Common language runtime

The Common Language Runtime shortly CLR , is the name of the virtual runtime environment of .NET - applications . The CLR thus represents a concrete implementation of the runtime environment of the common language infrastructure for the .NET framework. The CLR does not directly execute the program code of a high-level programming language, but interprets Common Intermediate Language code (ECMA designation, formerly Microsoft Intermediate Language). For this, the program code of a .NET language (C #, J #, F #, C ++ / CIL…) is translated into CIL code using a language-dependent compiler. Among other things, this has the advantage that parts of a program can be written in different programming languages.

Explanation and functionality

Simplified functional principle of the common language runtime in the .NET Framework

If a program is translated from a .NET programming language, assemblies (file extensions .exe or .dll ) are first generated which contain the translated CIL code as well as various headers and metadata. This step must be carried out by a language-specific compiler . CIL code is an intermediate code that is managed by the CLR and is therefore also referred to as managed code , as a differentiated from unmanaged code or native code . During the runtime of the program, the loaded assemblies are translated into native code (machine code) by a just-in-time compiler , which is part of the CLR, which can be executed by the CPU .

The services offered by the CLR can be used by the programming languages in which the respective application was programmed. These services include garbage collection , exception handling and ensuring code access security . The CLR relies on the Common Type System , which is a collection of types and functions that are supported in many programming languages.

The CLR is the implementation of the Virtual Execution System component , which belongs to the Common Language Infrastructure standard , for the .NET Framework .

Adaptations

There are other runtime environments that adapt the CLR and also use this name:

Mono contains a runtime environment based on the model of the .NET Framework; it is sometimes also referred to as CLR.
CoreCLR is the name of the runtime environment used in the modular, open source framework .NET Core .
.NET Native includes a runtime environment, which is also called CLR. It is used when running Universal Windows Platform Apps for Windows 10 . These applications are not in CIL code supplied , but directly into native code. Just-in-time compilation is no longer necessary.

literature

Don Box, Chris Sells: Essential .NET, Volume 1: The Common Language Runtime , Addison-Wesley 2002, ISBN 978-0-201-73411-9
Kevin Burton: .NET Common Language Runtime Unleashed , SAMS 2002, ISBN 978-0-672-32124-5
Jeffrey Richter: CLR via C # , 4th Edition, Microsoft Press 2012, ISBN 978-0-7356-6745-7
Dana L. Wyatt, Robert J. Oberg: Introduction to Visual Basic Using .NET , Prentice Hall 2002, ISBN 978-0-13-041804-3

Individual evidence

↑ Mohammad Rahman: C # Deconstructed: Discover how C # works on the .NET Framework , Apress 2014, ISBN 978-1-4302-6670-9 , p. 16
^ Neil McAllister: Microsoft takes lid off .Net Common Language Runtime sauce , in: The Register of February 3, 2015, accessed on Dec. 9, 2015
↑ Holger Schwichtenberg: Two in one stroke , in: Windows Developer No. 10/2015, p. 8 ff. ( Online edition , October 12, 2015, last accessed on December 16, 2016)

[1] Mohammad Rahman: C # Deconstructed: Discover how C # works on the .NET Framework , Apress 2014, ISBN 978-1-4302-6670-9 , p. 16

[2] Neil McAllister: Microsoft takes lid off .Net Common Language Runtime sauce , in: The Register of February 3, 2015, accessed on Dec. 9, 2015

[3] Holger Schwichtenberg: Two in one stroke , in: Windows Developer No. 10/2015, p. 8 ff. ( Online edition , October 12, 2015, last accessed on December 16, 2016)