What is GAC and how it use?

Question

What is GAC and how it use in .NET?

Sivasankar Gorantla · Answer

Hi, I will try to explain in simple terms. Before we are going to understand what is GAC, first we try to understand following question. Why GAC is required ? -Let's assume that you are implementing a banking application which uses a dll called BankingLogics.dll. Let's call this application as "Axis Bank Management System". You placed this dll into the local directory of this application. -Later Axis bank requested you to implement a new application for Axis mutual funds. Let's call it as "Axis Mutual Fund Management System". This application also requires BankingLogics.dll as this dll contains some core calculations of banking operations. Copying same dll here can lead into maintenance issues. For example: -After some days a new version of BankingLogics.dll is available in the market which has some interest calculation corrections and performance improvements. -You replaced the existing dll from the local directory of Axis bank Management System application. But forgot to replace it from the local directory of Axis Bank Mutual Funds Management System application. -This can result into many discrepancies as these applications are not referring same dll. Solution: So we need a common place where we can store all the dlls which can shared across multiple applications. That is GAC. It has many features like Version Control, Delay Signing, Strong Naming... etc Please let me know if you have any questions. Thanks, Siva

Puneet Kankar · Answer

The Global Assembly Cache (GAC) is a folder in Windows directory to store the .NET assemblies that are specifically designated to be shared by all applications executed on a system. The concept of GAC is the result of the .NET architecture whose design addresses the issue of "DLL hell" that existed in COM (Component Object Model). Unlike in COM, there is no need for the assembly in GAC to be registered before its use. Each assembly is accessed globally without any conflict by identifying its name, version, architecture, culture and public key.

Manikandan Murugesan · Answer

Global Assembly Cache :-- Assemblies can be shared among multiple applications on the machine by registering them in global Assembly cache(GAC). GAC is a machine wide a local cache of assemblies maintained by the .NET Framework. We can register the assembly to global assembly cache by using gacutil command. We can Navigate to the GAC directory, C:\winnt\Assembly in explore. In the tools menu select the cache properties; in the windows displayed you can set the memory limit in MB used by the GAC. GAC, Global Assembly Cache is the location where all the signed dll which can be used by all the application running in .NET manages environment. Here in your case, in both the project you will have your dll along with the exe of that project. If you register it in GAC, it will not be. The assembly will get loaded from GAC. This assembly will be shared across all the .NET applications run in your system, provided the privilege is granted. For additional info see this link: https://social.msdn.microsoft.com/Forums/vstudio/en-US/918c2493-cfaf-4bc6-acf3-626a25ce4523/why-use-gac?forum=netfxbcl