An assembly is essentially a portable executable or library file containing partially compiled code for use in deployment, security and versioning in Microsoft .NET's managed environment.  The assembly is compiled into the machine language instructions by the CLR.

Satellite Assemblies are special assemblies that only contain resources and are associated with the main assembly.  Satellite assemblies are used to store compiled localized application resources.  They contain only resource data and no other code.  Satellite assemblies are used to load the data dynamically depending upon the culture of the application.  They can be created using the AL utility tool provided with Microsoft .NET SDK.  With satellite assemblies, resources are embedded in a binary format within a DLL.  This makes the resources not very visible to the user and ensures faster access.  These assemblies can be deployed even after deployment of the application.

Refer to the earlier sections where we had already created a resource file that was intended for UK English culture.  We had then compiled the same to create a compiled resource file using the resgen utility.  Now we can use the AL utility shipped with the Microsoft .NET SDK to create a satellite assembly from a compiled resource file as shown below.

Listing 10

al /t:lib /culture:en-GB /embed: Internationalization.en-GB.resources
 /out: Internationalization.resources.dll

The output file Internationalization.en-GB.resources is a satellite assembly file that is created for the en-GB locale from the compiled resource file.  The .NET Framework Developer's Guide, MSDN, states, "Ideally, you should package the resources for the default or neutral assembly with the main assembly and create a separate satellite assembly for each language that your application supports."