Šiuo metu informacija yra sukaupta paskirstytuose šaltiniuose, kurie kaip saugojimo priemonę naudoja duomenų bazes. Šios bazės yra skirtingų tipų. Vartotojo tikslas yra naudoti keletą nepriklausomų informacijos šaltinių kaip vieną. Dėl savo nepriklausomumo nuo DBVS ir platformos tipo, XML tapo ypatingai naudingas atviroms susisiekiančioms sistemoms, kuomet duomenys apsikeičiami tarp paskirstytų duomenų šaltinių. Šiame darbe pateikiamas ontologijų, kaip dalykinės srities apibrėžimo informacijos paieškai, panaudojimas. Tai leidžia optimizuoti reikiamos informacijos paieškos procesą ir išvengti užklausos rezultatų pertekliškumo. / The main problem in heterogeneous database integration is data incompatibility in different databases. XML is perfect solution in data exchange between different databases as it is independent from OS, applications or hardware. To implement XML in data exchange XML must be created corresponding to the databases. This work propose use of ontologies for information retrieving from heterogenous data bases. Such method let optimize user query to avoid wasted information.

Multi-tier enterprise systems consist of more than two distributed tiers. The design of multi-tier systems is considerably more involved than two tier systems. Not all systems should be designed as multi-tier, but if the decision to build a multi-tier system is made, there are benefits to this type of system design. CSCources is a system that tracks computer science course information. The requirements of this system indicate that it should be a multi-tier system. This system has three tiers, client, business and data. Microsoft tools are used such as Visual Basic (VB) that was used to build the client tier that physically resides on the client machine. VB is also used to create the business tier. This tier consists of the business layer and the data layer. The business layer contains most of the business logic for the system. The data layer communicates with the data tier. Microsoft SQL Server (MS SQL) is used for the data store. The database containsseveral tables and stored procedures. The stored procedures are used to add, edit, update and delete records in the database. Microsoft Transaction Server (MTS) is used to control modifications to the database. The transaction and security features available in the MTS environment are used. The business tier and data tier may or may not reside on the same physical computer or server. Active Server Pages (ASP) was built that accesses the business tier to retrieve the needed information for display on a web page. The cost of designing a distributed system, building a distributed system, upgrades to the system and error handling are examined.Ball State UniversityMuncie, IN 47306 / Department of Computer Science