Chapter 2: Creating and Managing Serviced Components

Microsoft Exam Objectives Covered In This Chapter:

• Create and consume a serviced component.

  • Implement a serviced component.

  • Create interfaces that are visible to COM.

  • Manage the component by using the Component Services tool.

  • Create a strongly named assembly.

  • Register the component in the global assembly cache.

• Access unmanaged code from a Windows service and a serviced component.

The .NET platform offers many advantages for developing new applications. However, most organizations will not be able to give up their existing applications that were developed on and are running on the Windows 32/COM/COM+ platform, the standard for almost 10 years.

All code written by using the .NET Framework tools and designed to run under the Common Language Runtime (CLR) is known as managed code. Other applications that run on the Windows/COM platform, such as COM components and Visual Basic 6 applications, are known as unmanaged code. COM, or the Component Object Model, is the standard for component interoperability for all unmanaged code. COM defines a set of standard interfaces that enable components to discover the capabilities of other components and call their methods.

In this chapter, you are going to learn about using Windows/COM+ Component Services to host components created with the .NET Framework. By hosting the components in Component Services, you can take advantage of the infrastructure services provided by this environment; these are detailed in the next section. You will also learn how to call legacy COM components from a .NET application, how to call a .NET component from a legacy COM application, and how to call Windows Application Programming Interface (API) functions from a .NET application. Understanding when and how to use these different techniques will be useful to you as you start to integrate .NET technology with existing applications.

Note 

In any discussion of component technologies, you will find the terms component, class, object, and instance. It’s important to work from a common set of definitions because sometimes these terms are used incorrectly. A component is a compiled unit of executable code. A class is the source code that defines an object. An object is an in-memory construction of code and data that can be created from a class. Instance refers to a single runtime instance of the object, which has its own unique set of properties and data.