This paper presents a semantic-based dynamic service composition and adaptation framework. It explores WSMO, a starting point for the semantic-based composer construction using backward-chaining reasoning. WSMO and the orchestration procedure proposed by this model are described, together with the architecture of the proposed framework for semantic-based dynamic service composition and adaptation. The backward-chaining composer and Mule-based executor, are essential parts of the proposed framework. Its usage is illustrated by examples.