Towards distributed contract negotiation in component-based systems

The consideration of non-functional properties like QoS or security is crucial for many software applications, but it is also a challenging task. The combination of non-functional aspects and component-based software engineering aims at simplifying the development of those applications. The COMQUAD project has employed this approach and has allowed the specification of required and provided non-functional properties as well as resource demand at the component level. The runtime environment, in particular the component container, negotiates contracts between components of an application. In this paper we report on work in progress about a distributed contract negotiation mechanism between components running in different component containers on multiple nodes. We introduce a layered negotiation approach consisting of a coarse-grained negotiation between component containers and a fine-grained negotiation between components within a single container and across containers. We demonstrate our ideas with. a distributed video on-demand application.