Scalability and Congestion.

One of the major problems in Java-based volunteer computing is that currently, security restrictions dictate that applets running in users' browsers can only communicate with the Web server from which they were downloaded. This forces Java-based volunteer networks into star topologies, which have the disadvantage of having high congestion, no parallelism in communications, and not being scalable.

To solve this problem, we may allow volunteers who are willing to exert extra effort to download Java applications, and become volunteer servers. Volunteer server applications need to be run outside a browser, but do not have security restrictions. This lets them connect with each other in arbitrary topologies, as well as act as star hubs (centers) for volunteers running applets. Newer browsers such as Netscape and Microsoft Internet Explorer are starting to support signed applets, which will also be free of restrictions. These applets can be used as volunteer servers as well.