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a set of attributes that is similar to a relational datdbasetalzlc. The toolkit pro\!idcs each entry \\,ith a set ofbuilt-in attributes (such as title, creation and modificdtiondates, and author). I-he applications can thendcli\~cr additional attributcs.Tlic toolkit provides the means to retrieve, modi$,and iterate through the collection of entries in astr'~ightforward manner. Bcc~~lsc the attributes arep.lrt of the application description ~ n are d not storedin a separate database, the toolkit can use its lu~o\\.lcdgcof the attributes to simplif\r certain commonoperations. For example, because tmnsferring datafl-om M'I'ML. forms to the tiatabase and back is a b.~sicol.xration in colJaborati\~e 'ipplications, the toolkit canlink fields on forms to database attributes, making itpossilble to store them n~itli a single com~lland. To supporta djrn~mic de\fclopmcnt cnvironme~lt, the toollitalso upgradcs databases in real tinic as nc\v attributesarc added or deleted. This permits tlie applicationdci.eloper to conccntratc on the task at hand ratherthan \\.err\! about databasc managcmcnt tasks.Altl~ougl? the prirnar!, organi~ation ~ncchanism is '1fl~t table indcsed by docu~ncnt identifiers, the databascintegrates a hierarchical relationship ben\!een entries\\hen necessary. Because liier,lrcliies are cornrnon incollaborative applications (c.g., foldcrs/documentsand topics/replies)), it was important to reflect this ina natural way in the database.In addition to attributes, the datab.ise offers propcrties.Compared to attributes, \\~hicli arc stored for eachcntr!, in the databasc, properties arc stored withine,~cIi forum. Application clesigners can use these propertiesin an!! \fray tlic\r desire: the\, .Ire simple key-\valuerclationsliips. The Alta\iista For~lrn sohvare ~~scspops-ties to impleme~~t a \rariety of features, fromaccess co~ltrol policies to the I>acIkgro~~nd color of thescrccn display.User properties are an extension of standard forumproperties. They act like forum psopcrtics except thatthey arc tied to tlie user \\.lie is executing the transaction.User properties keep database loclung to a niinimumbecause, in collaborati\,e ,~pplic,~tions, a user \\,illt\~pic'~ll\' execute onl!, one transaction at a time.Indexing and Search: The Way of the Future?One Itcy design decision \\,as to include an inclexing,~nd search cnginc as a basic component of the product.Although the database is often the central piece ofa groupware product, an indexing and search engineoftcn plays a similar role for '1 WWW site. This develop~naitis completely consistent with tllc philosophyof the WWW-inbrmation is linked as needed, notncccssarily follou,ing any structure. Database use ismore suitable for inform,ition objects that have some~~niformity in their definitions.The basic function of the indexing engine is to mapa set oF\\~ords to a docunicnt containing thosc words.term docunient is ~~seti in ,I generic sense. It canbe any logical entity associated \irith a set or nlords.)-.I lie indcxing information IIILIS~ be stored in such a\\.a)r tliat subseq~~ent searchcs based on individual\\/orcis (and phrases) 'Ire efficient and speedy. Theindexing engine in the Alt~Vista Forum toollcit isbasically the same indexing cnginc '~\r,~ilable on theAltaVista \Web site.' l>esig~led and implemented atIligit,~l's System Research Center, it is liiglil!~ scalableand efficient.'.l'lie built-in databasc fi~nctions '1s a repository fixentries \\zit11 3 predefined set of attributcs. It pro\.idesfast retrieval when tlie entries arc identified using eitheran cntl-)I 113 or a hicrarcliical 113, and it pro\,idcs sirnplccreating, updating, and sorting f~~nctions associatedw~itli rctrie\~al. The indexing and search engine complementsthe AltaVista Forum ciat,lbase: it proi~ides acontent-based search method and f ~nctions at higherspccd. Since the search engine is extremely fast andsc,ll,~ble, \ve also use it to index some of tlie attribute\-alucs in the database. This allo\\rs us to use tlie se'~rcliengine for certain cornputci~~tc~lsi\~e scarches thatotlicr\\/isc \\,auld be performed by the database.Kascd on our expel-icncc, \\,c cxpcct the capabilitiesof the indexing and search cnginc to continue toexpand. As the popularity of the WM'W technologycontinues to grow, the vol~~mc of pi~blislied information\\till also increase. Only a small a~iio~unt of thisinformation can be effecti\,elv c
work on it was limited, \ve divided our efforts betweenmaking access control flexible and choosing defaultoptions that ~vould pro~note collaboration.\Ilk defined access control for the whole database(forum), rather than for individual entries and attributesof cntries. However, some e~itrp-level access controlis necessary. For example, it is preferable to let onlythe owner (or the creator) of an entry modify anddelete that entry. As a result, we allowed the group definitionto include cntr~l-spechc logcal users, ratherthan pro\kle a general meclianisni for entry-level accesscontrol. Therefore, a group may contain a memberwho is the o\vner of the current entry. During accesscontrol checking, the current entry's owner is loolccdup and matched against tlie currently logged-in user.Instead of letting the adniinistrator define accesscontrol for each possible incoming access/action, ourfi-ame\\lorlc allows the application definition to groupaccesses together into logical access rights. For esample,for the discussion application, we defined the followingaccess rights:Read-Includes all read URLs (different views,whether for a single entry or a list of entries)Contribute-IncludesModifj-Includesdeletionaddng a topic or replyany form of modification ori44odcratc-Includcs such fi~nctions as creating Itejlwords,polling options, controlling number oflevelsof replies, and setting certain entries as hiddcnAdliii~iistrate-Cha~~ge access control or otherlinds of resource consuniption policiesBy defining these access rights, the administrator onlyneeds to establish who can do these five operations,rather than define numerous other kinds of operations.It is still possible to change and add to thisgroup of access rights by ~nalci~lg simple modificationsto the application definition...Our basic strategy for making access control easy tomanage is to set up default policies of access controlthat apply to as many situations as possible, within reason.The default policy is added to the application definition.If the admillistrator is satisfied with the defaultpolicies, then the access control can be used as supplied.For the discussion application, die default policyis tlie following:Read-AllContribute-Allusers, including anonymoususers, escluduig arionyrnous~Modifj-Owner (creator) of entry and moderatorsModerate-O\vnerAdministrate-Ownerof the forumof tlie forumTo simplifj implcmcntation, we chose not to allownesting of groups. Our design allows for adding it inthe future as long as it nialtes management of accesscontrol policies easier.Future DirectionsTo date, we have receivcd encouraging feedback fiomusers. Of the ways that we can continue to improvethe AItaVista Forum product, we feel tlie follou~ingdeserve the highest priority.First, \\re need to provide better ways to help usersdeal with information o\!erflow. Although we havebuilt ways to filter and search information into ourapplication, further simplification is necessary. \Weare worlcing on srnart agents that bring the relevantinformation to the user's fingertips.Second, a number of the fi~nctions that we providecan be more easily performed on the client machine.The Java language is the best candidate for pro\jidingthese hnctions since it enables us to handle a widevariety ofclient platforms. Initially, we arc loolung intousing Java to improve certain user interface problems,such as opening additional \\.indows on the clientmachine to notify users of new information.Third, s)lnchronous collaboration using video,audio, and whiteboard will soon become feasible andcost effective. It is iniportant for LLS to help bring userstogether through both synchronous and asynchro-JIOUS methods of collaboration. For example, usersshould be able to use the calendar application toschedule a meeting over tlie Internet, and Windo\\ashould be available to the user automatically.Fourth, as the AltaVista Forum sohvare matures,we hope to add to its performance and increaseits scalability. As its environment evolves, we are lookinginto ways to bypass the CGI interface and use acompiled language for more of the toolliit iniplc~nc~itation.We also hope to add support for large commercialdatabases.Finally, will continue to add innovative applicationsto our product. We recently built a prototype ofa customer-support application that lteeps track ofproblem reporting. We are loolci~ig into other applicationssuch as project management, group review, andsurvey and decision-support systems.AcknowledgmentsWe wish to thank the AltaVista Forum developnientand management teams for their contributions to theprod~~ct. In particular, we wisli to thank Peter Hurleyfor his leadership in starting the effort; Ralph DeMent,Bob Travis, David Marques, and Rick Franltosky, whohave worlted with us throughout the lifetime of theproduct and with whom we have developed a specialcamaraderie; and Dan I
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Page 83: Printcd in U.S.A. EC-N7285-18/9612
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