Towards Net-based Formal Methods for Complex Event Processing

Complex event processing (CEP) systems evaluate continuous queries over event streams in order to detect event patterns that characterise a situation of interest. Over the last decade, models and systems for CEP have been an active area of research. A plethora of languages for the definition of queries as well as algorithms and architectures for their efficient and robust evaluation have been proposed. However, we argue that much of this work adopted a pragmatic view, striving for technical solutions of problems that are rooted directly in specific applications. As such, formal methods that help in the design and implementation of CEP systems are underdeveloped. In this paper, we put forward the idea of exploiting well-established formalisms for concurrent systems in the analysis of CEP systems. We discuss query verification, query parallelisation, and out-of-order event handling as three exemplary use cases for formal methods for CEP. Moreover, we outline our initial results on addressing these use cases through a Petri-net-based formalisation of event queries, event streams, and evaluation architectures.