There are three levels at which version policy can be
applied in .NET: application-specific policy, publisher policy and machine-wide
policy.
Application-specific Policy
Each application has an optional configuration file that can
specify the application’s desire to bind to a different version of a dependent
assembly. The name of the configuration file varies based on the application type.
For executable files, the name of the configuration file is the name of the
executable + a ".config" extension. For example, the configuration
file for "app1.exe" would be "app1.exe.config."
Configuration files for ASP.NET applications are always "web.config."
Example 5
An application APP1 was developed with .NET Framework 1.1
and now we want to direct the application to start with .NET Framework 2.0.
This means then, a XML file with the following codes and name of that file must
be app1.exe.config must be placed in the exact directory where app1.exe is
present and now APP1 will be redirected to .Net 2.0 when the application
starts.
Listing 3
<configuration>
<startup>
<supportedRuntime version="v2.0.50727"/>
<supportedRuntime version="v1.1.4322"/>
</startup>
</configuration>
Publisher Policy
While application-specific policy is set either by the
application developer or administrator, publisher policy is set by the vendor
of the shared assembly. We have already discussed this.
Machine-wide Policy
The final policy level is machine-wide policy (sometimes
referred to as Administrator policy). Policy statements made in machine.config
affect all applications running on the machine. Machine-wide policy is used by
Administrators to force all applications on a given machine to use a particular
version of an assembly.
