Explanatory Denotational Semantics for Complex Event Patterns

Recent years brought popularity and importance of complex event processing (CEP) and associated query languages. CEP systems can be hard to understand. It is often non-trivial to determine streams of events matched by a query, and sometimes we may not notice important edge cases. Hence, the desirabi...

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Bibliographic Details
Published inFormal aspects of computing Vol. 35; no. 4; pp. 1 - 37
Main Author Zieliński, Bartosz
Format Journal Article
LanguageEnglish
Published New York, NY ACM 20.11.2023
Subjects
Denotational semantics
Domain specific languages
Formal software verification
Regular languages
Semantics
Software and its engineering
Specialized application languages
Syntax
Theory of computation
Event processing
variable binding and scope
query language
denotational semantics
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Summary:Recent years brought popularity and importance of complex event processing (CEP) and associated query languages. CEP systems can be hard to understand. It is often non-trivial to determine streams of events matched by a query, and sometimes we may not notice important edge cases. Hence, the desirability of formal semantics permitting reasoning about resulting complex events and checking if actual matchings agree with our intentions follows. In the article, we introduce a pattern language PatLang with some unique syntactic features related to variable binding. We provide two distinct denotational semantics for PatLang: Minimal semantics, sufficient to describe when patterns match, and tree semantics, which provides detailed information about subpatterns with which the matched events actually match, i.e., information about interpretation of matched events induced by the pattern matching. The tree semantics is unnecessary for verifying correctness of pattern matching execution. However, we show that neither minimal semantics, nor semantics from the prior work suffices to effectively locate errors in patterns with respect to their intended meaning, and that the additional information provided by the tree semantics is crucial for that purpose. We prove that tree semantics can be mapped to minimal semantics. Finally, we provide some practical evaluation.
ISSN:0934-5043
1433-299X
DOI:10.1145/3608486