Question

I’m trying to consume JMS messages send over WebSphere MQ (WebSphere MQ Server v7) by .NET application using .NET WMQ API. I’m using WebSphere MQ Client v7.5 and amqmdnet.dll version 7.5.0.0.

There is some very strange behavior when reading JMSDeliveryMode property (Dlv property from jms RFH2 folder). The property value send by JMS application (servlet hosted in WebSphere Application Server v7) is set to Persistent (2) but my .NET client always reads 1 (which means Non_persistent). I need to read the correct value because my .NET application works as router/forwarder and it must forward message with correct configuration.

I tried to simulate JMS messages using RFHUtils. When I set delivery mode to 1 and send it to my .NET client it again reads 1 but if I also change persistence of MQ message in MQMD it reads 0. It looks like the value in JMSDeliveryMode is not used at all and .NET client always reads value from Persistence property but it is incorrect behavior! These two properties have different ranges of correct values:

JMSDeliveryMode correct values (from jms.jar):

• 1 – DeliveryMode.NON_PERSISTENT
• 2 – DeliveryMode.PERSISTENT

Persistence correct values (from amqmdnet.dll):

• 0 – MQC.MQPER_NOT_PERSISTENT
• 1 – MQC.MQPER_PERSISTENT
• 2 – MQC.MQPER_PERSISTENCE_AS_Q_DEF / MQC.MQPER_PERSISTENCE_AS_TOPIC_DEF

Answer 1

It is again bug in IBM’s amqmdnet.dll. After disassembling the library with .NET Reflector and checking the code responsible for reading JMS properties (GetJmsProperty private method of MQMessage class) I found this:

if (name.Equals("JMSDeliveryMode"))
{
   // Properties never contain the property with such name!
   if (this.properties.ContainsKey("JMSDeliveryMode"))
   {
      ...
   }
   return this.Persistence;  // Executes always
}

The problem is that properties collection never contains any property with JMSDeliveryMode as a key. properties collection contains RFH2 headers in format RFH2Folder.RFH2PropertyName. The correct property name for JMSDeliveryMode is jms.Dlv! Interestingly GetJmsHeader method reads all JMS properties and all other properties use correct RFH2 name when searching in properties collection!

The situation was even worse when I checked the reverse operation – private method SetJmsProperty from MQMessage class. Setting JMSDeliveryMode contains this code:

else if (name.Equals("JMSDeliveryMode"))
{
    if (value is int)
    {
        int num2 = Convert.ToInt32(value);
        switch (num2)
        {
            // Non persistent JMS message creates persistent MQ message  
            case 1:
                this.Persistence = 1;
                break;
            // Invalid value for JMS delivery mode            
            case 0:
                this.Persistence = 0;
                break;
            // Great if I try to create persistent JMS message I will 
            // get MQRC_PERSISTENCE_ERROR exception!            
            default:
                base.throwNewMQException(2, 0x7ff);
                break;
        }

        queue.Enqueue(num2);
        // Correct RFH2 identifier is used
        this.properties.Add("jms.Dlv", queue);
    }
    else
    {
        base.throwNewMQException(2, 0x9a9);
    }
}

So setting JMSDelivery mode will either fire exception or set invalid persistence! Here is small test for reproducing the problem:

[Test]
public void PutAndGetMessageWithDeliveryMode() {
    using (MQQueue queue = _queueManager.AccessQueue(TestQueue, MQC.MQOO_OUTPUT | MQC.MQOO_INPUT_AS_Q_DEF)) {

        MQMessage message = new MQMessage();
        message.SetInt4Property("JMSDeliveryMode", 2);
        message.WriteString("some string");
        message.Format = MQC.MQFMT_STRING;

        queue.Put(message); 

        MQMessage readMessage = new MQMessage();
        queue.Get(readMessage); 

        Assert.AreEqual(2, readMessage.GetInt4Property("JMSDeliveryMode"));

        queue.Close();
    }
}