Templeton, M., Brill, D., Dao, S., Lund, E., Ward, P., Chen, A., and MacGregor, R. (1987). Mermaid: a front end to distributed heterogeneous databases. Proceedings of the IEEE, 75(5):695--708.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....is often not only given by the schema but also further defined in a Data Dictionary explaining its relation to other data elements and defining the basis for transformation in terms of the data type, its valid ranges and further constraints. Early approaches to database integration like Mermaid [Templeton et al. 1987] even directly used Data Dictionaries for accessing information. In the absence of a well defined data model, context transformation rules do not apply, as source and goal context are not defined, this in turn makes it impossible to determine the kind of transformation to be applied. In order to ....

Templeton, M., Brill, D., Dao, S., Lund, E., Ward, P., Chen, A., and MacGregor, R. (1987). Mermaid: a front end to distributed heterogeneous databases. Proceedings of the IEEE, 75(5):695--708.

....parties using di#erent schemas now become as easy as figuring out the relations between the relevant parts of the shared canonical schema since it is all shared. Examples of this approach can be seen in the prototypes of Breitbart and Tieman (ADDS) 8] and Templeton, et al. Mermaid) [32], and more recently, the same strategy has shown up in systems using object oriented data models such as Pegasus [1] amongst others. In virtually all of the above cases, the technique used for conflict resolution is similar to that proposed by Dayal and Hwang [12] and involves the introduction ....

M. Templeton, et al. (1987). Mermaid --- a front end to distributed heterogeneous databases. Proceedings of the IEEE, 75(5):695-708.

....use a platform for heterogeneous database research currently under development at HKUST as the basis for our initial experiments. A first implementation of this architecture will consist of a commercial heterogeneous database manager, InterViso (previously called Mermaid as a research prototype) [24], and a prototype implementation of a specification language, LACE, for interdatabase integrity constraints in heterogeneous database schemas[5] The commercial system provides the substrate of the platform with robust implementations for communications, access services, schema definition, query ....

M. Templeton, D. Brill, A. Chen, S. Dao, E. Lund, R. Macgregor, P. Ward, "Mermaid: A front-end to distributed heterogeneous databases", Proc. IEEE: Special Issue on Distributed Database Systems, 75 (5), pp. 695-708, 1987.

....present a description of some projects concerning the several different research fields on HDDSs. At the end of this Section, we point out the differences and similarities between these works and our own. HDDSs with Global Schema. Projects Pegasus (DU, 1996) UniSQL M (KIM et al., 1993) MERMAID (TEMPLETON, 1987), and IRO DB (GARDARIN, 1996) are examples of systems adopting the global schema solution. These projects have research lines that study the resolution of conflicts among different schemas and data models. Although the existence of a unified global schema provides complete transparency to data ....

TEMPLETON, M., et al., 1987, "Mermaid - A Front End to Distributed Heterogeneous Databases". In: Proceedings of the IEEE, May.

....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 similar schema constructs, and specifying how and when objects from the di erent databases should be merged, and how ....

M. Templeton et al. MERMAID: A front-end to distributed heterogeneous databases. In ########### ## ### ####,May 1987.

....invisible and providing users with a uniform access to all the databases. The integration of several database systems will result in a distributed, heterogeneous database system. Many researchers have focused their work on the data model and the query and update language of such a system[LR 82, TBC 87, NS 88, KDN 90] Others focus on transaction management [BS 88, BST 90, DE 89, DEL 89, GS 87, LT 89, Pu 88, WV 90] A global transaction in an integrated database system is executed by the different existing database systems. Hence, the global transaction management has to deal with different ....

Templeton, D., Brill, A., Chen, S., et al: Mermaid - A Front-end to Distributed Heterogeneous Database Systems. Proceedings of the IEEE, Vol. 75, No. 5, 1987.

....research in this domain mainly concentrated on offering uniform data access, investigating issues such as database and schema integration, global query processing, and global transactions. But to the best of our knowledge, no existing FDBS product, prototype, or project (e.g. Pegasus [2] Mermaid [18], Carnot [22] focus on a migration of data from one component database system (CDBS) to another. Nevertheless, a wide spectrum of applications would benefit from a mechanism enabling migration of data (objects) within an FDBS. It may either be used as FDBS internal service or as external service ....

TEMPLETON, M., BRILL, D., CHEN, A., DAO, S., LUND, E., Mc GREGOR, R., AND WARD, P. Mermaid: A front-end to distributed heterogeneous databases. In Proc. IEEE 75, pages 695--708, 1987.

....coupled systems. The strongly coupled MDBS is a non federated database system (e.g. UNIBASE [9] Distributed database systems assume no autonomy and operations are performed uniformly by the global layer. The loosely coupled systems are called federated database systems (eg, MDSM [1] Mermaid [10]) where the global layer has no control over the local databases. In such system, there is a distinction between local and global operations. The MDBS technology, however, insufficiently addresses various interoperability issues. These issues involve the concepts of autonomy, cooperation and ....

....heterogeneous platforms (local database systems) is provided by middleware software (like CORBA [4] Connecting heterogeneous operating systems, however, is beyond the scope of this project. There are two major differences between the DOK approach and the existing multidatabase systems (such as [10]) The first difference relates to the perception of the role of different CDBS components. In most existing multidatabase architectures, functions that are performed at the global level are the responsibility of the global layer. Wrappers are seen only as interfaces between the global and local ....

M Templeton et al.: Mermaid - A Front End to Distributed Heterogeneous Databases. Proc of IEEE, May 1987, 75(5), 695-708.

....have been proposed, aiming at different levels of integration [38] The loosest degree of integration characterizes the multidatabase 1 approach [26, 27] in which users can query different databases with a single request, but have to specify where data are located. Federated approaches ([24, 45], for instance) support location transparency (users may ignore the actual location of data and nevertheless query distributed data) The major goal is site autonomy: each site controls the evolution of its local database (updates, restructuring) as well as the usage of its data from other sites ....

....database integration may be limited to support mainly modelling concepts from current DBMSs. However, in order to ensure proper understanding of the semantics of the input schemas, additional information has to be provided by the DBA (Data Base Administrator) before integration is performed [4, 39, 45] Finally, existence of extensions and programs is the most important peculiarity of 4 database integration versus view integration. Because of this, and its economical impact, database integration methodologies should carefully avoid modification of existing schemas (more precisely, avoid ....

[Article contains additional citation context not shown here]

M. Templeton, et al.: Mermaid: A front end to distributed heterogeneous databases, Proceedings IEEE 75, n5, May 1987, 695-708

....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 ....

M. Templeton, D. Brill, S. K. Dao, E. Lund, P. Ward, A. L. P. Chen, and R. McGregor. Mermaid --- a front-end to distributed heterogeneous databases. In Proceedings of IEEE, volume 75, number 5, pages 695--708, May 1987. 16

....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 ....

....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 several, independent databases. Of course, the problem of integration is trivial, unless the information sources are inconsistent: i.e. a portion of the real world is described differently by ....

M. Templeton, D. Brill, S. K. Dao, E. Lund, P. Ward, A. L. P. Chen, and R. McGregor. Mermaid --- a front-end to distributed heterogeneous databases. In Proceedings of IEEE, volume 75, number 5, pages 695--708, May 1987.

....problems. Some approaches use a generalization mechanism, typically implemented using an outerjoin operation, to combine types or relations from different schemas [3, 6, 7, 14, 29, 30] while other systems also have considered other ways that two or more relations or types might be combined [11, 39]. Object identification is implicit in the primary key construct in each data model. For example, two objects would be determined to be the same if they had the same key. TheMultibase system provided merge predicates that can be declared with a generalization specification [12, 38] The merge ....

M. Templeton et al. MERMAID: A front-end to distributed heterogeneous databases. In Proceedings of the IEEE,May 1987.

....based approach is the Pegasus project of Ahmed et.al. ASD 91] Pegasus defines a common object model for unifying the data models of the underlying systems. Landers and Rosenberg [LR82] uses the functional model of DAPLEX as the CDM in their Multibase project, while Mermaid (Templeton etal [Tem87] uses a relational CDM, and allows only for relational schema integration (with extensions to include text) Thus federation users may formulate queries using SQL. The major problem associated with the approaches in this category is the amount of human participation required for obtaining the ....

Templeton, M., et al. Mermaid: A front-end to distributed heterogeneous databases. In Proc. IEEE 75, 5, pages 695--708, May 1987.

....model (CDM) such as the relational model or an object oriented model. The individual schemas in a federation are mapped to the CDM, which acts as an interpreter among them. Examples of CDMs are DAPLEX as used in the Multibase project, Landers82] and the relational model as used in Mermaid, Templeton87] A recent approach for representing schema correspondences is to use a higher order language, such as F logic, Kifer90] or SchemaLog, Lakshmanan93] The advantage of using a higher order, logic based language is that it provides clear foundations, a sound formalism, and proof procedures and, ....

M. Templeton et. al., "Mermaid: A Front-end to Distributed Heterogeneous Databases, Proceedings of IEEE 75, pp. 695708,

....of the CDM based approach is the Pegasus project of Ahmed et al. 5] Pegasus defines a common object model for unifying the data models of the underlying systems. Landers and Rosenberg use the functional model of DAPLEX as the CDM in their Multibase project [32] Mermaid (Templeton et. al [52]) uses a relational CDM, and allows only for relational interoperability (with extensions to include text) Thus federation users may formulate queries using SQL. 4 The major problem associated with the approaches in this category is the amount of human participation required for obtaining the ....

Templeton, M., et al. Mermaid: A Front-end to Distributed Heterogeneous Databases. In Proc. IEEE 75, 5, pages 695--708, May 1987.

....research in this domain mainly concentrated on offering uniform data access, investigating issues such as database and schema integration, global query processing, and global transactions. But to the best of our knowledge, no existing FDBS product, prototype, or project (e.g. Pegasus [2] Mermaid [17], Carnot [20] focus on a migration of data from one component database system (CDBS) to another. Nevertheless, a wide spectrum of applications would benefit from a mechanism enabling migration of data (objects) within an FDBS. It may either be used as FDBS internal service or as external service ....

TEMPLETON, M., BRILL, D., CHEN, A., DAO, S., LUND, E., Mc GREGOR, R., AND WARD, P. Mermaid: A front-end to distributed heterogeneous databases. In Proc. IEEE 75, pages 695--708, 1987.

....the pivot data model supported for integrating the various data sources. In the 80s, most federated DBMSs were built around the relational model, which brought a simple uniform model to integrate smoothly alphanumeric data. The most well known project were then ADDS [5] SIRIUS [18] Mermaid [29], and Dataplex [9] To provide a better integration platform for applications, Multibase [17] adopts the functional model. With the advent of non standard data types such as document, image and video, richer data model integrating complex attributes and methods are required. New projects are also ....

M.Templeton and et. al., "Mermaid : A Front-End to Distributed Heterogeneous Databases" in Proceedings of the IEEE, 75(5) :695--708, May 1987.

....developed at Computer Corporation of America. Through the DAPLEX functional language, Multibase provides uniform access to a CODASYL database and a hierarchical database. The focus of Multibase is on query optimization and reconciliation of data, not consistent update across databases. Mermaid [31] has been developed at System Development Corporation. Unlike Multibase, Mermaid supports the relational view of data directly, through the ARIEL query language. Although language and model translation as well as schema integration are important problems, we refer the reader to a recent survey by ....

M. Templeton, D. Brill, S. K. Dao, E. Lund, P. Ward, Chen A.L.P., and R. MacGregor. MERMAID --- a frontend to distributed heterogeneous databases. Proceedings of the IEEE, 75(5):695--708, May 1987.

....systems. This work, in particular, has inspired our research in developing FINDIT for achieving interoperability in a large multidatabase system. 3 Multidatabases Most multidatabase systems provide resource sharing through a global schema (Miles Smith, et al. 1981) Templeton, et al. 1986) (Templeton, et al. 1987), Neuhold and Walter, 1982) Litwin, et al. 1982) which is usually obtained by integrating multiple schemas. Global queries are then executed using this global schema. The major problem associated with this technique is the translation of local languages and schemas into a global format. No ....

Templeton M., Brill D., Dao S.K., Lund E., Ward P., Chen A.L.P. and MacGregor R. Mermaid -- a Front--End to Distributed Heterogeneous Databases. Proc. of the IEEE, 75(5):695--708, 1987.

....accomplished through the use of the relational predicate graphs and the OODB predicate graphs. One advantage of using such a graph based approach is that we can achieve bidirectional translation between relational queries and OODB queries. 1 Introduction Heterogeneous database system techniques [2,8,11,13,14,16] can be used to allow users of one system to access data from different systems with ease. Schema transformers [3,18] and query translators [7,12] are critical components of heterogeneous database systems. Using object oriented systems as the front end system has been suggested by [4,13,16] In ....

Templeton, M. et al., Mermaid --- A Front-end to Distributed Heterogeneous Databases. Proc. IEEE, May 1987

....heterogeneity to overcome is making different query languages interoperate. The seventh level of heterogeneity to overcome is making different database applications (or views) interoperate. 2. 2 Global Schema Integration Most multidatabase systems provide data sharing through a global schema [36] [38] [37] 28] 25] 40] 24] This schema is usually the result of integrating multiple schemas in a tight and static manner. In the schema integration approach, a global schema is necessary for executing global queries. Usually, it means translations of languages, schemas, or both. The global schema ....

M. Templeton, D. Brill, S. K. Dao, E. Lund, P. Ward, A. L. P. Chen, and R. MacGregor. Mermaid - a front-end to distributed heterogeneous databases. Proceedings of the IEEE, 75(5):695--708, 1987.

.... e.g. MRDSM [Litwin and Abdellatif 1987] VIP MDBMS [Kuhn and Ludwig 1988] or insist that conflicts should be identified and reconciled, a priori, by some system administrator, in one or more shared schemas (as in tightly coupled systems; e.g. Multibase [Landers and Rosenberg 1982] Mermaid [Templeton et al. 1987]) In addition, the proposed framework plays a complementary role to an emerging class of integration strategies [Levy, Srivastav and Kirk 1995; Ullman 1997] where queries are formulated on an ontology without specifying a priori what information sources are relevant for the query. Although the ....

Templeton, M., Brill, D., Dao, S. K., Lund, E., Ward, P., Chen, A. L. P., and MacGregor, R. 1987. Mermaid --- a front end to distributed heterogeneous databases.

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T. Templeton, D. Brill, A. Chen, S. Dao, E. Lund, R. Macgregor, and P. Ward. Mermaid: A Front-End to Distributed Heterogeneous Databases. In International Conference on Data Engineering, pages 695--708, 1987.

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M. Templeton, D. Brill, S. Dao, E. Lund, P.Ward, A. Chen, and R. MacGregor. Mermaid --- a front-end to distributed heterogeneous databases. Proceedings of the IEEE, 75#5#:695#708, May 1987. Davidson et al.

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M. Templeton, D. Brill, A. Chen, S. Dao, E. Lund, R. McGregor, and P. Ward. Mermaid: a front end to distributed heterogeneous databases. In Special Issue on Distributed Database Systems, Proceedings of the IEEE 75, May 1987, pp. 695-708.

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M. Templeton, D. Brill, S. Dao, E. Lund, P. Ward, A. Chen, and R. MacGregor. Mermaid --- a front-end to distributed heterogeneous databases. Proceedings of the IEEE, 75(5):695--708, May 1987.

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M. Templeton, D. Brill, S. Dao, E. Lund, P. Ward, A. Chen, and R. MacGregor, "Mermaid-- A Front-End to Distributed Heterogeneous Databases," Proceedings of the IEEE, vol. 75, pp. 695--708, May 1987.

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Te87 M. Templeton et al., "Mermaid - A front end to distributed heterogeneous databases," Proc. IEEE, vol. 75, no. 5, 1987.

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M. Templeton, D. Brill, S. Dao, E. Lund, P. Ward, A. Chen, and R. MacGregor. Mermaid --- a front-end to distributed heterogeneous databases. Proceedings of the IEEE, 75(5):695--708, May 1987. Davidson et al.

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M. Templeton, D. Brill, A. Chen, S. Dao, E. Lund, R. McGregor, and P. Ward. Mermaid: a front end to distributed heterogeneous databases. In Special Issue on Distributed Database Systems, Proceedings of the IEEE 75, May 1987, pp. 695-708.

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Templeton, M., Brill, D., Dao, S., Lund, E., Ward, P., Chen, A., and MacGregor, R. Mermaid --- a front-end to distributed heterogeneous databases. Proceedings of the IEEE 75, 5 (May 1987), 695--708.

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M. Templteon, D. Brill, S. Dao, E. Lund, P. Ward, A. Chen, and R. MacGregor. Mermaid - a front-end to distributed heterogeneous databases. Proc. IEEE, 75(5):695--708, 1987.

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