Microcosm (abstract): an open hypermedia system

Microcosm is an open hypermedia system within which it is possible to make and follow links from one multimedia document to another. The open nature of the system gives rise to a number of difficult user interface issues which are demonstrated in the video. The system consists of a number of viewers which allow the user to view and interact with many different formats of information. The viewers communicate with Microcosm which then sends messages through a filter chain. Each filter has the opportunity to respond to the messages by processing them, passing them on or blocking them. Important filters are the link databases or linkbases which are able to respond by finding links to other information. In Microcosm documents are not marked up internally: instead the link data is held in these separate linkbases, and the viewers communicate with the linkbases to find what buttons and links exist. The video shows how Microcosm works in practice with two applications. The first is a package used for teaching cell biology and the second is a set of multimedia documents concerned with Yugoslavia during the second world war, which is used by history students as a study resource. Some features that are emphasised in this video areas follows: Microcosm allows a spectrum of link types. At one end of this spectrum are specific links or buttons which are manually authored links from a source point to a destination point. Much author effort is required to create such links and then they will tend to impose a particular view point that was intended by the author, but may not be the information required by the reader. Generic links are links that have a fixed destination, but which may be followed from any point in any document where the appropriate object (such as a specific text selection) occurs. These still impose some view intended by the author, but the information tends to be more Permission to copy without fee all or part of this material is grantad provided that the copies are not made or distributed for direct commercial advantage, the ACM copyright notice and the title of the publication and its date appear, and notica is given that copying is by permission of the Association for Computing 526 general in nature and each link need only be made once, rather than at every occurrence in every source document. As can be seen in the video, one of the key interface issues is whether users require sottme points for generic links to be highlighted (in the same way as buttons). The procedure required to implement this is very processor intensive and a compromise is currently achieved via a “show link” facility which is invoked at the users request. At the other end of the spectrum are computed links. These links are generated dymmically at run time using information retrieval techniques, and allow the author or user powerful tools, fully integrated with the hypermedia interface with which to explore a system of text documents that may be otherwise unlinked. Such links require no authoring effort and do not impose any view of the content upon the reader, but may result in a number of links being suggested that are not relevant. To the user, generic links and computed links are currently presented similarly for the sake of consistency. This can however be very confusing to users since the way the two types of links are derived is very different. Finally, because Micrccosm is an open system it is easily possible to make links into and out of applications that are not part of Microcosm. It is possible to program many Windows applications to talk to the Dynamic Data Exchange (DDE) and in this case it is possible to treat such an application as a Microcosm viewer. In the video we see Word for Windows in use as a Microcosm viewer. When it is not possible to use the DDE it is possible to communicate via the clipboard and we show links being followed by simply cutting a selection to the clipboard. This is one of the most powerful features of Micrccosm but leads to a number of problems with the design of an interface that is consistent across different applications. Machinery. To copy otherwise, or to republish, requires a fee and/or spacific permission. e 1993 ACM 0-89791 -575-5193 /000410526 . ..$1 .50