Chapter Nine. Using COM+(Enterprise Services)

In this chapter, I discuss how to use the COM+ Component Services from a managed application. COM+ was designed to facilitate the development of enterprise-class distributed applications. In support of this goal, COM+ provides the following services to middle-tier COM components:

• Fine-grained security.

• Distributed transactions.

• Thread synchronization.

• Load balancing.

• Asynchronous store and forward method invocation.

• Enhanced scalability through JIT activation, and pooling of objects and database connections.

These same services are accessible from the .NET Framework. In the .NET Framework, these services are referred to as the .NET Enterprise Services. It's best to think of the relationship between the .NET Enterprise Services and COM+ as one where the COM+ Component Services are used as the underlying implementation of the .NET Enterprise Services. In the future, it is likely that the .NET Enterprise Services will be built on an entirely managed foundation; it's also possible that these services will be implemented on non-Microsoft operating system platforms using other application server products like Transarc's Encina.

This chapter was not designed to be an exhaustive introduction to either COM+ or the .NET Enterprise Services. That would require an entire book. Because I've already written one (see The COM and COM+ Programming Primer [Prentice Hall]) I will direct you to that rather than rehash the same description of each of the services that is already contained there. In this chapter, my intention is to show you how to use the tools that the .NET Framework provides to make the COM+ Component Services available to managed applications. I also explain how the integration between the .NET Framework and the COM+ Component Services works.