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
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.
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.
- 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,
- 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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