Abstract. We build on a framework for modelling and investigating componentbased systems that strictly separates the description of behavior of components from the way they interact. We discuss various properties of system behavior as liveness, local progress, local and global deadlock, and robustness. We present a criterion that ensures liveness and can be tested in polynomial time.

We propose results ensuring properties of a component-based system from properties of its interaction model and of its components. We consider here deadlock-freedom and local progress of subsystems. This is done in the framework of interaction systems, a model for component based modelling described in [9]. An interaction system is the superposition of two models: a behavior model and an interaction model. The behavior model describes the behavior of individual components. The interaction model describes the way the components may interact by introducing connectors that relate actions from different components. We illustrate our concepts and results with examples.

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We describe ongoing work on a framework for automatic composition synthesis from a repository of software components. This work is based on combinatory logic with intersection types. The idea is that components are modeled as typed combinators, and an algorithm for inhabitation -is there a combinatory term e with type τ relative to an environment Γ? -can be used to synthesize compositions. Here, Γ represents the repository in the form of typed combinators, τ specifies the synthesis goal, and e is the synthesized program. We illustrate our approach by examples, including an application to synthesis from GUI-components.

We study architectural constraints for component systems in order to be able to guarantee safety-properties. Representing safety-properties, we investigate deadlock-freedom. We present a compositional and hence polynomial time condition for deadlock-freedom for a class of component-systems whose architecture is tree-like. The architectural constraints that are developed can be understood as a design pattern that helps to construct systems satisfying safety-properties on the one hand. On the other hand, they might help to draw attention to potentially critical situations in a design. To model component-systems we use the formalism of interaction systems as proposed by Sifakis et al. The ideas can be transferred to other formal models where subsystems are cooperating via synchronous communication.

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