M. Tresch, M. H. Scholl. Meta Object Management and its Application to Database Evolution. ER 1992, 299-321.  Home/Search   Document Details and Download   Summary   Related Articles   Check

.... existing instances) 18] Both aspects have been studied extensively for the relational and the object oriented data models, in the temporal and the non temporal variants [19] The results have been often incorporated into commercial or prototype database systems (e.g. Orion [3] O 2 [26] Cocoon [24], F2 [1] and Tigukat [7] More recently, in the software engineering field, the problem of software evolution is being dealt with a refactoring approach [16] A refactoring is a parameterized behavior preserving program transformation that automatically updates an applications design and source ....

# Tresch, M.; Scholl, M.H. "Meta Object Management and its Application to Database Evolution", 11th. Intl. Conf. on the Entity-Relationship Approach - ER'92, LNCS 645, Springer-Verlag, pp. 299-321.

....legal instance for the schema version . M 2E. 3 0 132 . As a final remark, it should be noted that the problem of the correctness of a schema under modifications has already been investigated in the schema evolution context. The main approach (adopted for instance by ORION [2] COCOON [27], O [1] consists in defining and enforcing a number of invariants: Closure Invariants All types in the type lattice have supertypes. 12 Acyclicity Invariant There are no cycles in the type lattice. Rootedness Invariant There is a single type which is the supertype of all types. Full ....

M. Tresch, M. H. Scholl, Meta Object Management and its Application to Database Evolution, in: Proc. of the 11th Int. Conf. on the Entity Relationship Approach (ER), Karlsruhe, Germany, 1992, pp. 299--321.

....to these new classes, none of their operations allow simultaneous modification of multiple types such as moving a field from one existing type to another. Another approach to schema evolution relies on the simultaneous maintenance of multiple versions of types and data[SZ86, Cla94, Bra92, MS92b, TS92] With these approaches, multiple versions of the same type exist within a single database. The advantage is that old and new code can operate on old and new data without requiring either to be changed. The disadvantage is that the maintainer must provide routines to make data appear to be of the ....

Markus Tresch and Marc H. Scholl. Meta object management and its application to database evolution. In Proceedings of the 11th International Conference on the Entity-Relationship Approach, pages 299--321, Karlsruhe, Germany, October 1992.

....schema is presented in [Ra Rundensteiner, 1995] In the system proposed here, partially derived classes can be defined with non derived elements in the intension as well as in the extension of the class. Other papers on schema evolution [Skarra Zdonik, 1986; Andany et al. 1991; Tresch, 1991; Tresch Scholl, 1992; Monk Sommerville, 1993; Brche et al. 1995; Ferrandina et al. 1995] offer such mechanisms as lazy conversion, or class or schema versioning, with elements common to the derivation relationship; but they do not offer the possibilities that derived and partially derived class definition ....

M. Tresch, M. Scholl, "Meta Object Management and its Application to Database Evolution," Proc. Int'l. Conf. on Entity-Relationship Approach, pp. 299-321, Karlsruhe, Oct. 1992.

....and dynamic program analysis techniques [9] could be used to improve the quality of the models. Metalevel constructs and evolution. Many efforts have been devoted to cope with the problem of evolution in the fields of SE and the SP. Among them, those based in the dynamic evolution of meta models [10,11,12] are of particular interest, due to the fact that a similar approach may be taken to define an evolvable WF meta model whose dynamic properties must include support to both structural and behavioral consistency. 4. Conclusions and future work In this paper we have pointed out that Software ....

Tresh M., Scholl M., Meta object management and its applications to database evolution. Proc. of the 11 th International Conference on the Entity-Relationship Approach, LNCS, Springer-Verlag, 1992.

....and prototypes do not allow free and dynamic changes to the schema. What is allowed is to perform schema changes by means of primitives (from here on called LLPs Low Level Primitives) close to the respective underlying data model. Taxonomies of such schema update primitives can be found in [1, 4, 5, 7, 6]. They deal with the creation, deletion or modification of the definitions of the data model, classes and properties (attribute and method) and some additional concepts specific to the ODBS. They might also differ regarding the level of integration between the data, the schema and the ....

....with the creation, deletion or modification of the definitions of the data model, classes and properties (attribute and method) and some additional concepts specific to the ODBS. They might also differ regarding the level of integration between the data, the schema and the meta schema, if any [7]. These primitives are considered as a first level of schema update primitives. In contrast to this, Software Development Environments (SDE) ought to support more declarative complex advanced operations occurring in the design process like generalization or merge of definitions. Most of the object ....

M.H. Scholl and M. Tresch. Meta Object Management and its Application to Database Evolution. In Proc. 11th International Conf. Entity--Relationship Approach, pages 299--321. Springer LNCS 645, Karlsruhe, Germany, October 1992. 32

....for a range of program analysis tools and browsers. Analysis tools typically need to have access to metalevel information of the system at hand to answer queries about the system itself. The database community has recognized early the power of self describing database systems [FGMS81, Bra87, TS92] and have used them extensively to allow the user to interactively build up a schema, and to query the structure of the schema. In the database context, the part of the system that contains the meta information is usually called data dictionary or meta database. Since the object oriented schema ....

Markus Tresch and Marc H. Scholl. Meta object management and its application to database evolution. ETH Zurich, Department of Computer Science, 1992.

....and execute programs to move the data prior to deleting the instance variables containing the data. Another approach to schema evolution relies on the simultaneous maintenance of multiple versions of types and data[Skarra and Zdonik 1986; Clamen 1994; Bratsberg 1992; Monk and Sommerville 1992; Tresch and Scholl 1992; Lautemann 1997a; Lautemann 1997b; Ra and Rundensteiner 1994] With these approaches, multiple versions of the same type exist within a single database. The advantage is that 1 Note that if the type being deleted is used as the type of an instance variable, we cannot in general replace its type ....

Tresch, M. and Scholl, M. H. 1992. Meta object management and its application to database evolution. In Proceedings of the 11th International Conference on the EntityRelationship Approach (Karlsruhe, Germany, October 1992), pp. 299-321.

....changed, requiring the information system to evolve as well. This means that the underlying data schema has to undergo yet another set of transformations to incorporate the new requirements. This observation has led to the development of so called evolving information systems (see e.g. BKKK87, TS92, PW95, OPF94, PW94, HEH 94] 1 1.1 Schema Design Through Transformations To further motivate our view on a schema modelling process as a transformation process, we first take a closer look at the involved transformations. A conceptual schema design process usually starts out with an initial ....

....of a data schema through all its stages of design, including that of evolution of the information system as a whole due to changed requirements. The resulting evolution mechanism is referred to as the CDM Evolver. Existing approaches to the modelling of data schema evolution (e.g. BKKK87, TS92, PW94] are only able to describe the evolution of either the conceptual level, or the internal level, but not both as a unity. For example, BKKK87, TS92] describe the evolution at the actual database level and not the conceptual level. EVORM ( PW94] on the other hand, only allows us to ....

[Article contains additional citation context not shown here]

M.T. Tresch and M.H. Scholl. Meta Object Management and its Application to Database Evolution. In G. Pernul and A.M. Tjoa, editors, 11th International Conference on the EntityRelationship Approach, volume 645 of Lecture Notes in Computer Science, pages 299--321, Karlsruhe, Germany, October 1992. Springer-Verlag.

....a (semi formal) semantics of schema updates restricted to object oriented databases. The ORION system, together with the GemStone ( PS87] BMO 89] and Sherpa ( NR89] systems, are among the first object oriented database systems to support schema type evolution. In the Cocoon project ( Tre91] TS92] an approach to the evolution of schemas in object oriented databases is followed in which schema objects (e.g. object types) are considered to be objects like others (from the application) We will do a similar thing, and consider objects of both levels as objects describing an evolution in the ....

....enforces the following properties: 1. 2. Due to this property, the communication between user and information system can be transaction oriented. The description of a (convenient) language for this communication falls outside the scope of this paper. For more details see [KBC 89] BMO 89] TS92] Pro94] and [PW95] At this point, we have demarcated the states and transitions of an evolving information system. Later, we will impose wellformedness restrictions on application model histories, and thus on the states of the evolving information system. We will use to denote that satisfies ....

M.T. Tresch and M.H. Scholl. Meta Object Management and its Application to Database Evolution. In G. Pernul and A.M. Tjoa, editors, 11th International Conference on the EntityRelationship Approach, volume 645 of Lecture Notes in Computer Science, pages 299--321, Karlsruhe, Germany, October 1992. Springer-Verlag.

....offers a more detailed taxonomy, together with a (semi formal) semantics of schema updates restricted to object oriented databases. The ORION system, together with the GemStone system ( 38] 7] are among the first object oriented database systems to support schema type evolution. In [52] and [53] an approach to the evolution of schemas in object oriented databases is followed in which schema objects (e.g. object types) are considered to be objects like others (from the application) We will do a similar thing, and consider objects of both levels as objects describing an evolution in the ....

M.T. Tresch and M.H. Scholl. Meta Object Management and its Application to Database Evolution. In G. Pernul and A.M. Tjoa, editors, 11th International Conference on the Entity-Relationship Approach, volume 645 of Lecture Notes in Computer Science, pages 299--321, Karlsruhe, Germany, October 1992. Springer-Verlag.

....has been designed to support exactly these kinds of change by using zones and zone contracts. 8.4 Schema Evolution and Versioning Schema evolution and versioning are two different approaches to dynamically changing a database schema. Schema evolution ( BKKK87, MSOP86, LH90, BBB 88, Bar91, TS92] systems tend to focus on how changes to the schema are described and ways of ensuring that changes do not invalidate the database contents. Versioning approaches ( BB88, SZ86, Zdo90, MS93, Cla92, Bra93] focus on how to allow multiple versions of an object to co exist at run time. The most ....

M. Tresch and M. H. Scholl. Meta object management and its application to database evolution. In Proceedings of the 11th International Conference on the Entity-Relationship Approach, 7--9 October 1992, Karlsruhe, Germany, pages 299--321, 1992.

....prototypes do not allow free and dynamic changes to the schema. They merely allow the performance of schema changes by means of primitives (from here on called LLPs Low Level Primitives) close to the respective underlying data model. Taxonomies of such schema update primitives can be found in [4, 10, 15, 26, 16]. They deal with the creation, deletion or modification of the schema definitions of the data model, classes and properties (attribute and method) and some additional concepts specific to the ODBS. They may also differ regarding the level of integration between the data, the schema and the ....

....the creation, deletion or modification of the schema definitions of the data model, classes and properties (attribute and method) and some additional concepts specific to the ODBS. They may also differ regarding the level of integration between the data, the schema and the meta schema, if any [26]. These primitives are considered as a first level of schema update primitives. In contrast to this, Software Development Environments (SDE) should support more declarative complex advanced operations occurring in the design process such as generalization or merge of definitions. Most of the ....

M.H. Scholl and M. Tresch. Meta Object Management and its Application to Database Evolution. In Proc. 11th International Conf. Entity--Relationship Approach, pages 299--321. Springer LNCS 645, Karlsruhe, Germany, October 1992.

....and prototypes do not allow free and dynamic changes to the schema. What is allowed is to perform schema changes by means of primitives (from here on called LLPs Low Level Primitives) close to the respective underlying data model. Taxonomies of such schema update primitives can be found in [3, 8, 11, 21, 12]. They deal with the creation, deletion or modification of the definitions of the data model, classes and properties (attribute and method) and some additional concepts specific to the ODBS. They might also differ regarding the level of integration between the data, the schema and the ....

....with the creation, deletion or modification of the definitions of the data model, classes and properties (attribute and method) and some additional concepts specific to the ODBS. They might also differ regarding the level of integration between the data, the schema and the meta schema, if any [21]. These primitives are considered as a first level of schema update primitives. In contrast to this, SDE environments ought to support more declarative complex advanced operations occurring in the design process like generalization or merge of definitions. Most of the object methodologies, like ....

M.H. Scholl and M. Tresch. Meta Object Management and its Application to Database Evolution. In Proc. 11th International Conf. Entity--Relationship Approach, pages 299--321. Springer LNCS 645, Karlsruhe, Germany, October 1992.

....and functions that have been defined in the schema. These meta objects not only serve as the data dictionary or objectbase catalog, they are also used as the basis for schema evolution. The COOL update operators can also be applied to the meta objects, so as to express schema modifications [TS92] The problem attacked here was to define the update operations and the meta types classes in such a way that schema modification automatically propagate to the instance level. Of course, an implementation will avoid eager transformation and try to use views, schema versions, or lazy ....

.... have been designed, implemented, and extensively tested and evaluated in comparison with various others [Jia90a, Jia92c] 7 Publications Outside publications: HS91, Jia89, Jia90b, Jia91, Jia92a, Jia92b, LS92b, SLT91, SLT90, SS90a, SS90b, SS91b, SS91a, SST92, SSW91, Sch92a, Sch92b, Tre91, TS92] Internal reports and non refereed publications: DHL 92, Jia90a, LS92c, RRS92, RS92, TRSB92, TS91] Theses: Boo91, Fie91, Fra91, Fri91, Gar91, Ger90, Goh91, Gro91, Jia92c, Kla91, Kla90, Kri90, Lae91, Loe91, Lue92, Mes91, MW89, Ngu91, Rec90, Vet89, Vet90, Wic91, Wil91] Acknowledgements The ....

M. Tresch and M.H. Scholl. Meta object management and its application to database evolution. In Proc. 11th Int'l Conf. Entity-Relationship Approach, Karlsruhe, Germany, October 1992. Springer.

....Furthermore, this object could result from the application of the member type function mtype to the class P ersons. Such a representation is an elegant way to make retrievals on the schema level and schema evolution feasible with a similar set of operations for the schema and the instancelevel [TS92] However, if we are interested in compile time type checking, we have to restrict this flexibility, because the type information must not be changed at runtime. Additionally, we have to exclude mixed level operations, such as, for example, the application of an operation to members of a set of ....

....been defined in the schema. These meta objects not only serve as the data dictionary or objectbase catalog, they are also used as the basis for schema evolution. The COOL update operators can also be applied to the meta objects, so as to express schema modifications. The problem attacked in [TS92] was to define the update operations and the meta types classes in such a way that schema modifications automatically propagate to the instance level. Of course, an implementation will avoid eager transformation and try to use views, schema versions, or lazy transformation of the instance objects ....

M. Tresch and M.H. Scholl. Meta object management and its application to database evolution. In Proc. 11th Int'l Conf. Entity-Relationship Approach, Karlsruhe, Germany, October 1992. Springer.

....functionality, typically prohibited in most DBMSs) those schema objects. We will show that the COOL language can be used to implement schema evolution by means of schema modification primitives that include propagation to the instance level (automatic database reorganization due to schema changes) [33, 34, 31]. Finally, the third line of evolution leaves the context of a single system and considers schema changes in the context of a stepwise integration of previously independent databases. It turns out that with very small extensions to the language semantics (mainly the introduction of an ....

....updates is given by the semantic concepts of the considered data model. Such sets of elementary schema updates can also be found for ORION [4] O 2 [35] and GemStone [18] For COCOON, these are changes of variables, functions, types, classes, and views. An exhaustive enumeration can be found in [33], here, we focus on the technique, how they are implemented. As we know, any elementary schema update is described as a tuple, consisting of a schema update and a database reorganization. We understand that u and r are performed as an atom, that is, both together or none of them are executed. ....

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M. Tresch and M.H. Scholl. Meta object management and its application to database evolution. In Proc. 11th Int'l Conf. on Entity-Relationship Approach, Karlsruhe, Germany, October 1992. Springer, LNCS 645.

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M. Tresch, M. H. Scholl. Meta Object Management and its Application to Database Evolution. ER 1992, 299-321.

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M.T. Tresch and M.H. Scholl. Meta Object Management and its Application to Database Evolution. In G. Pernul and A.M. Tjoa, editors, 11th International Conference on the EntityRelationship Approach, volume 645 of Lecture Notes in Computer Science, pages 299--321, Karlsruhe, Germany, October 1992. Springer-Verlag. 37

No context found.

M.T. Tresch and M.H. Scholl. Meta Object Management and its Application to Database Evolution. In G. Pernul and A.M. Tjoa, editors, 11th International Conference on the EntityRelationship Approach, volume 645 of Lecture Notes in Computer Science, pages 299--321, Karlsruhe, Germany, October 1992. Springer-Verlag. 37

No context found.

M.T. Tresch and M.H. Scholl. Meta Object Management and its Application to Database Evolution. In G. Pernul and A.M. Tjoa, editors, 11th International Conference on the EntityRelationship Approach, volume 645 of Lecture Notes in Computer Science, pages 299--321, Karlsruhe, Germany, October 1992. Springer-Verlag.

No context found.

M.T. Tresch and M.H. Scholl. Meta Object Management and its Application to Database Evolution. In G. Pernul and A.M. Tjoa, editors, 11th International Conference on the EntityRelationship Approach, volume 645 of Lecture Notes in Computer Science, pages 299--321, Karlsruhe, Germany, October 1992. Springer-Verlag.

No context found.

Markus Tresch and Marc H. Scholl. Meta object management and its application to database evolution. In G. Pernul and A. M. Tjoa, editors, Eleventh International Conference on the Entity-Relationship Approach, volume 645 of Lecture Notes in Computer Science, pages 299-321. Springer-Verlag, October 1992.

No context found.

Markus Tresch and Marc H. Scholl. Meta object management and its application to database evolution. In Proceedings of the 11th International Conference on the Entity-Relationship Approach, 7--9 October 1992, Karlsruhe, Germany, pages 299--321, 1992.

No context found.

Markus Tresch and Marc H. Scholl. Meta object management and its application to database evolution. In G. Pernul and A. M. Tjoa, editors, Eleventh International Conference on the Entity-Relationship Approach, volume 645 of Lecture Notes in Computer Science, pages 299-321. Springer-Verlag, October 1992.

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