The paper is an attempt to explore some of the principal obstacles of company's interoperability through the use of existing technologies. We present the needs of the technologies and approaches for building new web-services from a workflow of existing web-applications. We primary interested, by the problems of reverse engineering of the existing conceptual models of the Web-applications in functional specifications Web-based Service. The proposed approach is summarized as follows: We first propose a method of classification existing Web-applications. Then, we present a step of decomposition of these Web-applications for identify a high level of granularity and reuse of logics functionality. Next, we propose software of model transformation and we briefly present evaluation of existing software of model transformation according to offer functionality.