Monitoring Behavioral Compliance with Architectural Patterns based on Complex Event Processing

Architectural patterns assist in the process of architectural
decision making as they capture architectural aspects of proven solutions.
In many cases, the chosen patterns have system-wide implications
on non-functional requirements such as availability, performance, and
resilience. Ensuring compliance with the selected patterns is of vital importance
to avoid architectural drift between the implementation and its
desired architecture. Most of the patterns not only capture structural but
also signi cant behavioral architectural aspects that need to be checked.
In case all properties of the system are known before runtime, static
compliance checks of application code and con guration les might be
sucient. However, in case aspects of the system dynamically evolve,
e.g., due to manual recon guration, compliance with the architectural
patterns also needs to be monitored during runtime. In this paper, we
propose to link compliance rules to architectural patterns that specify
behavioral aspects of the patterns based on runtime events using stream
queries. These queries serve as input for a complex event processing component
to automatically monitor architecture compliance of a running
system. To validate the practical feasibility, we applied the approach to
a set of architectural patterns in the domain of distributed systems and
prototypically implemented a compliance monitor.