Technical Q&A IC02

noResponseErr from PPC Toolbox

Q: Sometimes we receive a noResponseErr (-915) from IPCListPorts, PPCStart, and StartSecureSession for no apparent reason. We know we have Program Linking enabled on both systems and that in the case of PPCStart and StartSecureSession, we have outstanding PPCInform requests pending. What does noResponseErr mean and what should we do when we receive it?

A: A noResponseErr means that the PLookupName request that IPCListPorts, PPCStart or StartSecureSession issued failed to get a match. PLookupName is being called by the PPC Toolbox with a retry interval of 1 (8-ticks) and a retry count of 12. That means that PPCStart tries to find the location for about one and a half seconds. If the server doesn't get a response back to the client in that time, then PPCStart will fail with noResponseErr.

Usually, that means that the system the PPC Toolbox is trying to contact is very busy (and cannot reply to NBP requests), or that your network is overloaded and the NBP replies are being lost. In either case, you may want to simply retry the PPC call a couple of times before assuming that the other system cannot be reached.