Real-time collaborative editing systems are groupware systems that allow members of a team to simultaneously edit shared documents from different sites. Shared objects involved in the team activity are subject to concurrent accesses and real-time constrains. Starting with the dOPT algorithm of Ellis and Gibbs various algorithms using operational transformation for maintaining consistency in collaborative systems have been proposed: adOPTed, GOT, GOTO and etc. All these algorithms are based on a linear representation of the document. In this work we discuses about algorithms based on a tree representation of the document. We propose several algorithms based on dOPT algorithms for operation transformations for XML based documents. Experimental development helps to evaluate and demonstrate practical application for algorithms testing. Detailed commented experiment supplements formal description with practical strategies and specifics.

Usability evaluation of collaborative writing system for education usage is very essential to improve its functionality to make it effective, efficient and satisfactory for future use. In this thesis, the usability of web office (ThinkFree doc) i.e. one of collaborative tool was tested using mix research approach. Usability evaluation was done in step by step process, where usability test was conducted using think aloud protocol and observation during testing was noted down. Test results were then analyzed and questionnaire was designed for quantitative survey. Questionnaires were then distributed among those students who have been using Thinkfree doc for educational collaborative work. Interviews were conducted with all selected participants individually for results validations. During usability evaluation process positive and negative effects regarding software‟s usage were noted down. The result revealed that overall system‟s response is very slow. The software needs to improve its processing speed to make it more efficient for future use. The system also needs to improve overall functionality (e.g. collaborative work, synchronization, uploading and track changes etc) to provide accurate and complete results according users‟ requirements. / First Author: M. Afsar Khan. Mohallah madani masjid nawan killi village & P.O Gujar Garhi District Mardan NWFP Pakistan, Second Author: Sher Hassan. Timergara Dir Lower NWFP Pakisan