LUA Program Receives Host Sign-On Screen Twice and then Hangs

• Microsoft SNA Server for Windows NT, versions 2.0, 2.1, and 2.11

SYMPTOMS

When you start your LUA program, the SSCP Welcome message screen appears twice, and the LUA program seems to hang.

CAUSE

Under certain timing conditions, when an LUA session is closed (with an SLI_CLOSE statement) and immediately reopened (with an SLI_OPEN statement) over a fast link, SNA Server may incorrectly resend the host SSCP welcome message a second time to the LUA program. As a result the LUA program may hang.

The following message flow causes this problem:

   LUA Program    SNA Server      Host
   -----------------------------------------------------
                                 <- UNBIND
                 UNBIND +RSP ->
                 NOTIFY(SLU disabled) ->
  SLI_CLOSE ->
  SLI_OPEN ->
                                 <- SSCP welcome message
                 <- SLI_OPEN(SSCP welcome message)
                                 <- NOTIFY +RSP
                 NOTIFY(SLU enabled) ->
                                 <- SSCP welcome message
  SLI_RECEIVE ->
                 <- SLI_RECEIVE (SSCP welcome message)
                                 <- NOTIFY +RSP

RESOLUTION

To resolve this problem, upgrade to SNA Server version 2.11 and install the updated file SNASERVR.EXE.

To work around this problem, you can put a small delay in the application between the SLI_CLOSE completing and issuing the new SLI_OPEN command.

STATUS

Microsoft has confirmed this to be a problem in SNA Server for Windows NT. This problem was corrected in the latest SNA Server for Windows NT, 2.11 U.S. Service Pack. For information on obtaining the Service Pack, query on the following word in the Microsoft Knowledge Base (without the spaces):

   S E R V P A C K