.NET Framework 3.5 Architecture

The architecture of the .NET Framework version 3.5 and 3.5 Service Pack 1 (SP1) builds upon the earlier versions of the .NET Framework.

.NET Framework Versions

The following table lists the versions of the .NET Framework that are included in the .NET Framework 3.5 and 3.5 SP1. There is no need to install any of the previous service packs if you installed the .NET Framework 3.5 or 3.5 SP1 because they are already included.

.NET Framework version	Features and notes
.NET Framework 3.5 SP1	Updates several assemblies that were included in the .NET Framework 3.5. The updates include non-breaking changes, new API elements, and additional functionality for the technologies that were included in the .NET Framework 3.5. The following technologies are included in the .NET Framework 3.5 SP1: ASP.NET Dynamic Data. ADO.NET Entity Framework. Data provider support for SQL Server 2008. Support for the .NET Framework Client Profile, a setup package that includes only assemblies used by client applications.
.NET Framework 2.0 SP2 and 3.0 SP2	These service packs are available only by installing the .NET Framework 3.5 SP1. They provide additional functionality for future infrastructure. They are not available as a separate install. Correction: Previously, this topic incorrectly stated that they were available as separate downloads.
.NET Framework 3.5	Provides the first additions to the base class libraries to the .NET Framework since version 2.0. The following technologies are introduced in the .NET Framework 3.5: Language Integrated Query (LINQ). New compilers for C#, Visual Basic, and C++. ASP.NET AJAX. For a complete list of features, see What's New in the .NET Framework Version 3.5.
.NET Framework 3.0 SP1	Updates .NET Framework 3.0 assemblies
.NET Framework 3.0	The .NET Framework 3.0 requires the .NET Framework 2.0 to be installed on the computer. If a user installs the .NET Framework 3.0 on a computer that does not have the .NET Framework 2.0 installed, the .NET Framework 2.0 is installed automatically. The following technologies are introduced in the .NET Framework 3.0: Windows Presentation Foundation (WPF). Windows Communications Foundation (WCF). Windows Workflow Foundation (WF).
.NET Framework 2.0 SP1	Updates .NET Framework 2.0 assemblies
.NET Framework 2.0	Provides the core architectural base for all subsequent versions of the Framework. The following technologies are included in the .NET Framework 2.0: Common language runtime (CLR) and base class libraries. Support for generic types and methods. Compilers for C#, Visual Basic, C++, and J#. ADO.NET. ASP.NET. Windows Forms. Web services. This is the last version of the Framework that supports side-by-side operations of the .NET Framework versions 1.0 through 2.0.

Memory Management in .NET Framework

 This article features a review discussing the function of memory management in Microsoft .NET framework in detail.

 Microsoft .NET framework memory management is taken care of by the Common Language Runtime, CLR system. It is a great feature as it takes care of memory management in Microsoft Dot Net framework and relieves the programmers from the duty of memory management which includes allocating and freeing up the memory.  Thus, we see that memory is allocated to the instantiations of .NET objects in a close manner from the managed heap, a pool of memory managed by the CLR.

 Till the time there is a reference to an object, either a direct reference to an object or through a graph of objects, it is believed to be in use by the Common Language R. When there is no reference to an object, and it cannot be reached or used, it becomes garbage. However, it still holds on to the memory allocated to it. Note that the Microsoft .NET framework memory management system consists of a garbage collector that runs on periodical basis on a different thread from the application's thread, which specifies all the unusable objects and get back the memory allocated to them.

 Garbage Collector (GC) in Microsoft .NET framework can be defined as a non-deterministic, compacting, mark-and-sweep garbage collector. It is in running state only when a definite amount of memory has already been used or the system is under pressure for memory. The Garbage Collector which is used for memory management in Microsoft .NET framework is actually a generational one. The objects are being assigned a generation and the newly formed objects come under Generation 0. The objects which successfully overcome garbage collection are named as Generation 1, and those objects of Generation 1 that successfully survive another Garbage collection are known as Generation 2 objects.

 The Microsoft .NET framework utilizes objects till the Generation 2 objects and the objects belonging to the higher generation objects are garbage collected less frequently as compared to the objects belonging to lower generations. It helps in enhancing the efficiency of garbage collection, as older objects are more likely to have a superior lifetime than the newer objects. Therefore by removing the older objects from the scope of a collection run, there would be lesser number of objects which required checking and compacting in process of memory management in Microsoft Dot Net framework.

.NET Framework is

A programming infrastructure created by Microsoft for building, deploying, and running applications and services that use .NET technologies, such as desktop applications and Web services. The .NET Framework contains three major parts:

1.       Common Language Runtime

2.       Framework Class Library

3.       ASP.NET.

CLR (Common Language Runtime)

A runtime environment that manages the execution of .NET program code and provides services such as memory and exception management, debugging and profiling, and security. The CLR is a major component of the .NET framework. CLR also is known as the Virtual Execution System (VES).

FCL (Framework class library)

The collective name for the thousands of classes that compose the .NET Framework. The services provided by the FCL include runtime core functionality (basic types and collections, file and network I/O, accessing system services, etc.), interaction with databases, consuming and producing XML, and support for building Web-based and desktop-based client applications, and SOAP-based XML Web services.

ASP.NET

A Microsoft server-side Web technology. ASP.NET takes an object-oriented programming approach to Web page execution. Every element in an ASP.NET page is treated as an object and run on the server. An ASP.NET page gets compiled into an intermediate language by a .NET Common Language Runtime-compliant compiler. Then a JIT compiler turns the intermediate code to native machine code, and that machine code is eventually run on the processor. Because the code is run straight from the processor, pages load much faster than classic ASP pages, where embedded VBScript or JavaScript had to be continuously interpreted and cached.  ASP.NET is used to create Web pages and Web services and is an integral part of Microsoft's .NET vision.

Features Included in the .NET Framework Versions

Each new version of the .NET Framework retains features from the previous versions and adds new features. Although the CLR is the core component of the .NET Framework, the CLR is identified by its own version number apart from the .NET Framework version number. Some versions of the .NET Framework include a new version of the CLR, but others use an earlier version. For example, the .NET Framework version 4 includes CLR version 4, but the .NET Framework 3.5 includes CLR 2.0. (There was no version 3 of the CLR.) The version of the CLR on which an application is running can be determined by retrieving the value of the Environment version property.

You do not have to install previous versions of the .NET Framework or the CLR before you install the latest version; each version provides the necessary components.

The following table provides a brief review of the .NET Framework versions and the associated CLR version. It also shows the Visual Studio version that provided the development environment when that version of the .NET Framework was introduced. However, with the multi-targeting feature of Visual Studio, you are not limited to only that version of the .NET Framework.

.NET Framework version	CLR version	Visual Studio version	Description
1.0	1.0	Visual Studio .NET	Contained the first version of the CLR and the first version of the base class libraries.
1.1	1.1	Visual Studio .NET 2003	Included updates to ASP.NET and ADO.NET. This version was subsequently updated twice, with Service Pack 1 (SP1) and SP2. This version also introduced side-by-side execution, which enables applications on a single computer to run against multiple versions of the CLR.
2.0	2.0	Visual Studio 2005	Introduced a new version of the CLR with additions to the base class libraries, including generics, generic collections, and significant additions to ASP.NET. This version was subsequently updated with SP1 and SP2.
3.0	2.0	Visual Studio 2005	This version is essentially .NET Framework 2.0 with the addition of Windows Presentation Foundation (WPF), Windows Communications Foundation (WCF), Windows Workflow Foundation (WF), and CardSpace. It was subsequently updated with SP1 and SP2.
3.5	2.0	Visual Studio 2008	Added new features such as AJAX-enabled Web sites and LINQ. The SP1 update added the .NET Framework Client Profile, Dynamic Data, and a small set of additional enhancements.
4	4	Visual Studio 2010	Includes a new version of the CLR, expanded base class libraries, and new features such as the Managed Extensibility Framework (MEF), dynamic language runtime (DLR), and code contracts.

Windows Installations of the .NET Framework

Some versions of the .NET Framework are installed automatically with the Windows operating system, but other versions must be installed separately. The following table identifies the .NET Framework versions and whether they are integrated into the installation of Windows or must be installed separately.

.NET Framework versions	Windows versions
1.0, 1.1, and 2.0	Not installed as part of the Windows operating system, but can be installed separately on Windows XP and earlier versions of Windows.
3.0 (and 2.0 SP2, which provides support for versions 3.0 and 3.5)	Installed by Windows Vista and Windows Server 2008.
3.5 SP1	Installed by Windows 7.
4	Not installed as part of the Windows operating system, but can be installed separately on Windows XP, Windows Server 2003, and later versions of Windows.