LUA or EIS Application Must Enforce 3270 Bracket Protocol

SYMPTOMS

When using the SNA Server LUA API to communicate with a host application, the SNA Server expects the LUA application to detect and handle bracket errors on the session. This simplifies the detection and handling of bracketing errors and prevents potential problems if SNA Server simultaneously receives a Begin Bracket (BB) request from both the LUA application and the host.

If the LUA application has written a 3270 message to initiate a bracket (causing the session to be in a bracket state), and later receives a new bracket request from the host, the LUA application should send a negative response to the host bracket request and send sense code 08130001: Bracket Bid Reject: The component was in the in-bracket state when a bracket request was received.

  LUA/RUI application   SNA Server service             Host
  ===================   ==================             =========
  RUI_WRITE (BC, BB, Data) ->
                        DLC FMD (RQE BC, BB, Data) ->
  RUI_WRITE (MC, Data) ->
         DLC FMD (MC) ->
  RUI_WRITE (MC, Data) ->
         DLC DATA (MC) ->
  RUI_WRITE (EC, CD, Data) ->
         DLC DATA (EC, CD) ->
                                                   <- DLC DATA (RQD BB, EB)
   <- RUI_READ complete (BB, EB, Data)
  RUI_WRITE (+RSP) ->
   <- RUI_WRITE -RSP (UNSUCCESSFUL / BRACKET ERROR)