Operational transformation

Operational transformation, abbreviated OT, is a technology for supporting collaboration functions in collaborative software systems. It was originally invented for consistency maintenance and concurrency control in collaborative editing of plain text documents, and its uses grew to include group undo, locking, conflict resolution and the editing of HTML, XML and tree-structured documents. Systems that use it typically keep a replicated copy of the document at each client; clients edit their own copy without locking and then transform the changes they receive from other clients before applying them, so that consistency criteria hold at every site. OT was pioneered by C. Ellis and S. Gibbs in the GROVE system in 1989, and in 2009 it was adopted as a core technique behind the collaboration features of Google Wave and Google Docs.