Title : MMConf : An Infrastructure for Building Shared Multimedia Applications
Authors : Terrence Crowley, Paul Milazzo, Ellie Baker, Harry Forsdick, and Raymond Tomlinson
Citation : CSCW '90 Proceedings
Reprinted in :Groupware and Computer Supported Cooperative Work by Ronald M. Baecker
This paper talks about the MMConf which is a shared multimedia tool. This project has designed an architecture that supports shared, real-time applications and has implemented that architecture on UNIX systems, partly as a user interface toolkit and partly in a separate conference manager process.
Some of the assumptions that have guided the work are that MMConf must operate across wide-area networks with a wide range of bandwidth and latency characteristics. It must also support highly graphical, highly interactive applications.
The MMConf has a replicated architecture. In a centralized architecture, a single copy of the application exists. The central server distributes output to all conference sites, including the local screen. In a replicated architecture, a copy of the application runs at every site in the conference. Servers at each site distribute input to each copy, using some control mechanism to ensure that every copy sees the same sequence of input events.
Replicated architecture tools require very low bandwidth because only input is to be distributed among the sites. The replicated systems are less sensitive to network latency. The primary disadvantage of a replicated architecture is the difficulty of maintaining the identical state across all copies of an application.
One of the features of the MMConf is the telepointer. It is a very large, conspicuous arrow that only appears within conference windows. The active user invokes the telepointer by holding down the middle mouse button. The MMConf has a sketching support directly within several discussion-oriented applications. The Presenter, a tool that manages a set of applications in a conference provides the ability to freeze any application it is managing.