Model-Driven Architecture for Hard Real-Time Systems: From Platform Independent Models to Code

The model-driven software development for hard real-time systems promotes the usage of the platform independent model as major design artifact. It is used to develop the software logic at a high level of abstraction and enables analysis like for example model checking of critical model properties. Ideally, starting with the platform independent model, the platform specific model serves only as an intermediate artifact which is derived automatically, and will finally result in a set of threads whose implementations guarantee the behavior, specified in the platform independent model. However, the current MDA approaches and tools for hard real-time software do not provide this ideal: While some of the MDA approaches could in principle support this vision, most approaches simply do not support an appropriate specification of time constraints in the platform independent model which have to be respected in the platform specific model or in the code. This is also true for UML models and UML State Machines in particular. Our approach overcomes those UML specific limitations by firstly proposing a syntactic extension and semantic definition of UML State Machines which provides enough details to synthesize an appropriate platform specific model that can be mapped to code for hard real-time systems automatically. Secondly, a new partitioning algorithm is outlined, which calculates an appropriate mapping onto a platform specific model by means of real-time threads with their scheduling parameters which can be straight forward transformed to code for the hard real-time system.