E.A. Rundensteiner and L. Bic, \Set Operations in Object-Based Data Models," IEEE Transactions on Knowledge and Data Engineering, Vo. 4, No. 3, 1992, pp.382-398.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....applications, where updatable (changeable) classes, objects and these lattices are very important to support. There are some proposals about using views (derived classes) as mechanism for schema evolution in OODB [13, 32] Languages supporting such facilities are mainly based on algebraic approach [32, 28]. They have been developed on the basis of nested relational data model and its query languages. Logic based languages for complex objects use object lattices to give semantics for the formulas [17, 18, 1, 34] Logical languages of complex objects support such important concepts of OO as object ....

....of (ISA) C1 iff ffl every property defined for C1 is also defined for C ffl every member of C is also a member of C1 Notice that, the class C is considered as the set of objects in C and all its subclasses. The similar definition for subclass relationships can be found by different authors [28]. Object algebra like relational algebra consists of set of basic operators that can be used to define derived operators. For object algebra the following basic operators are usually defined: selection, projection, extend and set operations such as union, intersection and difference. The type of ....

Rudensteiner E. A. and Bic L. Set Operations in Object-Based Data Models, IEEE Transactions on Knowledge and Data Engineering, Vol 4, No 3, 1992

.... we present a Boolean algebra of classes and their corresponding extents (i.e. the list of all instances of the class) We are mainly concerned with finding the datatype of unions, intersections, and complements of classes, and we show that the resulting classes form a closed, finite ISA hierarchy [Run92]. Then, this Boolean algebra is extended to include the types of collections such as bags, sets, lists, and arrays. For instance, using this model, the concatenation of a bag of flowers and a set of trees produces a bag of plants. This library s closure under its collection operations makes it ....

Rundensteiner E. and Bic, L., "Set Operations in Object-Based Data Models", IEEE Transactions on Knowledge and Data Engineering, Vol. 4, No. 3, Aug. 1992, pp.382-398.

....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 global ....

E.A. Rundensteiner and L. Bic. "Set operations in object-based data models". IEEE Transaction on Knowledge and Data Engineering, pages 382--398, 1992.

....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 global ....

E.A. Rundensteiner and L. Bic, Set operations in object-based data models, IEEE Transactions on Knowledge and Data Engineering, 4 (3) (1992) pp.382-398.

....x.properties y.properties x = SDN( x.SDN form) x.properties 675 The and operators which are used inside the definition correspond to propositional logic OR AND operators and set union intersection operators, respectively. As pointed out by Rundensteiner and Bic [16], there are other possible definitions of property inheritance, and the property inheritance hierarchy is not necessarily the same as the superset subset hierarchy of objects. However, using the above definition simplifies matters greatly, as well as allowing us to prove that the algebra is a ....

Rundensteiner E. and Bic, L., "Set Operations in Object-Based Data Models", IEEE Transactions on Knowledge and Data Engineering, Vol. 4, No. 3, Aug. 1992, pp.382-398.

....operators on two or more subqueries derived from the same entity. The structure of the involved subqueries being, in general, different, it is impossible to perform pure set oriented operations, and a more general approach is needed (see [24] for the specific solution adopted within QBD and [23] for a very general approach to this subject) Once the main concept has been selected, two different types of primitives are available for navigating in the schema. The first one allows the user to follow existing paths on the schema; the other one, called BRIDGE 2 , is used for comparing two ....

Rundensteiner E.A., Bic L. Set Operations in Object-Based Data Models. IEEE Transactions on Knowledge and Data Engineering, 1992, 4, 4: 382-398.

....via a view defined on the global schema. To realize the TSE approach in a working system, we need to utilize object oriented view mechanisms. We have based our TSE design on the MultiView object oriented view system [15] However, like all other current OO view systems that we are aware of [1, 10, 18, 17, 15, 16], the original MultiView prototype did not support capacity augmenting views. For TSE we clearly need views that augment the information content of a database by creating virtual classes with new stored attributes in addition to deriving data as a function of already existing data [21] 13] ....

....Last, a prototype of MultiView has been implemented at the University of Michigan and thus can be used as a platform for constructing the TSE system. Since our view schema evolution approach is built using the MultiView system, we use the view definition language of MultiView, an object algebra [15, 17, 16], as foundation of our TSE system. We find that a subset of MultiView s object preserving algebra is sufficient to achieve typical schema change modification, namely select, hide, difference, union, and refine. A de5 tailed definition of syntax and semantics of these operators can be found in ....

E. A. Rundensteiner and L. Bic, "Set Operations in Object-Based Data Models," IEEE Trans. on Data and Knowledge Engineering, pp. 382--398, June 1992.

....a solution to the first task of MultiView, while solutions to the second and third task are given in [Rund92d] and [Rund92c] respectively. Though MultiView is independent of particulars of the class derivation operators, we define a set of object algebra operators for the purpose of this work [Rund92b]. We study in particular the class relationships between the virtual and the source classes, since this is required for solving MultiView s second task. Class integration, the second task of MultiView, tackles the problem of how a virtual class relates to, and can be integrated with, the remaining ....

....identifier 1 . Let T be the set of all types. 1 To determine whether two property functions are identical is equally hard to proving that two programs are equivalent. We therefore ensure uniqueness of properties by associating a unique property identifier with each newly defined property [Rund92b]. For t 2 T , properties t corresponds to the set of property functions of t and domain p (t) denotes the domain of p in t. Let C be the set of all classes. A class C i 2 C has a unique class name, a type description and a set membership. The type associated with a class corresponds to a common ....

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Rundensteiner, E. A., and Bic, L., "Set Operations in Object-Based Data Models", in IEEE Transaction on Data and Knowledge Eng., vol. 4, issue 3, June 1992.

....multiple views for a wide range of design tasks. A design view generally contains a subset of relevant information from the global database reorganized in a fashion most suitable to the needs of particular users. The proposed mechanism, the object oriented view methodology called MultiView [26, 25], establishes a consistent mapping between the database and the tool interfaces, such that updates through the tool interface are consistently reflected in the underlying database. This strategy promises to eliminate the bottleneck, allowing each tool to work on their customized view of the data ....

....views nor easily modify existing ones. 2. 3 On Object Oriented View Mechanisms View mechanisms for object oriented databases have been identified as one of the few open problems in object oriented database research in [4] Recently, there have been several proposals for defining views for OODBs [18, 28, 1, 25]. Most of them use the query language defined for their respective object model as view specification language, namely, for deriving a virtual class. They generally do not discuss the integration of derived classes into the global schema nor do they generate complete view schemata. Instead, the ....

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Rundensteiner, E. A., and Bic, L., "Set Operations in Object-Based Data Models", in IEEE Transaction on Data and Knowledge Eng., vol. 4, issue 4, August 1992, pp. 382 -- 398.

....base schema transparent to the user (Section 4) Since TSE is built using MultiView, we utilize MultiView s view definition language, an object algebra [12, 13] as foundation of our TSE system. TSE requires only a subset of Multiview s algebra operators namely hide, difference, union and refine [14]. MultiView allows arbitrary queries composed by nesting these object algebra operators to serve as view definitions. After the execution of de fineVC name as query statement, name will appear as a persistent class with its extent of the virtual class name defined by the query ....

E. A. Rundensteiner and L. Bic, "Set Operations in Object-Based Data Models," IEEE Trans. on Data and Knowledge Engineering, pp. 382--398, June 1992.

....the specific needs of an application without affecting other application programs. Other advantages of relational views are data independence, access control and security. Perceiving the importance of views, many researchers have begun to investigate their counterpart in the object oriented world [1, 6, 9, 24, 22, 19, 21]. The diverse view mechanisms proposed typically provide the functionality to restructure a base schema by hiding classes, by adding classes, by customizing the behavior or extent of classes, and by rearranging the generalization hierarchy. However, since views correspond to derived data computed ....

....support at the data representation level. In this paper, we detail a view change approach that successfully addresses all of these issues. 3 Extending MultiView System for Transparent Schema Changes In this paper, we assume a typical OO data model, such as COCOON s [28] MultiView s [22] and Orion s [4] A list of basic terms of OO data models and views are found in the appendix. 3.1 MultiView: The Underlying Object Oriented View Support System Since our view schema evolution approach is based on object oriented view concepts, we describe below the view system we have developed ....

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E. A. Rundensteiner and L. Bic, "Set Operation in Object-Based Data Models," IEEE Trans. on Data and Knowledge Engineering, pp. 382--398, June 1992.

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E.A. Rundensteiner and L. Bic, \Set Operations in Object-Based Data Models," IEEE Transactions on Knowledge and Data Engineering, Vo. 4, No. 3, 1992, pp.382-398.

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E.A. Rundensteiner and L. Bic, \Set Operations in Object-Based Data Models," IEEE Transactions on Knowledge and Data Engineering, Vo. 4, No. 3, pp.382-398, 1992.

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