C# 4 and .NET 4

Programming Message Queuing ❘ 1369
static void Main()
{
var queue = new MessageQueue(@".\Private$\MyPrivateQueue");
queue.Formatter = new XmlMessageFormatter(
new string[] {"System.String"});
}
}
}
Message message = queue.Receive();
Console.WriteLine(message.Body);
code snippet SendMessage/Program.cs
The Receive() message behaves synchronously and waits until a message is in the queue if there is none.
enumerating Messages
Instead of reading message by message with the Receive() method, you can use an enumerator to walk
through all messages. The MessageQueue class implements the interface IEnumerable and thus can be used
with a foreach statement. Here, the messages are not removed from the queue, but you get just a peek at
the messages to get their content:
var queue = new MessageQueue(@".\Private$\MyPrivateQueue");
queue.Formatter = new XmlMessageFormatter(
new string[] {"System.String"});
foreach (Message message in queue)
{
Console.WriteLine(message.Body);
}
Instead of using the IEnumerable interface, the class MessageEnumerator can be used.
MessageEnumerator implements the interface IEnumerator, but has some more features. With the
IEnumerable interface, the messages are not removed from the queue. The method RemoveCurrent() of
the MessageEnumerator removes the message from the current cursor position of the enumerator.
In the example, the MessageQueue method GetMessageEnumerator() is used to access
the MessageEnumerator. The MoveNext() method takes a peek message by message with the
MessageEnumerator. The MoveNext() method is overloaded to allow a time span as an argument. This is
one of the big advantages when using this enumerator. Here, the thread can wait until a message arrives in
the queue, but only for the specified time span. The Current property, which is defined by the IEnumerator
interface, returns a reference to a message:
asynchronous read
var queue = new MessageQueue(@".\Private$\MyPrivateQueue");
queue.Formatter = new XmlMessageFormatter(
new string[] {"System.String"});
using (MessageEnumerator messages = queue.GetMessageEnumerator())
{
while (messages.MoveNext(TimeSpan.FromMinutes(30)))
{
Message message = messages.Current;
Console.WriteLine(message.Body);
}
}
The Receive method of the MessageQueue class waits until a message from the queue can be read. To
avoid blocking the thread, a timeout can be specified in an overloaded version of the Receive method.
To read the message from the queue after the timeout, Receive() must be invoked again. Instead of polling
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