The effectiveness and reliability of IS-based web services becomes a critical factor in business success. Known classical problems in the field of web services are imposed implicitly in the design and implementation of such systems, namely: description process of web service, publication process, discovery process, composition process, selection process, substitution, and adaptation process. The approach proposed in this paper allows the realisation of discovery and adaptation tasks based on the behavioural aspect of semantic web services. In this paper, we propose a new behaviour model for semantic web services using automata. The formal model used to specify the process of semantic web services is typed interface and weighted automaton (TIWA) with an operational semantics associated with different action necessary in the implementation of all the algorithms proposed in this paper.