Cooperative editing applications enable geographically distributed users to concurrently edit a shared document space over a computer network. These applications present several technical challenges related to the scalability of the system and the promptness with which relevant updates are disseminated to the concerned users. This paper presents Cooperative Semantic Locality Awareness (CoopSLA), a consistency model for cooperative editing applications that is scalable and efficient with regards to user needs. In CoopSLA, updates to different parts of the document have different priorities, depending on the relative interest of the user in the region in which the update is performed; updates that are considered relevant are sent to the user promptly, while less important updates are postponed. As a result, the system makes a more intelligent usage of the network resources, since (1) it saves bandwidth by merging postponed updates and (2) it issues fewer accesses to the network resources as a result of both update merging and message aggregation. We have implemented a collaborative version of the open source Tex editor TexMaker using the CoopSLA approach. We present evaluation results that support our claim that CoopSLA is very effective regarding network usage while fulfilling user needs (e.g. ensuring that relevant updates are disseminated in time).
Interest Aware Consistency for Cooperative Editing in Heterogeneous Environments
