Modeling And Behaviour Analysis Of Active Database Rule Based On Petri Net

It is gererally regarded that the active database system is composited of a database and active rule set built on the database. ECA rule is usually adapted to form the Active database rule. However, because of the interaction and interference between rules in the rule set, the behaviour of rules become rather complicated. The rule designer must estimate the side-effect of the rules, which they designed, to the state of the database. It is necessary to analysis the behaviour characters of rulesfor active database system.The complexity of the rules behaviour mostly exists in two aspects: termination and consistency, which are also called as the problem of the active rule behaviour characters. Considering a given rule set R, if we can find proper methods to judge under which conditions R hold the termination and consistency. Therefore, it is possible to construct analysis tool of rule behaviour for the ECA rule system, on which is the meaning of my research based on.Research in this field has been quite extensive. Many of the existing analysis have the disadvantage.Some based on the specific semantics of underling database system. Some heavily relyed on the underlying data model (relation/object-oriented). Among these methods, a common method named conjunction graph, which based on two graphs: the triggering graph and activation graph. It is the most generally applied approach to rule analysis. But, it had some disadvantages: it is difficult to extend for variours rule semantics and the conclusion of analysis is not precious enough.For Petri net is specially suitable to describe the asynchronous concurrent behaviour of rules, it is adapted to model the rule system and rule processing in this paper, which is able to properly express various rules semantics. Thus, it is feasible to analysis rule behaviour.In my research, Petri net is used as tools of modeling and analysis of active database.And, according to particularity of active rules modeling, suitable Petri net for active rule set is discussed. At the same time, based on the built model, termination and consisitency of rule behaviour is studied.In this paper, first of all, Petri net construction of subnet is decided, which is used to store active rule states.Single rule's Petri-net construction is combined by subnet.Then, Petri-net model of whole rule set is composed of that of single rule. Based on the built model, an algorithm of termnation analysis based on excution graph (EG) is provided, which is improved from RG In order to preserve the consistence of...