Risch, T. and Sköld, M. (1992). Active Rules based on Object-Oriented Queries. Technical Report LiTH-IDA-R-92-35, Department of Computer and Information Science, Linköping University, Sweden. To be published in special issue on Active Databases in IEEE Data Engineering. (bibtex),
Abstract: We present a next generation object-oriented database with active properties by introducing rules into OSQL, an Object-Oriented Query Language. The rules are defined as Condition Action (CA) rules and can be parameterized, overloaded and generic. The condition part of a rule is defined as a declarative OSQL query and the action part as an OSQL procedure body. The action part is executed whenever the condition becomes true. The execution of rules is supported by a rule compiler that installs log screening filters and uses incremental evaluation of the condition part. The execution of the action part is done in a check phase, that can be done after any OSQL commands in a transaction, or at the end of the transaction. Rules are first-class objects in the database, which makes it possible to make queries over rules. We present some examples of rules in OSQL, some implementation issues, some expected results and some future work such as temporal queries and real-time support.
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