如何在MSMQ队列上获取所有可用消息

Question

Whats the best way to get all the messages currently on a queue to process?

We have a queue with a large number of very small messages, what I would like to do is read all the current messages off and then send them through a thread pool for processing.

I can't seem to find any good resource which will show me how i can create a simple method to return an IEnnumerable for example

Thanks

Answer 1

Although I agree with Nick that the queue's purpose is more for FIFO style processing, and ArsenMkrt's solution will work, another option involves using a MessageEnumerator and piling the messages into your IEnumerable.

var msgEnumerator = queue.GetMessageEnumerator2();
var messages = new List<System.Messaging.Message>();
while (msgEnumerator.MoveNext(new TimeSpan(0, 0, 1)))
{
    var msg = queue.ReceiveById(msgEnumerator.Current.Id, new TimeSpan(0, 0, 1));
    messages.Add(msg);
}

Answer 2

For simple stuff...

public void DoIt()
    {

        bool continueToSeekForMessages = true;

        while (continueToSeekForMessages)
        {
            try
            {
                var messageQueue = new System.Messaging.MessageQueue(@"FormatName:Direct=OS:MyComputerNameHere\Private$\MyPrivateQueueNameHere");
                var message = messageQueue.Receive(new TimeSpan(0, 0, 3));
                message.Formatter = new System.Messaging.XmlMessageFormatter(new String[] { "System.String,mscorlib" });
                var messageBody = message.Body;

            }
            catch (Exception ex)
            {
                continueToSeekForMessages = false;
            }
        }
    }

.

Also, could use peek instead of taking the message off the queue.

Also, could use GetMessageEnumerator2

Answer 3

Doesn't that defeat the purpose of the queue? The queue is supposed to keep the order of the messages, so you have to loop through and keep pulling the first message off.

Answer 4

Latest versions of MSMQ also has the following feature:

You can get all messages in a single object such as follows: (Write your own "ReceiveCompleted event" handler)

private static void MyReceiveCompleted(Object source,
        ReceiveCompletedEventArgs asyncResult)
    {
        MessageQueue mq = (MessageQueue)source;
        try
        {
            Message[] mm = mq.GetAllMessages();
            foreach (Message m in mm)
            {
            // do whatever you want
            }
        }
        catch (MessageQueueException me)
        {
            Console.WriteLine(me.Message);
        }
        finally
        {

        }


        return;
    }