Web component-based development is a challenging development paradigm, whose attraction to practitioners is increasing more and more. One of the main advantages of this paradigm is the ability to build customizable and composable web application modules as independent units of development, and to share them with other developers by publishing them in libraries as web services or free components. In parallel, since many years, Web services confirmed their status of one of the most pertinent solutions for a service provider, like Google or Amazon, to open its solutions for third party development. The paper is an attempt to explore some of the principal obstacles of companiesinteroperability through the use of existing technologies. We present the needs of the technologies and approaches for building new web-services from legacy applications. We primary interest, to 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 a software of model transformation and we briefly present evaluation of existing software of model transformation according to offer functionality.