On-line services such as ICQ are becoming increasingly popular on the internet. This results in scalability problems as the unicast approach used in these applications concentrates the network load to a few, or even a single, point in the global network. By using multicast based serverless communication it is possible to reduce the network load considerably. In order to achieve this there is a need for multicast protocols that can be used on heterogeneous, large scale, networks such as the Internet. In this diploma thesis we describe our work on developing one such protocol, LwRM, and our attempt to create a small class library in Java2 to support it.