I. Schmitt and G. Saake. Integration of Inheritance Trees as Part of View Generation for Database Federations. In B. Thalheim, editor, Conceptual Modelling --- ER'96, Proc. of the 15th Int. Conf., Cottbus, Germany, October  Home/Search   Document Details and Download   Summary   Related Articles   Check

....urspr unglichen Schemata ein schon ausgiebig bearbeitetes Gebiet darstellt, wird andererseits eine entsprechende Behandlung von Integrit atsbedingungen nicht oder nur bruchst uckweise angegeben. Im Bereich der Schemaintegration gibt es zwar vielf altige Integrationsmethoden (etwa [SPD92, RPRG94, SS96a] doch werden, wenn uberhaupt, nur einzelne Arten von einfachen Integrit atsbedingungen dabei ber ucksichtigt (vgl. z.B. RPG95] In [VA96] wird die Bedeutung von Integrit atsbedingungen f ur die Interoperation von Datenbanksystemen deutlich hervorgehoben und einige zentrale Probleme der ....

....Im folgenden werden wir Restrukturierungsoperationen vorstellen, ohne dabei auf die Behandlung von zugeordneten Integrit atsbedingungen einzugehen. Diesem Punkt sind die darauffolgenden Abschnitte gewidmet. Wir schlagen hier eine Restrukturierung vor, die in zwei Phasen abl auft (siehe dazu auch [SS96a] Es werden die vorhandenen Klassenextensionen in Basisextensionen zerlegt, die danach als Grundlage f ur die Erzeugung neuer Klassenextensionen durch Zusammensetzen dienen sollen. Wir werden die urspr unglichen Klassenextensionen ab jetzt Ursprungsextensionen nennen. Analog dazu werden wir den ....

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I. Schmitt und G. Saake. Integration of Inheritance Trees as Part of View Generation for Database Federations. In B. Thalheim, Herausgeber, Conceptual Modelling --- ER'96, Proc. of the 15th Int. Conf., Cottbus, Germany, October 1996, Lecture Notes in Computer Science, Band 1157, S. 195--210, Berlin, 1996. Springer-Verlag.

....mapping between objects located in different local databases. This can be achieved by the use of metadata, which describes the shared objects in an abstract way and thus enables the system to identify objects within the whole system. More detailed discussions of schema integration can be found in [2, 10, 9, 4]. Another important aspect of the FDBS is the limited heterogeneity. This approach relies on identifiers for each entity. It is necessary that each tuple that may be updated can be unmistakably identified in the whole system. Another restriction is that all attributes affected by an update must ....

Schmitt, I. and Saake, G.: Integration of Inheritance Trees as Part of View Generation for Database Federations, Conceptual Modeling -- ER'96, Proc. of the 15 th International Conference on Conceptual Modeling (1996)

....systems different integration methodologies are available. Many methodologies use a semantical rich data model, e.g. an object oriented data model [CSGS94, RBB 95, TS93] Other integration methodologies are based on semantical poor data models. For example, the Generic Integration Model GIM [SS96] which is developed especially for the FDBS design, can be characterized as a semantical poor data model. The choice of the integration data model influences the derivation of conceptual schemata for file systems. Using the common data model or a similar data model for modeling an conceptual ....

....service. This discovery is also expressed in the improved conceptual schema (cf. Figure 8) Based on the derived conceptual schema, mapping to the structured files and a generic interface the local files system could be integrated in the FDBS according to common integration methodologies , e.g. SS96] 8 Conclusion and Outlook In this paper we suggested an approach for the integration of file based information systems in a database federation. Because of the problem of missing meta information for local file systems, we focus on the derivation of an equivalent structure description and, ....

I. Schmitt and G. Saake. Integration of Inheritance Trees as Part of View Generation for Database Federations. In Proc. of the 15th Int. Conf. on Conceptual Modelling (ER'96). LNCS, Springer-Verlag, Berlin, October 1996. To appear.

....data model due to its semantical richness. As common data model for homogenization in the GIM approach we use 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 ....

....of object oriented database is not new. YLCB96] for example, uses this technique to generate a class hierarchy depending on an intensional analysis. In contrast to our approach, however, YLCB96] does not consider extensional relationships and is therefore not useful for schema integration. In [SS96a, SS96b, SC97, SS98] we described how to decompose class extensions for schema integration. This decomposition enables us to use mechanisms of formal concept analysis for schema integration. Our improved algorithm was firstly published in [SS98] Query languages supporting the integration of ....

I. Schmitt and G. Saake. Integration of Inheritance Trees as Part of View Generation for Database Federations. In B. Thalheim, editor, Conceptual Modelling --- ER'96, Proc. of the 15th Int. Conf., Cottbus, Germany, October

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I. Schmitt, G. Saake. Integration of Inheritance Trees as Part of View Generation for Database Federations. In B. Thalheim, ed., Conceptual Modelling --- ER'96, LNCS 1157, pp. 195#210. Springer, 1996.

....Global applications can retrieve and update federated data through the federated schema. The main task during the design of a federated database is the transformation and integration of existing local schemata into a federated schema. The transformation [EJ95] and integration [LNE89,SPD92,RPG95,SS96a] of local schemata into a federated schema must fulfill the following requirements: 1. For each query against a local schema there exists a global query against the federated schema returning the same query result. This requirement avoids loss of information during the federation. This work ....

....and attached to the integrated class. In contrast to the mentioned approaches we integrate integrity constraints basing on set operations on class extensions. Extensions of local classes have to be decomposed into disjoint base extensions and later to be composed to the federated schema (cf. SS96a,SC97,CHS 97] Local integrity constraints are related to class extensions. This idea is already mentioned shortly in [BCW91] By decomposing and composing class extensions in a well defined way, we are able to derive integrity constraints for integrated schemata (as well as for arbitrary ....

[Article contains additional citation context not shown here]

I. Schmitt and G. Saake. Integration of Inheritance Trees as Part of View Generation for Database Federations. In B. Thalheim, editor, Conceptual Modelling --- ER'96, Proc. of the 15th Int. Conf., Cottbus, Germany, October 1996, Lecture Notes in Computer Science, Vol. 1157, pages 195--210. Springer-Verlag, Berlin, 1996.

....cases where we can simply transfer the local constraint to the integrated schema. However, we often have to face situations where this is not possible. In this paper we discuss such cases and point out possible and reasonable solutions. For presentation we use the Generic Integration Model GIM [SS96, SC97]. GIM provides an intermediate graphical notation in which the schemata to be integrated can be represented in a normalized way. We extend this notation in a straightforward way for representing integrity constraints. The remainder of this paper is organized as follows: First, we briefly ....

....binary references Integrity constraints similar to SQL2 GIM is not intended to be used as an interface to global applications. Rather, GIM is an intermediate representation form which is only used for integration purposes. A detailed description of GIM can be found, for instance, in [SS96, SC97]. Here, we introduce only the notation of GIM diagrams which are used to model GIM schemata (cf. Figure 1) The horizontal dimension of a GIM diagram refers to the extensional aspect of a class whereas the vertical dimension refers to the intensional aspect of a class. A class itself is ....

[Article contains additional citation context not shown here]

I. Schmitt and G. Saake. Integration of Inheritance Trees as Part of View Generation for Database Federations. In B. Thalheim, editor, Conceptual Modelling --- ER'96, Proc. 15th Int. Conf., pages 195--210, LNCS 1157, Springer, 1996.

....this paper, we present an approach to schema integration which considers binary as well as n ary extensional relationships. Further we allow the specification of so called existence requirements. The concepts of existence requirements is introduced in order to exactly state which base extensions [SS96a, SS96b] are non empty and, thus, must be considered by the integration algorithm. Often, the practical use of schema integration fails because the extensional relationships among all classes are not known or cannot be determined in an ad hoc manner [NS96] Usually, a semi correct and fast solution is ....

....inheritance can be used recursively to derive classes from derived classes, e.g. to derive the class P123 from the classes P12 and P 23. As a result, a recursive usage of upward inheritance may lead to an explosion of the number of derived classes. Therefore, we proposed an integration method [SS96b, SS96a, SS97] basing on a base extension set which is determined by the extensional relationships obtained during the extension analysis. Due to the fact that the designer often cannot overview all existing (relevant) extensional relationships of the universe of discourse at once, we suggest an incremental ....

[Article contains additional citation context not shown here]

I. Schmitt and G. Saake. Integration of Inheritance Trees as Part of View Generation for Database Federations. In B. Thalheim, editor, Conceptual Modelling --- ER'96, Proc. of the 15th Int. Conf., Cottbus, Germany, October 1996, Lecture Notes in Computer Science, Vol. 1157, pages 195--210. SpringerVerlag, Berlin, 1996.

....They take over the inheritance hierarchies from the local to the integrated schema level and adapt them to each other by adding new sub 2 or superclasses or deleting existing classes. In contrast to these approaches, we decompose overlapping class extensions into base extensions (cf. SS96b, SS96a] and use algorithms known from the theory of concept lattices [Wil92] The new aspect proposed in this work is that we combine this theory with schema integration and extensional decompositions. We mean here with the extension of a class a set of possible objects. Such extensions are detected ....

....p p Pubnr 1 p p p Pubnr 2 p p Table 7.2: Matrix with duplicated Pubnr Our proposed algorithm produces a new integrated schema as depicted in Fig. 7.2. We demonstrated here that we are able to transform an integrated schema into an equivalent schema without multiple specializations. In [SS96b, SS96a] another algorithm was shown which directly computes such schemata. 24 JP TR (C8) Title Author Publication (C1) ISBN Book (C2) Organization Journal P. C3) Pubnr Non Refereed TRnr Techn. Rep. C6) Volume ProJournal P. C4) Publisher Pubnr ProBook (C5) Figure 7.2: Result of removing ....

[Article contains additional citation context not shown here]

I. Schmitt and G. Saake. Integration of Inheritance Trees as Part of View Generation for Database Federations. In B. Thalheim, editor, Conceptual Modelling --- ER'96, Proc. of the 15th Int. Conf., Cottbus, Germany, October 1996, pages 195--210. LNCS 1157, Springer-Verlag, Berlin, 1996.

....Otto von Guericke Universitat Magdeburg Postfach 4120, D 39016 Magdeburg, Germany E mail: fconradjschmittjtuerkerg iti.cs. uni magdeburg.de Extended Abstract 1 Introduction At the time being, a large number of methods have been proposed for schema integration, e.g. SPD92, RPRG94, SS96a, SC97] Surprisingly, most of them do not consider the integration of existing integrity constraints. Sometimes restricted kinds of constraints are considered, like in [RPG95] As pointed out in [VA96] constraints play an important role for the interoperation of database systems. In [CHS 97] ....

.... one is a This work was partly supported by the German Federal State Sachsen Anhalt under grant number FKZ 1987A 0025 ( Federating heterogeneous data base systems and local data management components for global integrity maintenance ) subset of another one (cf. e.g. SPD92] As showed in [SS96a, SS96b] pairwise comparison of class extensions is not always sufficient because not all pieces of information necessary for an adequate integration can be found in that way. Instead, all class extension must be considered at the same time. The result of such an analysis can be presented in a ....

I. Schmitt and G. Saake. Integration of Inheritance Trees as Part of View Generation for Database Federations. In B. Thalheim, editor, Conceptual Modelling --- ER'96, Proc. of the 15th Int. Conf., Cottbus, Germany, October 1996, volume 1157 of Lecture Notes in Computer Science, pages 195--210, Berlin, 1996. Springer-Verlag.

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