.NET Assembly in GAC

Anyone who develops using .NET framework will encounter GAC, Global Assembly Cache. GAC is a shared repository of assemblies (DLL) maintained by the .NET runtime and all shared assemblies must be strongly named.

The usual location for a GAC assembly depending on your operating system are:

C:\Windows\Assembly
C:\Winnt\Assembly

Why a shared repository of assemblies?

Simply to facilitate code reuse instead of duplicating code between applications.

How to install an assembly in GAC?
You can use a utility called gacutil.exe

Installing assembly using gacutil.exe utility:
gacutil -i MyAssembly.dll

Uninstalling assembly using gacutil.exe utility
gacutil -i MyAssembly.dll

You can copy assemblies from GAC to a different location, i.e. for deploying from a development server to a production server.

How to copy an assembly from GAC?

1. On command prompt, goto the C:\Windows\Assembly directory.

2. Goto GAC_MSIL directory

3. Goto to CrystalDecisions.CrystalReports.Engine directory. I am using CrystalDecisions.CrystalReports.Engine as an example. The assembly that you want to copy would be in a different directory.

4. Goto the version directory, e.g. 10.5….. Then copy *.dll to c:\ or your location of choice.

And that’s how you copy an assembly from GAC for deployment.