Using vector clocks to monitor dependencies among services at runtime

Service-Oriented Architecture (SOA) enable organizations to react to requirement changes in an agile manner and to foster the reuse of existing services. However, the dynamic nature of Service-Oriented Systems and their agility bear the challenge of properly understanding such systems. In particular, understanding the dependencies among services is a non trivial task, especially if service-oriented systems are distributed over several hosts and/or using different SOA technologies. In this paper, we propose an approach to monitor dynamic dependencies among services. The approach is based on the vector clocks, originally conceived and used to order events in a distributed environment. We use the vector clocks to order service executions and to infer causal dependencies among services. In our future work we plan to use this information to study change and failure impact analysis in service-oriented systems.