C# 4 and .NET 4

1378 ❘ ChaPTer 46 messAGe QueuinG
must be called. To cancel a transaction (and have no messages written to the queue), the Abort()
method must be called, as you can see within the catch block:
using System;
using System.Messaging;
namespace Wrox.ProCSharp.Messaging
{
class Program
{
static void Main()
{
if (!MessageQueue.Exists(@".\MyTransactionalQueue"))
{
MessageQueue.Create(@".\MyTransactionalQueue", true);
}
var queue = new MessageQueue(@".\MyTransactionalQueue");
var transaction = new MessageQueueTransaction();
}
}
}
try
{
transaction.Begin();
queue.Send("a", transaction);
queue.Send("b", transaction);
queue.Send("c", transaction);
transaction.Commit();
}
catch
{
transaction.Abort();
}
Fessage queuing WiTh WCf
Chapter 43, “Windows Communication Foundation,” covers the architecture and core features of WCF.
With WCF, you can configure a Message Queuing binding that makes use of the Windows Message Queuing
architecture. With this, WCF offers an abstraction layer to Message Queuing. Figure 46-14 explains the
architecture using a simple picture. The client application invokes a method of a WCF proxy to send a message
to the queue. The message is created by the proxy. For the client developer, there’s no need to know that a
message is sent to the queue. The client developer just
invokes a method of the proxy. The proxy abstracts
dealing with the classes from the System.Messaging
namespace and sends a message to the queue. The
MSMQ listener channel on the service side reads
messages from the queue, converts them to method
calls, and invokes the method calls with the service.
Next, the Course Ordering application gets
converted to make use of Message Queuing from
a WCF viewpoint. With this solution, the three
projects done earlier are modified, and one more
assembly is added that includes the contract of the
WCF service:
➤
The component library ( CourseOrder)
includes entity classes for the messages that
Sender
Proxy
figure 46-14
Service
(Receiver)
MSMQ
Channel
Listener
www.it-ebooks.info