Handling LUA RUI_WRITE Completion Delays

SUMMARY

The following questions regarding the SNA Server LUA RUI_WRITE verb were raised by an application developer.

Generally, when issuing the RUI_WRITE verb, the successful posting response comes back within a second or two. However, in certain circumstances the RUI_WRITE verb takes longer than 30 seconds to complete, which is when our communications interface assumes the call is not going to complete, and returns a failure to the calling application.

Questions:

1. As we cannot issue another RUI_WRITE verb on the same flow until the previous one returns, are we always guaranteed to get a response from an RUI_WRITE verb, even if it takes longer than 30 seconds?
   
   Answer: Yes, the RUI application is guaranteed to receive a response to the RUI_WRITE call. If errors occur anywhere on the connection, session, client- server LAN session, and so forth, RUI_WRITE will complete with an error, otherwise it will complete successfully.
   
2. Is there a way of canceling an outstanding RUI_WRITE call? I am unaware of any method; my understanding is that RUI_PURGE only works with outstanding RUI_READS, and that RUI_TERM only works with RUI_INIT.
   
   Answer: RUI_PURGE can only be used for canceling RUI_READ verbs. There is no way of canceling an outstanding RUI_WRITE, apart from closing the entire session with RUI_TERM.