Chapter 5. Using Application Domains Effectively

If you're writing an extensible application or have reason to unload code without shutting down an entire process, you'll likely want to take advantage of application domains. Application domains enable you to isolate groups of assemblies from others running in the same process. Oftentimes, the isolation provided by application domains is used to run multiple applications in the same Win32 process as is done by CLR hosts such as Microsoft ASP.NET and Microsoft SQL Server. However, application domains are useful in a variety of other scenarios as well. For example, some applications use application domains to isolate individual controls running in the same process, whereas others use domains simply to support their requirements for dynamically unloading code.

This book includes two chapters on application domains. This first chapter introduces the concept of an application domain and gives general architectural guidelines to help you make the most effective use of domains within your application. Topics covered in this chapter include the role of application domains, a discussion of their internal structure, guidelines to follow when partitioning a process into multiple application domains, the relationship between domains and threads, and the use of application domains to unload code from a running process. In Chapter 6, I describe the various ways you can customize application domains to fit your particular scenario.