Strong Assembly Names

As discussed in the previous section, an assembly can be either private or shared. A private assembly resides in the client application directory, whereas a shared assembly resides in the GAC. Although private assemblies are straightforward and easy to use, there are two cases in which you should consider using shared assemblies. The first case is to support side-by-side execution of different versions of the same assembly. The second case is to share assemblies between multiple client applications. Sharing allows multiple applications to take advantage of an improved compatible version as soon as it’s available, without patching up each application’s private assemblies individually. Framework and class library vendors tend to use shared assemblies.


The client assembly can specify another location where its private assemblies are found using the .NET Configuration tool (presented later in this chapter).

The GAC is likely to contain assemblies from many vendors, so .NET must provide a way to uniquely identify shared assemblies. A friendly name such as MyAssembly isn’t good enough, because multiple vendors might come up with identical friendly names for their assemblies. .NET must have a way to guarantee assembly uniqueness. There are a number of ways to produce uniqueness. COM used globally unique identifiers (GUIDs)—unique 128-bit numbers assigned to each component. Using a GUID is simple enough, but it has a fatal flaw: any party can see it, duplicate it, ...

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