D. Maier, "Why isn't there an object-oriented data model?," in Information Processing 89 - IFIP World Computer Congress, ed. G.X. Ritter, pp. 793-798, North-Holland, 1989.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....integrity, but does not consider type and class hierarchies. Type and class hierarchies will be discussed in the subsequent section. We could extend any of several object oriented data models [3, 7, 16] for our discussion. As no standard or commonly agreed to object oriented data model exists [19] and as we do not expect all readers to be familiar with a particular model, we introduce a simple object oriented data model. It contains essential features of object oriented systems, but leaves out concepts and details not needed in this paper. Our purpose is not to introduce a new ....

D. Maier, "Why isn't there an object-oriented data model?," in Information Processing 89 - IFIP World Computer Congress, ed. G.X. Ritter, pp. 793-798, North-Holland, 1989.

....existing OOPLs rather than an objectorientation (OO) paradigm. If an OODB is named only for an ideal DB which satisfies all such features, what is expected of such an OODB I would like to discuss an OODB as an abstract framework from a point of view different from that of Professor David Maier [Ma]. 2 An Example First consider a set of deductive databases (DDBs) each of which consists of definite clauses. Consider each DDB as a set object with a type f dc g, where dc specifies a language. We can add an object identifier to each DDB and introduce an extent hierarchy [Ma] between ....

....David Maier [Ma] 2 An Example First consider a set of deductive databases (DDBs) each of which consists of definite clauses. Consider each DDB as a set object with a type f dc g, where dc specifies a language. We can add an object identifier to each DDB and introduce an extent hierarchy [Ma] between object identifiers. By using such a hierarchy, we can express various kinds of DDBs under the hierarchy, construct new DDBs dynamically by changing the hierarchy or modifying a DDB, and pose a query to a specific DDB by using its identifier. Many features of OODBs are frequently listed ....

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D. Maier, "Why Isn't There an Object-Oriented Data Model?", IFIP'89.

....only the essential parts, but recommended features as well; they do not comply with SRa, they may be considered to comply with SRb, it is arguable to which point they support SRc, and they do not comply with SRd. TAXIS, but not SDM, would support the essential part of Ed. There are many OO models ([Ma89]) and models that claim to be object oriented. Considering those which satisfy [At89] they are very expressive: generalization, cartesian and cover aggregations, definition of new methods; they also satisfy the essential part of SRa. Some modern OO models are equipped with an adequate language to ....

D. Maier: "Why Isn't There an Object Oriented Data Model?". In Information Processing 89 (Proc. IFIP WCC, San Francisco 1989), North Holland. Extended version as TR CS/E-89-002, OGC.

....relational system. As noted in a previous footnote, Section 2 could have been equally well written with the word constructed type and instance replaced by the words relation and tuple . In fact, in previous descriptions of POSTGRES [STON86] this notation was employed. Hence, others, e.g. [MAIE89] have characterized POSTGRES as an extended relational system. Lastly, POSTGRES supports the POSTQUEL type, which is exactly a nested relational structure. Consequently, POSTGRES could be classified as a nested relational system as well. As a result POSTGRES could be described using any of the ....

Maier, D., "Why Isn't There an Object-oriented Data Model?" Proc. 11th IFIP World Congress, San Francisco, Ca., August 1989.

....The mechanism is developed in Section 5, and the conclusion follows in Section 6. 4 System Model The system model has three elements: an object type model, a view model, and a data model. The object type model defines the structure of objects. No object type model has gained universal acceptance [32, 33]. Therefore we define a model which is common to many existing object oriented models [1, 4, 5, 6, 7] Note that we do not (yet) deal with methods, but focus on object structures. The data model is the relational model proposed by Codd [19] The view model contains a relational query 7 and ....

D. Maier, "Why Isn't There an Object-Oriented Data Model?," in Proc. IFIP 11th World Computer Congress, San Francisco, CA, Sept. 1989.

....languages of ooDBSs. They are either based on existing object oriented languages, like C and Smalltalk, or they have been newly developed. Thus, there exist no single object oriented data model, which was the case for traditional (hierarchical, network, and relational) database systems [50]. Nevertheless, there is consensus that a data model to be called object oriented has to exhibit the following core features [5] complex object modeling, object identity, encapsulation, types, inheritance, overriding with late binding, user definable types, and computational completeness. Complex ....

D. Maier, "Why isn't there an object-oriented data model?," in Information Processing 89 - IFIP World Computer Congress, ed. G.X. Ritter, pp. 793-798, North-Holland, 1989.

....will be our running example throughout the paper. We omit any details which do not contribute to the essential points of this paper. We could use any of several object oriented data models [2, 7, 23, 24] for our discussions. As no standard or commonly agreed to object oriented data model exists [26] and as we do not expect all readers to be familiar with a particular model, we introduce a simple objectoriented data model. It contains the essential features of object oriented systems, but leaves out concepts and details not needed in this paper. Our purpose is not to introduce a new ....

D. Maier, "Why isn't there an object-oriented data model?," in Information Processing 89 - IFIP World Computer Congress, ed. G.X. Ritter, pp. 793-798, North-Holland, 1989.

....of a common data model, ii) the lack of formal foundations and (iii) strong experimental activity. Whereas Codd s original paper [Codd 70] gave a clear specification of a relational database system (data model and query language) no such specification exists for object oriented database systems [Maier 89] We are not claiming here that no complete object oriented data model exists, indeed many proposals can be found in the literature (see [Albano et al. 1986] L ecluse and Richard 89] Carey et al. 88] as examples) but rather that there is no consensus on a single one. Opinion is slowly ....

D. Maier, "Why isn't there an object-oriented data model?" Proceedings IFIP 11th World Computer Conference, San Francisco, CA, August-September 1989.

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