Microsoft KB Archive/160876

= INFO: SNA Server Does Not Support Full Duplex APPC =

Article ID: 160876

Article Last Modified on 2/19/2007

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APPLIES TO


 * Microsoft Host Integration Server 2000 Standard Edition
 * Microsoft SNA Server 2.0
 * Microsoft SNA Server 2.1
 * Microsoft SNA Server 3.0
 * Microsoft SNA Server 3.0 Service Pack 4
 * Microsoft SNA Server 4.0

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This article was previously published under Q160876



SUMMARY
APPC is a peer-oriented program-to-program API where either Transaction Program (TP) can initiate a conversation. However, APPC/LU6.2 traditionally is half-duplex, where after the conversation is established, only one TP has direction to send on a conversation at a time. The state of the conversation, as viewed by a particular TP, governs which APPC verbs can be issued by the TP at a particular time. If the local TP views the conversation as being in a "send" state, then the partner TP would also be in a send state.

IBM now supports "full duplex" APPC where either program can issue both send and receive verbs at the same time, though this is a fairly new implementation of APPC.

The following is the option to set for full duplex functionality:

112 -- Full-duplex conversations and expedited data

SNA Server does not support option set 112; it only supports half-duplex, although either end can initiate the conversation.



MORE INFORMATION
See the "Conversation States" section of Chapter 2 of the SNA Server Programmer's Reference for a thorough explanation of conversation state changes.

Additional query words: HIS 2000

Keywords: kbinfo kbnetwork kbprogramming KB160876

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