One of fundamental differences between the normal CET working model and the Collaboration working model is how the World (cm/core/world.cm) is being used in a multiple-user environment.

In the normal CET working model, spaces, snappers, papers and miscellaneous data get stored in the World, and the World in its entirety is streamed to a .cmdrw file. The .cmdrw file can be used to reopen the drawing or shared to other users.

Normal CET	Collaboration

In the Collaboration working model, users create, connect to and work on a Collaboration Project, which is accessible via the server.

The World in not stored in the server, instead an empty world will be instantiated every time a user connects to a Project. What is stored in the server are project files and a database that ledges those files and versions. When a user loads a project file, the file will be downloaded from the server to a local workspace and subsequently the contents are loaded into the drawing (World).

Important points to take note of:

• Anything streamed with the World but not part of any project files will not be available to other users in the project. (E.g., data stored in the World auxiliary.)
• Reopening the same project on the same machine may have the auxiliary data retained, but this is due to caching of the project locally, not necessarily consistent across the Collaboration working model with multiple users/machines.
• The World auxiliary should be used as a temporary cache rather than persistent storage.
• An alternative for sharing data (e.g., Objects) is to derive from CollFileType or CollDataFileType. Learn more about Collaboration Custom Data here.