Web services foster functionality of current web to service oriented architecture. Nascent semantic web is capable of automating activities by annotating shared ontological semantics to documents and services. Although, a zillion web services with diversity have been made since the inception of its diffusion, it is not a panacea for software development and it is still in its infancy. A middle agent (broker) simplifies the interaction of service providers and service requester, especially in the case that an atomic web service cannot fulfill user's need. The broker composes a desired value-added service and orchestrates the execution of bundled sub-processes. It is inevitable that several constitutive web services may fail during the execution and become unavailable. In this paper, we propose replacement of a sequence of semantic web services in lieu of old composition subgraph which includes perished web service(s) that jeopardized the completion of whole process. We try to perform finding foreseeable replacing graphs, and their compatible alternative subgraphs and ranking of them before exploitation of composite web service. Furthermore, we illuminate an approach for resolving functional differences between old and new subgraphs.
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