Consistency issues in partially bound dynamically composed systems

Abstract

Dynamically composed systems are able to incorporate new components as they execute. Therefore, configurations of these systems are not fully elaborated until at least the time that they are executed, and they are perhaps never fully elaborated. Such incomplete configurations are termed partially bound configurations. Although partially bound, it is still important to be able to analyse these configurations to ascertain whether they meet certain assumptions about their composition. We are endeavouring to provide such support for the construction of dynamically composed systems through the application of configuration management concepts. One way in which these concepts can be applied in this domain is to explicitly state such assumptions and hence be able to validate partially bound configurations against these assumptions; in this way, inconsistencies can be reported as soon as they arise. This paper explores some of the issues involved in providing this kind of consistency mechanism for dynamically composed systems. In particular, the paper discusses consistency issues which arise in the context of systems where the generic structure of the system configuration is known, but the decision about which particular components comprise the configuration is deferred until execution.