The application demonstrates group communication patterns over a library called JavaGroups which was written by Bela Ban. Javagroups can supply reliable FIFO messageing and also contains sophisticated objects to perform complicated tasks as maintaining a distributed hash table and more. We choose to use the remote method invokation service of the JavaGroups package. The invokation is performed by a library thread using communication and java's reflect function. We used only the basic features of JavaGroups since , initially , not all of the current features were available.
Consistency is violated if two users have a different state.
Each node starts with an initial state or a state which is given from another node. Changes in the state are relative to the current state. The state is being built in an accumulative manner by a sequence of relative changes. A View is a local representation of the current membership of a group. Only one view is installed in a at a time.