Furthermore, it allows hypermedia resources to be created and modified by tools which may be completely unaware of the hypermedia environment, resulting in a pervasive distribution of information content. The weaknesses of the distributed link data approach are in those areas where the link server approach has strength. This limits the system's ability to maintain referential integrity when resources change, ability to assist the user in the navigation and visualization of the hyperweb, and ability to predict the effects of a change before it is made. It is our hypothesis that addressing the problems inherent in each approach requires the creation of a system which is a fusion of link server and distributed link data technology. All ovals, rounded squares, and rectangles are operating system processes.
Arrows represent either communication paths or data access.
Figure 1 shows a proposed architecture for such a system, consisting of three layers, the User Application layer, the Local Link Server layer, and the Link and Data Management layer, described in the sections below. These layers are connected using a software bus. The basic notion of a software bus is that it receives incoming messages, and then retransmits these messages to all interested parties. However, the message passing semantics vary for each particular bus. For this paper, we will assume our software buses may forward messages along to parties which have registered for them, and that the messages may encode either requests for future action, or notifications of prior activity.