Presentation support for distributed multimedia applications

The work documented in this report also features in the following available papers: The Opera multimedia research group are investigating storage architectures, database paradigms and programming support for emerging multimedia uses. Bacon93b] and Moody93] describe overviews of this work. Chapter 5 of this dissertation is partly concerned with active objects and their connguration. Bates93] describes an approach to this problem. A paper based entirely on the work in this dissertation is published as Bates94]. A demonstration video showing experimental applications is also available. Acknowledgements I am grateful to all members of the Computer Laboratory who have been of assistance. My Ph.D. supervisor Jean Bacon is wonderful. She has been a great source of encouragement and advice. She has also made many useful suggestions regarding the contents of this report. Ken Moody has good advice for all occasions. Cormac Sreenan, now of Bell Laboratories, has been a great source of help. I enjoyed and beneetted from discussions with Heather Brown, of the University of Kent, during her sabbatical year in Cambridge. Derek McAuley has been helpful with equipment requisition and system advice. Thanks are also due to the following people for reading and commenting on parts of this report: who have been of assistance. I am indebted to Andy Hopper for the use of a Pandora box in my third year of research. Damian Gilmurray and Andy Jackson have always been ready to help with Pandora system issues. I would like to thank all my friends at Lancaster University for their continuing encouragement. Andy Colebourne has been particularly helpful with aspects of the X window system. UNIX is a registered trademark of Novell ii Summary Distributed computing environments can now support digital continuous media (such as audio and video) in addition to still media (such as text and pictures). The work presented in this dissertation is motivated by the desire of application developers to create applications which utilise these multimedia environments. Many important application areas are emerging such as Computer-Aided Instruction (CAI) and Computer-Supported Cooperative Working (CSCW). Building multimedia applications is currently a diicult and time-consuming process. At run-time, an application must manage connections to a range of heterogeneous services to access data. Building applications directly on top of environment-speciic features roots them to those features. Continuous media introduces new problems into application management such as control of Quality of Service (QoS) and synchronisation of data items. An application may also …