International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / TechSat21 is sponsored by the Air Force Research Laboratory Space Vehicles Directorate and the Air Force Office of Scientific Research1. Its mission is to control a cluster of satellites that, when combined, create a “virtual satellite” with which to conduct various experiments in sparse aperture sensing and formation flying. Customers of the TechSat21 database include mission planners and system engineers. Mission Planners need information that allows them to make high level planning and scheduling decisions. System Engineers need information to predict satellite sub-system problems and conduct satellite design and performance trade studies. This paper describes those users and the project database.

After well-known structured technology, object-oriented technology has become another paradigm of system development and a hot topic in the field of software engineering. The Unified Modeling Language (UML) has become a standard means for the analysis and design of object-oriented after it passed the certification of the Object Management Group (OMG) in 1997, and it was widely used in many industries. Although it becomes a standard of object-oriented modeling language, UML hasn¡¦t provided principles or guidelines for mapping classes to tables. The purpose of this study is to investigate the guidelines for transforming UML class diagram to object-relational model. The transferring methods include both static structure transfer and dynamic behavior transfer. An example of automobile ordering system is used to illustrate the guideline and application. With these guidelines, analysts can easily use the UML class diagram to express database designing and thereby improve the efficiency and effectiveness of UML modeling.

Semantic query optimization is an important issue in many contexts of databases including information integration, view maintenance and data warehousing and can substantially improve performance, especially in today's database systems which contain gigabytes of data. A crucial issue in semantic query optimization is query containment. Several papers have dealt with the problem of conjunctive query containment. In particular, some of the literature admits SQL like query languages with aggregate operations such as sum/count. Moreover, since real SQL requires a richer semantics than set semantics, there has been work on bag-semantics for SQL, essentially by introducing an interpreted column. One important technique for reasoning about query containment in the context of bag semantics is to translate the queries to alternatives using aggregate functions and assuming set semantics. Furthermore, in SQL, order by is the operator by which the results are sorted based on certain attributes and, clearly, ordering is an important issue in query optimization. As such, there has been work done in support of ordering based on the application of the domain. However, a final step is required in order to introduce a rich semantics in support. In this work, we integrate set and bag semantics to be able to reason about real SQL queries. We demonstrate an ordered bag semantics for SQL using a relational algebra with aggregates. We define a set algebra with various expressions of interest, then define syntax and semantics for bag algebra, and finally extend these definitions to ordered bags. This is done by adding a pair of additional interpreted columns to computed relations in which the first column is used in the standard fashion to capture duplicate tuples in query results, and the second adds an ordering priority to the output. We show that the relational algebra with aggregates can be used to compute these interpreted columns with sufficient flexibility to work as a semantics for standard SQL queries, which are allowed to include order by and duplicate preserving select clauses. The reduction of a workable ordered bag semantics for SQL to the relational algebra with aggregates - as we have developed it - can enable existing query containment theory to be applied in practical query containment.

Semantic query optimization is an important issue in many contexts of databases including information integration, view maintenance and data warehousing and can substantially improve performance, especially in today's database systems which contain gigabytes of data. A crucial issue in semantic query optimization is query containment. Several papers have dealt with the problem of conjunctive query containment. In particular, some of the literature admits SQL like query languages with aggregate operations such as sum/count. Moreover, since real SQL requires a richer semantics than set semantics, there has been work on bag-semantics for SQL, essentially by introducing an interpreted column. One important technique for reasoning about query containment in the context of bag semantics is to translate the queries to alternatives using aggregate functions and assuming set semantics. Furthermore, in SQL, order by is the operator by which the results are sorted based on certain attributes and, clearly, ordering is an important issue in query optimization. As such, there has been work done in support of ordering based on the application of the domain. However, a final step is required in order to introduce a rich semantics in support. In this work, we integrate set and bag semantics to be able to reason about real SQL queries. We demonstrate an ordered bag semantics for SQL using a relational algebra with aggregates. We define a set algebra with various expressions of interest, then define syntax and semantics for bag algebra, and finally extend these definitions to ordered bags. This is done by adding a pair of additional interpreted columns to computed relations in which the first column is used in the standard fashion to capture duplicate tuples in query results, and the second adds an ordering priority to the output. We show that the relational algebra with aggregates can be used to compute these interpreted columns with sufficient flexibility to work as a semantics for standard SQL queries, which are allowed to include order by and duplicate preserving select clauses. The reduction of a workable ordered bag semantics for SQL to the relational algebra with aggregates - as we have developed it - can enable existing query containment theory to be applied in practical query containment.

SUMMARY Thesis presents object-relational mismatch research as actual problem in the information technology systems targeted for business domain applications. Programmers are working with objects, whereas they use relational databases to make the data persistent. This leads for the need to unite the two theories – object and relational. The aim of the thesis is to overview object-relational mismatch. Advantages and disadvantages are overviewed and the solutions are given. Requirements for the state-of-the-art object-relational mapping layer will be presented. Those object-relational mapping layers are used in current business processes based system. Practical aim of the thesis is to propose object-relational mapping framework for real client-server system, based on current the most popular object-relational mapping layers in the market. In the practical part of the thesis feature based analysis of selected object-relational mapping frameworks is being performed. Those object relational mapping layers are being used for tests on real insurance industry based software system. Theoretical propositions and the results discovered are illustrated with 16 pictures and 6 tables. The thesis is based on 15 different literature sources in the Lithuanian and English languages. Two appendices are given and the end of the work.

This work is analyzing problems, arising because of sematical gap between relational and object-oriented approaches and discusses how to utilize object-relational mapping for solving this problem. After analysis of object-relational mapping framework (further – ORM) principles and features of existing ORM frameworks a model is suggested, that allows to implement ORM by utilizing MVP principles in a way that retains major portion of both approach pros and is perfect for transitioning existing relational structures to object-oriented. Further, project and implementation of prototype framework, that uses the following principles and suggested model, is described and utilized as for implementing imaginary domain ORM mapping example application.

Geographic features change over time, this change being the result of some kind of event or occurrence. It has been a research challenge to represent this data in a manner that reflects human perception. Most database systems used in geographic information systems (GIS) are relational, and change is either captured by exhaustively storing all versions of data, or updates replace previous versions. This stems from the inherent diffculty of modelling geographic objects in relational tables. This diffculty is compounded when the necessary time dimension is introduced to model how those objects evolve. There is little doubt that the object-oriented (OO) paradigm holds signi cant advantages over the relational model when it comes to modelling real-world entities and spatial data, and it is argued that this contention is particularly true when it comes to spatio-temporal data. This thesis describes an object-oriented approach to the design of a conceptual model for representing spatio-temporal geographic data, called the Feature Evolution Model (FEM), based on states and events. The model was used to implement a spatio-temporal database management system in Oracle Spatial, and an interface prototype is described that was used to evaluate the system by enabling querying and visualisation.

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Två grundläggande paradigm inom datavetenskap är objektorienterad programmering och relationsdatabasteknik. En kombinering av applikationer gjorda i ett objektorienterat programmeringsspråk med den beständighet och funktionalitet som ges av relationsdatabaser är en möjlig vidareutveckling av ens kunskaper inom dessa områden. Kombinationen av dessa båda förutnämnda paradigm innebär åtminstone ett problem som uppkommer då en relationsdatabas lagrar data i tabeller och en objektorienterad applikation lagrar data i objekt. Detta problem kallas objekt/relations paradigmens missanpassning. På grund av detta problem så måste kopplingen mellan paradigmen skötas av ett ramverk av något slag. I vår rapport så undersöker vi två av de ramverk som behandlar kopplingen mellan paradigmen. Specifikt i våran studie kommer vi att fokusera på kvalitetsattributet användbarhet. De ramverk som vi undersöker heter Java Database Connectivity (JDBC) och Hibernate. Båda dessa verktyg är skapade för det objektorienterade programmeringsspråket Java. / Two of the fundamental paradigms within computer science are object oriented programming and relational databases. A combination of an object oriented application with the persistence and functionality provided by relational databases is a further development of one’s knowledge within these areas. The combination of the two aforementioned paradigms will yield at least one problem, which occurs because in a database data is stored in tables whereas an object oriented application stores data in objects. This problem is called the object/relational paradigm mismatch. Because of this problem the connection between the paradigms must be handled by some kind of framework. In our report we investigate two of the frameworks which handle the connection between the paradigms. Specifically in our study we will focus on the quality attribute usability of the two frameworks and conduct a comparison between these two. The frameworks we investigate are called Java Database Connectivity (JDBC) and Hibernate. Both of these tools are created for the object oriented programming language Java.

Updating XML data is very wide area, which must solve a number of difficult problems. From designing language with sufficient expressive power to the XML data repository able to apply the changes. Ways to deal with them are few. From this perspective, is this work very closely dedicated only to the language XQuery. Thus, its extension for updates, for which the candidate recommendation by the W3C were published only recently. Another specialization of this work is to focus only on the XML data stored in the object­relational database with that repository will enforce the validity of documents to the scheme described in XML Schema. This requirement, combined with the possibility of updating of data in the repository is on the contradictory requirements. In this thesis is designed language based on XQuery language, designed and implemented evaluating of the update queries of the language on the store and a description and implementation of the store in object­relational database.