Department of Computer Science and Technology

Technical reports

An architecture for distributed user interfaces

Stephen Martin Guy Freeman

July 1994, 127 pages

This technical report is based on a dissertation submitted 1994 by the author for the degree of Doctor of Philosophy to the University of Cambridge, Darwin College.


Computing systems have changed rapidly since the first graphical user interfaces were developed. Hardware has become faster and software architectures have become more flexible and more open; a modern computing system consists of many communicating machines rather than a central host. Understanding of human-computer interaction has also become more sophisticated and places new demands on interactive software; these include, in particular, support for multi-user applications, continuous media, and ‘ubiquitous’ computing. The layer which binds user requirements and computing systems together, the user interface, has not changed as quickly; few user interface architectures can easily supportthe new requirements placed on them and few take advantage of the facilities offered by advanced computing systems.

Experiences of implementing systems with unusual user interfaces has shown that current window system models are only a special case of possible user interface architectures. These window systems are too strongly tied to assumptions about how users and computers interact to provide a suitable platform for further evolution. Users and application builders may reasonably expect to be able to use multiple input and output devices as their needs arise. Experimental applications show that flexible user interface architectures, which support multiple devices and users, can be built without excessive implementation and processing costs.

This dissertation describes Gemma, a model for a new generation of interactive systems that are not confined to virtual terminals but allows collections of independent devices to be bound together for the task at hand. It provides mediated shared access to basic devices and higher-level virtual devices so that people can share computational facilities in the real world, rather than in a virtual world. An example window system shows how these features may be exploited to provide a flexible, collaborative and mobile interactive environment.

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BibTeX record

  author =	 {Freeman, Stephen Martin Guy},
  title = 	 {{An architecture for distributed user interfaces}},
  year = 	 1994,
  month = 	 jul,
  url = 	 {},
  institution =  {University of Cambridge, Computer Laboratory},
  number = 	 {UCAM-CL-TR-342}