Microsoft .Net - FAQ

5. What languages are available for programming in Microsoft .Net?

Visual Studio .NET (The IDE for Microsoft .Net) ships with languages such as Visual Basic .NET, Visual C#, and Visual C++ with managed extensions, as well as the JScript scripting language. You can also write managed code for the Microsoft .NET Framework in other languages. Third-party tools and compilers exist for Fortran, Cobol, Perl, and a host of other languages. The Common Language Specification (CLS) defines the minimum standards to which .NET language compilers must conform. Thus, the CLS ensures that any source code successfully compiled by a .NET compiler can interoperate with the Microsoft .NET Framework.

6. What is Language Independence? What does cross-language compatibility mean?

The Microsoft .NET Framework is designed for cross-language compatibility. This simply means, that Microsoft .NET components can interact with each other no matter what supported language they were written in originally. So, an application written in Microsoft VB.NET might reference a dynamic-link library (DLL) file written in C#, which in turn might access a resource written in managed Visual C++ or any other .NET language. This language interoperability extends to full object-oriented inheritance. A VB.NET class might be derived from a C# class, for example, or vice versa.

This level of cross-language compatibility is possible because of the CLR. When a Microsoft .NET application is compiled, it is converted from the language in which it was written (VB.NET, C#, or any other .NET-compliant language) to Microsoft Intermediate Language (MSIL or IL). Because all Microsoft .NET executables and DLLs exist as MSIL, they can freely interoperate.

The CTS ensures type compatibility between .NET components. Because Microsoft .NET applications are converted to IL prior to deployment and execution, all primitive data types are represented as .NET types. Thus, a VB Integer and a C# int are both represented in IL code as a System.Int32. Because both languages use a common type system, it is possible to transfer data between components and avoid time-consuming conversions or hard-to-find errors.

7. How is a Microsoft .Net Application compiled? What is MSIL?

Applications written in any language on the .NET Framework compile into an intermediate language known as the Common Intermediate Language, or CIL (formerly known as Microsoft Intermediate Language, or MSIL). MSIL is a low-level language that the CLR can read and understand. In Microsoft's implementation, this intermediate language is not interpreted, but rather compiled in a manner known as just-in-time compilation (JIT) into native code. The combination of these concepts is called the Common Language Infrastructure (CLI), a specification; Microsoft's implementation of the CLI is known as the Common Language Runtime (CLR).

8. What are Microsoft .Net Assemblies?

The primary unit of a .NET application is the assembly. The Microsoft .Net Applications pseudo code is compiled into intermediate CIL (MSIL) code and is stored in .NET assemblies. An assembly is a self-describing collection of code, resources, and metadata.

Assemblies are stored in the DLL and EXE files. The assembly consists of one or more files. Each assembly has one and only one assembly manifest, which contains the metadata or description information for the assembly.

An assembly contains one or more modules. A module contains the code that makes up your application or library, and it contains metadata that describes that code. When you compile a project into an assembly, your code is converted from pseudo code to IL. Because all managed code is first converted to IL code, applications written in different languages can easily interact. For example, one developer might write an application in Visual C# that accesses a DLL in Visual Basic .NET. Both resources will be converted to IL modules before being executed, thus avoiding any language-incompatibility issues.