Monitoring requirements: a case study

In our study of composite systems, we found a class of requirements that could not be guaranteed to hold. Specifically, these requirements required the environment of the overall system to behave in ways that could not be controlled. The best we could do in such cases was to note the assumptions placed on the environment for the requirements to be met, and then monitor the environment at runtime to detect deviations from our assumptions about its behavior. This paper discusses a short example of carrying out this type of monitoring. It introduces three tools to support requirements monitoring: (1) a tool to capture a requirement formally, (2) a tool to translate that requirement into a runtime specification, and (3) a tool to actually do the runtime monitoring.