PRACTIC

PRACTIC is a parallel Object-Oriented Database system that is based on a concurrent object data model. PRACTIC means PaRallel ACTIve Classes and is based on the vertical partitioning and concurrent management of the database schema classes and meta-classes, which are collectively called active objects. Active objects are permanent processes in memory that encapsulate their definitions, methods and management procedures. Semi-active and passive objects exist to realise abstract classes and instances (the actual data), respectively. The object model gives rise to a query/method execution model that provides parallelism on all levels of the instantiation hierarchy. The abstract PRACTIC machine directly maps the model to a MIMD machine, providing a hierarchical architecture and a hierarchical de-clustering scheme.

A first prototype of PRACTIC system is being implemented on a transputer network, using CS-Prolog as the implementation language. When the prototype has been tested, PRACTIC will be ported to a network of workstations.

Relevant Publications

N. Bassiliades and I. Vlahavas, "A Multiprocessor System for the Efficient Management of Large Knowledge Bases" (in Greek), Proc. 6th Hellenic Physics Conference, Xanthi, Greece, March 1993.
N. Bassiliades and I. Vlahavas, "A Multiprocessor Machine for the Parallel Management of an Active Object-Oriented DataBase" (in Greek), Proc. 4th Hellenic Conference on Informatics, Patra, Greece, December 1993, pp. 501-512.
N. Bassiliades and I.Vlahavas, "Constraint Checking in a Parallel Object-Oriented Database System", Journal of Parallel Algorithms and Applications, Vol. 5, 1995, pp. 129-147
N. Bassiliades and I.Vlahavas, "PRACTIC: A Concurrent Object Data Model for a Parallel Object-Oriented Database System", Information Sciences , Vol. 86 (1-3), pp. 149-178, 1995.
I. Vlahavas and N. Bassiliades, "A Parallel Active Knowledge Base System", submitted for publication, 1995.
N. Bassiliades and I.Vlahavas, "A Non-Uniform Data Fragmentation Strategy for Parallel Main-Memory Database Systems", Proc. 21st International Conference on Very Large Data Bases, VLDB'95, Zurich, Switzerland, 1995, pp. 370-381.
N. Bassiliades and I. Vlahavas, "Hierarchical Query Execution in a Parallel Object-Oriented Database System", Parallel Computing, Vol. 22 (7), pp. 1017-1048, Elsevier, 1996.
I. Vlahavas and N. Bassiliades, "Parallel, Object-Oriented, and Active Knowledge Base Systems", book to be published by Kluwer Academic Publishers, 1998.

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