Infrastructure
Remote Computation and Storage: The applications and infrastructure developed in this project are based on an architecture in which large databases like the Visible Human data set, and the core applications that work with them, reside on a small number of servers. A somewhat larger number of client workstations interact with the server applications to provide a collaborative working environment that can encompass multiple sites.
Multicast: Our client applications permit multiple views of the same data set. They also permit collaborative interactions to be led from any workstation. The leader can control the views displayed at all workstations and can position a pointer visible to all participants. The ability to do this depends on the Multicast protocol.
Unfortunately, the multicast protocol is not uniformly implemented, and regional network support personnel appear to have little knowledge of its implementation. This became a major limitation on the use of our applications. As illustrated below on the Abilene network map, we routinely experienced a delay of up to 70 seconds for multicast setup time.
