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Q184505: CPI-C Accept_Conversation (cmaccp) Does Not Block As Expected

Article: Q184505
Product(s): Microsoft SNA Server
Version(s): WINDOWS:2.0,2.1,2.11,3.0,4.0
Operating System(s): 
Keyword(s): 
Last Modified: 12-JUN-2001

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The information in this article applies to:

- Microsoft SNA Server, versions 2.0, 2.1, 2.11, 3.0, 4.0 
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SYMPTOMS
========

If a CPI-C (Common Programming Interface for Communications) application calls
WinCPICStartup followed by Accept_Conversation (cmaccp), then the cmaccp() will
function in blocking mode. However, the cmaccp() will never complete, because no
local TP (transaction processing) name has been specified for the application.

In order to associate a TP (Transaction Program) name with the cmaccp() call,
Specify_Local_TP_Name (cmsltp) must be called prior to cmaccp(). However, this
causes cmaccp() to function in "non-blocking" mode. This can cause the cmaccp()
to fail immediately with an error 25 (CM_PROGRAM_STATE_CHECK) instead of waiting
for an incoming attach request.

CAUSE
=====

This behavior is by design, according to the Windows CPI-C specification.

RESOLUTION
==========

To force blocking behavior of cmaccp, Wait_For_Conversation (cmwait) must be
called after cmsltp() and cmaccp() in order to cause the application's thread to
block. All CPI-C functions operate in blocking mode by default, except the
cmaccp() function, which requires the application to call cmwait() in order to
force blocking behavior.

There are no plans to change the Windows CPI-C specification or to modify the SNA
Server CPI-C API (application programming interface) to behave differently than
it does in the current design.

Additional query words:

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Keywords          :  
Technology        : kbAudDeveloper kbSNAServSearch kbSNAServ300 kbSNAServ200 kbSNAServ211 kbSNAServ400 kbSNAServ210
Version           : WINDOWS:2.0,2.1,2.11,3.0,4.0
Issue type        : kbprb

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