Differences to Earlier Versions

 

Compared to its predecessors ConceptBase V5.2.3 is a significantly improved version concerning functionality, efficiency and stability. The most important new system components are the cost-based query optimizer, the view mechanism, an active rule engine, and the modular object base.

• The cost-based query optimizer [SOI96] improves the performance of complex queries and avoids some worst-case situations in query evaluation. The query execution time is on an average reduced by about 50%, in some cases the execution is 1000 times faster. However, the compilation of queries needs some more time.
• Complex views based on the query class paradigm allow the specification of arbitrary subsets of an O-Telos network of objects preserving the links between them instead of projecting them to attributes of one, central answer object. The view concept is combined with a mapping to C++ classes (together with extraction methods for their initialization) around which a client program can be built.
• Based on the view maintenance algorithm presented in [SJ96] a view maintenance mechanism and change notification mechanism developed in [QUI96] is able to propagate base data changes to views gain combined with corresponding methods on the clients data structures.
• The object base can be partitioned into modules. The notion of modules covers import and export functions as well as global and local assertions.
• An ECA rule component improves the ``active" system behavior by allowing to specify arbitrary actions to be performed if certain events/conditions hold in the object base.

We tried hard to guarantee maximum compatibility to older versions of ConceptBase. The release notes to CB 5.2.3 give hints how to port applications of older versions to 5.2.3.