Automatic Monitoring of SLAs of Web Services

The distributed nature of web services, absence of a single stakeholder and the resulting fact that there is no control on the individual web services makes it difficult to ensure that the computation underlying the web service composition proceeds as intended. Thus, it is essential to monitor the computations at runtime to satisfy the needs of the user safety and QoS properties. In this paper, we describe the design and development of a runtime monitor which executes concurrently with the runtime system of a web service orchestration language. The monitoring property, is specified either as wanted/unwanted scenarios or specified as a formula using a subset of temporal logic called SL. From the given properties, we derive the observers as reactive automata using a synchronous framework and integrate them with the underlying engine of the web service specification language, for our implementation, we have used Orc. We illustrate our implementation through examples of monitoring various web service properties.