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Performance characteristics, such as response time, throughput, and scalability, are key quality attributes of distributed applications. Current practice, however, rarely applies systematic techniques to evaluate performance characteristics. We argue that evaluation of performance is particularly crucial in early development stages, when important architectural choices are made. At first glance, this contradicts the use of testing techniques, which are usually applied toward the end of a project. In this chapter, we assume that many distributed systems are built with middleware technologies, such as the Java 2 Enterprise Edition (J2EE) or the Common Object Request Broker Architecture (CORBA). These provide services and facilities whose implementations are available when architectures are defined. We also note that it is the middleware functionality, such as transaction and persistence services, remote communication primitives, and threading policy primitives, that dominates distributed system performance. Drawing on these observations, this chapter presents a novel approach to performance testing of distributed applications. We propose to derive application-specific test cases from architecture designs so that the performance of a distributed application can be tested based on the middleware software at early stages of a development process. We report empirical results that support the viability of the approach.

Performance characteristics, such as response time, through put and scalability, are key quality attributes of distributed applications. Current practice, however, rarely applies systematic techniques to evaluate performance characteristics. We argue that evaluation of performance is particularly crucial in early development stages, when important architectural choices are made. At first glance, this contradicts the use of testing techniques, which are usually applied towards the end of a project. In this paper, we assume that many distributed systems are built with middleware technologies, such as the Java 2 Enterprise Edition (J2EE) or the Common Object Request Broker Architecture (CORBA). These provide services and facilities whose implementations are available when architectures are defined. We also note that it is the middleware functionality, such as transaction and persistence services, remote communication primitives and threading policy primitives, that dominate distributed system performance Drawing on these observations, this paper presents a novel approach to performance testing of distributed applications. We propose to derive application-specific test cases from architecture designs so that performance of a distributed application can be tested using the middleware software at early stages of a development process. We report empirical results that support the viability of the approach.

We demonstrate how the use of synchronization primitives and threading policies in distributed object middleware can lead to deadlocks. We identify that object middleware only has a few built-in synchronization and threading primitives. We suggest to express them as stereotypes in UML models to allow designers to model synchronization and threading of distributed object systems at appropriate levels of abstraction. We define the semantics of these stereotypes by a mapping to a process algebra. This allows us to use model checking techniques that are available for process algebras to detect the presence or absence of deadlocks. We also discuss how the results of these model checks can be related back to the UML diagrams.