Hosting Policies
[This documentation is for preview only, and is subject to change in later releases. Blank topics are included as placeholders.]
The in-process side-by-side hosting API consolidates policies by providing a default activation policy, a compatibility policy available through the ICLRMetaHostPolicy interface, and an extension to the configuration file. These features allow greater control over host activation. For information about the configuration file, see the Configuration File Schema for the .NET Framework topic.
Side-by-Side Default Activation Policy
Installing the .NET Framework version 4 Beta 1 side by side with previous versions does not affect the existing runtime environment, and existing application behavior does not change. Because MSCorEE.dll is unconditionally updated each time a new version of the .NET Framework is added, rules were implemented to support the default behavior for assemblies, applications, components, and assemblies loaded by legacy hosts) that were compiled against the common language runtime (CLR) in the .NET Framework versions 1.0, 1.1, and 2.0.
Application Bindings
Applications will bind to the CLR version they were compiled against if that version is installed. Otherwise, an application will bind to the latest CLR version that is installed, up to version 2.0.50727.
The following table lists some common scenarios and the resulting CLR binding.
Note
In the following table, "No effect" indicates that the binding behavior does not change if the specified version of the CLR is installed.
CLR application was compiled against |
CLR 1.0 installed? |
CLR 1.1 installed? |
CLR 2.0 installed? |
CLR 4.0 installed? |
Result |
|---|---|---|---|---|---|
1.0 |
Yes |
No effect |
No effect |
Yes |
Bind to CLR 1.0 |
1.1 |
Yes |
Yes |
No effect |
Yes |
Bind to CLR 1.1 |
2.0 |
Yes |
No effect |
No effect |
Yes |
Bind to CLR 2.0 |
1.0 |
No |
Yes |
No |
Yes |
Bind to CLR 1.1 |
1.0 |
No |
No effect |
Yes |
Yes |
Bind to CLR 2.0 |
1.0 |
No |
No effect |
No |
Yes |
Failure |
1.1 |
No effect |
No |
Yes |
Yes |
Bind to CLR 2.0 |
1.1 |
No effect |
No |
No |
Yes |
Failure |
COM Component Bindings
COM components will bind to the latest CLR that is installed on the computer, up to CLR version 2.0.50727.
The following table lists some common scenarios and the resulting CLR binding.
CLR COM component was compiled against |
CLR 1.0 installed? |
CLR 1.1 installed? |
CLR 2.0 installed? |
CLR 4.0 installed? |
Result |
|---|---|---|---|---|---|
1.0 |
No effect |
No effect |
Yes |
Yes |
Bind to CLR 2.0 |
1.0 |
No effect |
Yes |
No |
Yes |
Bind to CLR 1.1 |
1.1 |
No effect |
Yes |
No |
Yes |
Bind to CLR 1.1 |
1.1 |
No effect |
No effect |
Yes |
Yes |
Bind to CLR 2.0 |
2.0 |
No effect |
No effect |
Yes |
Yes |
Bind to CLR 2.0 |
1.0 |
No effect |
No effect |
Yes |
Yes |
Bind to CLR 2.0 |
1.0 |
No effect |
No effect |
No |
Yes |
Failure |
1.1 |
No effect |
No effect |
Yes |
Yes |
Bind to CLR 2.0 |
1.1 |
No effect |
No effect |
No |
Yes |
Failure |
Assemblies Loaded by Legacy Native Hosts
For legacy native hosts, the following functions bind to the latest CLR that is installed on the computer, up to version 2.0.50727:
CorBindToRuntime with pwszVersion as null.
CorBindToRuntimeEx with pwszVersion as null.
CorBindToRuntimeHost with pwszVersion as null.
GetRequestedRuntimeInfo with pExe, pwszVersion, and pConfigurationFile as null.
LoadLibraryShim with szVersion as null.
GetCORSystemDirectory, when called and there is no CLR loaded into the process.
.NET Framework 4.0-Only Default Activation Policy
Having only the .NET Framework 4 Beta 1 installed does not impact applications and components that were compiled against a previous version of the .NET Framework. Because MSCorEE.dll is unconditionally updated each time a new version of the .NET Framework is added, the following rules were implemented to avoid unpredictable behavior in older applications and components:
Application bindings: If the computer has only the .NET Framework 4 Beta 1 installed, and you try to run an application that was compiled against a previous version, a modal dialog box will instruct you to obtain the correct version of the .NET Framework, and the application will not load.
COM component bindings: If the computer has only the .NET Framework 4 Beta 1 installed, and the COM component to be activated was compiled against a previous version, the activation will fail with a specific HRESULT.