Nowadays, adaptive web information systems use partially the Web to provide different kinds of content, navigation tools and layouts according to user needs. We focus on AWIS for which users share a common knowledge to work together. For us, AWIS design is an intensive knowledge driven process. We propose the methodology and architecture used in the flexible composition engine called SCARCE. The paper presents the key issues for reusing the content in the methodology: interoperability and W3C standards, consistency of the delivered document and the distinct specification and management of AWIS components. The main benefits of this approach are: i) a generic AWIS architecture which is reusable in different contexts, ii) this architecture is tuned to the explicit knowledge of communities and provide a method for AWIS design.