Microsoft KB Archive/246222
Article ID: 246222
Article Last Modified on 2/23/2007
- Microsoft Message Queuing 2.0
- Microsoft Message Queue Server 1.0
This article was previously published under Q246222
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
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.
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.
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.
MSDN Online help for the MSMQQueueInfo object type.
Visual Basic Programmers Guide
246218 MSMQMessage Object IsAuthenticated 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
Keywords: kbbug kbprb KB246222