Amihai Motro. Superviews: Virtual integration of multiple databases. Transactions on Software Engineering, SE-13(7):785-798, July 1987.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....directions. The first involves showing that the Merge result, when applied to models and mappings that are templates for instances, has an appropriate interpretation on instances. This will demonstrate the usefulness of Merge in specific applications such as data integration and view integration [13, 20]. In some of our experiments we encountered a complex structure in one model that expressed a similar concept to a complex structure in another model, but there was no obvious mapping for the individual elements even though the structures as a whole were similar. An open question is how best to ....

Motro, A. Superviews: Virtual Integration of Multiple Databases. Trans. on Soft. Eng., SE-13(7). 785-798.

....directions. The first involves showing that the Merge result, when applied to models and mappings that are templates for instances, has an appropriate interpretation on instances. This will demonstrate the usefulness of Merge in specific applications such as data integration and view integration [21, 31]. In some of our experiments, we encountered a complex structure in one model that is similar to a complex structure in another model. But rather than relating the elements by a complex expression, we wanted to relate individual elements but only in the context of that complex structure. An open ....

Motro, A. Superviews: Virtual Integration of Multiple Databases. Trans. on Soft. Eng., SE-13(7). 785-798.

....Community. There is now a great deal of work in mediated systems techniques. In this paragraph, we merely explain the relationship between code call conditions and existing work on data and software integration. For example, there have been several efforts to integrate multiple relational DBMSs [26, 72] and relational DBMSs, object oriented DBMSs and or file systems [36, 52, 89] However, to date, the semantics of mediators that take actions has not been explored. The work in this paper builds upon mediation efforts reported upon in our HERMES effort described previously in [20, 61, 61, 94, 63] ....

A. Motro. Superviews: Virtual Integration of Multiple Databases. IEEE Transactions on Software Engineering, 13(7):785--798, 1987.

....[44] 8.2 Data integration Assume we have a collection of (materialized) data sources S 1 , S n , and a global, virtual database G, that integrates data from S 1 , S n . According to the local as view approach, we can look at the data sources, S i , as views of the global schema G [59, 74, 65]. Now, given a query Q to G, one can generate a query plan that extracts the information from the sources [57, 58, 39] In the global as view approach, the global database is defined as a view over the data sources. Sometimes one assumes that certain ICs hold in the global system, and those ICs ....

Motro, A. Superviews: Virtual Integration of Multiple Databases. IEEE Transactions on Software Engineering, 1987, 13(7):785--798.

....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 schema enriched by new super subclasses and specialization relationships among them. DS96] for ....

A. Motro. Superviews: Virtual Integration of Multiple Databases. IEEE Transactions on Software Engineering, 13(7):785--798, July 1987.

....has to confirm, or deny, the correspondences proposed by the tool. We assume that knowledge of view correspondences is provided by users or the DBA to the view integration tool. That knowledge may be expressed using either declarative or procedural statements. The latter approach is found in [26] [27], in the context of database integration. Following Motro, the user specifies his global 10 schema by defining how it is built from the set of schemas of existing databases. The mapping specification uses a set of restructuring primitives (later called schema editing operations) This approach ....

A. Motro, "Superviews: Virtual Integration of Multiple Databases", IEEE Transactions On Software Engineering, Vol. SE-13, n 7, July 1987, 785-798

....the result presentation phase. After that, we indicate the strategies for using this process. In the last section, we conclude. 2 Existing Work A lot of different work has been done on schema integration. This goes from works on the tools to help the designer to get two schemas without conflicts [1], to work on the formal presentation of the integration rules [2] An overview of the variety of existing work can be found in [3] Generally, the integration process is divided in four phases. The first phase is the pre integration one. It consists in translating the schemas under study into a ....

.... These differences react on the structure chosen to represent the phenomenon, but also on the terminology used to name it (homonymy and synonymy conflicts) The less recent approaches describe how to merge several schemas with regard to a set of correspondences between the schemas under study [1, 6, 4]. These approaches were based on relational, functional and entity relationship models. The interschema assertions had to be supplied by the designer, and the conflict solving depended on the designer s common sense. Some recent approaches, in most cases based on object oriented models, proposed ....

A. Motro. Superviews : virtual integration of multiple databases. Transaction on software engineering, SE-13(7):785--798, July 1987.

....using first order logic. Research in the area of schema integration has been carried out since the beginning of the 1980s. A comprehensive survey of the area can be found in [Batini86] Most of the 3 work has been done in the context of the relational model [Biskup86] the functional model [Motro87], or (some extended version of) the ER model, Larson89] Spaccapietra92] Johannesson93a] Johannesson93b] Johannesson93c] Most work has focused on how to merge a number of schemas given a set of proposed schema correspondences. In recent years, however, several researchers have also shown ....

A. Motro, "Superviews: Virtual Integration of Multiple Databases", IEEE Transactions on Software Engineering, vol. 13, no. 7, pp. 785-798, 1987.

....external databases were mapped to schemas in the common data model, and similar schema constructs from di erent schemas were integrated into generalization hierarchies. Subsequently, many other systems were proposed or implemented with integration based on an outerjoin or generalization mechanism [1, 10, 11, 12, 13, 23, 31, 36, 33],aswell as systems which allowed for more general ways in which objects may be related or merged [5, 15, 24, 37, 42] The systems and techniques just referenced all provide support for what was referred to as data integration in the previous section. Data integration is the process of merging ....

A. Motro. Superviews: Virtualintegration of multiple databases. #### ############ ## ######## ###########, 13(SE-7):785-798, July 1987.

....virtual multi database containing homonyms, synonyms and redundant data possibly organised in several different ways. There is, however, a transformation which maps an instance of this multi database to an instance of our warehouse schema so that the warehouse turns out to be a view (or superview) [9, 11] in the most general sense. Even if we assume a copy semantics, i.e. data in operative databases will be time stamped and added to the existing data in the view, this will not cause a significant change. The basic assumption of data warehouses being organised as separate databases then turns ....

A. Motro. Superviews: Virtual integration of multiple databases. IEEE ToSE, 13(7), 1987.

....virtual multi database containing homonyms, synonyms and redundant data possibly organized in several di erent ways. There is, however, a transformation which maps an instance of this multi database to an instance of our warehouse schema so that the warehouse turns out to be a view (or superview) [10, 12] in the most general sense. Even if we assume a copy semantics, i.e. data in operative databases will be time stamped and added to the existing data in the view, this will not cause a signi cant change. The basic assumption of data warehouses being organized as separate databases then turns into ....

A. Motro. Superviews: Virtual integration of multiple databases. IEEE ToSE, 13(7), 1987.

....Information units depend on the database schema. They represent data in a standard, intuitive framework that allow high performance access. Information units modelling can be compared with the modelling of semistructured data. Then information units turn out to be generalized views on the database [3, 14]. The generalization should support data condensation and supplementary facilities to enable an adequate representation to the user. We restrict the rule system used for generating units from the database to the smallest possible system. The rule system can be extended by inclusion of di erent ....

A. Motro, Superviews: Virtual integration of multiple databases. IEEE ToSE, 13, 7, July, 1987.

....federated database systems (FDBS) integration is a function regularly performed at different levels and by different services depending on the organization of the FDBS environment. The value of the problem is well known, various approaches, techniques and sometimes tools were proposed (see, eg, [7, 22, 35, 36, 30, 29, 26] and surveys [2, 27] In spite of the diversity of approaches, several common points can be well identified. Integration consists of schema integration composing a global schema from the set of local ones, and data integration computing virtual extension of the global schema. Schema ....

A. Motro. Superviews: Virtual integration of multiple databases. IEEE TOSE, 13(7):785--798, 1987.

....Schema integration is a main component of conceptual design which is itself a part of the overall activity of database design. This explains the significant interest in schema integration methodologies: a vast diversity of various approaches, techniques and sometimes tools were proposed (see, eg, [10, 30, 42, 43, 40, 39, 36] and surveys [4, 37, 33] Moreover, to date the value of the issue has increased greatly due to the evident tendency of organizing modern (and of the nearest future) information systems on cooperative federal principals. Indeed, in the context of federated database systems (FDBS) integration is ....

A. Motro. Superviews: Virtual integration of multiple databases. IEEE TOSE, 13(7):785--798, 1987.

....show the interest of separating the conflict declaration and the conflict resolution. Finally, the conclusion analyzes possible extensions to our work. 3 2 Schema Comparison Procedural integration methodologies propose to successively modify input schemas, by using a set of operators [4] 10] [15], 24] to remove discrepancies and put them in conformity [1] No semantic verification can be performed and erroneous manipulations cannot be detected by the system. Moreover, this approach leaves to the user the responsibility of solving conflicts. On the contrary, assertion based methodologies ....

..... A semantic conflict between two related classes 1 occurs when the corresponding sets of real world objects are not exactly the same. This kind of conflict has been extensively dealt with in the literature and is usually solved with the use of the generalization (Is A) concept [4] 14] [15]. More recently, the multi instanciation concept or May Be A link [17] adds a new perspective. Moreover, the administrator can choose how to use this concept, among all possibilities, to solve semantic conflicts. A structural conflict occurs when related real world items are modeled with ....

Motro A., "Superviews: Virtual Integration of Multiple Databases", IEEE Transaction on Software Engineering, Vol. SE-13, n 7, July 1987, 785-798

....perform some sort of translation from potentially different underlying database models to a common intermediary model. Various approaches to schema merging have been proposed; see [2] for a survey. These vary from sets of tools for manipulating two schemas into some form of consistency ([3, 4]) to algorithms which take two schemas together with some constraints and produce a merged schema. In practice a method that lies somewhere between these two extremes is usually desirable: a certain amount of user intervention is inevitable, though, once any conflicts have been resolved and the ....

....says that arrows are, in some sense, preserved by specialization, so that, if p is a specialization of q and q has an a arrow of class s, then p also has an a arrow with class at least as specific as s. These axioms are equivalent to those given for functional schemas in [4] and also in [3] (though the latter used unlabeled arrows) Let us consider the ER diagram of a University Business Office database shown in figure 3. The diagram indicates that there are two ways of classifying University Employees (UE) as research employees (Res UE) or as academic employees (Ac UE) Teaching ....

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A. Motro, "Superviews: Virtual Integration of Multiple Databases," IEEE Transactions on Software Engineering, vol. SE-13, pp. 785--798, July 1987.

....[24] this approach developed integration rules for a variety of data models. A generic description of schema correspondences among different data models was provided. Other approaches defined a set of operators to build a virtual integration of multiple databases or to customize virtual classes [19], 20] 22] Yet another approach asserted that the different constructs of component schemas be standardized before the integration. Several transformation rules were then proposed for the view integration process [12] In this paper, we present a schema integration mechanism to achieve a ....

....generic data model. Besides, we consider the construction of class hierarchies in the integrated schema, which was not discussed in [24] In the process of schema integration, we use integration operators to restructure and integrate the component schemas. Different from the operators provided in [19] and [22] our class restructuring operators can be used to restructure the attributes and class hierarchies of a class. Thus, the conflicts in component schemas can be resolved before the integration. The class integration operators can be used to integrate the information in two classes or a set ....

A. Motro. "Superviews : Virtual integration of multiple databases". IEEE Transactions on Software Engineering, pages 785--798, 1987.

....different data models this work was partially supported by the Republic of China National Science Council under Contract No. NSC 83 0408 E 007 030. was provided. Other approaches defined a set of operators to build a virtual integration of multiple databases or to customize virtual classes [18], 23] 24] Yet another approach asserted that the different constructs of component schemas be standardized before the integration. Several transformation rules were then proposed for the view integration process [13] In this paper, we present a schema integration mechanism to achieve a ....

....generic data model. Besides, we consider the construction of class hierarchies in the integrated schema, which was not discussed in [20] In the process of schema integration, we use integration operators to restructure and integrate the component schemas. Different from the operators provided in [18] and [24] our class restructuring operators can be used to restructure the attributes and class hierarchies of a class. Thus, the conflicts in component schemas can be resolved before the integration. The class integration operators can be used to integrate the information in two classes or a set ....

[Article contains additional citation context not shown here]

A. Motro, Superviews : Virtual integration of multiple databases, IEEE Transactions on Software Engineering, 13 (7) (1987) pp.785-798.

....that will allow different database systems to exchange information. For the most part, this research has been either in the context of view integration as part of the database design process (e.g. 4, 9, 12] or in the context of systems for virtual merging of independent databases (e.g. [13, 14, 7]) For overviews of this area, see [2, 5] Compared to this focus on intensional inconsistency, the equally challenging problem of extensional inconsistency has received much less attention. Extensional inconsistencies surface only after all intensional inconsistencies have been resolved, at a ....

....3. A collection (D 1 ; C 1 ; d 1 ) D n ; C n ; d n ) of databases. 4. A collection (D; D 1 ) D; D n ) of scheme mappings. 5. A collection (C; C 1 ) C; C n ) of constraint mappings. This definition may be considered a formalization of virtual databases defined in [7]. Scheme mapping may be considered an abstraction of the different solutions that have been advanced to the task of relating global schemes to individual schemes (e.g. 7, 1, 13] Note that the mappings from D and C to the individual databases are not necessarily total ; i.e. not all views ....

[Article contains additional citation context not shown here]

A. Motro. Superviews: Virtual integration of multiple databases. IEEE Transactions on Software Engineering, SE--13(7):785--798, July 1987.

....from a collection of distributed, heterogeneous and overlapping databases. 1 A standard approach to this problem has been to integrate the independent databases by means of a comprehensive global scheme that models the information contained in the entire collection of databases (for example, [23, 38, 7, 30]) This global scheme is fitted with a mapping that defines the elements of the global scheme in terms of elements of the schemes of the member databases. Algorithms are designed to interpret queries on the global scheme. Such global queries are translated (using the information captured in the ....

....in one database with equivalent views (or satisfaction of equivalent constraints) in another database. In a multidatabase, the former database is the global database, and the latter is a member database. This definition may be considered a formalization of virtual databases defined in [30]. Scheme mapping may be considered an abstraction of different solutions that have been advanced to the task of relating global schemes to schemes of member databases (e.g. 23, 38, 7, 30] 11 3.5 Integrability Assumptions The purpose of multidatabases is to integrate information from ....

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A. Motro. Superviews: Virtual integration of multiple databases. IEEE Transactions on Software Engineering, SE--13(7):785--798, July 1987. 27

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Amihai Motro. Superviews: Virtual integration of multiple databases. Transactions on Software Engineering, SE-13(7):785-798, July 1987.

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Amihai Motro. Superviews: Virtual integration of multiple databases. Transactions on Software Engineering, SE-13(7):785-798, July 1987.

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Motro A. Superviews: Virtual integration of multiple databases. IEEE Transaction on Software Engineering, 1987; 13(7):785--798.

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A. Motro. Superviews: Virtual Integration of Multiple Databases. IEEE Transactions on Software Engineering, 13#7#:785#798, 1987.

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Motro, A., "Superviews: A Virtual Integration of Multiple Databases," IEEE Transactions on Software Eng., Vol. 13, No. 7., pp. 785-798, July 1987. 23

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