S. E. Bratsberg. Evolution and Integration of Classes in Object-Oriented Databases. Dissertation, The Norwegian Institute of Technology, University of Trondheim, June 1993.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....the Generic Integration Model GIM which enables an efficient algorithm to derive an integrated schema in a user friendly data model. The data model GIM was firstly introduced in [SS95, SS96a] The extensional conflict as one main conflict is topic of many publications, e.g. DH84, Mot87, MNE88, Bra93, SGN93, TS93, KS95, NS96] They usually resolve this conflict directly in an object oriented model by using specialization. The original classes are often classes of the integrated schema enriched by new super subclasses and specialization relationships among them. DS96] for example, suggests ....

S. E. Bratsberg. Evolution and Integration of Classes in Object-Oriented Databases. Dissertation, The Norwegian Institute of Technology, University of Trondheim, June 1993.

....all new buildings (S1.Buildings not specialized to old buildings) are included in the second database as habitable buildings. S1.Building: S1.Old Building: S2.Building: S2.Habitable Building: 1 2 3 4 5 Figure 2: Extensional Overlapping of Input Classes Most existing integration approaches [13, 12, 21, 3, 7, 22, 15, 8, 14] do only mark pairs of classes with a possibly non empty population intersection as candidates for integration. Additionally, attributes may be marked to be corresponding. The resulting integration assertions can be listed in the notation proposed by [22] S1fflBuilding S2fflBuilding ....

S.E. Bratsberg. Evolution and Integration of Classes in Object-Oriented Databases. Dissertation, The Norwegian Institute of Technology, University of Trondheim, June 1993.

....right canonical data model can be found in [SCG91] The choice of the canonical data model influences the quality of the integration step, which is the most difficult step of the design process. Most of the recent proposals prefer an object oriented data model (e.g. in [TS93, RPRG94, GCS95, PBE95, Bra93] It is often argued that only a semantically rich data model can be the right canonical data model because no or only little semantics is lost during the transformation from an object oriented local schema to the canonical data model (see also [SCG91] Instead, we propose the use of a ....

S.E. Bratsberg. Evolution and Integration of Classes in Object-Oriented Databases. Dissertation, The Norwegian Institute of Technology, University of Trondheim, June 1993.

....the local schemata into a canonical data model. In the second step schematic heterogeneity has to be overcome. In general, this step is a very complex task due to many kinds of conflicts. Therefore, different integration methodologies were proposed in [BLN86, NEL86, LNE89, SP94, SPD92, Bra93, TS93, Dup94, RPRG94, GCS95, PBE95] There are different requirements attributed to the integration of local schemata into an integrated schema (adopted from [BLN86] page 337) ffl Completeness and Correctness: The integrated schema must contain all concepts present in any component schema ....

....to old buildings) are included in the second database as habitable buildings. Extensional Overlappings S1.Building: S1.Old Building: S2.Building: S2.Habitable Building: 1 2 3 4 5 Figure 2: Extensional Overlapping of Input Classes Most existing integration approaches [NEL86, LNE89, SPD92, Bra93, Dup94, SP94, RPRG94, GCS95, PBE95] do only mark pairs of classes with a possibly non empty population intersection as candidates for integration. Additionally, attributes may be marked to be corresponding. The resulting integration assertions can now be listed in the notation proposed by ....

S.E. Bratsberg. Evolution and Integration of Classes in Object-Oriented Databases. Dissertation, The Norwegian Institute of Technology, University of Trondheim, June 1993.

....changing a database schema. Schema evolution ( BKKK87, MSOP86, LH90, BBB 88, Bar91, TS92] systems tend to focus on how changes to the schema are described and ways of ensuring that changes do not invalidate the database contents. Versioning approaches ( BB88, SZ86, Zdo90, MS93, Cla92, Bra93] focus on how to allow multiple versions of an object to co exist at run time. The most obvious similarity between such database systems and DRASTIC is that a process booted over a DRASTIC platform with a persistent store must be able to access the state in the store after any evolution. Schema ....

S. E. Bratsberg. Evolution and Integration of Classes in Object-Oriented Databas es. PhD thesis, Department of Computer Systems and Telematics, Norwegian Institu te of Technology, June 1993.

....data. As we have seen, data may require several forms thus it must always be possible to access the original form, subject to appropriate authorisation. Many researchers have investigated the support of evolution in object oriented database systems [Andany et al. 1991, Coen Porsini et al. 1991, Bratsberg, 1993, Ferrandina et al. 1995, Odberg, 1995, Lerner, 1996, Roddick et al. 1996] They address such problems as adding and deleting class definitions in an existing populated database, and modifying definitions by adding, removing, altering and moving class attributes. Method definitions and any ....

Bratsberg, S.E. (1993) Evolution and Integration of Classes in Object-Oriented Databases.

....evolution and integration. Section 4 defines the meaning of class evolution in our framework. Sections 5 and 6 show how the framework is applied to class derivation (incremental changes to class hierarchies) and class integration. Section 7 concludes the paper. Further reading may be found in [5, 4, 6]. 2 Related Work Various kinds of class evolution problems have been studied in object oriented databases. We will classify these according to if they update existing classes (destructive) or not (additive) Specialisation is a simple, additive evolution technique that adds new classes to a ....

....of the relation is equal to applying the function in the relation to the domain side of the relation. In addition to this the object must be propagated to all classes reachable in the extent graph from all classes the object is a member of. A more formal version of this definition is found in [5]. 3.5 Consistency Maintenance To implement consistency maintenance we will introduce operation consistency relations, which are special kinds of triggers. An operation consistency relation is an operation automatically requested as a side effect of requesting a given operation. An operation ....

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S. E. Bratsberg. Evolution and Integration of Classes in Object-Oriented Databases. PhD thesis, The Norwegian Institute of Technology, University of Trondheim, June 1993. 225 p., ISBN 82-7119-515-8.

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