ChooChooMessenger is a communication tool for a comunity. Users (or clients) of a community form a circle and documents are passed around the circle. For example, assuming that there are 4 participants in a community, namely A, B, C, and D, a document X is posted by A, then the document X is passed to B. If B want to edit it, B can edit it and passes X' to C. Or, B can just pass X as it is. It looks like messages traveling around a circle of a community.