tailieunhanh - An Event-Condition-Action Logic Programming Language ?

The READ and WRITE filters are intended to work on any file descriptor, and the ident field contains the descriptor number. These filters closely mirror the be- havior of poll() or select(), in that they are intended to return whenever there is data ready to read, or if the ap- plication can write without blocking. The kernel func- tion corresponding to the filter depends on the descriptor type, so the implementation is tailored for the require- ments of each type of descriptor in use. In general, the amount of data that is ready to read (or able to be writ- ten) will be returned in the data field within the. | An Event-Condition-Action Logic Programming Language J. J. Alferes1 F. Banti1 and A. Brogi2 1 CENTRIA Universidade Nova de Lisboa Portugal jja banti@ 2 Dipartimento di Informatica Universita di Pisa Italy brogi@ Abstract. Event-Condition-Action ECA languages are an intuitive and powerful paradigm for programming reactive systems. Usually important features for an ECA language are reactive and reasoning capabilities the possibility to express complex actions and events and a declarative semantics. In this paper we introduce ERA an ECA language based on and extending the framework of logic programs updates that together with these features also exhibits capabilities to integrate external updates and perform self updates to its knowledge data and classical rules and behaviour reactive rules . 1 Introduction Event Condition Action ECA languages are an intuitive and powerful paradigm for programming reactive systems. The fundamental construct of ECA languages are reactive rules of the form On Event If Condition Do Action which mean when Event occurs if Condition is verified then execute Action. ECA systems receive inputs mainly in the form of events from the external environment and react by performing actions that change the stored information internal actions or influence the environment itself external actions . There are many potential and existing areas of applications for ECA languages such as active and distributed database systems 26 6 Semantic Web applications 21 24 distributed systems 13 Real-Time Enterprize and Business Activity Management and agents 11 . To be useful in a wide spectrum of applications an ECA language has to satisfy several properties. First of all events occurring in a reactive rule can be complex resulting from the occurrence of several basic ones. A widely used way for defining complex events is to rely on some event algebra 10 1 . to introduce operators that define complex events as the result of compositions of