Professional Visual Basic® 2010 and .NET 4

Appendix D. Enterprise Services

Chapter 28 explored the vast hinterland of legacy software known as COM. This appendix 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 appendix explores the .NET Enterprise Services. In particular, it looks at transaction processing and queued components using the classes of the System.EnterpriseServicesnamespace. The System.EnterpriseServices provides a number of classes that wrap the technologies that composed COM+. These include the classes that represent the ObjectContext, and the component interfaces that assist the system in transactions and queuing.

This is an enormous subject that could ...