MSMQQueueInfo Object IsTransactional property returns an integer (246222)

SYMPTOMS

The IsTransactional property of a Microsoft Message Queuing queue MSMQQueueInfo object returns an Integer result rather than a Boolean. IsTransactional property returns a 1 if the queue is transactional 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 "queueinfo.IsTransactional" and "Not queueinfo.IsTransactional" evaluates true. In the following example code, if the queue is transactional both message boxes appear:

If queueinfo.IsTransactional Then
   MsgBox "The queue is transactional."
End If

If Not queueinfo.IsTransactional Then
   MsgBox "The queue is not transactional."
End If

RESOLUTION

There are two possible workarounds for the problem:

Explicitly test the value of the IsTransactional property against 0 and 1. A value of 1 indicates that the queue is transactional, a value of 0 indicates that the queue is not transactional. An example of this test is shown in the following code:
```
If MSMQQueueInfoObject.IsTransactional = 1 Then
   MsgBox "The queue is transactional."
End If

If MSMQQueueInfoObject.IsTransactional = 0 Then
   MsgBox "The queue is not transactional."
End If
						
```
Avoid "negative" tests that use the Not operator with the IsTransactional 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 Microsoft Message Queuing 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 IsTransactional property as follows:

MSMQQueueInfo.IsTransactional

Return Values
   1 
      The queue is only used in transactions. 
   0 
      The queue is not used in transactions.

REFERENCES

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

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245753 MSMQQueue Object IsOpen Property Returns an Integer

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246460 MSMQMessage Object IsLastInTransaction Property Returns An Integer