.NET’s CLR
How does it really work?
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Bhavani Sankar Ikkurthi CS 795 Presentation
3/23/2016
Overview
CLR : Common Language Runtime
Platform for software development that provides services
by consuming metadata
Standards based, Component oriented
What is CLR
Benefits
Inside CLR
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Bhavani Sankar Ikkurthi CS 795 Presentation
3/23/2016
CLR BASICS
Core of .NET vision
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Bhavani Sankar Ikkurthi CS 795 Presentation
3/23/2016
CLR as a development platform
It provides
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Bhavani Sankar Ikkurthi CS 795 Presentation
3/23/2016
Runtime
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A piece of code written by platform vendor
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Provides services to the software that you write
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Visual Basic Runtime, the SQL Server Engine and the
COM+/MTS runtime.
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Bhavani Sankar Ikkurthi CS 795 Presentation
3/23/2016
Runtime
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Bhavani Sankar Ikkurthi CS 795 Presentation
3/23/2016
Libraries
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CLR's Base Class Library allow us to interact with the
runtime, and provide additional useful functionality.
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How do you take advantage of runtime?
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BCL includes ASP.NET, XML Parser and other thousands
of classes
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Bhavani Sankar Ikkurthi CS 795 Presentation
3/23/2016
Languages
How do I take advantage of libraries and runtime
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C#,Visual Basic.NET, IL, C++, and JScript.NET
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How is CLR different then??
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Bhavani Sankar Ikkurthi CS 795 Presentation
3/23/2016
Components
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Component oriented programming from Hardware
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Software systems can be built from software components
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Organizing components can ease maintenance
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Every piece of CLR functionality that we run must belong
to a component
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Bhavani Sankar Ikkurthi CS 795 Presentation
3/23/2016
Standards
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A standard is a document that describes a convention or
protocol that everyone agrees to follow
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HTTP standard
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Explicit support for XML and SOAP
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CLI
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Bhavani Sankar Ikkurthi CS 795 Presentation
3/23/2016
.NET is cross-platform
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Compiled .NET apps run on any supported platform:
APP.exe
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Win64
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Win32
(XP,2K,98)
WinCE
Bhavani Sankar Ikkurthi CS 795 Presentation
3/23/2016
How is cross-platform achieved?
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Cross-platform execution realized in two ways:
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Apps are written against Framework Class Library (FCL),
not underlying OS
Compilers generate generic assembly language which must be executed by the
Common Language Runtime (CLR)
• Framework Class Library
– 1000's of predefined classes
– common subset across all
platforms & languages
– networking, database access, XML
processing, GUI, Web, etc.
– Goal? FCL is a portable operating
system
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Bhavani Sankar Ikkurthi CS 795 Presentation
3/23/2016
The Common Language Runtime (CLR)
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The CLR defines a common programming model and a standard type system
for cross-platform, multi-language development.”
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All .NET-aware compilers generate Intermediate Language (IL) instructions and
metadata.
The runtime's Just-in-Time (JIT) compiler convert the IL to a machine-specific
(native) code when an application actually runs.
Because the CLR is responsible for managing this IL, the code is known as
managed code.
Bhavani Sankar Ikkurthi CS 795 Presentation
3/23/2016
Intermediate Language (IL)
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All .NET-aware compilers generate Intermediate Language (IL) instructions
and metadata.
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Bhavani Sankar Ikkurthi CS 795 Presentation
3/23/2016
Assemblies
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1 assembly = 1 or more compiled classes
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.EXE represents an assembly with classes + Main program
.DLL represents an assembly with classes
code.vb
code.vb
code.cs
Development Tools
.EXE / .DLL
assembly
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Bhavani Sankar Ikkurthi CS 795 Presentation
3/23/2016
.NET Application Design
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Monolithic app: all source code compiled into one .EXE
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not the norm on Windows…
APP.exe
• Component-based app: .EXE + one or more .DLLs
– standard practice on Windows…
compute.dll
GUI.exe
data.dll
– team programming
– multi-language development (I like C#, you like C++, he/she likes VB)
– code reuse (e.g. across different .EXEs)
– independent updating (update just component X)
– FCL ships as a set of components!
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Bhavani Sankar Ikkurthi CS 795 Presentation
3/23/2016
CLR-based execution
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Common Language Runtime must be present to execute code:
APP.exe
OS Process
other FCL
components
JIT Compiler
obj code
Core
FCL
CLR
Underlying OS and HW
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Bhavani Sankar Ikkurthi CS 795 Presentation
3/23/2016
CLR-based execution revisited
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CLR must be able to locate all assemblies:
.DLL
.DLL
.DLL
.EXE
OS Process
other FCL
assemblies
JIT Compiler
obj code
obj code
obj code
obj code
Core FCL
assembly
CLR
Underlying OS and HW
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Bhavani Sankar Ikkurthi CS 795 Presentation
3/23/2016
mscoree.dll - Common Object Runtime Execution Engine
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Bhavani Sankar Ikkurthi CS 795 Presentation
3/23/2016
Memory Management
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Bhavani Sankar Ikkurthi CS 795 Presentation
3/23/2016
Memory Management
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Bhavani Sankar Ikkurthi CS 795 Presentation
3/23/2016
References
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http://www.theserverside.net/tt/articles/showarticle.tss?id
=DM_CLR
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http://msdn.microsoft.com/enus/library/8bs2ecf4(VS.71).aspx
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C# and the .NET Platform, Second Edition by
Andrew Troelsen
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Bhavani Sankar Ikkurthi CS 795 Presentation
3/23/2016
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Bhavani Sankar Ikkurthi CS 795 Presentation
3/23/2016