Microsoft KB Archive/162626

= RUI_READ Stops When Processing Buffers Larger Than 3 KB =

Article ID: 162626

Article Last Modified on 11/26/2003

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APPLIES TO


 * Microsoft SNA Server 2.0
 * Microsoft SNA Server 2.1
 * Microsoft SNA Server 3.0
 * Microsoft SNA Server 2.11 Service Pack 1
 * Microsoft SNA Server 3.0 Service Pack 4

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This article was previously published under Q162626





SYMPTOMS
An RUI_READ (immediate) will stop when an RU size is greater than 3 KB. No errors are generated; however, the application does not respond.



CAUSE
When an application has issued an RUI_BID verb, the WINRUI32 library will post the verb as soon as 12 or more bytes of RU data are available to return to the application. Normally, due to the nature of the message- passing mechanism between SNA Server and the RUI library, this means that the complete RU has been received by the RUI library, and when the application issues a subsequent RUI_READ(immediate), the RUI_READ will complete successfully.

However, when the RU size on the session exceeds a certain size (just over 3 KB), SNA Server will split the messages it sends to the RUI library into smaller blocks. The RUI library, however, continues to complete the RUI_BID when it receives the first block of a new RU. If the application issues an RUI_READ(immediate) before the remainder of the RU arrives, the RUI_READ will complete with a return code of UNSUCCESSFUL. This will confuse any application that (rightly) expects all the data to be available when the RUI_BID is posted.



RESOLUTION
A fix to the RUI library has been created to prevent it from posting an RUI_BID until all the blocks of a large RU have been received. Updated files:

Windows NT: \System\Winrui32.dll

Windows 95: \System\Winrui32.dll

Windows 3.x: \System\Winrui.dll

OS/2: \System\Rui.dll

MS-DOS: \Dosacs.lib (application must be relinked)



STATUS
Microsoft has confirmed this to be a problem in SNA Server versions 2.0, 2.1, 2.11, 2.11 Service Pack 1, and 3.0. This problem was corrected in the latest SNA Server for Windows NT, 2.11 and 3.0 U.S. Service Packs. For information on obtaining these service packs, query on the following word in the Microsoft Knowledge Base (without the spaces):

S E R V P A C K

Additional query words: prodsna

Keywords: kbnetwork KB162626

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