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Note

WCF does not currently provide a way to build serviced components. However, it does provide a manner

for WCF services to communicate with existing COM+ objects. If you need to build serviced components using C#,

you will need to make direct use of the 

System.EnterpriseServices

namespace. Consult the .NET Framework

3.5 SDK documentation for details.

The Role of MSMQ

The Microsoft Message Queuing (MSMQ) API allows developers to build distributed systems that

need to ensure reliable delivery of message data on the network. As we all know too well, in any dis-

tributed system there is the risk that a network server is down, a database is offline, or connections

are lost for mysterious reasons. Furthermore, a number of applications need to be constructed in

such a way that they hold message data for delivery at a later time (known as 

queuing data). 

At first, MSMQ was packaged as a set of low-level C-based APIs and COM objects. As well, using

the System.Messaging namespace, .NET programmers could hook into MSMQ and build software

that communicated with intermittently connected applications in a dependable fashion. Last but

not least, the COM+ layer incorporated MSMQ functionality into the runtime (in a simplified for-

mat) using a technology termed Queued Components (QC).

Regardless of which programming model you used to interact with the MSMQ runtime, the

end result ensured that applications could deliver messages in a reliable and timely fashion. Like

COM+, MSMQ is still certainly part of the fabric of building distributed software on the Windows

operating system.