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Methods materialisation in object-oriented databases: implementation and experimental evaluation

Jezierski J., Masewicz M., Wrembel R.

Foundations of Computing and Decision Sciences

2004

Vol. 29, No. 3

171-192

A method can be a very complex program, whose computation may last long. Therefore the efficient execution of a method has a great impact on a query response time. Optimising access to data returned by methods is difficult as methods are written in a high-level programming languages. Moreover, estimating a method's execution cost is another serious problem because of the complexity of a method's code. In this paper we propose a framework for the materialisation of method results in object-oriented databases. A materialisation of a method consists in computing the result of a method once, store it persistently in a database and then use the persistent value when the method is invoked. However, the result of a materialised method has to be kept up to date after updating objects used to compute the value of this method. To this end, we use additional data structures representing links between materialised methods and objects used to compute these methods. When such an object is updated, the system uses these data structures in order to invalidate outdated results. In our approach, the materialisation of method m results also in the materialisation of intermediate results of methods called from m. We call this technique hierarchical materialisation. When an object used to materialise the result of in is updated, then in is invalidated. Next invocation of in for the same object, results in the recomputation of in by using unaffected intermediate materialised results of methods called from in. Thus, the recomputation time overhead is reduced. The hierarchical materialisation technique was implemented and evaluated in a prototype based on the FcistObjects t7 object-oriented database.

Modelowanie informacji w zintegrowanym projektowaniu produktów i procesów produkcyjnych

Macioł A., Macioł P.

Archiwum Technologii Maszyn i Automatyzacji

2004

Vol. 24, nr 3 sp

99-108

Celem artykułu jest przedstawienie takiego modelowania informacji projektowej, aby było możliwe jej wykorzystanie w zautomatyzowanych procedurach decyzyjnych i przekazywanie pomiędzy różnymi uczestnikami procesu projektowego, także poprzez Internet. Problem ten przedstawiono na przykładzie doboru technologii wykonania odlewu. W artykule zamieszczono przegląd procedur i narzędzi służących do wspomagania procesów projektowania wyrobu, technologii wytwarzania i organizacji procesu produkcyjnego oraz omówiono problemy związane z wymianą informacji projektowej. Na konkretnym przykładzie rozważono przydatność technologii XML i obiektowych baz danych do modelowania informacji na potrzeby systemu eksperckiego doboru technologii odlewania.

In this paper authors shows, that in present market conditions it is necessary to integrate stages of products, and technologies planning. The most important problem to be solved is creating models of project information. This problem presentation will be based on metal industry example. Authors present two concepts of ontologies that can be used in information modeling for selection of the casting process using an expert system. The first one is based on XML technology and the second on object database. Integrating expert systems with the database or XML documents give them the power of data management features in integrated product and process planning.