Software Design Blog

The previous post described how to design a highly scalable solution using queue oriented architecture.

This post will cover the fundamentals to get started with Microsoft Message Queuing (MSMQ). Code examples are provided to illustrate how to create a queue, write messages to a queue and read messages from a queue synchronously and asynchronously.

Setup

The pre-requisite is to install MSMQ, which comes free with Windows.

Creating a queue

The following code was used for creating the queue named orders.

  
using System.Messaging;

if (!MessageQueue.Exists(@".\Private$\Orders"))
{
    MessageQueue.Create(@".\Private$\Orders");
} 

The orders queue and messages on the queue can be viewed using Computer Management as shown below.

Writing Messages

The following code was used for writing the OrderModel DTO instance (message) to the queue using a BinaryMessageFormatter.

  
    [Serializable]
    public class OrderModel
    {
        public int Id { get; set; }
        public string Name { get; set; }
    }

    using (var queue = new MessageQueue(@".\Private$\Orders"))
    {
        queue.Formatter = new BinaryMessageFormatter();

        var order = new OrderModel()
        {
            Id = 123,
            Name = "Demo Order"
        };
        queue.Send(order);
    }

Reading Messages

Blocking Synchronous Read

  
    using (var queue = new MessageQueue(@".\Private$\Orders"))
    {
        queue.Formatter = new BinaryMessageFormatter();

        var message = queue.Receive();
        var order = (OrderModel)message.Body;
    }

A read timeout duration can be specified. The code below will use a 1 sec timeout limit and catch the MessageQueueException raised due to the timeout. A custom ReadTimeoutException is thrown to notify the client that a timeout has occured.

  
    public class ReadTimeoutException : Exception
    {
        public ReadTimeoutException(string message, Exception innerException) 
               : base(message, innerException)
        {
            
        }
    }

    using (var queue = new MessageQueue(@".\Private$\Orders"))
    {
        queue.Formatter = new BinaryMessageFormatter();
        Message message = null;

        try
        {
            message = queue.Receive(TimeSpan.FromSeconds(1));
        }
        catch (MessageQueueException mqException)
        {
           if (mqException.MessageQueueErrorCode == MessageQueueErrorCode.IOTimeout)
           {
               throw new ReadTimeoutException("Reading from the queue timed out.", 
                            mqException);
           }
           throw;
        }
    }

Asynchronous Read

  
private async Task<OrderModel> ReadAsync()
{
    using (var queue = new MessageQueue(@".\Private$\Orders"))
    {
        queue.Formatter = new BinaryMessageFormatter();

        var message = await Task.Factory.FromAsync<Message>(
                              queue.BeginReceive(), queue.EndReceive);
        return (OrderModel)message.Body;
    }
}

Summary

This post covered the fundamentals of using a MSMQ to read and write messages.

The next post describes various message delivery strategies.