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Source Code

The AppConfigReaderApp application can be found under the Chapter 15 subdirectory.

The Machine Configuration File

The configuration files you’ve examined in this chapter have a common theme: they apply only to a

specific application (that is why they have the same name as the launching application). In addi-

tion, each .NET-aware machine has a file named machine.config that contains a vast number of

configuration details (many of which have nothing to do with resolving external assemblies) that

control how a specific version of the .NET platform operates.

The .NET platform maintains a separate *.config file for each version of the framework

installed on the local machine. For example, the machine.config file for .NET 2.0 can be found

under the C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\CONFIG directory (your version

may differ). If you were to open this file, you would find numerous XML elements that control

ASP.NET settings, various security details, debugging support, and so forth. However, if you wish to

update the machine.config file with machinewide application settings (via an  ele-

ment), you are free to do so.

Although this file can be directly edited using Notepad, be warned that if you alter this file

incorrectly, you may cripple the ability of a specific version of the runtime to function correctly. This

scenario can be far more painful than a malformed application *.config file, given that XML errors

in an application configuration file affect only a single application, but erroneous XML in the

machine.config file can break a specific version of the .NET platform.

Summary

This chapter drilled down into the details of how the CLR resolves the location of externally refer-

enced assemblies. You began by examining the content within an assembly: headers, metadata,

manifests, and CIL. Then you constructed single-file and multifile assemblies and a handful of

client applications (written in a language-agnostic manner).

As you have seen, assemblies may be private or shared. Private assemblies are copied to the

client’s subdirectory, whereas shared assemblies are deployed to the GAC, provided they have been

assigned a strong name. Finally, as you have seen, private and shared assemblies can be configured

using a client-side XML configuration file or, alternatively, via a publisher policy assembly.

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