this paper can be employed to support performance evaluation in all phases in which traditional MSCs are used, i.e. from the early design phases down to detailed design and testing. For example, performance requirements identified during the requirements analysis and specified with the extended MSCs can be validated by model based performance evaluations during the design of the system and later on by means of measurements of the implemented system. In the paper, we describe an extension of MSC-96 [12] (see [17] for an introduction) to integrate performance aspects. This allows to employ MSCs for performance evaluation. The cospecification has several advantages. The use of a single model ensures the consistency between the functional and the performance model. This saves effort and valuable time. In addition, the use of a description technique that is employed during several phases of the development process allows to easily reuse information once it is specified. This motivates engineers to formally specify performance aspects and to employ performance evaluation. Other advantages of MSCs for performance evaluation result from its orientation towards use cases. This allows to concentrate on specific, important uses of the system. In addition, MSCs are highly deterministic even if they are used in early design stages. This eases the evaluation of the performance of the system. Especially the evaluation of the performance data for different use cases, e.g. response time figures, can be easily supported by our approach. In addition, the extension of MSC allows for the functional validation of the system in the presence of time. This is especially important to evaluate mechanisms to handle overload. The language extensions for MSC-96 described in this paper are based on e...

We present a new approach for early performance prediction based on MSC specified systems in the context of SDL. Our approach isintegrated into existing design methodologies as proposed by commercial tool vendors where communication software is fully specified in SDL and the final implementation is derived from there. Obviously the structure of the SDL specification will influence the performance of the final system. Thus it is very important to make performance estimates for the target system available at design time to steer important design decisions. The key to performance evaluation is the development of performance models, which are evaluated either with analytical, simulation or monitoring techniques. Our approach is scenario-based and uses non-functional annotations of MSCs to formalize additional performance requirements. These MSCs are automatically transformed to an SDL specification which yields a prototype implemention via a code generation tool chain. The resulting implementation is executed on the target machines with the target system software from which many performance characteristics can be evaluated using monitoring techniques. We call the implementation "synthetic" since it is artificially derived from MSC specifications and the generated SDL is not designed to be subsequently reused through functional refinement. This paper describes the automatic transformation from MSC to the SDL specification and its environment with a special focus on dynamic issues.

Based on the methodology for the development of communication systems, a framework for early performance evaluation and hardware/software codesign of such systems is presented. We describe how performance requirements can be formulated in a formal way during the analysis phase of a project and how these requirements are used by the synthesis tools for hardware/software codesign during the design and implementation phase of the development cycle. Additionally, the concepts of our codesign tools and a heterogeneous rapidprototyping environment are described. It is shown, how our prototyping board can be used for validating the results of the early performance evaluation. We demonstrate the approach on an example of a real-time communication system. 1