What is .Net

Gary Devendorf

.Net Framework• .Net framework works like the Domino Objects only

much lower level and very complete• It is part of the OS (or can be added)• Replaces win32 API calls - mostly• Decoupled from OS• Supports many programming languages with the CLR

(Common Language Runtime)

.NET Framework Design Goals

• Unifies programming models• Dramatically simplifies development• Provides robust execution

environment• Supports multiple programming

languages• Natively supports XML Web Services

Robust Environment• Automatic lifetime management

• All objects are garbage collected

• Exception handling• Error handling 1st class and mandatory

• Type-safety• No buffer overruns, No unsafe casts,

uninitialized variables

• Deployment and management• Assemblies, side-by-side execution• No more DLL hell!

Terminology "ABC"

• CLR: Common Language Runtime• One runtime for many programming languages

• Intermediate Language (IL)• One intermediate, high-level assembly-style

language that is emitted by language compilers

• Assembly• Container for code, metadata and resources – your

new term for what you used to call "D-L-L"

• Metadata• Information that describes the shape of data and the

runtime behavior of a program

Operating SystemOperating System

Common Language RuntimeCommon Language Runtime

Base Class LibraryBase Class Library

ADO.NET and XMLADO.NET and XML

ASP.NETASP.NETWeb Forms Web ServicesWeb Forms Web Services

Mobile Internet ToolkitMobile Internet Toolkit

WindowsWindowsFormsForms

Common Language SpecificationCommon Language Specification

VBVB C++C++ C#C# JScriptJScript ……V

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Framework, Languages, And Tools

Multi-Language Platform• The .NET Platform is language neutral

• All .NET languages are first class players• Complete cross-language integration• Highly leveraged tools

• Microsoft is providing• Visual Basic®, C++, C#, Java, JScript®

• Industry and academia• APL, COBOL, Eiffel, Fortran, Haskell, ML, Perl, Python,

RPG, Scheme, Smalltalk, …

Common Language Runtime (CLR)

• Execution Environment for "managed code"• Managed?

• Code resides on disk as IL• Must be translated into machine code

• Code references other code• Other code residing in other Assemblies must be found

• Memory must be managed• Server applications must be 100% leak free• .NET employs a Garbage Collector to do that job

• Execution must be as secure as possible

AssemblyAssembly

CLR Execution Model: Conceptual

Source Source CodeCode

Language Language CompilerCompiler

CompilationCompilation

Before installation or Before installation or the first time each the first time each method is calledmethod is called

ExecutionExecution

JIT JIT CompilerCompiler

NativeNative

CodeCode

Code (IL)Code (IL)

MetadataMetadata

Global Assembly Cache (GAC)•Used as a centralized repository to store all shared assemblies

•Used to store the code downloaded from the Internet

•Repository for prejitted code

•gacutil /i BookFlight.dll

Side by Side Execution

ApplicationBookFlightV 1.0.0.5

ApplicationBookFlightV 1.0.1.9

ApplicationBookFlightV 2.0.0.0

GACGACPrivatePrivate

PolicyPolicy

Travel Portal (.asmx)Reference: BookFlight, v 1.0.0.5Travel Portal (.asmx)Reference: BookFlight, v 1.0.0.5

IBookflightIBookflight

IDispatchIDispatch

IUnknownIUnknown

COM CallableCOM CallableWrapperWrapper

COM Interoperability

BookFlightBookFlight

IBookFlightIBookFlight

Common Language RuntimeCommon Language Runtime

ISeatResISeatRes

SeatRes

Runtime CallableRuntime CallableWrapperWrapper

LegacyClient

Summary

• Unifies programming models• Dramatically simplifies development• Provides robust execution

environment• Supports multiple programming

languages• Natively supports XML Web Services

Read More at

• http://www.microsoft.com/net/basics/