Initially the Internet was a communication channel and a text-based content dissemination vehicle. With the advent of e-commerce and Web's unfolding, it became a systems deployment platform. At the same time, software development also evolved, through the use of new software engineering concepts, such as components, reuse and design patterns. This work aims at helping to develop practices and technologies that improve software development by conciliating these two evolution trends. Swell is an environment that helps Web Based Systems development, having as a cornerstone the semantic selection of web- services. It is a tool whose objective is to help in the application design and development tasks, aiming to reach a high degree of reuse. This is achieved through the support for the description, search and selection of web services for application composition. The Swell environment was conceived as a framework with support for the evolution of web components technologies. It provides hot spots that allow for adaptation of new web services descriptions and reflection of these changes in the search engine.