt lt EXPR gt OR AND AND NOT lt INDEXFIELD gt VALUES lt INDEXFIELD gt gt lt SIMPLEVALUE gt lt lt SIMPLEVALUE gt BETWEEN lt INDEXFIELD gt UName UGroup Host Group lt VALUES gt lt VALUE gt lt VALUE gt VALUES lt VALUE gt lt SIMPLEVALUE gt lt SIMPLEVALUE gt x SIMPLEVALUE value AND values must be true ordinary word all words with prefix simplevalue all words gt simplevalue o ObjectByIdQuery int ObjectByIdQuery ObjectIdArray amp ObjectField amp const RString query Like GetObject this command is used to retrieve the object records with the object s attributes from object IDs of ObjectIdArray This command is more powerful in that it lets you retrieve a number of object records with one command In addition a query may be performed on the object records to narrow down the Ji set of objects retrieved The query is not limited to the indexed attributes and is more powerful than the index query of the GetObjByQuery commands but slower as it is performed directly on the att
59. in groups and sent back to the Group class for displaying in the Group Window If an error occurs the error message is stored in filter and sent back to the Group class to display the error Possible error codes are 1 Database busy o getParSubDes int getParSubDes RString amp filter RStringArray amp dpa RStringArray amp ipa RStringArray amp dsub RStringArray amp isub RString amp des This method is called to show all attributes of a certain group in the Group Window It sends back all direct and indirect parent groups dpa ipa all direct and indirect subgroups dsub isub and the last description of the group with name filter It first gets the object Id with the HG CSP message Get0bjByQuery and then uses the message GetObject to retrieve the full object record After all attributes are received the corresponding RStringArrays are filled and sent back to the Group class To get indirect subgroups and indirect parent groups first all direct and then recursively all indirect ones are searched Remember Hyper G uses a group hierarchy which is an acyclic directed graph If no error occurs all attributes are displayed in the Group Window Possible error codes are 1 Database busy 2 Get Object failed o getLockedParentsDess int getLockedParentsDess RString amp filter RStringArray amp parents RStringArray amp dess This command is used to get all attributes of a group for editing The procedure works in the
60. ing the InterViews LVC89 LCV87 It takes advantage of Hyper G s structuring and retrieval facilities to provide both intuitive navigational facilities and informative feedback about the location of information 5 1 Architecture Harmony is a multi process Unix application as illustrated in Figure 5 1 Harmony eh iiim Session port 418 Hyper G ee HG CSP Server t p 4 T x Image 2 2 Harmony j E Fim j Pu 4 d j PostScript External _ control stdin documents Figure 5 1 The Architecture of Harmony A uhapter o Lhe Harmony Vilent for Hyper ix The main part of Harmony is the Session Manager which communicates with the Hyper G server The Session Manager provides navigational facilities and co ordinates all other activities As mentioned in the previous chapters Hyper G structures its documents in so called collections which in turn can be members of other collections This recursive definition provides the collection hierarchy which is an acyclic directed graph The Session Manager displays this collection hierarchy in the collection browser and uses it to give the user an easy way to navigate through the information space see Figure 5 2 Collections may be opened and closed and documents activated by double clicking Already visited documents or collections are marked with a tick the number of documents belong
61. ing to a certain collection maybe displayed etc The History List is a list of user s previously accessed collections The user can easily go back to certain collections or documents by double clicking them and the Session Manager shows the location of the selected collection or document This feature is called location feedback 5 2 Viewers Harmony supports several native document viewers sharing a common user interface style e lext Viewer e mage Viewer MPEG Film Viewer Audio Clips 3D Scene Viewer e Postscript Files The Harmony native viewers are illustrated in Figure 5 3 The Text Viewer uses a generic SGML parser to display marked up text doc uments like Hyper G s HTF and WWW s HTML format It supports scrolling searching selecting and inline images in TIFF GIF and JPEG format Links are displayed as hot spots and activated by double clicking The mage Viewer accepts raster images of TIFF GIF and JPEG format Links can be assigned as rectangles polygons circular or elliptical areas The Film Player Mar95 displays MPEG 1 videostreams An important feature of Hyper G are links in such video streams 2 Viewers J Tools TLS I HarAdmin Description E HarAdmin Main Window 3 IICM Views 4 Harmony Widgets I About il BubbleWindow HelpWindow _ Colour Dialog Adj Value Cursors for X windows Field Editor old Field Editor and Field Browser for IV 3 1 L FieldSlide
62. jede ze n zosswioiy jede ze n Z0SSUIIII jede zea ny zosswong snoul uoup AAA snowAuoue SNOW UOUB MAM ZEZ Jajseuummm 69 L J9 19sBu ZEZ Jajseuummm 69 L Jaasasby ZEZ Jajseuummm ZEZ Jajseuummm ZEZ Jajseuummm ZEZ Jajseuummm ZEZ Jajseuummm yallo L uluoO sasn paioa es si sn snowAuoue ojuiBu snow uoue MMmM snow uoue MMmAM SnOUI UOUP AAAA SnOUI UOUB MAAA awen Jaquiny ts FT TTT _09 buosas u eui ayepdn spuo2 s 09 Jod ez p s lnultu g Jad Lz G s lnultu 09 Jad 3979 je ad 7g 2 Xepu e2ueuuojiag spuoaas gp s lnultu Lg sinou G s ep HL 6 6L 60 0 0L S6 eui dn san au 2907 PZ 10 SL EL LLISE f Bupnjpun aaa uonguuojul WOII WLN JaAIaS Figure 5 11 The Status Browser of Harmony uhapter o Lhe Harmony Vilent for Hyper ix 5 6 Sending Mails With Harmony the user has the possibility to archive or send mails or messages Hginsmail Sch95 is a mail archive server written in Perl for archiving mails Mails are inserted as text documents and if they are related reply mails they are linked together The advantages of this are you can use the search facilities of Har mony to find certain mails you can see the thread of discussions or easily navigate through the mail hierarchy etc With Hgsendmail you can send messages to other people the messages can be hypermedia messages because of the link anchors in a document Chapter 6 HarAdmin The Harmony Administrat
63. lected highlighted and all attributes of the group are displayed Otherwise all groups are shown and by double clicking the left mouse button the attributes of the selected group are shown For example to display groups with the prefix x type in the Group field x and press Enter Group s A list of all currently matching groups on the current Hyper G server The number of matching groups is displayed in the line above the column 0 9 Managing User Groups ol Parent Group s A list of all groups of which the selected group is a member As said before Hyper G structures groups in a hierarchy Beside the root group all groups can have parent and subgroups Indirect groups are shown in form groupname Subgroup s A list of all subgroups Indirect groups are shown in the form groupname Description A short description of the selected group usually the meaning of the group There can be more than one description of a group but only one description the last is displayed in the Group Window Special feature You also can select a group in the columns Parent Group s and Subgroup s to see its the attributes Button Options You can change the look of the Group Window either by X Defaults or with the Options Window shown in Figure 6 5 The corresponding X Defaults are listed in Appendix A Show Group vf Descriptions A Parent Groups vf Sub Groups Ok Cancel al Figure 6
64. me Nowadays over 15 archie servers exist and they index over 1500 FTP servers worldwide The content of each archie server is updated monthly 2 2 2 WAIS WAIS Wide Area Information Server Ste91 developed in 1989 by Thinking Ma chines Apple Computer and Dow Jones supports a powerful search engine for full text searching large previously indexed databases WAIS clients send queries to servers display ranked results and fetch and display desired documents WAIS has no functionality for browsing hyperlinks or structuring information contents but it can be considered real search engine An important feature of WAIS is rele vance feedback Parts of the search result can be taken as input for a further search and the search can be refined to find certain documents Many Gopher and WWW servers can use WAIS to provide search functionality 2 2 3 Gopher Gopher was developed at the University of Minnesota in 1991 as a campus wide information system and was the first information system that includes browsing and full text searches The design philosophy of Gopher was to make it possible for departments and other groups at the University to publish information on their own desktop systems and to hide the distributed nature of the server from the user using the system AAL 92 Gopher MA95 structures information as a hierarchy of menus comparable with a file system which is easy to use but has many weaknesses For the user browsing through t
65. ministrator 6 4 Managing Users A Hyper G user account is not identical to a Unix user account a user can have different Unix accounts on different machines but access a single Hyper G account To gather information about which users exist or which attributes a certain user has on the current Hyper G server press the User button in the Main Window Figure 6 1 and the User Window in Figure 6 11 appears A user account is at least made up a username one or more passwords and a personal home collection 6 4 1 The User Window of HarAdmin The function of the User Window is displaying several user accounts and attributes of the currently selected user With the topmost button bar you can Create new users Edit existing users Delete multiple users Change the look of the User Window The first time the User Window appears the User field is set to the name of the identified user the Group field is set to and all attributes of the user are shown automatically see Figure 6 11 Rows and Columns of the User Window Only the fields User and Group are not read only They together build the selection string for searching the Hyper G user database To change the selection edit the User and or the Group field and press Enter During searching the mouse pointer changes to an hour glass and no other database commands can be made After a short time the matching user s are displayed and the mouse cursor changes back to a
66. n e New User Choose this to insert a new user e New Group Choose this to insert a new group e Edit User Choose this to edit a new user e Edit Group Choose this to edit a new group e Identify Choose this to reidentify yourself e Update Help Choose this to update Hyper G help entries 4 1 2 Managing Users To see all user accounts existing on the current Hyper G host choose the number 3 from the Main Screen then type in or nothing and press Enter If you want only see user accounts with prefix c type in c and press Enter Unapter 4 server Administration 10015 Inserting a New User Choose number 1 from the Main Screen enter the name of the new user press Enter and this leads to gt gt gt gt gt gt gt gt gt gt gt gt gt gt gt New User lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt gt gt UserName newUser gt gt gt gt 1 Add Host gt gt 2 Add to Parent Group gt gt 3 Add Password gt gt 4 Add Password encrypted form gt gt 5 Add Description gt gt 6 Add Name of home collection gt gt 7 Rem Host gt gt 8 Rem from Parent Group gt gt 9 Rem Password gt gt 10 Rem Password encrypted form gt gt 11 Rem Description gt gt 12 Rem Name of home collection gt gt 13 Insert User Object gt gt gt gt 14 qluit Commands of the New User Screen e Add Host Add a new Host entry enter lt username gt lt h
67. n has been adapted from the technical report Hyper G Client Server Protocol HG CSP Version 7 05 written by Gerald Pani and Frank Kappe This chapter contains a short description of messages used by HarAdmin to main tain users and user groups implemented in files haradmin Ch The Hyper G Client Server Protocol messages are implemented in the C class HgStub o GetObject boolean GetObject const int ObjectID ObjectRecord amp Har Admin uses this message to retrieve the full object record Send the 0bjectID and if no error occurs the 0bjectRecord contains a list of attributes of this object Possible errors RSERV NRESP Remote server not responding NOTFOUND The object could not be found NOACCESS No read permission for the object amp GetObjbByQuery int GetObjByQuery const RString amp indexquery ObjIdArray amp This command is used for searching on indered attributes of Hyper G objects The search is performed on a set of attributes over the whole database of the con nected Hyper G server Use GetObjectByIdQuery command to match a set of 95 Appendix D HAl m UDE Lommands used by HarAdm n objects returned by this command against other non indexed attributes If no er ror occurs it returns the IDs of the matching objects in ObjIdArray If nothing is found the count of ObjIdArray is 0 Possible errors CMD SYNTAX indexquery is invalid Q OVERFLOW too many intermediate results Indexed Hyper G attributes
68. ndow already exists the User Window is only mapped again At the beginning the user filter is set to the identified lhese filters are used to search the database for user and the group filter to existing users getUsers To send the filters to the class Haradmin the method FiltersAccept is used which builds the selection string sends it to Haradmin and t NE U TT lass otructure Ol MarAdmin after receiving the matching objects updates the User Window o userMenuUpdate void userWindowUpdate It is activated when the user double clicks on a certain user in the column User s to display all attributes of the selected user new User Window void newUserWindow This command builds and initializes the lines in the New User Window edit UserWindow void editUserWindow This command builds and initializes the lines in the Edit User Window showAll lt H Q ul 5 o m H H Las It is called when the All button in the User Window is pressed It changes the user and group filters to and calls the method FiltersAccept to update the o showGroup lt S H O p m 2 o im a S H d fer d N It is activated when the Show Group button in the User Window is pressed or double clicked on a certain group in the column Group s in the User Window It checks if a group is selected and then activates the method showGroupDetails of the class Group to display
69. nks Figure 4 8 Page for Access Control 3 File System Links The Netscape Commerce Server distinguishs between two different database for mats DBM format which is a high speed database format NCSA style which is a simple text format file including user names and pass words each line is in the form of userl passwordi user2 password2 4 2 2 Changing a Text File to DBM Format The big advantages to have a NCSA file is that the system administrator can use such an text file to add many users to an existing database and Netscape can convert it to a DBM format database the passwords can be encrypted or not Note that you must give the absolute path of the text file The text file is stored in the server root in the subdirectory userdb An example usr3 ns home userdb cwinddb2 pwf is a NCSA style text format file including the users userl passwordi user2 password2 See Figure 4 9 for more detailed information The Big Differences to Har Admin e It is a simple user interface Unapter 4 server Administration 10015 e It has no hierarchical structure of user groups e Is supports no browsing through the user group hierarchy e User object consists of a username and one password eb Choose a file to be converted First you should choose a file to be converted to DBM format The file should have one user to a line The username should come first followed by acolon and then the password for example userl
70. nn 44 The 3D Scene Viewer laoa aa aaa 45 Search Facilities of Harmony 2 2 nun 46 The Local Map s 48 The Information Landscape lens 49 Inserting New Objects rn 50 The Multilingual Feature 2 2 e 51 9 10 5 11 6 1 6 2 6 3 6 4 6 5 6 6 6 7 6 8 6 9 6 10 6 11 6 12 6 13 6 14 6 15 6 16 6 17 6 18 6 19 7 1 Credits biol VE FIUURESD Creating Links 2 ee 52 The Status Browser of Harmony 2 2 222m nenn 53 The HarAdmin Main Window 57 The HarAdmin Identify Window 58 A Group Hierarchy for a University 2 2 len 59 The HarAdmin Group Window nn 60 Group Window Options Group En m nn 61 Creating the Group university 2222s 63 Creating the Group networks es 63 Displaying the Group university 2 Coon 64 Displaying the Group informatics llle 65 Group Window Delete Dialog 2 2 2 2 2 nn nenn 65 The HarAdmin User Window 67 The HarAdmin User Option Window 2 2 22 222m nennen 68 The HarAdmin New User Window 2 004 69 An Example of a Complete New User 2 2 2 222 70 Example Group Hierarchy for Deleting Group a 72 Displaying the Group a 2 2 on 73 Example User Window Group Window and Delete Dialog 73 Example Windows for Deleting Group a b d and all direct IL en 74 Example Group Hier
71. nt point is that the hgserver splits operations that might take a long time into a number of smaller and therefore faster transactions for the dbserver and ftserver client client client hgserver hgserver 5 gener dbserver Local Link Server I Remote Link Server Figure 3 6 Internals of Link Server Hgserver can also connect to dbserver and ftserver of remote servers and this feature makes it possible to perform a distributed search over a number of servers in parallel Searching the Hyper G Database Searches in the Hyper G database are performed in three steps Kap93 1 Find the ID of the object that matches the query It can be done in O log n where n is the number of objects in the server An array of object IDs is 9 9 Lne Hyper server 49 returned If the content of a document is searched the search is done by ftserver otherwise by dbserver 2 This returned array is matched against a set of activated collections The object IDs found are returned to the client done by hgserver and dbserver 3 The client must request the full object for the set of objects IDs found done by hgserver alone 3 3 3 Document Cache Server dcserver Whenever a document is needed the link server fetches it from the document cache server The document cache server stores local documents and caches remote ones therefore it speeds up the retrieval of documents by clients at least for d
72. ocuments which are retrieved very often All document requests are routed through the local document cache server When a client needs a document the client sends the document cache object in cluding ID host port protocol path etc to the document cache server If a document is not in the cache the document cache server fetches it from the remote document server otherwise the document is send to the client directly When space is exhausted the server removes the least recently accessed document from the cache Hyper G copes with a typical problem of caching in distributed environments Which version of a document is the newest When a document is modified the new document gets as described before a new ID which is passed to the client when the user visits that document The old version is also stored in the document cache server but it never can be accessed again and after a certain time it will be deleted anyway as a result of the recently accessed cleansing strategy The document cache server can also be used as a protocol and format converter If information is stored in other databases like Gopher WAIS and WWW clients may connect to the document cache server The document cache server retrieves the information and caches it for the client The client may request the document in a specific representation the document cache server converts it for the client and caches it This feature makes clients more simple and software main
73. of Hyper G Hyper G combines a number of navigational structuring and search facilities to help overcome the Lost in Hyperspace syndrome as shown in Figure 3 1 15 10 uhapter o Hyper ix document IURE gt cluster o ii I l 6 collection search link Figure 3 1 The Hyper G Data Model Hyperlinks In Hyper G the user navigates by clicking on a hyperlink displayed as a hot spot attached to a document The destination of the link can either be a certain area in another document or the whole document itselfs which in turn can contain hyper links Not only text documents can contain links but also image audio and film clips Mar95 3D scenes and PostScript documents Structuring Hyper G structures its information in so called collections Collections may them selves belong to one or more collections to create the collection hierarchy an example of which is shown in Figure 3 2 The collection hierarchy is actually an acyclic directed graph rather than a strict hierarchy since objects may belong to multiple parent collections The three main purposes of the collection hierarchy are e Navigation Whenever the user opens and closes collections and sub collections starting at topmost root collection or activates a certain document no matter if selecting it by clicking or as a destination of a hyperlink the location is displayed in the collection hi
74. onymous to fully identified e Support for a hierarchical structure of user groups e Access rights per user and or user group for documents and collections 3 3 The Hyper G Server The material in this section has been adapted from the paper Hyper G A Distrib uted Hypermedia System Kap93 written by Frank Kappe The Hyper G server AKM95b is a rather complex object oriented database of objects i e descriptions of documents links anchors remote databases etc as well as relations between such objects attributes metadata full text index and users and groups The Hyper G server stores not only documents but also anchors collections users user groups and server descriptions 3 3 1 Architecture Hyper G uses the Client Server Model with clients and servers connected over Internet using TCP IP Unlike Gopher or WWW clients Hyper G clients usually talk to the same server for an entire session If information from a remote server is needed the local Hyper G server fetches it and delivers it to the client This approach has many advantages e The clients can be kept very simple because the Hyper G server can convert protocols and document formats for the client e connection oriented protocol can be used there is no point in opening and closing the connection for every request e Remote information can be cached in the local server see Document Cache Server e User accounts and access rights have to be maintained
75. or User accounts groups home collections and access rights are central features of Hyper G Users in Hyper G can have their own user accounts which consist of a username one or more passwords and a home collection Home collections are comparable with UNIX home directories in which users can manage their own private files grant or deny access rights to certain users or user groups and hotlists pointers to resources HarAdmin is a tool for administrating user accounts and user groups It is a graphical X Window based tool written in C Str91 and using the InterViews UI Toolkit LVC89 LCV87 The basic functionalities are based on the V T100 terminal based tool hgadmin Mau96 and on the Hyper G Client Server protocol KP94 6 1 Setting Up and Running HarAdmin HarAdmin is not automatically installed with the Hyper G server software but is part of the Harmony client It is available by anonymous ftp from ftp iicm tu graz ac at in the directory pub Hyper G Harmony for several major platforms e SUN Sparc SunOS and Solaris e HP 700 series HPUX e DEC Alpha OSF 1 e SGI IRIX e IBM PC compatibles LINUX There are two ways to start HarAdmin 95 Unapter 0 HDarAdm n Lhe Harmony Administrator e stand alone By typing haradmin in the command line the user comes to the Main Window shown in Figure 6 1 The default Hyper G host is info tu graz ac at with port number 418 Change the default values with haradmin
76. ostname gt This attribute is used for an automatic identification after invoking a client Client sends the UNIX user name and corresponding encrypted password the host address is known from the con nection e Add to Parent Group Add the new user to a parent group to inherit access rights from the group e Add Password Add a new Password entry for the user e Add Password encrypted Add a new Password entry in encrypted form for the user It must be an exact copy from the UNIX password file if it s used for automatic identification The encrypted password is stored under UNIX in the directory etc passwd Multiple passwords are allowed e Add Description Choose this command to add a short description of the user to the user object for example the whole name of the user 4 1 hgaamun l e Add Name of home collection Specify the name of the user s home collection e Rem Host Group Password Password encrypted To remove an at tribute of the user the corresponding text of the attribute has to entered between square brackets e Rem Name of home collection Choose this to remove the user s home collec tion name e Insert User Object If no error occurs the new user object is inserted in the Hyper G database Remember only the system administrator and members of the group system are allowed to insert new user objects Editing an Existing User Choose number 3 from the Main Screen enter the name of the use
77. passwordi user password2 user3 password3 You should give an absolute pathname to the file Convert this text database usr3 ns home userdb cwinddb2 pwf L Passwords encrypted Next you should specify whether the passwords are already encrypted or if they need to be encrypted If you are using this form to process users in batch mode you will probably want to leave the passwords unencrypted in the file and have the converter encrypt them for you The passwords are already encrypted Please encrypt the passwords GL Name of target database Choose aname for the target database This name will be used throughout the rest of the forms to refer to the database If the database does not exist it will be created for you To this DBM database cwinddb GL Existing users Sometimes a user may be entered twice into a database You can choose how the convertor will behave under this circumstance either it can overwrite the existing user or it can leave the user unchanged and keep track of those users If a user exists already do not overwrite the existing user If a user exists already overwrite the previous entry Figure 4 9 Changing a Text File to DBM Format For more information about the Netscape Commerce Server see http home netscape com comprod netscape commerce html Chapter 5 The Harmony Client for Hyper G Harmony AK94 is a graphical X Windows based Hyper G client written in C Str91 and us
78. ple 129 27 153 18 e Alias Name for example jupiter The display format can be specified by X Defaults or by selection in the Op tion Window see Figure 6 12 The corresponding X Defaults are listed in Appendix A Passwords list of encrypted passwords Groups user is a member of at least one group Hyper G uses a group hierarchy to coordinate access rights For all indirect parent groups HarAdmin uses the form groupname Only members of group system have the right to add users to groups Account Hyper G supports billing in sofar as documents can have a price A user has a certain amount of virtual money to access charged documents Only Unapter 0 HDarAdm n Lhe Harmony Administrator members of group system have the right to change the Account attribute for a certain user The server decrements this value whenever the user accesses a priced document until the value would become negative In this case the document is not transferred and the server sends an error code Description A short description of the selected user usually the full name of the user There can be more than one description for a user but only one description the last is displayed in the User Window Home Collection In Hyper G a user generally has a personal home collection Such a home collection is comparable to a home directory under UNIX and a hotlist A home collection can be created by using Hyper G clients such as Harmony Amadeus
79. pointer If only one user matches the user is marked and the user s attributes are shown automatically otherwise all matching users are displayed and only by double clicking the left mouse button are the attributes of the selected user shown For example 1 To see all users with user names beginning with c type in the User field c in the Group field and press Enter to send the selection string to the database 2 To see all users of group iicm set the User field to the Group field to iicm and press Enter to send the selection string to the database 0 4 Managing Users ol New Edit Delete Options User cwind Group 1 User s Hosts Passwords Groups cwind 129 27 153 12 sapRxms5VOuy6 ed95_part cwind 129 27 153 14 iicm cwind 129 27 153 17 system cwind 2129 27 153 18 vy cwind 129 27 153 21 Description Claudia Windisch Home Collection cwind Account 6345678 All Close j Figure 6 11 The HarAdmin User Window cwind User s All users according to the selection string User Group field The number of matching users is displayed in the line above the column Hosts Is a list of hosts from which automatic identification is possibly An entry is in form of user host A host is displayed in one of the following formats e Domain Name for example fiicmal01 tu graz ac at e IP Address for exam
80. r Glyph Utilities Widgets spin offs _ HgRaster d List Box Option Button Menu Items Glyph Utilities Widgets spin offs User cwind system Host info iicm tu graz ac at Harmony History Browser 13 19 Claudia Windisch s Home Collection 13 19 CI Tools TLS 13 20 I Harmony Widgets 13 20 E Field Editor and Field Browser for IV 3 1 13 20 E Glyph Utilities Widgets spin offs 13 20 __ List Box Option Button Back Forward Close Figure 5 2 The Session Manager 4o L6 pX8 e Dade Buipiing WOII 34L L08 L aBbuey Giz wel re le miele n PUM 2g o wog ine Harmony VLLent ior I1yper Vr yooloig sseguad H EDEL s aded 104 led J Jgu193u smoday Buigoea J puuosiag C uhapter o au eujsny ABojouu 5 Jo ys salun ZLIN Jo eIpapyy M N papoddns Jayndwios gt pue Burssa2o44 uonguuoju 10 1nll sul 6881 aynyysuj y jo uoneanBneu f WOII 9u 32 494485 H 19d H aly Burssa22e Mou ale noA soBeui ullu WOII ES Aeq WON 2140442313 EJ uononpoaul wol eur inoqy WOI ayp 1noqy gt 4 A49S siu jnogy C WOII ayy 0 awoojam i TE Figure 5 3 Viewers of Harmony 9 2 Viewers 9 The Audio Player can be configured to use either the Network Audio Server or local audio commands to play audio files in a variety of common formats Hyper G also supports 3D scene documents
81. r and press Enter If you do not type any username you get a list of all existing users If you type c you get a list of all users with prefix c This may lead to gt gt gt gt gt gt gt gt gt gt gt gt gt gt gt Select User lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt gt gt UserName c gt gt gt gt 1 cderler Christian Derler gt gt 2 cwind Claudia Windisch gt gt gt gt 3 qluit Now choose one of the displayed users This may lead to gt gt gt gt gt gt gt gt gt gt gt gt gt gt gt Edit User lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt gt gt Host cwind0129 27 153 12 fiicmsg01 tu graz ac at gt gt Host cwind0129 27 153 14 fiicmds06 tu graz ac at gt gt Host cwind 129 27 153 17 fiicmhpO1 tu graz ac at gt gt Host cwind0129 27 153 18 fiicmal01 tu graz ac at gt gt Host cwind0129 27 153 21 fiicmpc21 gt gt Host cwind0129 27 153 25 fiicmss03 gt gt Host cwind 129 27 153 3 fiicmsg02 gt gt Host cwind 129 27 153 4 fiicmhp02 tu graz ac at gt gt Host cwind 129 27 153 5 fiicmss01 tu graz ac at gt gt Host cwind 129 27 153 7 fiicmds03 tu graz ac at gt gt Host cwind 129 27 153 8 fiicmss02 tu graz ac at gt gt Host cwind 129 27 191 40 fiicmipc40 gt gt Password s4pRxms5V0uy6 gt gt Group Liicm Unapter 4 server Administration 10015 gt gt Group system gt gt
82. r fKeywords or Content Extended Search Options Objects found 130 Displayed 100 Testing cluster with user defined layout a The Harmony Film Player User Manual E C J The Harmony User Guide SI ThinkPad Delivery Problems Prompt User to Recons I Three New Products Help User Link Mainframes to T Typische Netz User I UR 205 Identification through User Defined Specif I UR 205 Identification through User Defined Specif I UR 205 Identification through User Defined Specif 4 UR 205 Identification through User Defined Specif Testing cluster with user defined layout Figure 5 5 Search Facilities of Harmony 9 9 Inserting NEW VDJECLS icon to activate a certain document The Session Manager shows the whole path and the document is displayed in the corresponding viewer The information landscape Ey195 is a three dimensional graphical overview map as shown Figure 5 7 The collection hierarchy is visualized as three dimensional cubes on a plane Users can fly over the landscape and activate cubes by double clicking Again the Session Manager is updated and the location of the collection or document is displayed An overview window shows the local map from a bird s eye view to help the user to orientate 5 3 Inserting New Objects To insert new objects in Harmony the user has to select nsert from the File menu of the Session Manager For example if the user wants to inser
83. rent groups are the nearest parents of a group For example in Fig ure 4 1 group f has direct parent group group c An indirect parent group is a group with an higher hierarchical level than a direct parent group For example group f has indirect parent group group a Direct and Indirect Subgroups Direct subgroups are the nearest subgroups of a group In Figure 4 1 group a has direct subgroups group b and group c An indirect subgroup is a group with an 2d Unapter 4 server Administration 10015 lower hierarchical level than a direct subgroup For example group a has indirect subgroup group d group e and group f Hyper G has two server administration tools e hgadmin which is a VT100 terminal based tool e HarAdmin which is a graphical X Windows based tool with the same look and feel as the Harmony client 4 1 hgadmin Hgadmin Mau96 is a VT100 terminal based administration tool that is automati cally installed with the Hyper G server software It has the same basic functionality as HarAdmin but HarAdmin is a graphical X Windows based administration tool and supports somewhat more functionality e g browsing through the user group space and deleting multiple groups and users with one command Hgadmin has following options and parameters h help Shows short help text and default values hghost hghost Hyper G server host to connect to Default is hyperg or HGHOST from environment hgport port Portnumber of Hyper
84. revious GetAndLock oper ation on that object The lock flag is also removed when the connection that locked the object is closed Note that this command does not return a response No errors can occur o InsertObject boolean InsertObject const RString amp objRecord const RString amp params ObjectID Allows to insert an arbitrary object into the Hyper G database objRecord is the object record to insert while params allows to specify parameters that are not part of the object record On successful return Object ID which is the new object ID that has been assigned for this object See appendix C for a list of all possible error codes o DeleteObject boolean deleteObject const ObjectID This command deletes the object with ID ObjectID Before you can delete a object you must lock the object see GetAndLock Possible errors LUU Appendix D IHii voli Lommands used by HarAdm n NOACCESS No permission to delete object NOTEMPTY Attempt to delete non empty collection e g you try to delete a group which contains members or subgroups See appendix C for a list of all possible error codes Appendix C HG CSP Error Codes The material in this section has been adapted from the technical report Hyper G Client Server Protocol HG CSP Version 7 05 written by Gerald Pani and Frank Kappe An error code of 0 means that no error occurred The following table Mau96 shows the link server error codes with their asso
85. ribute values Send the ObjectIDs returned from GetObjectByQuery and retrieve the matching object records ObjectField The syntax of query is as follows lt EXPR gt lt EXPR gt I lt EXPR gt NOT lt EXPR gt lt EXPR gt OR lt EXPR gt amp amp lt EXPR gt AND lt ATTRIBUTE gt lt OPERATOR gt lt VALUE gt lt ATTRIBUTE gt any attribute name Author DocumentType lt OPERATOR gt equal lt LESS THAN STRING COMPARE gt greater than string compare Tn regular expression matching It is here and at the simple GetObject command where Hyper G s read access rights are checked This is because access rights to objects are contained within the Rights attribute so that the object record has to be fetched from the low level database in order to determine whether a user is allowed to access it This is why it is normal that this call may return fewer object records than have been requested The commands that return object IDs always return all object IDs even if the user is not supposed to access them o Identify void Identify const RString amp name const RString amp passwd boolean encrypt This command is used to identify the user to the Hyper G database This com mand must be used before any of the commands that modify the database can be used otherwise the NOACCESS error will occur when such a command is use
86. ror message is displayed 6 6 Getting And Changing Information without HarAdmin It is possible to use other Hyper G utilities to obtain information about users and groups direct from the database For example to display all existing users on the current Hyper G server using the hginfo utility hginfo hghost yourserver hgport yourport formatted key UName attr UName mult To display all existing groups of the current Hyper G server hginfo hghost yourserver hgport yourport Gport formatted key UGroup attr UGroup mult To change an attribute of a certain user on the current Hyper G server you can use the hgmodify utility For example to add a new description for user testperson to the user object hgmodify hghost yourserver hgport yourport formatted key UName testperson comm add Descr New Description To see all descriptions of user testperson using hginfo hginfo hghost yourserver hgport yourport formatted key UName testperson attr Descr As in HarAdmin only the system administrator or members of the group system receive the whole information For more detailed information about hginfo and hgmodify see Mau96 Unapter 0 HDarAdm n Lhe Harmony Administrator Chapter 7 The Implementation of HarAdmin Hyper G maintains user accounts and user groups in the server as objects It is essentially the same mechanism as for storing document meta information in Hyper
87. rver leen Server Administration Tools 4 1 hgadmin oaa sos 4 1 1 Using hgadmin es 4 1 2 Managing Users non 4 1 3 Managing Groups es 4 2 Netscape Commerce Server aoaaa a a 4 21 Managing Users 2 oo 22e 4 29 0 Changing a Text File to DBM Format 1 10 10 11 11 11 12 14 15 15 18 20 20 21 25 25 UUINLEUN LO 5 The Harmony Client for Hyper G 41 5 1 Architecture 22 222 rs 41 5 2 Viewers 4 ehh sos 42 5 3 Inserting New Objects e AT 5 4 Linking Objects 2 20 0 0 0 00000 00 00000004 AT 5 5 Communicating with Other Users 2 22 nn 47 5 6 Sending Mails 2 ll rs 54 6 HarAdmin The Harmony Administrator 55 6 1 Setting Up and Running HarAdmin leen 55 6 2 Identifying Yourself to the Server lens 57 6 3 Managing User Groups ee e s 58 6 3 1 The Group Window of HarAdmin 59 6 3 2 Creating a New Group 0 00000 0000 s 7 62 6 3 3 Editing an Existing Group 000 63 6 3 4 Deleting A Group se 64 6 4 Managing Users 2 2 oo ere 66 6 4 1 The User Window of HarAdmin 66 6 4 2 Creating a New User 2 en 69 6 4 3 Editing an Existing User lens 71 6 4 58 Deleting Users 222 on ee 71 6 5 Example of Group Deletion 0 20 004 71 6 6 Getting And Changing Information without HarAdmin 75 7 The Implementation of HarAdmin 77 7 1 The Hyper G User Object 2 a 17 7 2
88. same way as GetParSubDes but sends back only direct parent groups and an array of all found descriptions The group must be first locked HG CSP GetAndLock to avoid that other persons can edit the group at the same time The object is locked until the method insEditGroup is called Possible error codes are 1 Database busy Unapter i Lne Implementation or Haraadm n 2 Group is already locked o insNewGroup int insNewGroup RString amp groupname RStringArray pgrps RStringArray ds It is called if the Commit button in the New Group Window is clicked It checks if the parent groups exist If not the insert process is stopped and an error message is sent back to the Group class The Group class displays an error box and sets the focus to the line which contains the wrong value If no error exists the new group is inserted HG CSP InsertObject and no error is sent back to the Group class Possible error codes are 1 Database busy 2 Parent Group does not exist 3 InsertObject failed o insEditGroup int insEditGroup RString amp groupname RStringList pgrps RStringList ds This command is called if the Commit button in the Edit Group Window was clicked It checks if the parent groups really exist If not the insert process is stopped and an error message is sent back to the Group class The Group class displays an error box and sets the focus to the line which contains the wrong value For each change it uses the HG
89. t Groups Subgroups No parent groups Description Example HrAdmin Example HrAdmin o Subgroups a Delete Group a yf Selected Users vf Selected Subgroups Figure 6 17 Example User Window Group Window and Delete Dialog Unapter 0 HDarAdm n Lhe Harmony Administrator 12 User s Hosts Passwords No hosts 4 No passwords No groups hi New Edit Delete Options Delete Group a wf Selected Users M i Ho Parent urona iv Selected Subgroups cds Ok J Cancel d 25 Group s Parent Groups Subgroups e ed95 part Description Example HarAdmin Figure 6 18 Example Windows for Deleting Group a b d and all direct users Figure 6 19 Example Group Hierarchy after Deleting Groups a b and d 0 0 Getting And Unanging Information without Haradm n 2 The procedure for deleting groups a b and d 1 All selected users are deleted Group d is deleted if no direct users of group d exist Group e is unlinked from group b Group c is unlinked from group a Group b is deleted if no direct users of group b exist D CO Fe C N Group a is deleted if no direct users of group a exist 7 Group Window and User Window are updated with selection strings If a group cannot be deleted usually direct users exist an er
90. t a new document with an English title special keywords and access rights and afterwards the user adds a German title to the new inserted documents the result might be similar to Figure 5 8 Harmony supports multiple languages and changes the user interface control elements and displays the text in the selected language an example is shown in Figure 5 9 5 4 Linking Objects As mentioned in the previous chapters Hyper G provides links between text doc uments MPEG video clips audio images PostScript documents and 3D scenes Harmony gives an easy way with the Link Creatorto link them together Figure 5 10 shows an example of linking a text document and an image document together The text document contains the source anchor the words Main Window are marked and you have to define the destination anchor by selecting the destination document or part of a document in the collection browser here HarAdmin Main Window and after pressing the Create Link button in the Harmony Link Creator Window the link is created displayed as a hot spot in the source document HarAdmin Descrip tion 5 5 Communicating with Other Users The Status Browser shown in Figure 5 11 displays a list of current logged in users the local time the up time the performance index and the name of the current Hyper G server You can select multiple users by holding the shift key and selecting with the left mouse button and talk sending messages
91. t eg the object is already locked CMDSYNTAX Error in command syntax CHANGEBASEFLD Change of base attribute i e attributes that cannot be changed like ObjectI D or Type NOTREMOVED Attribute not removed e g because the value was wrong FLDEXISTS Attribute already exists and may exist only once Errors are listed in Appendix C amp GetAndLock boolean GetAndLock const ObjectID Object amp Similar to GetObject returns object record from object ID provided that access permissions are OK However the object is also marked as locked in the database That means that another user trying to use GetAndLock on the same object would fail until the object has been unlocked again with the Unlock command or the connection of the user that locked the object is closed Clients must use this mechanism to implement write locks to ensure that no two users can modify the same object at the same time Specifically the ChangeObject commands have to be surrounded by GetAndLock and UnLock Unlike GetObject this command guarantees that the attributes returned are the current state of the object and cannot be modified by somebody else between operations Possible errors NOACCESS No permission to access object LOCKED Object is locked by another user try again later See appendix C for a list of all possible error codes amp UnLock boolean UnLock const ObjectID Removes the lock flag from object ObjectID after a p
92. tenance easier because only the cache s servers code has to be modified to support new protocols or file formats 3 3 4 Full Text Server ftserver The full text server is dedicated to uhapter o Hyper ix e full text retrieval e document clustering e automatic link generation It maintains an inverted index of all text documents for searching Whenever a new document is inserted it is sent to the full text server for indexing it When the document is removed its index is removed too Searches can be full text queries and the full text server supports fuzzy boolean queries and WAIS like nearest neighbour searches based on the vector space model The result is a ranked list of objectIds Chapter 4 Server Administration Tools Hyper G maintains user accounts and user groups to deny or grant access rights to certain parts of the information structure Users may be combined in user groups which are hierarchically structured into groups and subgroups The group hierarchy is an acyclic directed graph since a group may belong to multiple parent groups An example of a group hierarchy is shown in Figure 4 1 a i higher X LE b 2 EN lower d f Figure 4 1 A Small Group Hierarchy Within a group hierarchy there exist direct and indirect parent groups and direct and indirect subgroups Direct and Indirect Parent Groups Direct pa
93. th URL telnet userChost News Usenet Use with URL news newsgroup article Gopher Gopher protocol with URL gopher Host port selectorstring WAIS Wide Area Information Server with URL wais Host port selectorstring e HTTP Hypertext Transfer Protocol HTTP is an ASCII protocol atop TCP IP and implements a fast and flexible mechanism for following references between units of distributed information The name is often misinterpreted it doesn t only transfer hypertext also other kind of information e g audio e HTML Hypertext Markup Language HTML is the most important document format in WWW it is an SGML Structured Generalized Markup Language encoded text format for WWW and is used to create hypertext documents with a logical structure With HTML WWW embeds links and inline graphics in documents lt Unapter 2 internet Information oystems WWW structures its information in documents and links them together Hierar chies are presented as lists of hyperlinks and it is a distributed hypermedia system i e documents can comprise text image audio and film WWW uses HTML to embed links within text documents but it supports no links from other kinds of documents e g links in film clips WWW is a great step forward but except hyperlinks it has no structural facilities and links are not bidirectional The user can t find out which other documents point to a particular document This is a limitation of WWW because in usin
94. the huge amount of information available on the Internet the user has difficulty to gain an overview to know how much information exists to a certain topic etc Hyper G has navigational structuring and search facilities to help cope with this problem Two particular features are Hyper G s user accounts and its hierarchical scheme of user groups which are used to grant or deny access to specific parts of the information space Hgadmin a VT100 terminal and HarAdmin a graphical X Windows based tool for user and group administration are explained in detail in this thesis HarAdmin is based on the Hyper G Client Server Protocol and on hgadmin It provides func tionality for browsing through the user group hierarchy displays all existing users and groups of the current Hyper G server and makes it easy to create delete and manipulate user accounts and user groups Contents Introduction Internet Information Systems 2 1 Basic Internet Applications 2s 2 2 First Generation Information Systems 2 llle n 2 2 1 Archie 2222 ee 2 2 2 WAIS ee 2 2 3 Gopher on 2 24 WWW 2 3 Second Generation Information Systems Hyper G 3 1 Special Facilities of HyperG _ _ _ 3 2 Interoperability a 3 3 The Hyper G Server 2l ee 3 3 1 Architecture aoaaa 3 3 2 Link Server hgserver aoaaa r s s 3 3 3 Document Cache Server deserver 2 2 2222 3 3 4 Full Text Server ftse
95. tination At the destination the IP and TCP envelopes are unpacked and the original data is reconstructed and checked eg are packets out of order corrupted or got lost etc LU Unapter 2 internet Information oystems 2 1 Basic Internet Applications Since the beginning of the Internet in 1983 four basic Internet applications exist e Remote Login telnet Telnet is used for logging into other computers on the Internet The user can access all services the remote machine provides Telnet command telnet address of foreign host eg telnet iicm tu graz ac at e l ile Transfer Protocol ftp The ftp is used to move files from one computer to another There are two different ways to receive files from the foreign computer ascii for text files and binary for program files And there also exists two different access modes anonymous password can be the whole email address and identified account name and password Ftp command ftp address of foreign ftpserver eg ftp ftp iicm tu graz ac at e Electronic Mail email Email is the most used Internet application because it is easy to use and much more faster than the traditional surface mail The mail is sent from one com puter to the next until it reaches its destination Today many mail programs exist the most popular being SMTP Simple Mail Transfer Protocol Mail has some weaknesses like security which is on a low level and foreign people can snoop around in your own private mail
96. tring groupname void deleteSubGroups HgStub RStringArray amp subgrps RString groupname int getUsers RString amp ufilter RString gfilter RStringArray amp duser RStringArray amp iuser int getHPGDHA RString filter RStringArray amp hs RStringArray amp pws RStringArray amp grps RStringArray amp dgrps RString amp des RString h RString amp a int getLockedHPGDHA RString amp filter RStringArray amp hs RStringArray amp pws RStringArray amp gs RStringArray amp ds RString amp h RString amp a int insNewUser RString amp un RStringArray pws RStringArray hs RStringArray gs RStringArray ds RString h RString a int insEditUser RString un RStringlist pws RStringList hs RStringList gs RStringList ds RString h RString a int remUser RStringArray amp users RString amp error void getSubGroupsAndUsers RString groupfilter RStringArray amp dgrps RStringArray amp igrps RStringArray amp du RStringArray amp iu o getGroups int getGroups RString amp filter RStringArray amp groups 4 Lhe Vor vUlass otructure of MarAdadmin OL This command is used to retrieve all groups with selection string filter First the HG CSP message GetObjByQuery is used to get all matching ObjectIds searches on indexed attributes here UGroup Then the HG CSP message ObjectByIdQuery is used to get all object records for the previous retrieved ObjectIds The names of the matching group objects are stored
97. u above the buttons Commit Clear Close The focus is set automatically A complete new user can look like the one shown in Figure 6 14 User testperson Password Retype Password Encr User Host testperson jupiter testperson fiicmsg02 Description Testperson for HarAdmin cwind D c Parent Group iicm Account 23 Home Collection testperson Add UsergHost Commit Clear x Close Figure 6 14 An Example of a Complete New User l Insert a new user by pressing the Commit button If no error occurs the entries can be inspected in the User Window The newly created user is automatically selected as the current user and the user s attributes are displayed in the User Window 0 9 EXample of Group Veletion 1 Button Commit Sends the user objects to the database for insertion The values of the new user are not cleared except the user name This is useful for adding multiple users with the same attributes eg Hosts Groups to the database If an error occurs a message box is displayed and the focus is set to the attribute which contains wrong values Button Clear Clears all field entries in the New User Window Once a field has been edited the background colour of the field is changed to indicate an edited value Button Close Closes the New User Window but does not destroy it If you create a new user again the old entries are displayed except the us
98. uch as in MPEG video clips images 3D scenes PostScript documents and audio The main functions of the link server are Kap93 e It assigns unique object IDs to objects similar to an ISBN number ensuring that no two objects share the same ID When an object is modified it receives a new ID and the user can distinguish between the old and new version If the object is deleted the ID is never reused Currently the local object ID is a 32 bit entity there are 2 object IDs per server By concatenation of the local object ID and a 32 bit server ID we get a 64 bit global object ID which is globally unique e Only the link server stores more information about an object like author title keywords etc If an object has to be modified only the information stored in the link server has to be modified And of course it receives a new object ID e It is aware of the collection hierarchy to maintain database consistency e g making sure that every user is a member of at least one group uhapter o Hyper ix e It performs complex boolean and fuzzy boolean queries over the whole data base or a subset of the collection hierarchy Every document and every collec tion 1s indexed on creation e It contains a scheme of access rights to allow or disable access to certain documents or collections to certain users and user groups Clients connect to the link server to browse and search through the information space The client sends a quer
99. va merges techniques of hypertext information retrieval and wide area networking Text documents can include hyperlinks images etc Most WWW Servers have no integrated search facilities but uses WAIS as an add on search engine It is based on three basic concepts URL Uniform Resource Locator HTTP Hypertext Transfer Protocol and HTML Hypertext Markup Language Because of the huge amount of information available on the Internet the user has despite the existing systems difficulty to gain an overview to know is this all the user can see is this information up to date Hyper G under development at Graz University of Technology the first sec ond generation hypermedia information system AKMS95 is designed to cope with this problem of distributed hypermedia systems called disorientation or the Lost in Hyperspace syndrome It provides search orientational and navigational fa cilities structures its information in so called collections and builds a hierarchical o Unapter 1 introduction structure called collection hierarchy Hy per G stores hyperlinks separatly from doc uments rather than embedded within them and hence supports links in all kinds of documents such as MPEG video clips Mar95 images audio PostScript and 3D scenes Hyper G uses the collection hierarchy to provide a structural overview of the information space for the user and to grant or deny access rights to parts of the information structure Hyper
100. ver Protocol HG CSP The Hyper G Client Server Protocol has the following features e it is based on TCP IP e it is a connection oriented protocol stays open for duration of a session e it is asynchronous e and almost stateless The client sends messages to the server which initiate server transactions and the server returns messages with the results of transactions and or error codes The client opens the connection by opening a TCP connection to the server s port generally port 418 If any error occurs HarAdmin displays the error in a message box The frequently used HG CSP message is o GetObject boolean GetObject const int ObjectID ObjectRecord amp Har Admin uses this message to retrieve the full object record Send the 0bjectID and if no error occurs the 0bjectRecord contains a list of attributes of this object Possible errors RSERV NRESP Remote server not responding NOTFOUND The object could not be found NOACCESS No read permission for the object 6 4 Lhe Vor vUlass Structure or MarAdadmin 3 Further HG CSP message used by HarAdmin are e GetObjByQuery ObjectByIdQuery Identify ChangeObject Get AndLock UnLock Insert Object DeleteObject A detailed description of the above messages is given in Appendix B 74 The C Class Structure of HarAdmin HarAdmin is written in C The three main classes are Haradmin User and Group as shown in Figure 7 1
101. w the New User Window shown in Figure 6 13 is displayed User Password Retype Password Encr User Host Description Parent Group Account 0 Home Collection Add Password Clear Close Figure 6 13 The HarAdmin New User Window The fields correspond to attributes of the Hyper G user object Unapter 0 HDarAdm n Lhe Harmony Administrator User The name is unique for the current Hyper G server and has to be a single word The username is mapped to lower case letters on insertion Password The password is entered in clear text Individual characters are echoed as The password must be entered twice to counter possible typing mis takes Password encrypted The encrypted password is stored under UNIX in the file etc passwd or you can get the encrypted password with the SUN Yellow Pages command ypcat passwd The advantage of this method is that the system administrator can set up a user with the user s Unix password without knowing the password itself User Host If the host is unknown or already exists a message box appears and after pressing OK the focus is set to the corresponding line The host can be entered as Domain Name IP Address or Alias Name HarAdmin maps the host names to IP Addresses ur Home Collection A home collection has the form followed by the name of the new user To add more attributes choose the corresponding one from the selection men
102. wGroup void insNewGroup It is called when the Commit button in the New Group Window is pressed It stores all given attributes in arrays and sends the arrays and the group name to the class Haradmin for insertion insNewGroup If an error occurs the method displays the error in a message box and sets the focus to the line which contains Unapter i Lne Implementation or Haraadm n the error If no error occurs it calls the method groupWindowUpdate to display the new group and the group s attributes in the Group Window removeGroup void removeGroup This command is used to delete one group it checks if a group is selected and calls the method remGroup of the class Haradmin If an error occurs eg if the group has sub groups and or members the methods getSubGroupsAndUsers of class Haradmin then deleteUsersFromGroup and removeSubGroups are called Chapter 8 Future Work HarAdmin has extended the functionality of hgadmin the VT100 terminal based administration tool with graphical components to make the management of user accounts and user groups easier but it is not finished yet There can be done much more to help the system administrator and other users to manage their servers Ways in which the current version of HarAdmin could be extended include e In this version of HarAdmin you cannot change the name of the user or group easily You must delete the user or group object and create it new again with the desire
103. y amp du RStringArray amp iu This command returns all users direct and indirect and all sub groups direct and indirect for a certain group groupfilter To find indirect users and sub groups the group hierarchy is searched recursively The functions for maintaining users have the same mechanism as the ones pre viously discussed for groups insNewUser Possible error codes are 1 Database busy 2 InsertObject failed 30 Specify account user host 31 Host doesn t exist 32 Host already exists for user 4 Group doesn t exist insEdit User Possible error codes are Unapter i Lne Implementation or Haraadm n 1 Database busy 2 ChangeObject failed 30 Specify account user host 31 Host doesn t exist 32 Host already exists for user 4 Group doesn t exist 7 4 2 Class User The class User manages all activities of the User Window the New User Window and the Edit User Window It sends requests to classes Haradmin and Group class User t public User Haradmin only initialize variables void userMenu void removeUser void newUserWindow void editUserWindow void FiltersAccept FieldEditor31 char void deleteUsersFromGroup RStringArray dusers RStringArray iusers RString group private void userWindowUpdate void showAll void showGroup void insNewUser void insEditUser amp userMenu void userMenu It is used to build the User Window If the User Wi
104. y to the link server which returns a number of objects The client lets the user choose of the list of hits and sends the object ID of the selected one to the document cache server to retrieve the whole document Links are represented in the database by means of a number of objects and relations between objects there exists a number of different objects KPS93 as shown in Figure 3 5 Document Object The document object holds information about a document including document type author title and access information like host port and protocol Anchor Object It represents an anchor by a position attribute The format depends on the doc ument type of the anchor text document or MPEG video clip image audio PostScript The anchor is used by clients to interpret the document Link Object The link object stores information about the link like link type author access rights and it is used to search for certain links The corresponding relations Document Anchor Relation Specifies which anchor belongs to which document by means of their object IDs Link Anchor Relation Joins anchors the source and the destination anchor and a link object to form a link The destination anchor can be a part of a document or a whole document Note No destination anchor object exists rather the destination anchor field of the Link Anchor Relation stores the destination document Example For Document Anchor Relation 1 The client sends a r

HarAdmin: A Graphical Tool for Hyper G Server

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