Research And Implementation Of Constrained Real-time Collaborative Editing System In WebGIS

With the rapid development of internet, network has been the trend of GIS and WebGIS has come into being. The WebGIS-oriented collaborative editing has also become an important research topic in the rapid development of WebGIS and editing tasks magnify. Because of the unique characteristics of manifestation and render of WebGIS Data, a lot of mature methods in other fields of co-design cannot be used directly in WebGIS field. Therefore it has practical significance that studying how to learn from the collaborative design research to solve the existing problems in the collaborative editing of WebGIS.In the respect of architecture, this paper assigns the data and tasks according to the characteristics of layer’s granularity of vector map, in which the data of the same layer is managed by the same layer server, and a central server is used to coordinate each layer server. The internal problems of layer server can be solved independently and only the problems between the layers need to be coordinated by the central server, which increases the concurrency of the collaborative editing. The node status is monitored by editing node monitoring strategy, which allows the nodes to dynamically join and leave, making the applicability of the system be enhanced. When the system is running, the legitimate operations are real-time broadcast, in which each node can sync to the latest edit status.In the respect of collaborative editing concurrency control strategy, the paper uses an object-oriented hidden locking strategy based on the parallel operation matrix that determines whether the editing operation requires lock. When require lock, object is locked automatically, which can avoid the drawbacks that locking granularity and locking timing is difficult to choose by users.This paper introduces the concept of constraint, because there is some limit when edit. When operate in the collaborative editing system, the system does constraints detection and constraint-oriented conflict resolution based on multi strategy included rule-based digestion, case digestion, consultation and arbitration. Constraint management and digestion is a hierarchical construct where the central server handles after constraint is dealt by the layer servers.Finally, based on the foregoing analysis and design, achieve a WebGIS-oriented collaborative editing system and verify the feasibility of the theory according the actual operation of the system.