ASP.NET.in.a.Nutshell.Second.Edition [Electronic resources] نسخه متنی

6.3 Sharing Controls Across Applications

The
architecture of
the .NET Framework makes using a custom server control or other
assembly as simple as copying that assembly to the

bin subdirectory of your application and adding
the appropriate directives and tags to your page. However, there may
be times when you would like multiple applications on the same
machine to be able to use the same control, without having multiple
local copies of the control's assembly floating
around.

Fortunately, .NET addresses this need with the Global Assembly Cache
(GAC), a repository of shared assemblies that are accessible to all
.NET applications on a given machine. Adding your own control
assemblies to the GAC is a relatively straightforward process that
requires four steps:

1. Use the

   sn.exe command-line utility to create a
   public key pair for use in signing your control:

   sn.exe -k Blog.snk

2. Add the AssemblyKeyFileAttribute to the file
   containing the control code, passing the path to the keyfile created
   in Step 1 as an argument. (This is an assembly-level attribute, so it
   should be placed outside of any namespace or class definitions.) When
   compiled, this attribute will result in a strongly named assembly
   that can be placed in the GAC:

   [assembly: AssemblyKeyFileAttribute("Blog.snk")]

3. Recompile the control.

4. Add the control to the GAC, either by dragging and dropping the
   assembly in Windows Explorer or by using the
   

   gacutil.exe utility, as follows:

   gacutil -i Blog.dll

   Note that as with the csc.exe and vbc.exe command-line compilers, using the sn.exe and gacutil.exe utilities without a fully qualified path requires that you have the path to these utilities registered as part of your PATH environment variable. The sn.exe and gacutil.exe utilities are typically located in the \FrameworkSDK\bin directory, which is installed either under ProgramFiles\Microsoft.NET or ProgramFiles\Microsoft Visual Studio .NET 2003\SDK\v1.1\Bin , depending on whether you've installed just the .NET Framework SDK or Visual Studio .NET.

Once you've added the
control assembly to the GAC, you can use it from any application on
the machine. One caveat: to use custom controls that are installed in
the GAC, you must supply the version, culture, and public key
information for the assembly when adding the @
Register directive for the control, as shown in
the following snippet (which should appear on a single line):

<%@ Register TagPrefix="aspnetian" Namespace="aspnetian" Assembly="Blog,
Version=0.0.0.0, Culture=neutral, PublicKeyToken=6bd31f35fc9a113b" %>

If you've added your control to the Visual Studio
.NET toolbox, when you use the control from the toolbox, the correct
@ Register directive will be
generated for you automatically.