抄録
Streaming views of stable video images are now available to any household thanks to today's widespread Internet use and faster speeds. Seminars that combine moving images with documents are now proliferating, particularly in markets that target user education. The POWERLIVE GigaCast online seminar system was developed based on an overall system design that focuses primarily on user interaction. With a balance of stable basic functions and optimized interactive functions, the system supports large-scale communications at a significantly reduced cost. Throughout the development of GigaCast, we have identified the following 3 elements in regards to the user interaction: 1) information which should be synchronized with user actions; 2) information which provides the illusion of being synchronized as long as kept within a certain timing in order; and 3) information which does not require to be synchronized. Especially, for the above 2) and 3), we have discovered that it is possible to free up some space in design by dispersing the load required to the server system through providing explicit control while taking advantage of their characteristics.
