garyn@handies.ucar.edu (Gary Nutt) (04/12/89)
We have built a C-based system for Sun workstations to edit, animate, and simulate AND-OR graphs -- pretty similar to Petri nets, (but different). Our graphs are interpreted, allowing us to write our interpretations in any language callable via Sun RPC, e.g., C. With our system, one can draw an AND-OR graph, mark it with tokens, and watch it run. Also, one can annotate the nodes and edges to label the graph and to provide the interpretations. Our implementation uses client-server model to separate the editor and console from the interpreter. In the current implementation, several frontends can connect to the server through a common socket interface; as a result, each copy of the editor sees the same model interpretation. Also, if any editor changes the model, all editors see the change very quickly. The interpreter uses the RPC mechanism (mentioned above) to call procedures whenever the corresponding node in the AND-OR graph node -- read transition -- is fired. We have done three or four different frontends, the first being built on SunView, another on NeWS, and a third on a Symbolics that accesses the Sun server. Our code is really not quite in a state to distribute, since it is in various stages of development (and we never planned to release it to others). Our goal has not been to make a Petri Net simulator, but rather to experiment with modeling and programming systems that use graph models. If you are interested in using it, or if you want to know more about the system then drop me a note or call (303) 492-7581. Gary Nutt Department of Computer Science University of Colorado.