The
.NET Framework is a
software frameworkIn computer programming, a software framework is an abstraction in which software providing generic functionality can be selectively changed by user code, thus providing application specific software...
that runs primarily on
Microsoft WindowsMicrosoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
. It includes a large
libraryThe Base Class Library is a standard library available to all languages using the .NET Framework. .NET includes the BCL in order to encapsulate a large number of common functions, such as file reading and writing, graphic rendering, database interaction, and XML document manipulation, which makes...
and supports several
programming languageA programming language is an artificial language designed to communicate instructions to a machine, particularly a computer. Programming languages can be used to create programs that control the behavior of a machine and/or to express algorithms precisely....
s which allows language interoperability (each language can use code written in other languages). Programs written for the .NET Framework execute in a software environment (as contrasted to
hardwareHardware is a general term for equipment such as keys, locks, hinges, latches, handles, wire, chains, plumbing supplies, tools, utensils, cutlery and machine parts. Household hardware is typically sold in hardware stores....
environment), known as the
Common Language RuntimeThe Common Language Runtime is the virtual machine component of Microsoft's .NET framework and is responsible for managing the execution of .NET programs. In a process known as just-in-time compilation, the CLR compiles the intermediate language code known as CIL into the machine instructions...
(CLR), an application virtual machine that provides important services such as security,
memory managementMemory management is the act of managing computer memory. The essential requirement of memory management is to provide ways to dynamically allocate portions of memory to programs at their request, and freeing it for reuse when no longer needed. This is critical to the computer system.Several...
, and
exception handlingException handling is a programming language construct or computer hardware mechanism designed to handle the occurrence of exceptions, special conditions that change the normal flow of program execution....
. The class library and the CLR together constitute the .NET Framework.
The .NET Framework's
Base Class LibraryThe Base Class Library is a standard library available to all languages using the .NET Framework. .NET includes the BCL in order to encapsulate a large number of common functions, such as file reading and writing, graphic rendering, database interaction, and XML document manipulation, which makes...
provides
user interfaceThe user interface, in the industrial design field of human–machine interaction, is the space where interaction between humans and machines occurs. The goal of interaction between a human and a machine at the user interface is effective operation and control of the machine, and feedback from the...
,
data accessData access typically refers to software and activities related to storing, retrieving, or acting on data housed in a database or other repository...
,
database connectivityA database connection is a facility in computer science that allows client software to communicate with database server software, whether on the same machine or not. A connection is required to send commands and receive answers....
,
cryptographyCryptography is the practice and study of techniques for secure communication in the presence of third parties...
,
web applicationA web application is an application that is accessed over a network such as the Internet or an intranet. The term may also mean a computer software application that is coded in a browser-supported language and reliant on a common web browser to render the application executable.Web applications are...
development, numeric
algorithmIn mathematics and computer science, an algorithm is an effective method expressed as a finite list of well-defined instructions for calculating a function. Algorithms are used for calculation, data processing, and automated reasoning...
s, and network communications. Programmers produce software by combining their own
source codeIn computer science, source code is text written using the format and syntax of the programming language that it is being written in. Such a language is specially designed to facilitate the work of computer programmers, who specify the actions to be performed by a computer mostly by writing source...
with the .NET Framework and other libraries. The .NET Framework is intended to be used by most new applications created for the Windows platform. Microsoft also produces a popular
integrated development environmentAn integrated development environment is a software application that provides comprehensive facilities to computer programmers for software development...
largely for .NET software called
Visual StudioMicrosoft Visual Studio is an integrated development environment from Microsoft. It is used to develop console and graphical user interface applications along with Windows Forms applications, web sites, web applications, and web services in both native code together with managed code for all...
.
History
Microsoft started development on the .NET Framework in the late 1990s originally under the name of Next Generation Windows Services (NGWS). By late 2000 the first beta versions of .NET 1.0 were released.
Version 3.0 of the .NET Framework is included with Windows Server 2008 and
Windows VistaWindows Vista is an operating system released in several variations developed by Microsoft for use on personal computers, including home and business desktops, laptops, tablet PCs, and media center PCs...
. Version 3.5 is included with Windows 7, and can also be installed on
Windows XPWindows XP is an operating system produced by Microsoft for use on personal computers, including home and business desktops, laptops and media centers. First released to computer manufacturers on August 24, 2001, it is the second most popular version of Windows, based on installed user base...
and the
Windows Server 2003Windows Server 2003 is a server operating system produced by Microsoft, introduced on 24 April 2003. An updated version, Windows Server 2003 R2, was released to manufacturing on 6 December 2005...
family of operating systems. On April 12, 2010, .NET Framework 4 was released alongside Visual Studio 2010.
The .NET Framework family also includes two versions for
mobileMobile computing is a form of human–computer interaction by which a computer is expected to be transported during normal usage. Mobile computing has three aspects: mobile communication, mobile hardware, and mobile software...
or
embeddedAn embedded system is a computer system designed for specific control functions within a larger system. often with real-time computing constraints. It is embedded as part of a complete device often including hardware and mechanical parts. By contrast, a general-purpose computer, such as a personal...
device use. A reduced version of the framework, the
.NET Compact FrameworkThe Microsoft .NET Compact Framework is a version of the .NET Framework that is designed to run on resource constrained mobile/embedded devices such as personal digital assistants , mobile phones, factory controllers, set-top boxes, etc...
, is available on Windows CE platforms, including
Windows MobileWindows Mobile is a mobile operating system developed by Microsoft that was used in smartphones and Pocket PCs, but by 2011 was rarely supplied on new phones. The last version is "Windows Mobile 6.5.5"; it is superseded by Windows Phone, which does not run Windows Mobile software.Windows Mobile is...
devices such as smartphones. Additionally, the
.NET Micro FrameworkThe .NET Micro Framework is an Open Source .NET platform for resource-constrained devices with at least 256 KBytes of flash and 64 KBytes of RAM. It includes a small version of the .NET CLR and supports development in C#, Visual Basic .NET, and debugging using Microsoft Visual Studio...
is targeted at severely resource-constrained devices.
| Version | Version Number | Release Date | Visual Studio | Default in Windows |
| 1.0 |
1.0.3705.0 |
2002-02-13 |
Visual Studio .NET |
Windows XP Tablet and Media Center Editions |
| 1.1 |
1.1.4322.573 |
2003-04-24 |
Visual Studio .NET 2003 |
Windows Server 2003 |
| 2.0 |
2.0.50727.42 |
2005-11-07 |
Visual Studio 2005 |
Windows Server 2003 R2 |
| 3.0 |
3.0.4506.30 |
2006-11-06 |
|
Windows Vista, Windows Server 2008 |
| 3.5 |
3.5.21022.8 |
2007-11-19 |
Visual Studio 2008 |
Windows 7, Windows Server 2008 R2 |
| 4.0 |
4.0.30319.1 |
2010-04-12 |
Visual Studio 2010 |
|
| 4.5 |
4.5.40805 |
2011-09-13 (Developer Preview) |
Visual Studio '11' |
Windows 8, Windows Server 8 |
A more complete listing of the releases of the .NET Framework may be found on the
List of .NET Framework versions.
Design features
Interoperability
- Because computer systems commonly require interaction between new and older applications, the .NET Framework provides means to access functionality that is implemented in programs that execute outside the .NET environment. Access to COM
Component Object Model is a binary-interface standard for software componentry introduced by Microsoft in 1993. It is used to enable interprocess communication and dynamic object creation in a large range of programming languages...
components is provided in the System.Runtime.InteropServices and System.EnterpriseServices namespaces of the framework; access to other functionality is provided using the P/InvokePlatform Invocation Services, commonly referred to as P/Invoke, is a feature of Common Language Infrastructure implementations, like Microsoft's Common Language Runtime, that enables managed code to call native code.-Explicit:...
feature.
Common Language Runtime Engine
- The Common Language Runtime
The Common Language Runtime is the virtual machine component of Microsoft's .NET framework and is responsible for managing the execution of .NET programs. In a process known as just-in-time compilation, the CLR compiles the intermediate language code known as CIL into the machine instructions...
(CLR) is the execution engine of the .NET Framework. All .NET programs execute under the supervision of the CLR, guaranteeing certain properties and behaviors in the areas of memory management, security, and exception handling.
Language Independence
- The .NET Framework introduces a Common Type System
In Microsoft's .NET Framework, the Common Type System is a standard that specifies how Type definitions and specific values of Types are represented in...
, or CTS. The CTS specification defines all possible datatypes and programming constructs supported by the CLR and how they may or may not interact with each other conforming to the Common Language InfrastructureThe Common Language Infrastructure is an open specification developed by Microsoft and standardized by ISO and ECMA that describes the executable code and runtime environment that form the core of the Microsoft .NET Framework and the free and open source implementations Mono and Portable.NET...
(CLI) specification. Because of this feature, the .NET Framework supports the exchange of types and object instances between libraries and applications written using any conforming .NET language.
Base Class Library
- The Base Class Library
The Base Class Library is a standard library available to all languages using the .NET Framework. .NET includes the BCL in order to encapsulate a large number of common functions, such as file reading and writing, graphic rendering, database interaction, and XML document manipulation, which makes...
(BCL), part of the Framework Class Library (FCL), is a library of functionality available to all languages using the .NET Framework. The BCL provides classesIn object-oriented programming, a class is a construct that is used as a blueprint to create instances of itself – referred to as class instances, class objects, instance objects or simply objects. A class defines constituent members which enable these class instances to have state and behavior...
which encapsulate a number of common functions, including fileA computer file is a block of arbitrary information, or resource for storing information, which is available to a computer program and is usually based on some kind of durable storage. A file is durable in the sense that it remains available for programs to use after the current program has finished...
reading and writing, graphic renderingRendering is the process of generating an image from a model , by means of computer programs. A scene file contains objects in a strictly defined language or data structure; it would contain geometry, viewpoint, texture, lighting, and shading information as a description of the virtual scene...
, databaseA database is an organized collection of data for one or more purposes, usually in digital form. The data are typically organized to model relevant aspects of reality , in a way that supports processes requiring this information...
interaction, XMLExtensible Markup Language is a set of rules for encoding documents in machine-readable form. It is defined in the XML 1.0 Specification produced by the W3C, and several other related specifications, all gratis open standards....
document manipulation and so on.
Simplified Deployment
- The .NET Framework includes design features and tools that help manage the installation
Installation of a program is the act of putting the program onto a computer system so that it can be executed....
of computer software to ensure that it does not interfere with previously installed software, and that it conforms to security requirements.
Security
- The design is meant to address some of the vulnerabilities, such as buffer overflow
In computer security and programming, a buffer overflow, or buffer overrun, is an anomaly where a program, while writing data to a buffer, overruns the buffer's boundary and overwrites adjacent memory. This is a special case of violation of memory safety....
s, that have been exploited by malicious software. Additionally, .NET provides a common security model for all applications.
Portability
- While Microsoft has never implemented the full framework on any system except Microsoft Windows, the framework is engineered to be platform agnostic, and cross-platform implementations are available for other operating systems (see Silverlight and the Alternative implementations section below). Microsoft submitted the specifications for the Common Language Infrastructure
The Common Language Infrastructure is an open specification developed by Microsoft and standardized by ISO and ECMA that describes the executable code and runtime environment that form the core of the Microsoft .NET Framework and the free and open source implementations Mono and Portable.NET...
(which includes the core class libraries, Common Type SystemIn Microsoft's .NET Framework, the Common Type System is a standard that specifies how Type definitions and specific values of Types are represented in...
, and the Common Intermediate LanguageCommon Intermediate Language is the lowest-level human-readable programming language defined by the Common Language Infrastructure specification and is used by the .NET Framework and Mono...
), the C# language, and the C++/CLI language to both ECMAEcma International is an international, private non-profit standards organization for information and communication systems. It acquired its name in 1994, when the European Computer Manufacturers Association changed its name to reflect the organization's global reach and activities...
and the ISOThe International Organization for Standardization , widely known as ISO, is an international standard-setting body composed of representatives from various national standards organizations. Founded on February 23, 1947, the organization promulgates worldwide proprietary, industrial and commercial...
, making them available as open standards. This makes it possible for third parties to create compatible implementations of the framework and its languages on other platforms.
Architecture
Common Language Infrastructure (CLI)
The purpose of the Common Language Infrastructure (CLI) is to provide a language-neutral platform for application development and execution, including functions for
Exception handlingException handling is a programming language construct or computer hardware mechanism designed to handle the occurrence of exceptions, special conditions that change the normal flow of program execution....
,
Garbage CollectionIn computer science, garbage collection is a form of automatic memory management. The garbage collector, or just collector, attempts to reclaim garbage, or memory occupied by objects that are no longer in use by the program...
, security, and interoperability. By implementing the core aspects of the .NET Framework within the scope of the CLI, this functionality will not be tied to a single language but will be available across the many languages supported by the framework. Microsoft's implementation of the CLI is called the
Common Language RuntimeThe Common Language Runtime is the virtual machine component of Microsoft's .NET framework and is responsible for managing the execution of .NET programs. In a process known as just-in-time compilation, the CLR compiles the intermediate language code known as CIL into the machine instructions...
, or CLR.
The
CILCommon Intermediate Language is the lowest-level human-readable programming language defined by the Common Language Infrastructure specification and is used by the .NET Framework and Mono...
code is housed in
.NET assembliesIn the .NET framework, an assembly is a compiled code library used for deployment, versioning, and security. There are two types: process assemblies and library assemblies . A process assembly represents a process that will use classes defined in library assemblies...
. As mandated by specification, assemblies are stored in the
Portable ExecutableThe Portable Executable format is a file format for executables, object code and DLLs, used in 32-bit and 64-bit versions of Windows operating systems. The term "portable" refers to the format's versatility in numerous environments of operating system software architecture...
(PE) format, common on the Windows platform for all
DLLDynamic-link library , or DLL, is Microsoft's implementation of the shared library concept in the Microsoft Windows and OS/2 operating systems...
and
EXEEXE is the common filename extension denoting an executable file in the DOS, OpenVMS, Microsoft Windows, Symbian, and OS/2 operating systems....
files. The assembly consists of one or more files, one of which must contain the manifest, which has the
metadataThe term metadata is an ambiguous term which is used for two fundamentally different concepts . Although the expression "data about data" is often used, it does not apply to both in the same way. Structural metadata, the design and specification of data structures, cannot be about data, because at...
for the assembly. The complete name of an assembly (not to be confused with the filename on disk) contains its simple text name, version number, culture, and public key token. The public key token is a unique hash generated when the assembly is compiled, thus two assemblies with the same public key token are guaranteed to be identical from the point of view of the framework. A private key can also be specified known only to the creator of the assembly and can be used for strong naming and to guarantee that the assembly is from the same author when a new version of the assembly is compiled (required to add an assembly to the
Global Assembly CacheThe Global Assembly Cache or GAC is a machine-wide .NET assemblies cache for Microsoft's CLR platform. The approach of having a specially controlled central repository addresses the shared library concept and helps to avoid pitfalls of other solutions that led to drawbacks like DLL hell.-...
).
Security
.NET has its own security mechanism with two general features:
Code Access SecurityCode Access Security , in the Microsoft .NET framework, is Microsoft's solution to prevent untrusted code from performing privileged actions. When the CLR loads an assembly it will obtain evidence for the assembly and use this to identify the code group that the assembly belongs to. A code group...
(CAS), and validation and verification. Code Access Security is based on evidence that is associated with a specific assembly. Typically the evidence is the source of the assembly (whether it is installed on the local machine or has been downloaded from the intranet or Internet). Code Access Security uses evidence to determine the permissions granted to the code. Other code can demand that calling code is granted a specified permission. The demand causes the
CLRThe Common Language Runtime is the virtual machine component of Microsoft's .NET framework and is responsible for managing the execution of .NET programs. In a process known as just-in-time compilation, the CLR compiles the intermediate language code known as CIL into the machine instructions...
to perform a call stack walk: every assembly of each method in the call stack is checked for the required permission; if any assembly is not granted the permission a security exception is thrown.
Class library
The .NET Framework includes a set of
standardA standard library for a programming language is the library that is conventionally made available in every implementation of that language. In some cases, the library is described directly in the programming language specification; in other cases, the contents of the standard library are...
class libraries. The class library is organized in a hierarchy of
namespacesA namespace is an abstract container or environment created to hold a logical grouping of unique identifiers or symbols . An identifier defined in a namespace is associated only with that namespace. The same identifier can be independently defined in multiple namespaces...
. Most of the built in APIs are part of either
System.* or
Microsoft.* namespaces. These class libraries implement a large number of common functions, such as file reading and writing, graphic rendering, database interaction, and XML document manipulation, among others. The .NET class libraries are available to all CLI compliant languages. The .NET Framework class library is divided into two parts: the Base Class Library and the Framework Class Library.
The
Base Class LibraryThe Base Class Library is a standard library available to all languages using the .NET Framework. .NET includes the BCL in order to encapsulate a large number of common functions, such as file reading and writing, graphic rendering, database interaction, and XML document manipulation, which makes...
(BCL) includes a small subset of the entire class library and is the core set of classes that serve as the basic API of the
Common Language RuntimeThe Common Language Runtime is the virtual machine component of Microsoft's .NET framework and is responsible for managing the execution of .NET programs. In a process known as just-in-time compilation, the CLR compiles the intermediate language code known as CIL into the machine instructions...
. The classes in
mscorlib.dll and some of the classes in
System.dll and
System.core.dll are considered to be a part of the BCL. The BCL classes are available in both .NET Framework as well as its alternative implementations including
.NET Compact FrameworkThe Microsoft .NET Compact Framework is a version of the .NET Framework that is designed to run on resource constrained mobile/embedded devices such as personal digital assistants , mobile phones, factory controllers, set-top boxes, etc...
,
Microsoft SilverlightMicrosoft Silverlight is an application framework for writing and running rich Internet applications, with features and purposes similar to those of Adobe Flash. The run-time environment for Silverlight is available as a plug-in for web browsers running under Microsoft Windows and Mac OS X...
and
MonoMono, pronounced , is a free and open source project led by Xamarin to create an Ecma standard compliant .NET-compatible set of tools including, among others, a C# compiler and a Common Language Runtime....
.
The
Framework Class LibraryThe Framework Class Library is a standard library and one of two core components of Microsoft .NET Framework. The FCL is a collection of thousands of reusable classes , interfaces and value types...
(FCL) is a superset of the BCL classes and refers to the entire class library that ships with .NET Framework. It includes an expanded set of libraries, including
Windows FormsWindows Forms is the name given to the graphical application programming interface included as a part of Microsoft .NET Framework, providing access to native Microsoft Windows interface elements by wrapping the extant Windows API in managed code...
,
ADO.NETADO.NET is a set of computer software components that programmers can use to access data and data services. It is a part of the base class library that is included with the Microsoft .NET Framework. It is commonly used by programmers to access and modify data stored in relational database systems,...
,
ASP.NETASP.NET is a Web application framework developed and marketed by Microsoft to allow programmers to build dynamic Web sites, Web applications and Web services. It was first released in January 2002 with version 1.0 of the .NET Framework, and is the successor to Microsoft's Active Server Pages ...
,
Language Integrated QueryLanguage Integrated Query is a Microsoft .NET Framework component that adds native data querying capabilities to .NET languages, although ports exist for Java, PHP and JavaScript....
,
Windows Presentation FoundationDeveloped by Microsoft, the Windows Presentation Foundation is a computer-software graphical subsystem for rendering user interfaces in Windows-based applications. WPF, previously known as "Avalon", was initially released as part of .NET Framework 3.0. Rather than relying on the older GDI...
,
Windows Communication FoundationThe Windows Communication Foundation , previously known as "Indigo", is an application programming interface in the .NET Framework for building connected, service-oriented applications.-The architectures:...
among others. The FCL is much larger in scope than standard libraries for languages like
C++C++ is a statically typed, free-form, multi-paradigm, compiled, general-purpose programming language. It is regarded as an intermediate-level language, as it comprises a combination of both high-level and low-level language features. It was developed by Bjarne Stroustrup starting in 1979 at Bell...
, and comparable in scope to the
standard libraries of JavaThe Java Class Library is a set of dynamically loadable libraries that Java applications can call at run time. Because the Java Platform is not dependent on any specific operating system, applications cannot rely on any of the existing libraries...
.
Memory management
The .NET Framework CLR frees the developer from the burden of managing memory (allocating and freeing up when done); instead it does the memory management itself by detecting when memory can be safely freed. Memory is allocated to instantiations of .NET types (objects) from the managed heap, a pool of memory managed by the CLR. As long as there exists a reference to an object, which might be either a direct reference to an object or via a
graphIn computer science, a graph is an abstract data structure that is meant to implement the graph and hypergraph concepts from mathematics.A graph data structure consists of a finite set of ordered pairs, called edges or arcs, of certain entities called nodes or vertices...
of objects, the object is considered to be in use. When there is no reference to an object, and it cannot be reached or used, it becomes garbage, eligible for collection. NET Framework includes a
garbage collectorIn computer science, garbage collection is a form of automatic memory management. The garbage collector, or just collector, attempts to reclaim garbage, or memory occupied by objects that are no longer in use by the program...
which runs periodically, on a separate thread from the application's thread, that enumerates all the unusable objects and reclaims the memory allocated to them.
The .NET
Garbage CollectorIn computer science, garbage collection is a form of automatic memory management. The garbage collector, or just collector, attempts to reclaim garbage, or memory occupied by objects that are no longer in use by the program...
(GC) is a non-deterministic, compacting, mark-and-sweep garbage collector. The GC runs only when a certain amount of memory has been used or there is enough pressure for memory on the system. Since it is not guaranteed when the conditions to reclaim memory are reached, the GC runs are non-deterministic. Each .NET application has a set of roots, which are pointers to objects on the managed heap (
managed objects). These include references to static objects and objects defined as local variables or method parameters currently in scope, as well as objects referred to by CPU registers. When the GC runs, it pauses the application, and for each object referred to in the root, it
recursivelyRecursion is the process of repeating items in a self-similar way. For instance, when the surfaces of two mirrors are exactly parallel with each other the nested images that occur are a form of infinite recursion. The term has a variety of meanings specific to a variety of disciplines ranging from...
enumerates all the objects reachable from the root objects and marks them as reachable. It uses .NET metadata and
reflectionIn computer science, reflection is the process by which a computer program can observe and modify its own structure and behavior at runtime....
to discover the objects encapsulated by an object, and then recursively walk them. It then enumerates all the objects on the heap (which were initially allocated contiguously) using reflection. All objects not marked as reachable are garbage. This is the
mark phase. Since the memory held by garbage is not of any consequence, it is considered free space. However, this leaves chunks of free space between objects which were initially contiguous. The objects are then
compacted together to make used memory contiguous again. Any reference to an object invalidated by moving the object is updated by the GC to reflect the new location. The application is resumed after the garbage collection is over.
The GC used by .NET Framework is actually
generational. Objects are assigned a
generation; newly created objects belong to
Generation 0. The objects that survive a garbage collection are tagged as
Generation 1, and the Generation 1 objects that survive another collection are
Generation 2 objects. The .NET Framework uses up to Generation 2 objects. Higher generation objects are garbage collected less frequently than lower generation objects. This helps increase the efficiency of garbage collection, as older objects tend to have a larger lifetime than newer objects. Thus, by removing older (and thus more likely to survive a collection) objects from the scope of a collection run, fewer objects need to be checked and compacted.
Standardization and licensing
In August 2000,
MicrosoftMicrosoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...
,
Hewlett-PackardHewlett-Packard Company or HP is an American multinational information technology corporation headquartered in Palo Alto, California, USA that provides products, technologies, softwares, solutions and services to consumers, small- and medium-sized businesses and large enterprises, including...
, and Intel worked to standardize CLI and the C# programming language. By December 2001, both were ratified
ECMAEcma International is an international, private non-profit standards organization for information and communication systems. It acquired its name in 1994, when the European Computer Manufacturers Association changed its name to reflect the organization's global reach and activities...
standards (
ECMA 335 and
ECMA 334). ISO followed in April 2003 - the current version of the ISO standards are ISO/IEC 23271:2006 and ISO/IEC 23270:2006.
While Microsoft and their partners hold patents for the CLI and C#, ECMA and ISO require that all patents essential to implementation be made available under "
reasonable and non-discriminatory termsReasonable and non-discriminatory licensing is a type of licensing typically used during standardization processes. When joining a standardization body, companies normally agree that if they receive any patents on technologies which become essential to the standard they agree to allow other...
". In addition to meeting these terms, the companies have agreed to make the patents available royalty-free.
However, this does not apply for the part of the .NET Framework which is not covered by the ECMA/ISO standard, which includes
Windows FormsWindows Forms is the name given to the graphical application programming interface included as a part of Microsoft .NET Framework, providing access to native Microsoft Windows interface elements by wrapping the extant Windows API in managed code...
,
ADO.NETADO.NET is a set of computer software components that programmers can use to access data and data services. It is a part of the base class library that is included with the Microsoft .NET Framework. It is commonly used by programmers to access and modify data stored in relational database systems,...
, and
ASP.NETASP.NET is a Web application framework developed and marketed by Microsoft to allow programmers to build dynamic Web sites, Web applications and Web services. It was first released in January 2002 with version 1.0 of the .NET Framework, and is the successor to Microsoft's Active Server Pages ...
. Patents that Microsoft holds in these areas may deter non-Microsoft implementations of the full framework.
On 3 October 2007, Microsoft announced that much of the
source codeIn computer science, source code is text written using the format and syntax of the programming language that it is being written in. Such a language is specially designed to facilitate the work of computer programmers, who specify the actions to be performed by a computer mostly by writing source...
for the .NET Framework
Base Class LibraryThe Base Class Library is a standard library available to all languages using the .NET Framework. .NET includes the BCL in order to encapsulate a large number of common functions, such as file reading and writing, graphic rendering, database interaction, and XML document manipulation, which makes...
(including
ASP.NETASP.NET is a Web application framework developed and marketed by Microsoft to allow programmers to build dynamic Web sites, Web applications and Web services. It was first released in January 2002 with version 1.0 of the .NET Framework, and is the successor to Microsoft's Active Server Pages ...
,
ADO.NETADO.NET is a set of computer software components that programmers can use to access data and data services. It is a part of the base class library that is included with the Microsoft .NET Framework. It is commonly used by programmers to access and modify data stored in relational database systems,...
, and
Windows Presentation FoundationDeveloped by Microsoft, the Windows Presentation Foundation is a computer-software graphical subsystem for rendering user interfaces in Windows-based applications. WPF, previously known as "Avalon", was initially released as part of .NET Framework 3.0. Rather than relying on the older GDI...
) was to have been made available with the final release of Visual Studio 2008 towards the end of 2007 under the
shared sourceShared source is an umbrella term covering some of Microsoft's legal mechanisms for software source code distribution. Microsoft's Shared Source Initiative, launched in May 2001, includes a spectrum of technologies and licenses...
Microsoft Reference License. The source code for other libraries including
Windows Communication FoundationThe Windows Communication Foundation , previously known as "Indigo", is an application programming interface in the .NET Framework for building connected, service-oriented applications.-The architectures:...
(WCF),
Windows Workflow FoundationWindows Workflow Foundation is a Microsoft technology that provides an API, an in-process workflow engine, and a rehostable designer to implement long-running processes as workflows within .NET applications...
(WF), and
Language Integrated QueryLanguage Integrated Query is a Microsoft .NET Framework component that adds native data querying capabilities to .NET languages, although ports exist for Java, PHP and JavaScript....
(LINQ) were to be added in future releases. Being released under the non-open source Microsoft Reference License means this source code is made available for debugging purpose only, primarily to support integrated debugging of the BCL in Visual Studio.
Criticism
Some concerns and criticism relating to .NET include:
- Applications running in a managed environment tend to require more system resources than similar applications that access machine resources more directly.
- Unobfuscated
Obfuscated code is source or machine code that has been made difficult to understand for humans. Programmers may deliberately obfuscate code to conceal its purpose or its logic to prevent tampering, deter reverse engineering, or as a puzzle or recreational challenge for someone reading the source...
managedManaged code is a term coined by Microsoft to identify computer program code that requires and will only execute under the "management" of a Common Language Runtime virtual machine ....
CILCommon Intermediate Language is the lowest-level human-readable programming language defined by the Common Language Infrastructure specification and is used by the .NET Framework and Mono...
bytecode can often be easier to reverse-engineer than native code. One concern is over possible loss of trade secretA trade secret is a formula, practice, process, design, instrument, pattern, or compilation of information which is not generally known or reasonably ascertainable, by which a business can obtain an economic advantage over competitors or customers...
s and the bypassing of license control mechanisms. Since Visual Studio .NET (2002), Microsoft has included a tool to obfuscate code (DotfuscatorDotfuscator is software used for obfuscation of .NET assemblies. Among its abilities are mangling of identifier names into unreadable characters, but also changing control flow into being more unreadable at the IL-level for a human and other relatively advanced changes.Note that name mangling...
Community Edition).
- Newer versions of the framework (3.5 and up) are not pre-installed in versions of Windows below Windows 7 (although newer versions are available via Windows Update
Windows Update is a service provided by Microsoft that provides updates for the Microsoft Windows operating system and its installed components, including Internet Explorer...
). For this reason, applications must lead users without the framework through a procedure to install it. Some developers have expressed concerns about the large size of the .NET Framework runtime installers for end-users. The size is around 54 MB for .NET 3.0, 197 MB for .NET 3.5, and 250 MB for .NET 3.5 SP1 (while using web installer the typical download for Windows XP is around 50 MB, for Windows Vista - 20 MB). The size issue is partially solved with .NET 4 installer (x86 + x64) being 54 MB and not embedding full runtime installation packages for previous versions. The .NET 3.5 SP1 full installation package includes the full runtime installation packages for .NET 2.0 SP2 as well as .NET 3.0 SP2 for multiple operating systems (Windows XP/Server 2003 and Windows Vista/Server 2008) and for multiple CPU architectures (x86, x86-64x86-64 is an extension of the x86 instruction set. It supports vastly larger virtual and physical address spaces than are possible on x86, thereby allowing programmers to conveniently work with much larger data sets. x86-64 also provides 64-bit general purpose registers and numerous other...
, and IA-64).
- The first service pack for version 3.5 mitigates this concern by offering a lighter-weight client-only subset of the .NET Framework. Two significant limitations should be noted, though. Firstly, the client-only subset is only an option on an existing Windows XP SP2 system that currently has no other version of the .NET Framework installed. In all other scenarios, the client-only installer will install the full version of the .NET Framework 3.5 SP1. Secondly, the client-only framework does not have a 64-bit option. However, the 4 release of the .NET Framework Client Profile will be available on all operating systems and all architectures (excluding Itanium
Itanium is a family of 64-bit Intel microprocessors that implement the Intel Itanium architecture . Intel markets the processors for enterprise servers and high-performance computing systems...
) supported by the full .NET Framework.
- The .NET Framework currently does not provide support for calling Streaming SIMD Extensions
In computing, Streaming SIMD Extensions is a SIMD instruction set extension to the x86 architecture, designed by Intel and introduced in 1999 in their Pentium III series processors as a reply to AMD's 3DNow! . SSE contains 70 new instructions, most of which work on single precision floating point...
(SSE) via managed codeManaged code is a term coined by Microsoft to identify computer program code that requires and will only execute under the "management" of a Common Language Runtime virtual machine ....
. However, MonoMono, pronounced , is a free and open source project led by Xamarin to create an Ecma standard compliant .NET-compatible set of tools including, among others, a C# compiler and a Common Language Runtime....
has provided support for SIMDSingle instruction, multiple data , is a class of parallel computers in Flynn's taxonomy. It describes computers with multiple processing elements that perform the same operation on multiple data simultaneously...
Extensions as of version 2.2 within the Mono.Simd namespace; Mono's lead developer Miguel de IcazaMiguel de Icaza is a Mexican free software programmer, best known for starting the GNOME and Mono projects.-Early years:Miguel de Icaza was born in Mexico City and studied at the Universidad Nacional Autonoma de México but never received a degree. He came from a family of scientists in which his...
has expressed hope that this SIMD support will be adopted by the CLR ECMA standard. Streaming SIMD Extensions have been available in x86 CPUs since the introduction of the Pentium IIIThe Pentium III brand refers to Intel's 32-bit x86 desktop and mobile microprocessors based on the sixth-generation P6 microarchitecture introduced on February 26, 1999. The brand's initial processors were very similar to the earlier Pentium II-branded microprocessors...
. Some other architectures such as ARMARM is a 32-bit reduced instruction set computer instruction set architecture developed by ARM Holdings. It was named the Advanced RISC Machine, and before that, the Acorn RISC Machine. The ARM architecture is the most widely used 32-bit ISA in numbers produced...
and MIPSMIPS is a reduced instruction set computer instruction set architecture developed by MIPS Technologies . The early MIPS architectures were 32-bit, and later versions were 64-bit...
also have SIMD extensions. In case the CPU lacks support for those extensions, the instructions are simulated in software.
- While the standards that make up .NET are inherently cross platform, Microsoft's full implementation of .NET is only supported on Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
. Microsoft does provide limited .NET subsets for other platforms such as XNAMicrosoft XNA is a set of tools with a managed runtime environment provided by Microsoft that facilitates video game development and management. XNA attempts to free game developers from writing "repetitive boilerplate code" and to bring different aspects of game production into a single system...
for Windows, Xbox 360The Xbox 360 is the second video game console produced by Microsoft and the successor to the Xbox. The Xbox 360 competes with Sony's PlayStation 3 and Nintendo's Wii as part of the seventh generation of video game consoles...
and Windows Phone 7Windows Phone is a mobile operating system developed by Microsoft, and is the successor to its Windows Mobile platform, although incompatible with it. Unlike its predecessor, it is primarily aimed at the consumer market rather than the enterprise market...
, Silverlight for Windows and Mac OS XMac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...
. Alternative implementations of the CLR, base class libraries, and compilers also exist (sometimes from other vendors). While all of these implementations are based on the same standards, they are still different implementations with varying levels of completeness in comparison to the full .NET version Microsoft ships for Windows and are on occasion incompatible.
Alternative implementations
The Microsoft .NET Framework is the predominant implementation of .NET technologies. Other implementations for parts of the framework exist. Although the runtime engine is described by an ECMA/ISO specification, other implementations of it may be encumbered by patent issues; ISO standards may include the disclaimer, "Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights." It is more difficult to develop alternatives to the base class library (BCL), which is not described by an open standard and may be subject to copyright restrictions. Additionally, parts of the BCL have Windows-specific functionality and behavior, so implementation on non-Windows platforms can be problematic.
Some alternative implementations of parts of the framework are listed here.
- Microsoft's .NET Micro Framework
The .NET Micro Framework is an Open Source .NET platform for resource-constrained devices with at least 256 KBytes of flash and 64 KBytes of RAM. It includes a small version of the .NET CLR and supports development in C#, Visual Basic .NET, and debugging using Microsoft Visual Studio...
is a .NET platform for extremely resource-constrained devices. Suman includes a small version of the .NET CLRThe Common Language Runtime is the virtual machine component of Microsoft's .NET framework and is responsible for managing the execution of .NET programs. In a process known as just-in-time compilation, the CLR compiles the intermediate language code known as CIL into the machine instructions...
and supports development in C# (though some developers were able to use VB.NET, albeit with an amount of hacking, and with limited functionalities) and debugging (in an emulator or on hardware), both using Microsoft Visual StudioMicrosoft Visual Studio is an integrated development environment from Microsoft. It is used to develop console and graphical user interface applications along with Windows Forms applications, web sites, web applications, and web services in both native code together with managed code for all...
. It also features a subset of the .NET base class libraries (about 70 classes with about 420 methods), a GUIGui or guee is a generic term to refer to grilled dishes in Korean cuisine. These most commonly have meat or fish as their primary ingredient, but may in some cases also comprise grilled vegetables or other vegetarian ingredients. The term derives from the verb, "gupda" in Korean, which literally...
framework loosely based on Windows Presentation FoundationDeveloped by Microsoft, the Windows Presentation Foundation is a computer-software graphical subsystem for rendering user interfaces in Windows-based applications. WPF, previously known as "Avalon", was initially released as part of .NET Framework 3.0. Rather than relying on the older GDI...
, and additional libraries specific to embedded applications.
- Mono
Mono, pronounced , is a free and open source project led by Xamarin to create an Ecma standard compliant .NET-compatible set of tools including, among others, a C# compiler and a Common Language Runtime....
is an up-to-date implementation of the CLI and the .NET Base Class Library (BCL), and provides additional functionality. It is dual-licensed under free softwareFree software, software libre or libre software is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with restrictions that only ensure that further recipients can also do...
and proprietary softwareProprietary software is computer software licensed under exclusive legal right of the copyright holder. The licensee is given the right to use the software under certain conditions, while restricted from other uses, such as modification, further distribution, or reverse engineering.Complementary...
licenses. It includes support for ASP.NET, ADO.NET, and Windows FormsWindows Forms is the name given to the graphical application programming interface included as a part of Microsoft .NET Framework, providing access to native Microsoft Windows interface elements by wrapping the extant Windows API in managed code...
libraries for a wide range of architectures and operating systems. It also includes C# and VB.NET compilers.
- Portable.NET
Part of the DotGNU project, Portable.NET is a free software and open source software initiative aiming to build a portable toolchain and runtime for Common Language Infrastructure applications. The project focuses on compatibility with the ECMA-334 and ECMA-335 standards and support for .NET's...
(part of DotGNUDotGNU is a part of the GNU Project that aims to provide a free software replacement for Microsoft's .NET Framework by Free Software Foundation...
) provides an implementation of the Common Language Infrastructure (CLI), portions of the .NET Base Class Library (BCL), and a C# compiler. It supports a variety of CPUs and operating systems.
- Microsoft's Shared Source Common Language Infrastructure
The Shared Source Common Language Infrastructure , previously codenamed Rotor, is Microsoft's shared source implementation of the CLI, the core of .NET. Although the SSCLI is not suitable for commercial use due to its license, it does make it possible for programmers to examine the implementation...
is a non free implementation of the CLR component of the .NET Framework. However, the last version only runs on Microsoft Windows XP SP2, and was not updated since 2006, therefore it does not contain all features of version 2.0 of the .NET Framework.
- CrossNet is an implementation of the CLI and portions of the .NET Base Class Library (BCL). It is free software
Free software, software libre or libre software is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with restrictions that only ensure that further recipients can also do...
using the open source MIT LicenseThe MIT License is a free software license originating at the Massachusetts Institute of Technology . It is a permissive license, meaning that it permits reuse within proprietary software provided all copies of the licensed software include a copy of the MIT License terms...
. As of September 2011, it seems that CrossNet development is not active since October 2007.
External links