>Since a processing time is a split second it's not a problem. Each user creates a request file with a unique generated name. If the FoxPro server is busy, the request file just stays in the directory until it is picked up. So there is a natural queue. On testing I had problems related to the server being too fast. For example, if there is no error handling routine, you may hit "File Access Denied" message while processing the request file. I take it that the request file just written into the directory is being picked up before the OS really releases it after writing. You can easily handle this in ON ERROR routine, and the simplest way I tried was just ON ERROR RETRY.
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>I also tried to run more than one instance of the FoxPro server PRG, and the problem was that it was so fast, that two instances might pick up and process the same request, or one instance picked the request file name too, but when it tried to open it, the file already had been deleted by the second instance.

All right, thank you very much Nick.