Interoperable Document Collaboration

To provide office applications with an easy interoperable document merge capability and to enable the usage of document revision across applications, it is necessary to not only standardize the representations of a document state, but also of the changes made to the document during the editing process. Tracking the changes during editing retains the information usually being recovered afterwards. This avoids costly and time consuming processes like document comparison and diff heuristics [1]. To this day, file formats such as the OpenDocument file format (ODF) do only specify all possible document variations of a document representing the final state of user data. Interoperability is therefore only given on a document level: One ODF application saves a document and a different application is able to load and continue work on the same document state. Common scenarios of document exchange have been by floppy disc, attached to email and exchange across networks via file services such as Dropbox. Nowadays, the Internet is ubiquitous and multiple users want to work simultaneously on the same document. In that context the transfer of a whole document from user to user is inefficient. Additionally, finding and merging changes in XML-based documents appears to be complex and possibly error-prone [2]. For this reason, the OASIS Advanced Document Collaboration subcommittee has started to simplify collaboration by specifying the changes applicable to an ODF document and raising ODF application interoperability from a full document level to a more granular document change level. In this paper, we present an approach to ODF change representation called "Merge enabled Change-Tracking" (MCT), which is based on the Operational Transformation approach [3].