ACE (editor)

ACE (ACE – a collaborative editor) is a platform independent, collaborative real time editor. It is a real time cooperative editing system that allows multiple geographically dispersed users to view and edit a shared text document at the same time.

ACE is a simple text editor with standard features such as copy/paste and load/save. Multiple documents can be edited at the same time. Furthermore, ACE can share documents with other users on different computers, connected by communication networks (LAN, Internet). ACE also discovers users and their shared documents automatically in a local area network. Users can opt to join any discovered shared document. For all this, no configuration is necessary because it is based on zero configuration networking. Once a user has joined a shared document, he can freely edit the document at the same time with all participants as a virtual team. So called awareness information helps to avoid unnecessary conflicts (that is, two users editing at the same time and text location). Awareness information includes the cursor and the currently selected text of the other users marked with the color of the respective user. The heart of the application is a concurrency control algorithm based on the innovative concept of operational transformation, which allows for lock free editing of a document by multiple users. It imposes no editing constraints and resolves all conflicts automatically. The algorithm overcomes one of the most significant challenges in designing and implementing real time collaborative editing systems, namely consistency preservation. That is, to ensure that at quiescence (that is, when no messages are in transit) the shared document is identical for all participants. ACE builds upon open technologies such as BEEP (RFC 3080) and zero conf networking. All this leaves the possibility open to communicate even with different applications that understand the public protocol of ACE. ACE runs on all major operating systems such as Windows, Mac OS X, or Linux and is free software.

Consider a collaborative editing session with three participants, named Bill, Steve, and Scott, as depicted by the figure. There is also a fourth user, named Sam, who does not participate in the session. The document which the users collaboratively edit is Collaboration. txt. User Scott is the owner and publisher of it. Note that users Steve and Bill work on Microsoft Windows OS, whereas Scott uses Mac OS X and Sam Linux OS. Note that the blue color always denotes the text written by the local user of the ACE instance. The color to matching a participant is depicted in the participants view of the GUI.