||Many Web applications are available on the World Wide Web; thus, it is often desirable to integrate multiple Web applications to produce a more powerful new service. However, a typical Web application is often not a good candidate for integration. Although new Web Service technology for service integration is promising, Web application owners are often reluctant to carry out the adaptation process because of problems such as the poor design of the legacy Web application, the new knowledge required to build Web Services, and evolving standards. In this thesis, the presentation-layer-based Web application to Web Service adaptation approach using Web Application Wrapper (WAW) is introduced. This is a feasible solution for service integration before Web Services become standard technology for future Web applications. Our adaptation approach is based on the information obtained from the presentation layer (HTML file) of the Web application. It can be initiated by anyone who is interested in the advantages provided by Web Services. Furthermore, assistance or cooperation from relevant Web application owners is not needed.