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Microsoft KB Archive/246218

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Knowledge Base


Article ID: 246218

Article Last Modified on 2/22/2007



APPLIES TO

  • Microsoft Message Queue Server 1.0
  • Microsoft Message Queuing 2.0



This article was previously published under Q246218

SYMPTOMS

The IsAuthenticated property of a Microsoft Message Queuing queue MSMQMessage object returns an Integer result rather than a Boolean result. IsOpen returns a 1 if the message is authenticated and a 0 if it is not. This can cause logic errors in a Visual Basic (VB) program if the property is used in the expression portion of an If, While, or similar conditional statement.

When a numeric value is used in a condition statement in VB, 0 is evaluated as false and all non-zero values are evaluated as true. The Not operator in VB inverts the bits of a value when used on a numeric value. The expression "Not 1" produces the result "-2" which is considered a "true" value in a VB condition statement.

Since VB evaluates both "1" and "Not 1" as true statements, if a queue is open both "message.IsAuthenticated" and "Not message.IsAuthenticated" evaluates true. In the following example code, if the message is authenticated both message boxes appear:

If message.IsAuthenticated Then
   MsgBox "The message is authenticated."
End If

If Not message.IsAuthenticated Then
   MsgBox "The message is not authenticated"
End If
                

RESOLUTION

There are two possible workarounds for the problem:

  1. Explicitly test the value of the IsAuthenticated property against 0 and 1. A value of 1 indicates that the message is authenticated, a value of 0 indicates that the message is not authenticated. An example of this test is shown in the following code:

    If MSMQMessageObject.IsAuthenticated = 1 Then
       MsgBox "The message is authenticated."
    End If
    
    If MSMQMessageObject.IsAuthenticated = 0 Then
       MsgBox "The message is not authenticated"
    End If
                            
  2. Avoid "negative" tests that use the Not operator with the IsAuthenticated property.


STATUS

It is safe to test explicitly for the 1 and 0 values. These values will not be changed in any future version of MSMQ and will remain consistent. Future versions of the Microsoft Message Queuing ActiveX components may add a property that may be evaluated as a true Boolean type for testing this characteristic.

MORE INFORMATION

The MSDN Online help describes the return values for the IsAuthenticated property as follows:

MSMQMessage.IsAuthenticated

Returned Value
1 
   The sending application requested authentication. The receiving Queue
   Manager authenticated the message when it received the message. 
0 
   The sending application did not request authentication. The receiving
   Queue Manager did not attempt to authenticate the message when it 
   received the message. 
                

REFERENCES

MSDN Online help for the MSMQMessage object type.
Visual Basic Programmers Guide

246222 MSMQQueueInfo Object IsTransactional Property Returns An Integer



245753 MSMQQueue Object IsOpen Property Returns an Integer



246225 MSMQQueueInfo Object IsWorldReadable Property Returns and Integer



246458 MSMQMessage Object IsFirstInTransaction Property Returns An Integer



246460 MSMQMessage Object IsLastInTransaction Property Returns An Integer



Additional query words: MSMQ MSMQMessage IsAuthenticated

Keywords: kbbug kbprb KB246218