Assemblies

Assembly Structure:

An assembly consists of assembly metadata describing the complete assembly, type metadata describing the exported types and methods, MSIL code, and resources. All these parts can be inside one file or spread across several files.

In the following eg, the assembly metadata, type metadata, MSIL code, and resources are all in one file – component.dll, the assembly consists of a single file.

Component.dll

Assembly Metadata Type Metadata IL Code Resources

 Assembly meta data also references a module call util.netmodule, which itself includes only type meta data and MSIL code for a class. A module has no assembly metadata. Thus the module itself has no version information; it also cannot be installed separately. All the three files in this ex make up a single assembly. The assembly is the installation Unit.

NAMESPACES, ASSEMBLIES, AND COMPONENTS

How does a namespace fit into the assembly concept? The namespace is completely independent of an assembly. You can have different namespaces in a single assembly, but the same namespace can spread across assemblies. The namespace is just an extension of the type name

Viewing Assemblies

Assemblies can be viewed using the command line utility ildasm, the MSIL disassembler. An assemply can be opened by starting ildasm from the command line, with the assembly as argument or by selectin ghte menu File-open.

Understanding Strong assembly names

All assemblies contain a name, version, and a culture. However assemblies can contain a public key. An assembly containing all four pieces of information is said to be strongly named.  Only assemblies that contain strong names can be stored in the global assembly.GAC  is a disk based collection of .NET assemblies that can be accessed by any piece of .NET code on the machine containing the GAC. You can place assemblies with different strong names side by side in the global assembly cache, even if the segment names match. For example version 1.0.0.0 of an assembly named assembly.dll can be installed in GAC along with version 2.0.0.0