Navigation through large hypermedia information spaces is complex and is an important application area for adaptive hypermedia systems. User navigation can be best supported when the design of the hypermedia system is embedded in an evolutionary process model that takes into account the decentralization of data sources and the variety of users. The paper deals with distributed frameworks for open hypermedia systems; it focuses on the design work done to make adaptive an existing actor-based architecture for hypermedia. The approach follows the initial design approach used in the definition of the hypermedia platform, i.e. the actor-based computational model. We present in detail the new actor classes and the cooperative schemes which allow adaptation within the resulting architecture.
