Enhanced Component Interfaces to Support Dynamic Adaption and Extension

Current component systems offer the possibility to integrate different enterprise systems, e.g., by wrapping legacy components or integrating several object protocols such as RMI, Corba-IIOP, etc. A disadvantage of todays component systems is that the interface descriptions of their component model do not give alone sufficient information to deploy a component correctly and reliably. Therefore the definition of new interface models, which are enhanced by (semantic) applicability information, play an important role in enterprise application integration. This paper describes a new model of software component interfaces, using an extension of finite state machines to describe the protocol to use a component’s offered services, and the sequences of calls to external services the component requires to fulfill its offered services. Our model concentrates on protocol issues of interoperability, such as: (a) Checking whether a component will be used according its protocol in its environment during system integration (i.e., before the component is actually used). (b) Adaptation of the protocol of a component which describes the component’s offered services, in case the environment does not offer all resources the component requires to offer all its services in the expected protocol. In this case the adapted component still offers a subset of its services, to the contrary of todays component systems, which do not allow any integration in this case at all. (c) Computation the similarity of two interfaces, e.g., to see which legacy component fits some new requirements best. (d) Extension of component protocols by plug-ins during run-time in a correct, secure and reliable way. In current component systems the interfaces simply do not model enough information for a component to decide whether to accept a plug-in component (because it fulfills all requirements) or to reject it, e.g., due to reasons of security. In our paper we present a description of our new interface model and present the algorithms for integration checking, automatic adaption and dynamic extension. These algorithms are implemented in our CoCoNut/J-prototype.