CompuServe Messages

Chris, One of two mechanisms… semaphores or messages. Have a master process, the 'brain' if you will. This would be the traffic cop of the system, all database access must ask permission of the master program (via a message or semaphore) and wait for a reply to continue before it goes on. When it's done, it tells the master program it's done. Thus, the master can allow multiple searches to run at once, or a single add plus a search….but won't allow and updates, resturctures or deletes to occur until all searches are finished (or anything else that would conflict). When a program has made a request for an action, and until it receives permission to proceed…it simply waits for the master to tell it to proceed. WaitPort() would be appropriate for this if you were using messages. The process calling WaitPort() will sleep until a message is received. The master can be a very simple program. It only needs a local stack where it stores what operation(s) are in progress and a 2nd stack of what requests have been made. And then of course, it needs the IPC facilities. Don