Research Of Application Sharing Approach In Cooperative Workflow

Workflow technology is used widely in adminstrative and production field. Single user's task is not isolated in transition process of workflow instance. Mostly, a group of users need to edit the same document, or the same data object in the same. They need to edit it cooperatively to complete their task.The existing workflow systems show their limits when users need to work cooperatively. Several good excellent cooperative editors, such as Grove, REDUCE, support real-time cooperative editing efficiently, howerver, as editing tools, they are not good as some common single-user application, such as MS Word, in function and usability. To expend single-user application to support cooperative editing is a approach, it can reach both good function and usability and cooperative editing.An approach based on single-user application sharing is proposed to support collaborative editing in coopertive workflow. And a coopertive workflow system supporting collaborative editing is designed and implemented.The approach supports unconstrained collaboration, and uses operational transformation to maintain data consistency. Not documents with any structure can support operational transformation algorithm, operational transformation algorithm requires the objects in a document to be addressable by positional references in a one- or multi-dimensional address space. Because of this requirement, a sequece table is set outside of single-user application to address the objects in document. Traditional operational transformation algorithms support only inserting and deleting operation. David Sun proposed a expended algorithm that can support updating operatin besides. However, the algorithm can not work correctly in all conditions. An improvement of David Sun's extending operational transformation algorithm on the control layer is proposed to support sharing control to documents which have complex object structure.A prototype system is designed and implement based on the approach of expending single-user application, and MS Word is used as a example of single-user application. An existing traditional workflow system-Shark workflow system is chosed and improved. Integrate single-user application into Shark workflow system to implement a cooperative workflow system supporting cooperative editing. The whole system uses B/S and C/S architechture together, and mutilple programming languages are used to implement this system. The whole system can divide into four components:worf low engine server, coopertive data server, coopertive client and single-user application. Coopertive client is the important part of all, and it bonds the other three components together. Coopertive client is divided into three modules:workflow client, cooperative data client and single-user application agent. Sigle-user application agent is the core of coopertive client. It monitors and controls MS Word through windows hook technology and COM interface and synchronize concurrent operations of mutlple uses through operational transformation algorithm.The prototype system implemented shows that the approch based on single-user application sharing is correct.