N. G. Volchenkov, A. I. Dmitrenko, V. V. Klimov, A. V. Orlov, B. A. Shchukin

In accordance with the recommendations of the W3C semantic web-services are formed as a result of special superstructure over WSDL, for what a special language for describing the semantics - OWL-S - is offered. It is declared that search in inquiries is carried out more qualitatively and faster for those services which semantics is described by means of OWL-S, based on the using of service object domain ontology, and, moreover, this description can be used for automatic composition of services. OWL-S language introduces the concept of a process, both an atomic one, corresponding to WSDL operations, and a composite one, whose analogue can be choreography of services, and reduces а composition of services to а composition of processes. The process is given by the quadruple of sets , where I is a set of types of inputs, defined by the classes of the object domain ontology, O - a set of types of outputs, precondition P - a logical expression to describe the state of the object domain fragment before performing the service, the effects E - a logical expression to describe the state of the object domain fragment after performing the service. The description of a direct connection of inputs and outputs is not supported, there are described only «side» effects. Meanwhile, the implementation of the considerable part of the services does not lead to changes in the object domain, for example, services which are carrying out searching, and, hence, their semantics is completely determined by enumeration of inputs and outputs. A request for search of services can also be reduced to enumerating of inputs and outputs, i. e. it can actually be referred to search in keywords, in descriptions of the services presented in OWL-S syntax. Moreover, in a similar manner we can speak about the composition of services.