Taming the Complexity of Distributed Multimedia Applications

The Medusa environment for networked multimedia uses Tcl to compose applications out of low-level processing blocks called modules. A medium-sized application such as a two way multistream videophone already uses around one hundred interworking modules, running in parallel on several host machines. This paper shows how we overcome the inherent complexity of such applications: to deal with parallelism we use a multi-threaded library hidden behind a single-threaded Tcl interpreter; to build higher order components than the modules we use the object oriented extension [incr Tcl]; and to exploit the variety of available input and output devices we adopt the Model-View-Controller paradigm.