Summary form only given. We describe aa collaborative Web based architecture in terms of a collection of generic architectural patterns that define how the different components of the framework interact. Based on a J2EE specification and on EJB components, we detail the implementation of this framework in a distributed Web services environment. The main goal of the design and the implementation of the framework was to provide information system designers with a collaborative Web CASE, adaptable to their requirements and easy to use and to access. We present the adopted solutions for team collaborative work conflict resolution in a distributed workspace.