LogCEP - Complex Event Processing based on Pushdown Automaton

Abstract

Complex (or Composite) event processing systems have become more popular in a number of areas. Non-deterministic finite automata (NFA) are frequently used to evaluate CEP queries. However, it is complex or difficult to use the traditional NFA-based method to process patterns with conjunction and negation. In this paper, we proposed a new CEP system LogCEP using pushdown automaton to support efficient processing of conjunction and negation. First, the semantic and query language specification of LogCEP system are presented. Then, an automaton named LogPDA is proposed for query processing in LogCEP system. LogPDA construction method describes how to convert a query to LogPDA automation. The LogPDA execution approach describes how to detect the specified pattern using LogPDA. Meanwhile, most of previous NFA-based optimizations can be employed to improve the evaluation efficiency. Finally, our simulation based experimental results show that our method not only extended the expressibility and processing capability but also didn't lead to efficiency decreasing.