The behaviour of a distributed system is largely determined by the use of synchronization primitives and threading policies of the underlying middleware. The inherent parallel nature of distributed systems may cause liveness problems, such as deadlocks and livelocks. An increasing number of distributed systems is built using object middleware. We exploit the fact that modern object middleware offers only a few built-in synchronization and threading primitives by suggesting UML stereotypes to represent each of these primitives in distributed object design. We define the semantics of the stereotypes using a process algebra. We use that semantics to translate UML diagrams into behaviourally equivalent process algebra representations and can then use model checking techniques to find potential deadlocks. The paper also shows how the model checking results can be related back to the original UML diagrams.

The behaviour of a distributed system is largely determined by the use of synchronization primitives and threading policies of the underlying middleware. The inherent parallel nature of distributed systems may cause liveness problems, such as deadlocks and livelocks. An increasing number of distributed systems is built using object middleware. We exploit the fact that modern object middleware offers only a few built-in synchronization and threading primitives by suggesting UML stereotypes to represent each of these primitives in distributed object design. We define the semantics of the stereotypes using a process algebra. We use that semantics to translate UML diagrams into behaviourally equivalent process algebra representations and can then use model checking techniques to find potential deadlocks. The paper also shows how the model checking results can be related back to the original UML diagrams.

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Abstract. Distributed systems are increasingly built using distributed object or component middleware. The dynamic behaviour of those distributed systems is influenced by the particular combination of middleware synchronisation and threading primitives used for communication amongst distributed objects. A designer may accidentally choose combinations that cause a distributed application to enter undesirable states or violate liveness properties. We exploit the fact that modern object and component middleware offer only a small number of underlying synchronisation primitives and threading policies. For each of these we define a UML stereotype and a formal process algebra specification of the stereotype semantics. We devise a means to specify safety and liveness properties in UML and again map those to process algebra safety and liveness properties. We can thus apply model checking techniques to verify that a given design does indeed meet the desired properties. We propose how to reduce the state space that needs to be model checked by exploiting middleware characteristics. We finally show how model checking results can be related back to the input UML models. In this way we can hide the formalism and the model checking process entirely from UML designers, which we regard as critical for the industrial exploitation of this research.

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