The CLR is the layer of the .NET Framework that makes language independence work. Written mostly in Microsoft’s new language, C#, the CLR provides services that any .NET program can use. Because of .NET’s component architecture, software written in any language can call upon these services.

Microsoft has also submitted a subset of the CLR to ECMA, the European information and communications standards organization. This subset is referred to as the Common Language Infrastructure (CLI).

CLR provides following services:

• Language Integration
• Memory Management (Memory Allocation and Garbage Collection)
• Memory Type Safety (Memory Leaks)
• Security
• Thread management
• Exception handling

There are three types JIT (just in time) compiler. Those are as follows…

• Pre-JIT compiler (Compiles entire code into native code completely)
• Econo JIT compiler (Compiles code part by part freeing when required)
• Normal JIT compiler (Compiles only that part of code when called and places in cache)

JIT (just-in-time) is a CLR’s (Common Language Runtime) compiler. The JIT Compiler function is responsible for compiling a method’s IL code into native CPU instructions. Because the IL(intermediate language) is being compiled "just in time," this component of the CLR is frequently referred to as a JITter or a JIT compiler.

When JIT called, the JIT Compiler function knows what method is being called and what type defines this method. The JIT Compiler function then searches the defining assembly’s metadata for the called method’s IL. JITCompiler next verifies and compiles the IL code into native CPU instructions. The native CPU instructions are saved in a dynamically allocated block of memory. Then, JITCompiler goes back to the type’s internal data structure and replaces the address of the called method with the address of the block of memory containing the native CPU instructions. Finally, JITCompiler jumps to the code in the memory block. This code is then implementation means particular code get executed.

The Microsoft .NET platform consists of the following product groups/ main components…

• Development tools A set of languages, including C#, VB.NET, J#, a set of development tools, including Visual Studio.NET (a suite of language-independent developer tools, a set of programming interfaces), .NET Framework (for building web and Windows applications, as well as web services), and Common Language Runtime, which is the execution engine for .NET Framework applications

• .NET Enterprise servers A suite of e-business infrastructure applications that run XML web services – SQL Server 2000, Exchange Server 2000, BizTalk Server 2000 and others. These servers are used to store relational data, data exchange and business-to-business (B2B) commerce

• Web services (building block services) A set of commercial web services, which includes customer services (.NET MyServices), authentication and identification services (.NET Passport) and communication services (.NET Alerts). Developers can use these services to build applications that require knowledge of user identity

• .NET device software Consisting of Windows XP, Windows Me, Windows CE, Windows Embedded, the .NET Framework and .NET Compact Framework, this software enables a new set of .NET-enabled devices – from mobile phones to PDAs and game boxes.

   

Microsoft .NET platform defines a standard around which a system can be developed. Microsoft .NET platform provides countless opportunities for different services and systems to interact, allowing programmers to develop powerful solutions for the internet. A major theme of Microsoft .NET platform is the idea of Web services, allowing software to communicate directly with other software using Internet technologies. The .NET Framework and Visual Studio.NET, two more core aspects of this initiative, provide a multi-language environment in which developers can create Web services and other kinds of applications.

Microsoft .NET platform is an umbrella term that applies to a wide collection of products and technologies from Microsoft. The technologies that Microsoft has placed under the .NET umbrella today include the following:

• The .NET Framework
• Visual Studio.NET
• .NET My Services
• The .NET Enterprise Servers