Y.-G. Ra and E. A. Rundensteiner. A transparent schema-evolution system based on object-oriented view technology. IEEE Transactions on Knowledge and Data Engineering, 9(4):600--624, 1997.  Home/Search   Document Not in Database   Summary   Related Articles   Check

.... changes divergent changes Figure 3: Convergent versus divergent parallel changes Such versioning mechanisms have been extensively used for schema evolution in object oriented databases in order to support forward and backward compatibility of applications with schemas and existing objects [31, 36, 39]. The previous discussion refers to the ability to create and to deploy di#erent versions of a component. We will now classify the di#erent kinds of versioning, and the mechanisms needed to support them. Software changes may be carried out sequentially or in parallel (see Fig. 2) With ....

Y.-G. Ra and E. A. Rundensteiner. A transparent schema-evolution system based on object-oriented view technology. IEEE Transactions on Knowledge and Data Engineering, 9(4):600--624, 1997.

....she has been in recent years one of the most active scientists in the schema evolution and versioning field. The primary goal of her research in this context was to develop transparent schema change technology that allows on line modification of databases without disturbing existing applications [40]. Ongoing projects include the study of an extensible, re usable and flexible 26 framework based on the integration of a fixed set of invariant preserving primitive change operations (with the standard object query language OQL as the vehicle for flexible object migration) 41] and the ....

Y.-G. Ra, E. A. Rundensteiner, A Transparent Schema-Evolution System Based on ObjectOriented View Technology, IEEE Transactions on Knowledge and Data Engineering 9 (4) (1997) 600--624.

....by means of a view definition language, hereafter referred to as VDL. This language allows the definition of virtual classes derived from classes of the root schema. Virtual classes are populated with objects selected through queries on the root class extensions. Proposed VDLs [Ber91, LST91, RR95] differ in their underlying view data models as well as other aspects such as data integration and schema evolution. Our VDL is an extension of O 2 C, the native language of O 2 [dSW95] It implements the view data model O 2 Views [ADdS94, dS95a] and is based on the OQL query language [ABD ....

....purpose. As opposed to our model, there is only an extension phase. As a consequence, over time, a large number of classes and underlying object instances decreases the performances of the system and makes consistent view removal necessary [CTR96] Regarding the objects, object slicing technique [KRR95] is used: a conceptual object (a kind of abstract object) is made up of several objects of implementation. This makes rather simple data updates and method execution (the look up strategy dispatches the selector to the right object of implementation) The drawback is to multiply the objects of ....

Y-G. Ra and E.A. Rundensteiner. A Transparent Schema Evolution System Based on Object--Oriented View Technology. In IEEE Int. Conf. on Data Engineering, Tapei, Taiwan, Vancouver, Canada, March 1995.

....A view is expressed by means of a view definition language, hereafter referred to as VDL. This language allows the definition of virtual classes derived from classes of the root schema. Virtual classes are populated with objects selected through queries on the root class extensions. Proposed VDLs [8, 22, 23] differ slightly according to the underlying view data model and to the particular aspects addressed such as data integration and schema evolution. Our VDL is an extension of O 2 C, the native language of O 2 [15] It implements the view data model O 2 Views, as defined in [2, 14] and is based on ....

Y-G. Ra and E.A. Rundensteiner. A Transparent Schema Evolution System Based on Object--Oriented View Technology. In IEEE Int. Conf. on Data Engineering, Tapei, Taiwan, Vancouver, Canada, March 1995.

....context, views should be still used as shorthand in queries, should support the integration of heterogeneous databases, should be the basis for content dependent authorization and, finally, should support the simulation of schema changes. Indeed, as it has been recognized by several researchers [8, 11, 34], views allow to dynamically modify a database schema yet retaining its older versions, a very important capability for advanced applications [24] Moreover, a foundation for external schemas will complete the development of a three level schema architecture for object oriented database systems, ....

....was first proposed in [8] Views can support the implementation of a schema versioning mechanism, such that any object stored in the database can be accessed and modified from any schema version including a view of the object class. Recently, other view models have considered that use of views [11, 27, 34]. The properties of a view mechanism determines which schema modifications can be simulated. For instance, the models presented in [11, 34] allow to THEORY AND PRACTICE OF OBJECT SYSTEMS (Year) simulate the addition of a new attribute to a class because they consider views which can include ....

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Ra, Y. and Rundensteiner, E.A. (1995). A Transparent Schema Evolution System Based on Object-Oriented View Technology. In Proc. Eleventh IEEE Int'l Conf. on Data Engineering, pages 165--172.

....Systems that enable interoperability for multiple software applications in dynamic environments must allow applications to evolve and flexibly change their data requirements, while minimizing or even eliminating the impact of such change on other existing applications. Several approaches [3, 11, 15, 17, 18] have been proposed to support schema evolution and or data integration needs by using object oriented views. Nevertheless, these approaches run into a potential problem of generating a large number of schema versions over time resulting in an excessive build up of classes and underlying object ....

....presented in Section 7 confirm, performance improvements will be achieved for the propagation of updates from a base class to its derived classes 1 given fewer materialized derived classes. In this paper, we demonstrate our solution of the SVR problem on the MultiView [13] and the TSE systems [18]. However, while we base our experiments on given systems, we believe the proposed methods also benefit other similar systems [1, 22, 24] Removing obsolete view schemas will also shorten the forward backward conversion function search for Lautemann s work [15] on schema versions, and a similar ....

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Y. G. Ra and E. A. Rundensteiner. A Transparent Schema Evolution System Based on Object-Oriented View Technology. IEEE Transactions on Knowledge and Data Engineering, pages 600--624, Sept. 1997. 34

....Another important issue focuses on providing support for existing applications that depend on the old schema, when other applications change the shared schema according to their own requirements. Research to address this issue has followed along two possible directions, namely, views [RRL97, RR95, RR97, Ber92] and versions [SZ86, Lau97b] Some of this on going research may need to be re examined in order to handle the complex notion of transformations as introduced by our templates. 3 The SERF Framework The SERF Framework addresses the limitation of current OODB technology that restricts ....

Y. G. Ra and E. A. Rundensteiner. A Transparent Schema Evolution System Based on ObjectOriented View Technology. IEEE Transactions on Knowledge and Data Engineering, pages 600--624, Aug/Sept 1997.

.... current database technology, objectoriented database systems (OODBs) can support very complex object models like the ODMG object model [4] These complex object models have paved the road for modelling dynamic applications which by their very nature have frequent schematic changes and upgrades [17]. Unfortunately, the existing support for schema evolution provided by current OODBs [1, 18, 3, 9, 8] is limited to a pre defined taxonomy of simple fixed semantic schema evolution operations. However, such simple changes, typically to individual types only, are not sufficient for many advanced ....

Y. G. Ra and E. A. Rundensteiner. A Transparent Schema Evolution System Based on Object-Oriented View Technology. IEEE Transactions on Knowledge and Data Engineering, 9(4):600--624, September 1997.

....called GemStone. The first impression I got from the article, is that most of the article is about the algorithms and methods which are involved by the application of this system. 2 An exploration of the problem 2. 1 Preface In the second chapter I will look at the most important chapter of [1], chapter 5. Chapter 5 discusses the central idea of the whole article. It describes the viewsystem which must contribute to a solution of the discussed problem in the first chapter. This is the so called MultiView system. This system can be used by the development of the TSE system. The ....

....around. Set changes the values of the properties of an object. Add and Remove will respectively add and remove an existing object from a class. 2. 4 A final statement about this chapter When you give a detailed description of the operators and terms discussed in chapter 5 of Ra and Rundensteiner [1], you get a better view of the problematic nature of the discussed topics. For me this chapter has more understandable contents. 3 Applications of the described concepts In this third chapter I will give a review of the algorithms which are made from the previously discussed concepts. These ....

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Ra, Y.-G. and Rundensteiner, E.A., A Transparent Schema-Evolution System Based on ObjectOriented View Technology, IEEE magazine, 4: 601-623, July/August 1997.

....Another important issue focuses on providing support for existing applications that depend on the old schema, when other applications change the shared schema according to their own requirements. Research to address this issue has followed along two possible directions, namely, views [RLR98, RR97, Ber92] and versions [SZ86, Lau97] Some of this on going research may need to be re examined in order to handle the complex notion of transformations as introduced by our templates. 3 The SERF Framework In this section we present the fundamental principles of our proposed transformation ....

Y. G. Ra and E. A. Rundensteiner. A Transparent Schema Evolution System Based on ObjectOriented View Technology. IEEE Transactions on Knowledge and Data Engineering, pages 600--624, September 1997.

.... is to define a number of invariants that must be satisfied by the schema and then to define rules for maintaining these invariants (e.g. 3] To avoid expensive changes to existing applications dependent on the original schema, researchers studied other approaches such as object oriented views [35, 36, 44] and versions [19, 25] 32] proposes an axiomatic model to provide a common framework for defining and comparing different schema evolution policies. All of these typically support the schema change taxonomy initially proposed for ORION [3] In this paper, we focus instead on the real time ....

Y.G. Ra, and E.A. Rundensteiner, "A Transparent Schema Evolution System Based on Object-Oriented View Technology," to appear in IEEE Transactions on Knowledge and Data Engineering, 1997.

....among ISs when very different source description languages are used. None of the two projects address the particular problem of evolution under capability changes of participating external ISs. We give a solution for a related problem in our transparent schema evolution (TSE) project [RR95, RR97] namely, to use view technology to handle schema changes transparently. However, this TSE work is all done in a centralized environment, assuming one single global database that is cooperating, i.e. that is maintaining all information possibly still used by any views defined on top of it. In ....

Y. G. Ra and E. A. Rundensteiner. A transparent schema-evolution system based on object-oriented view technology. IEEE Transactions on Knowledge and Data Engineering, September 1997.

....sources when very different source description languages are used. None of the two projects address the particular problem of evolution under capability changes of participating external information sources. We give a solution for a related problem in our transparent schema evolution (TSE) project [11, 12], namely, to use view technology to handle schema changes transparently. However, this TSE work is all done in a centralized environment. In the TSE framework, a user specifies schema changes against her special tailored view schema defined over one common base schema. The TSE system is ....

Y. G. Ra and E. A. Rundensteiner. A transparent schema-evolution system based on object-oriented view technology. IEEE Transactions on Knowledge and Data Engineering, September 1997.

....applications [11, 6, 7] These mechanisms must allow applications to evolve and flexibly change their data requirements, while minimizing or even eliminating the impact of such change on other integrated applications. In this vein, we are developing a Transparent Schema Evolution system called TSE [9, 10], which simulates schema evolution (SE) using object oriented views This workwas supported in part by the NSF RIA grant #IRI 9309076, NSF NYI grant #IRI 94 57609, and the University of Michigan Faculty Award Program. We would also like to thank our industrial sponsors, in particular, AT T, ....

....this paper to optimize schema removal, such as establishing an ordering for class removal processing, have not been developed for conventional SE. 3 The TSE System The TSE system combines schema evolution with schema versioning where a schema version is defined to be a dynamic view of the schema [10]. stored data STORED DATA User Application Program1 User Application Program2 virtual data1 view schema VS1 SCHEMA SPECIFY SCHEMA CHANGE global schema GS stored data MODIFIED STORED DATA EXTENDED SCHEMA User Application Program1 User Application Program2 view schema VS2 virtual data2 virtual data1 ....

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Y. G. Ra and E. A. Rundensteiner. A Transparent Schema Evolution System Based on Object-Oriented ViewTechnology. Accepted by IEEE Transactionson Knowledge and Data Engineering, 1996.

....applications [12, 18] These mechanisms must allow applications to evolve and flexibly change their data requirements, while minimizing or even eliminating the impact of such change on other integrated applications. In this vein, we are developing a Transparent Schema Evolution system called TSE [15, 16] that simulates schema evolution (SE) using object oriented views. Given a schema change request, TSE computes a new view schema with the desired semantics; while preserving all existing view schemas (and thus old applications) 1 . While the TSE approach offers numerous advantages over ....

....no other classes and or class relationships in the global schema as well as in all other view schemas are unexpectedly affected and that the resulting schema meets all schema invariants. Based on these concepts, we have implemented a first prototype of the TSE optimizer tool on top of TSE GemStone [15, 16]. Finally, we report our evaluation studies that validate our approach and demonstrate its impact on the performance of the TSE system. 2 Related Work Several other approaches towards transparent schema evolution using views have been recently presented in the literature [3, 4] However, none ....

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Y. G. Ra and E. A. Rundensteiner. A transparent schema evolution system based on objectoriented view technology. In to appear in IEEE Trans. on Knowledge and Data Engineering, 1996.

....Another important issue focuses on providing support for existing applications that depend on the old schema, when other applications change the shared schema according to their own requirements. Research to address this issue has followed along two possible directions, namely, views [RRL97, RR95, RR97, Ber92] and versions [SZ86, Lau97b] Some of this on going research may need to be re examined in order to handle the complex notion of transformations as introduced by our templates. 3 The SERF Framework In this section we present the fundamental principles of our proposed transformation ....

Y. G. Ra and E. A. Rundensteiner. A Transparent Schema Evolution System Based on ObjectOriented View Technology. September 1997.

....underlying these two solutions are given below. 5 The capacity of a schema is defined as the set of possible states of the database under the schema. The TSE1 Approach. For TSE1, we overcome the limitation of views by extending objectoriented view mechanisms to also support capacityaugmentation [19, 29]. This means that stored data can now be associated with a virtual class even if this data is not maintained with any base class. The TSE1 methodology described in depth in [29] proceeds as follows. Given a requested schema change applied to VS1, TSE1 computes a new schema (VS2) as a view ....

....overcome the limitation of views by extending objectoriented view mechanisms to also support capacityaugmentation [19, 29] This means that stored data can now be associated with a virtual class even if this data is not maintained with any base class. The TSE1 methodology described in depth in [29] proceeds as follows. Given a requested schema change applied to VS1, TSE1 computes a new schema (VS2) as a view derived from the global schema that provides the desired enhanced interface rather than directly modifying the old schema (VS1) The preservation of VS1 allows for continued support of ....

[Article contains additional citation context not shown here]

Y. G. Ra and E. A. Rundensteiner. A transparent schema evolution system based on object-oriented view technology. In to appear in IEEE Trans. on Knowledge and Data Engineering, 1997.

....work. Another important issue focuses on providing support for existing applications that depend on the old schema, when other applications change the shared schema according to their own requirements. Research to address this issue has followed along two possible directions, namely, views [RLR98, RR97, Ber92] and versions [SZ86, Lau97] To the best of our knowledge, optimization of schema evolution execution and even worse yet sequences of such operations in such multi layered systems that would require rippling changes through possibly several different schema models remains un explored. 3 ....

.... if they increase the capacity of the schema, for instance, by adding a class, capacity reducing if they decrease the capacity of the schema, for instance, by deleting a class, or capacity preserving if they do not change the capacity of the schema, for instance, by changing the name of a class [RR97] For each schema evolution primitive its capacity type is shown in the third column of Table 1. 4 Formal Foundations of Schema Evolution Sequence Analysis To establish a foundation for our optimization principles we now develop a formal characterization of the schema evolution operations, ....

Y. G. Ra and E. A. Rundensteiner. A Transparent Schema Evolution System Based on ObjectOriented View Technology. IEEE Transactions on Knowledge and Data Engineering, 9(4):600-- 624, September 1997.

....user is transparent to (not seen by) other users even though they share a common portion of the schema and the associated data. Our transparency approach is to simulate schema changes as views instead of executing in place changes on a shared schema, thus shielding other users from these changes [RR97] However, conventional view mechanisms, being derived functions on the stored database, cannot simulate capacity augmenting 2 schema changes due to their inherent limitation of not augmenting the underlying schema. It has been assumed that one either has to limit oneself to ....

....2 schema changes due to their inherent limitation of not augmenting the underlying schema. It has been assumed that one either has to limit oneself to non capacity augmenting schema changes or utilize an advanced (capacity augmenting) view mechanism. In an earlier effort, we [RR95, RR97] as well as Bertino [Ber92] chose the latter approach by extending traditional object oriented view mechanisms to also support capacity augmenting views. This means that the view mechanism must be capable of the storage of base data directly with view classes. While we have indeed built such an ....

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Y. G. Ra and E. A. Rundensteiner. A Transparent Schema Evolution System Based on Object-Oriented View Technology. IEEE Transactions on Knowledge and Data Engineering, pages 600--624, September 1997.

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Y. G. Ra and E. A. Rundensteiner. A transparent schema-evolution system based on object-oriented view technology. IEEE Transactions on Knowledge and Data Engineering, September 1997.

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Y.-G. Ra and E. A. Rundensteiner. A transparent schema-evolution system based on object-oriented view technology. IEEE Transactions on Knowledge and Data Engineering, 9(4):600--624, 1997.

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Ra Y-G and Rundensteiner E A, A transparent schema-evolution system based on objectoriented view technology, in: IEEE Transactions on Knowledge and Data Engineering, 9 (1997) 600-624.

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Ra, Y.-G. and Rundensteiner, E.A., A Transparent Schema-Evolution System Based on Object-Oriented View Technology. IEEE Transactions on Knowledge and Data Engineering, 1997, 9(4): p. 600-624.

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Y.-G. Ra and E. A. Rundensteiner, "A Transparent Schema-Evolution System Based on ObjectOriented View Technology", IEEE Transactions on Knowledge and Data Engineering, Vol. 9, No. 4, pp. 600-624, 1997.

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Y.-G. Ra and E. A. Rundensteiner, "A Transparent Schema-Evolution System Based on Object-Oriented View Technology", IEEE Transactions on Knowledge and Data Engineering, Vol. 9, No. 4, pp. 600-624, 1997.

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Ra., Y.-G., Rundensteiner, E. A., "A Transparent Schema-Evolution System Based on ObjectOriented View Technology", IEEE Transactions on Knowledge and Data Engineering, Vol. 9, No. 4, July/Aug. 1997, pp. 600-624

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Ra., Y.-G., Rundensteiner, E. A., "A Transparent Schema-Evolution System Based on Object-Oriented View Technology", IEEE Trans. Knowledge & Data Engg., 9(4), 1997, pp. 600-624

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Ra., Y.-G., Rundensteiner, E. A., "A Transparent Schema-Evolution System Based on Object-Oriented View Technology", IEEE Transactions on Knowledge and Data Engineering, Vol. 9, No. 4, July/Aug. 1997, pp. 600-624

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Ra., Y.-G. & Rundensteiner, E. A., "A Transparent Schema-Evolution System Based on Object-Oriented View Technology", IEEE Transactions on Knowledge and Data Engineering, Vol.9, No.4, July/Aug.1997, pp.600624

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RA Y.-G., RUNDENSTEINER E. A., "A Transparent Schema-Evolution System Based on Object-Oriented View Technology", IEEE Transactions on Knowledge and Data Engineering, Vol.9, No.4, July/Aug.1997, pp. 600-624

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Ra., Y.-G. & Rundensteiner, E. A.: A Transparent Schema-Evolution System Based on Object-Oriented View Technology. IEEE Transactions on Knowledge and Data Engineering, Vol.9, No.4, July/Aug.1997, pp.600-624

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