A Study Of Key Technologies For Web-based Synchronous Collaborative CAD Modeling Systems

The opportunities offered by Internet technologies have resulted in numerous new types of applications, among which collaborative design systems. Collaborative design systems distributed in locations are multiple-user systems that are both concurrent and synchronized. During collaborative session, many users are connected each other in order to perform design and evaluation together. Collaborative modeling system is one kind of such applications.The research on collaborative modeling systems is only at an early stage at present, so only a few existing systems are developed. Most collaborative modeling systems are mainly based on client-server architecture. So far collaborative modeling systems have been developed according to two patterns, including client-server and browser-server. Two prototypes of both architectures are realized in this paper. There are many key technologies as following during the realization of these systems:· Socket technology for communicating between different network entities;· Component Object Model/Distributed Component Object Model;· Data exchanging technology based on XML;· Modeling synchronization based on incremental messages.The client-server architecture in this paper is realized and based on existing CAD software, Unigraphics. It has been developed into a network application from single user to multiple user. Real-time and collaborative modeling activities can be performed now. This modeling prototype system is based on message flow. The server offers the functions of managing and routing message. The client explains the message and finishes modeling functions via local modeling module interface in order to achieve collaberative operations. During collaborative session, the problems of sending and rebuilding of feature model are resolved by message delivery. The ways to transfer modeling operations are called command copying.Collaberative modeling system in B/S pattern is another resolution and way to collaberative design system. It uses the applications based on Java language to act as interface with the client while interacting with the server. The prototype in this paper owns such simple functions as editing, querying and labelling. It will be a basic foundation and meaningful for persistent researching in the future.