COM+ Programming with Visual Basic

Using COM+ Services

I hesitate to write this section because many things are going to change down the road with respect to using .NET assemblies in COM+ applications. However, for the sake of completion, let’s talk about how to add a .NET class to a COM+ application as of Beta 1.

In the future, the MTS (now COM+) team will migrate all the COM+ services to work seamlessly with all the .NET architecture. For now, we must use a few COM interop tricks. In essence, the interaction occurs through the same mechanism explained earlier, by which you must make your .NET class look like a COM class by adding information to the registry and using MSCorEE.dll as the COM server wrapper for your assembly. However, we must also add information to the COM+ catalog. Microsoft provides another tool called RegSvcs.exe that does the job of RegAsm with the /tlb command-line switch, plus adds information about the class to the catalog. In addition, RegSvcs.exe is able to interpret certain attributes from the assembly, which enables you to set the declarative attributes in COM+.

For Beta 1, if you want a .NET class to work with COM+ services, you must derive the class from System.ServicedComponent. Because RegSvcs is going to generate COM information for the registry, you should also manage the IIDs and CLSIDs with attributes. For example, the following VB.NET code shows an interface named IAccount implemented in a Checking class:

<Assembly: System.Runtime.InteropServices.GuidAttribute("1D1D3D4C-52BE-46de-9100- ...