Tài liệu DotNetOverview docx

development platform servers services.NET Overview • .NET is a sweeping marketing term for a family of products – development tools and languages Visual Studio .NET Common Language Runti

.NET Overview

– development and execution model

• Examine simple C# program

development platform servers services

.NET Overview

• NET is a sweeping marketing term for a family of products

– development tools and languages

Visual Studio NET

Common Language Runtime Framework Libraries SQL Server BizTalk

SharePoint

My Services Alerts

Passport

Evolution of the platform

• NET is the next evolutionary step for the Microsoft platform

– new languages largely replace classic C++ and Visual Basic

– new runtime model reduces need for COM style integration

– XML web services used in place of DCOM

– Windows Forms replace MFC

– ASP.NET improves on ASP

– etc

Language power

• All languages can access NET infrastructure

C#

class Hello {

static void Main() {

System.Console.WriteLine ("hello");

} }

VB.NET

Class Goodbye

Shared Sub Main() System.Console.WriteLine ("goodbye") End Sub

End Class

static void Main() {

System.Console.WriteLine(Greeting.Message());

} }

Class Greeting Shared Function Message() As String Return "hello"

End Function End Class

VB.NET

Language variability

• Not all NET languages have exactly the same capabilities

– differ in small but important ways

class Hello {

static void Main() {

int i;

uint u;

} }

Class Greeting Shared Sub Main() Dim i as Integer End Sub

signed integer

unsigned integer

signed integer only

Common Language Specification

• Common Language Specification (CLS) defines type subset

– required to be supported by all NET languages

– limiting code to CLS maximizes language interoperability

– code limited to CLS called CLS compliant

public class Calculator {

public uint Add(uint a, uint b) {

return a + b;

} }

not CLS compliant

to use uint in public

interface of public class

.NET Framework class library

Library

• Extensive set of standard libraries available

– for wide range of application types

– called NET Framework class library

Collections

Web development

Input/Output

Database access Windows Forms GUI

Networking

XML processing

Threading Reflection

Debugging

Calc c = new Calc();

int sum = c.Add(2, 4);

C# compiler

JIT runtime compile

• IL is compiled into machine code at runtime by the CLR

– compiles methods as needed

– called just in time (JIT) compile

• JIT compilation model:

– first time method is called the IL is compiled and optimized

– compiled machine code is cached in transient memory

– cached copy used for subsequent calls

IL code F() G()

JIT runtime

machine code for F()

NGEN install time compile

• Can compile IL into machine code when app installed

– use native image generator ngen.exe

– can speed startup time since code pre-compiled

– but cannot do as many optimizations

– original IL must still be available for type information

CLR

cache

machine code

Execution command

• CLR automatically invoked when NET application executed

C:\> MyApp hello

execute

Required CLR

• CLR and NET Framework required to run NET app

– will be incorporated into Windows and service packs

– developers install as part of NET Framework SDK

– users can run dotnetredist.exe

C# program

• C# program basics

– source file has cs extension

– namespace used to group related types

– class defines new type

– Main is application entry point

– WriteLine writes output

– { and } delimit code block

namespace MyNamespace {

class MyApp {

static void Main() {

System.Console.WriteLine("hello");

} }

Building console executable

• Can use C# compiler to build console executable

– use /t[arget]:exe

– use /out:<name> to specify output file name

• Default values can simplify use

– default target type is console executable

– default name adds exe to base name of file containing Main

C:\> csc /target:exe /out: MyApp.exe MyApp.cs

Building Windows executable

• Can use C# compiler to build windows executable

– use /t[arget]:winexe

C:\> csc /target:winexe MyWinApp.cs

build Windows

application

Building library

• Can use C# compiler to build library

– use /t[arget]:library

• Controlling output file name:

– can use /out:<name> to specify output file name

– default: adds dll to base name of first input file

C:\> csc /target:library /out: MyLib.dll MyLib.cs

create

library

• NET requires multiple steps to develop and run software

– code in one of the many NET languages

– compile into IL

– install the CLR

– execute

• CLR JIT compiles IL at runtime

– always executes compiled code

– never interpreted

• Can target CLS compliance

– to maximize language interoperability