So far in this book we've looked at Microsoft's latest application design methodology, the Distributed interNet Applications (DNA) architecture, how it uses components to implement the business rules and functions, and how these components can be integrated with Microsoft Transaction Server (MTS) to produce robust and reliable distributed applications. It's now time to explore the second headline technology from the title of the book, Microsoft Message Queue Server (MSMQ).
MSMQ, like MTS, is part of the Windows NT4 Option Pack and an integral part of Windows NT5. It fills the final gap in a distributed application, something that we intimated may be of concern way back in Chapter 1 when looking at what our Wrox Car Co application was designed to do. The question we asked at the time was: 'What happens if the head office database, or the network that connects our showroom to it, is out of action?' In this chapter, you'll see the answer.
Before we go into details, however, we'll take an overview of the whole topic of message queuing. You won’t be surprised to know that it isn't a Microsoft invention, but has been a core part of distributed applications on other platforms for quite some time. We'll be covering:
We won’t be adding the final message queuing features to our sample Wrox Car Co application in this chapter—we'll do this in Chapter 6 when we come to finalize the application and the two different client interfaces.