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POMSMQ Peek Permissions Only (i.e. without Receive Permissions)?
 

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    <p><strong>Summary (tl;dr):</strong> We're trying to set up a queue with <code>Peek</code> access but not <code>Receive</code> access for testing purposes (so a <code>Receive</code> request will fail but a <code>Peek</code> will succeed), but it seems MSFT has made that more difficult than anticipated.</p> <p><strong>Background:</strong> We have a local private MSMQ queue from which one process receives and processes (/consumes) messages. In some situations the processing can't be completed and the message stays in the queue (e.g. forwarding destination temporarily offline). A monitor was therefore added to peek at the queue every ~10 minutes and see if the message at the top is the same or not - if the consumer is stalled (the same message is at the top), the monitor triggers an alarm to indicate that something's wrong.</p> <p>To force the queues to stall for testing purposes (to make sure the monitor function works), we thought we'd just remove (but not <em>deny</em>) <code>Receive</code> permissions from the queue itself but still <em>allow</em> <code>Peek</code> (restarting MSMQ and everything to enforce new permissions), which would ideally allow the monitor to <code>Peek</code> the messages without allowing anyone to <code>Receive</code> (/remove) the messages, 'stalling' the queue and generating an alarm.</p> <p>While testing this scenario out, however, I ran into an exception that seems to foil this approach:</p> <pre><code>System.Messaging.MessageQueueException: Access to Message Queuing system is denied. at System.Messaging.MessageQueue.MQCacheableInfo.get_ReadHandle() at System.Messaging.MessageQueue.StaleSafeReceiveMessage(UInt32 timeout, Int32 action, MQPROPS properties, NativeOverlapped* overlapped, ReceiveCallback receiveCallback, CursorHandle cursorHandle, IntPtr transaction) at System.Messaging.MessageQueue.ReceiveCurrent(TimeSpan timeout, Int32 action, CursorHandle cursor, MessagePropertyFilter filter, MessageQueueTransaction internalTransaction, MessageQueueTransactionType transactionType) at System.Messaging.MessageQueue.Peek(TimeSpan timeout) </code></pre> <p>This indicates (to me at least) that <code>Peek()</code> internally calls <code>ReceiveCurrent()</code> and must try a transactional <code>Receive</code> that it will then roll back /abort after it's done getting the message. Firing up .NET Reflector, I found that all instances of <code>Peek</code> call some variant of <code>Receive</code>, so a different <code>Peek</code> won't help. So it seems like <code>Receive</code> permissions are <em>required</em> in order to <code>Peek</code> as well, which seems kind of dumb as far as queue design goes.</p> <p>Note that both the consumer and monitor use the same account (/permissions) and changing the monitoring <em>method</em> (using <code>Peek</code>) isn't a viable option at this point (as that would require significant changes to requirements, specifications, and production code that would cost more than its worth) (though I guess you could propose monitoring methodology changes anyways if you really have to as they might be useful to others if they run into the same thing).</p> <p><strong>Finally, the Question:</strong> Is there a better (or even just different :p) way to <code>Peek</code> at the top of the queue without needing <code>Receive</code> permissions? Or a different way to set the permissions (via permissions interface, via code, etc.) such that <code>Receive</code> itself fails but <code>ReceiveCurrent</code> and other methods required to <code>Peek</code> work?</p>
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