Synchronous collaborative development of UML models on the Internet

This paper discusses the synchronous viewing and editing of object-oriented models based on the Unified Modeling Language (UML) by multiple users on the internet. Each user works on a copy of the model, which is continuously synchronized with the master copy on a central server. A group of users can work together in the common single writer-multiple reader mode, controlled by a token that can be passed from user to user. Alternatively, different users can lock different parts of the model for exclusive editing while the changes are visible to all other users. One can improve on basic granular locking by considering the semantics of the graphical notation. A semantics-based locking mechanism has been designed and implemented for UML class diagrams in order to allow users to collaborate more effectively. A prototype collaborative UML (CUML) editing system has been implemented in Java to validate the design.