Patent US 8,024,661

A method, apparatus, and article of manufacture enables users to collaborate on an actual stored drawing document across a network. A single document is stored on a server who establishes a collaboration session with multiple users that collaborate in real time and dynamically view modifications executed by the users. Users maintain simultaneous write access to the document. Asynchronous commands are received from users, that have a delay of a defined time period, include any modifications made in real time by the user transmitting the asynchronous command, and cause the server to transmit any modifications to all of the multiple users in the collaboration session. The server also maintains a history of all modifications to the actual stored drawing document. The history can be used by a user to undo any user's modifications.