Preservation of Timing Properties with the Ada Ravenscar Profile

Modern methodologies for the development of high-integrity real-time systems leverage forms of static analysis that gather relevant characteristics directly from the architectural description of the system. In those approaches it is paramount that consistency is kept between the system model as analyzed and the system as executing at run time. One of the aspects of interest is the timing behavior. In this paper we discuss how the timing properties of a Ravenscar compliant system can be actively preserved at run time. The Ravenscar profile is an obvious candidate for the construction of high-integrity real-time systems, for it was designed with that objective in mind. Our motivation was to assess how effective the Ravenscar profile provisions are to the attainment of property preservation. The conclusions we came to was that a minor but important extension to its standard definition completes a valuable host of mechanisms well suited for the enforcement and monitoring of timing properties as well as for the specification of handling and recovery policies in response to violation events.