Test Case Specification with Real-Time TTCN

The ever increasing dissemination of distributed real-time and multimedia applications makes testing of real-time constraints an important issue. The current conformance testing methodology does not define the means to cope with this new requirement. Especially, the test notation TTCN (Tree and Tabular Combined Notation) cannot be used to express and thus test real-time behaviour. In order to adapt the well established conformance testing methodology to this new need, we extend TTCN with real-time features. This is achieved by annotating TTCN statements with time intervals specifying the earliest and latest execution times. In this paper we introduce real-time TTCN and discuss its features and characteristics. To motivate our work, in the main part of the paper we evaluate real-time TTCN against TTCN and assess its suitability for testing real-time constraints by defining test cases for real applications. It turns out that without additional assumptions concerning the execution speed of test systems, TTCN cannot be used for testing real-time constraints.