Date: Sun Jan 15 18:32:33 2006

Title: A Framework of Programmable Multicast Applications Using Flexcast and Java Applet

Authors: Shin-ichi Minato, Hirokazu Takahashi, Takeru Inoue, Hiroshi Tohjo, and Kan Toyoshima


  • First name: Shin-ichi
  • Last name: Minato
  • Address: Division of Computer Science, Hokkaido University, North 14, West 9, Sapporo, 060-0814 Japan.
  • Email:

Abstract. As broadband Internet access is more commonly provided, streaming applications gain popularity and wide-area multicast technology will be more important. Recently, a new overlay multicast protocol, ``Flexcast'' has been proposed to realize the wide-area multi-point contents delivery. Flexcast provides the multicast function in a higher layer than the IP routing; Flexcast streaming packets are forwarded between routers by using unicast. Therefore, Flexcast can work well even if the legacy routers remain in the Internet. In addition, Flexcast features that an efficient delivery tree is autonomously constructed and maintained. Flexcast is a promising technology to realize wide-area multicasting in a reasonable cost on the Internet. While Flexcast addresses the multicast routing problem, there is another difficult problem in distributing multicast application programs. In the streaming applications, the software must be consistent among all servers and clients. However, especially when uncountable many (or public) users are targeted, it is hard to distribute the application programs to all prospective users, and also quite difficult to keep uncountable servers and clients up-to-date. In this paper, we propose a new framework of programmable multicast applications based on Flexcast protocol and Java Applet. Currently, Java Applet technology is widely utilized for various practical applications; however, all of those are limited to use unicast communications. Our work is the first practical approach to develop the multicast streaming software with Java Applet. Since Applets are distributed among clients on demand, they are kept up-to-date without any explicit synchronizing mechanism. The service providers do not need to distribute the application programs to all users beforehand, and it is anytime possible to update or modify their programs. They can design and customize their original service freely, not restricted by the specifications of a commercial streaming player which is dominant in the market. This paper describes the structure of our application framework. The experimental results confirm the feasibility of our method.

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