Chapter 25 explored the vast hinterland of legacy software known as COM. This chapter looks at "what COM did next" and how it fits into the world of .NET, in the form of .NET Enterprise Services.
To understand Enterprise Services, you must go back in time (all the way to the last century!) when a number of technologies began to emerge from Microsoft, including Microsoft Transaction Server (MTS), Microsoft Message Queuing (MSMQ), and Microsoft Clustering Services. The aim of these developments was to increase the scalability, performance, and reliability of applications.
Handling transactions involved a considerable extension to the NT/COM runtime. It also involved the introduction of several new standard COM interfaces, some to be used or implemented by transactional components and some to be used or implemented by the underlying resource managers, such as SQL Server. These additions, along with some other innovations relating to areas such as asynchronous COM, came to be known as COM+.
This chapter explores the .NET Enterprise Services. In particular, it looks at transaction processing and queued components using the classes of the
System.Transactions namespaces. This is an enormous subject that could easily fill a whole book by itself, so this chapter only scratches the surface of it. However, by the end of the chapter, you will understand how all the pieces fit together. Let's begin by looking at what transactions are, ...