Timely and efficient information communication is a key factor in ensuring successful collaboration in engineering collaborative design. This work proposes a database approach to support information communication between distributed and autonomous CAD systems. It provides the designer with an easy and flexible way, a project-based propagation meta-table, to specify what parts of a CAD information model should be communicated to other collaborating designers. A CAD peer manager, containing a peer database that stores information to be exchanged with the other collaborators, wraps each participating CAD system. The peer manager identifies changes made to the CAD model by using stored procedures and active rules in the peer database that are automatically generated based on the propagation meta-table. The identified updates are propagated in a timely manner to other peers via inter-database message passing, thereby minimizing the volume of necessary information to be exchanged. Furthermore, remote peer designers can flexibly incorporate, filter, or delete received updates by using a propagation control interface, which is also used to issue user's commands to download the data from the CAD system to the peer database and lookup the received messages in the peer database. The approach is applicable on any CAD system having a CORBA interface and can also be applied to other kinds of object-oriented interfaces. Figure 8. A solid model of a steam engine.
CONCLUSIONS AND FUTURE WORKA generic approach is proposed to support engineering information communication between distributed and autonomous CAD systems. Each participating CAD system has workplace information stored in an object-oriented peer DBMS supporting active rules and message exchanges with database peers. Updates made in the CAD system are automatically identified by the peer database and only updates of the specified types are propagated to other peers using stored database procedures and active database rules, and inter-database message passing. When the system is set up, the stored procedures and active rules are automatically generated based on a simple propagation meta-table specified by the designer. Furthermore, remote peer designers are able to flexibly incorporate, filter, or delete updates received from others by using a propagation control interface.CAD data in the database are treated as independent objects identified by unique keys rendering the communication mechanisms simple and system independent. Together with dynamic rule generation, which makes the system scalable, extensible, and easy to maintain, this approach can be plugged into any CAD system having CORBA and other types of object-oriented interface.In the approach, a local designer is able to easily specify project-based CAD information to be communicated and the remote site designer can flexibly incorporate, filter, or delete updates received