For some time now, designers of hypermedia systems have recognised the need to move away from closed systems to open environments which separate the link structure from the data in the system, and enable separate link and data processing. The main motivations behind this development are the need to reduce authoring effort in large-scale hypermedia applications and to make them more easily modifiable, customisable and extensible. Microcosm is one such open hypermedia system which has been developed at the University of Southampton. At the heart of Microcosm is the Link Service, which allows links maintained by the system to be applied to information native to third-party applications in the host environment. This paper describes the Microcosm system and discusses the benefits of combining its link service capabilities with the WWW distributed technology.