Assemblies and Side-by-Side Execution

Let us consider that we have 2 applications A & B in a system, where A is an old application using an older version (say x1) of an assembly, not B is a new application and wants to use a new version (say x2) of the same assembly, how can this be achieved?

If the Assemblies are private assemblies then we don’t have an issue as the applications A & B will contain their own version of the assembly in their application folder and use the assemblies independently. But what is the assembly is a shared assembly, how can be maintain and use 2 different versions of the same assembly? This is where side-by-side execution comes into play.

Side-by-Side execution enables applications in a system to user different versions of the same assembly and also different versions of the .Net run-time by configuring and binding the applications to the appropriate version and run-time.

The Global Assembly Cache (GAC) contains the set of installed shared assemblies in the system. Since all the assemblies installed in the GAC are strongly signed, the GAC enables multiple versions of the same assembly to co-exist in the GAC, the applications using the assemblies can specify and load the required version of the assembly dynamically from their application.