Microsoft KB Archive/216672

= Misleading Error or Inaccurate Data Returned using TCP/IP Connectivity & CICS MS Link Model =

Article ID: 216672

Article Last Modified on 3/31/2004

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APPLIES TO


 * Microsoft COM Transaction Integrator for CICS and IMS 4.0 SP2

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This article was previously published under Q216672



SYMPTOMS
COMTI can return incorrect data to a client program or write an inaccurate and misleading error message to the Application Event Log.

Such errors may be observed when using a COMTI component library where the Interface Properties specify:

Remote Environment (RE) type: 'CICS and IMS Using TCP/IP',

Target Environment: 'CICS',

Server mode: 'MS Link'.

The error is produced when an invalid value is specified for the 'Host Names' 'Transaction ID' property of a method.

While incorrect data may be returned under some conditions, a code conversion error or an error message similar to the following may be returned under other conditions.

Event ID: 102

Source: COMTI

Type: Error

Category: General

(102) COM Transaction Integrator reported the following exception to the client:

Component: Cedar.Bank.1

Method: getaccts

Exception description:

(2159) The TCP transport received a socket error while attempting to receive user data. Expected length: 128, received length: 128. IP Address: 157.56.24.23, port: 3000, transid: BO42.



CAUSE
COMTI sends a Transaction Request Message (TRM) to the CICS listener program. Because it contains an invalid transaction identifier for the concurrent listener program, for example the MS Link sample supplied with COMTI, an unusual reply to the TRM is returned to COMTI.

This TRM reply message consists of all nulls. In one case, there were 132 bytes of nulls. COMTI has no expectations for the TRM reply message, just that it gets one. First, COMTI issues a receive for the 4-byte length of the TRM reply message. In this case, it is zero because the message was all nulls. Then, COMTI issues a receive for the TRM reply data with length zero. Therefore, in this case, 128 nulls still have to be received (132 bytes - 4 bytes [the length received] = 128 bytes).

Subsequently, COMTI sends the application [input] data to the host CICS region and issues a receive for the application reply data. This receive is satisfied immediately with the 128 bytes of nulls of the TRM reply message still outstanding and awaiting to be received.

If the amount of application [output] data expected by COMTI is less than the number of nulls awaiting a receive, then COMTI receives only the amount of null bytes it expects and passes them to the data conversion routines. If no conversion error results, the data may be passed to the client program and it is NOT application data. Instead, it is derived from the TRM reply message.

Alternatively, there may not be enough nulls in the TRM reply message residual to satisfy the receive for application [output] data. In this case, COMTI would write an error message to the Event Log similar to the one presented in the "Symptoms" section.



WORKAROUND
Supplying the correct Transaction ID for the method is the preferred workaround.



STATUS
Microsoft has confirmed that this is a problem in Microsoft COM Transaction Integrator for CICS and IMS, version 4.0 SP2.

Keywords: kbbug kbpending KB216672

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