Question

I’m using WebSphere MQ v7 Server and WebSphere MQ Client v7.5 with amqmdnet.dll 7.5.0.0 as .NET library for communicating over WebSphere MQ. Sometimes when I try to read MQMessage from the queue I get MQException with MQRC_RFH_FORMAT_ERROR reason.

var message = new MQMessage();
queue.Get(message);

This behavior seems dependent on the sender of the message and on its content. It usually doesn’t work with systems on different platform sending messages with float or double properties.

Answer 1

This is a globalization bug in IBM’s amqmdnet.dll. After turning on MQ tracing on the client (strmqtrc.exe) I tried to receive message again and I found this in one of trace files:

00001F21 11:48:00.351013   7104.1           :       Exception received
System.FormatException
Message: Input string was not in a correct format.
StackTrace:
   at System.Number.ParseSingle(String value, NumberStyles options, NumberFormatInfo numfmt)
   at System.Convert.ToSingle(String value)
   at IBM.WMQ.MQMarshalMessageForGet.GetValueAsObject(String dt, String propValue)
   at IBM.WMQ.MQMarshalMessageForGet.ProcessAllAvailableRFHs()
00001F22 11:48:00.351115   7104.1           :       We are not sucessful in parsing one of theRFH2Header.Raise the RFH_FORMAT exception and breakfurther processing in loop
00001F23 11:48:00.351825   7104.1           :       MQException CompCode: 2 Reason: 2421

Decompiling MQMarshalMessageForGet with .NET Reflector showed this:

private object GetValueAsObject(string dt, string propValue)
{
    ...

    switch (dt)
    {
        ...

        case "r4":
            return Convert.ToSingle(propValue);

        case "r8":
            return Convert.ToDouble(propValue);

        ...
    }

    ...
}

The messages are read in the current system’s culture not in transport expected culture (which should be same on all platforms)! Simple test to reproduce the issue:

[Test]
public void PutAndGetMessageWithFloatProperty() {
    using (MQQueue queue = _queueManager.AccessQueue(TestQueue, MQC.MQOO_OUTPUT | MQC.MQOO_INPUT_AS_Q_DEF))
    {
        Thread.CurrentThread.CurrentCulture = new CultureInfo("en-US");

        MQMessage message = new MQMessage();
        message.SetFloatProperty("TEST_SINGLE", 14.879f);
        message.WriteString("some string");
        message.Format = MQC.MQFMT_STRING;

        queue.Put(message); // Writes property value as 14.879

        Thread.CurrentThread.CurrentCulture = new CultureInfo("cs-CZ");

        MQMessage readMessage = new MQMessage();
        queue.Get(readMessage); // Throws MQException because 14,879 is correct format

        queue.Close();
    }
}

Workaround

I’m using this simple scope class:

public class CultureForThreadScope : IDisposable {
    private readonly CultureInfo oldCulture;

    public CultureForThreadScope(CultureInfo culture) {
        oldCulture = Thread.CurrentThread.CurrentCulture;
        Thread.CurrentThread.CurrentCulture = culture;
    }

    public void Dispose() {
        Thread.CurrentThread.CurrentCulture = oldCulture;
    }
}

And I’m wrapping every Get call to the scope.

using (new CultureForThreadScope(CultureInfo.InvariantCulture)) {
    destination.Get(message, getOptions);
}