Extending real-time collaborative editing systems with asynchronous communication

The integration of synchronous and asynchronous modes of communication and the possibility of alternating them along the stages of a project is an important issue for the customization of the collaborative work in the engineering domain. We present the synchronous and asynchronous modes of collaboration for two main classes of documents, namely, textual and graphical. We describe how the real-time collaborative systems that we have developed can be extended to support also asynchronous functionality. We present two approaches for the asynchronous communication: synchronizing the private workspace against a central repository and against another private workspace.