Introduction to .Net framework

BY-Teach4u.in

The .NET Framework

What is Microsoft .NET?A programming model: CLR + ClassesXML Web servicesServer and Client software and tools

Common Language Runtime (CLR)It’s a VM (Java-like) on which any

(supported) language can run.Why a VM?

Memory ProtectionCross-languageSupport for strong-typing across languages

(the data are typed)Thread support

JIT compilation in the VM

Languages in CLRLanguage of choice is C# (“C-sharp”) a Java-like

languageNo inner classesBetter type checking

Other languages will run on CLR, but only within the CLR constraintsVisual Basic, JScript are full fledged CLR languagesFor example, only C++ that is VM-safe will runThat subset looks much like C#

Under CLR, all languages get object features Inheritance used extensivelyEvery language gets constructors

Languages compile to MSILLanguages compile to MSIL (Microsoft

Intermediate Language)Can you say “bytecodes”?

MSIL is shipped in portable executable (PE) unitsCan you say .class files or applets?

An application is made up of assemblies

Assemblies In general, a static

assembly can consist of four elements:

The assembly manifest, which contains assembly metadata.

Type metadata. Microsoft intermediate

language (MSIL) code that implements the types.

A set of resources.

Assemblies can be spread across .NET

Assemblies are the security unitEach assembly has a set of corresponding

grants Each grant allows certain permissions

DnsPermission, Environment, FileDialog, FileIO, IsolatedStorage, Reflection, Registry, Security, UI, WebPermission, SocketPermission

The set of grants establishes a security policy

Class LibraryData classes support persistent data

management and include SQL classes. XML classes enable XML data manipulation

and XML searching and translations.Windows Forms support development of

Windows GUI applications across CLRWeb Forms include classes that enable you to

rapidly develop web GUI applications.

System.ObjectPublic methods:

EqualsGetHashCodeGetTypeToString

Overriding inherited behaviors is common

Web, Windows, WhateverPart of the idea is to smooth transitions

between Windows and WebWeb interfaces become easier for Windows

developersWindows apps become .NET Web-based apps

Data <-> XML, EverywhereAll CLR data can be

serialized to XMLAll XML can be expanded

into CLR dataThus, anything can be

shipped around on the Web

Typing through XML Schema

XML Schema<xsd:complexType name="Person"> <xsd:sequence> <xsd:choice> <xsd:element name="name" type="xsd:string" xsi:nillable="true" /> <xsd:element name="id" type="xsd:string" /> </xsd:choice> <xsd:any processContents="lax"/> </xsd:sequence> </xsd:complexType> <xsd:complexType name="AgedPerson"> <xsd:complexContent mixed="false"> <xsd:extension base="target:Person"> <xsd:choice> <xsd:element name="age" type="xsd:double" /> <xsd:element name="timeOnEarth" type="xsd:double" /> </xsd:choice> </xsd:extension> </xsd:complexContent> </xsd:complexType> <xsd:element name="don" type="target:Person" />

Example Instance<ns:don xmlns:ns="uuid:048b2fa1-d557-473f-ba4c- acee78fe3f7d" > <name>Don Box</name> <niceStuffForDon/> </ns:don>

Second Example Instance<ns:don xmlns:ns="uuid:048b2fa1-d557-473f-ba4c-acee78fe3f7d" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:type="ns:AgedPerson" > <name>Don Box</name> <niceStuffForDon/> <age>26</age></ns:don>

A Simpler Schema

<element name="Book"><complexType> <element name="author"

type="xsd:string"/> <element name="preface"

type="xsd:string"/> <element name="intro"

type="xsd:string"/></complexType></e:Book>

Another Example Instance

<e:Book> <author>Henry Ford</author> <preface>Prefatory text</preface> <intro>This is a book.</intro></e:Book>

XML Schema Defined Types

Class Library Data Hierarchy

Reading in XML DataXmlReader reader = new XmlTextReader("http://foo.com/don.xsd");

XmlSchema schema = XmlSchema.Load(reader, null);schema.Compile(null); // turn xml into objectsreader.Close();

ALL Interprocess Communication via SOAPALL Interprocess communication (across

network or on same machine) is through SOAPSimple Object Access ProtocolIt’s a way of exchanging data and even calling

other methods/threads, all via XML and plain old HTTP requests

Example SOAP RequestPOST /StockQuote HTTP/1.1Host: www.stockquoteserver.comContent-Type: text/xml; charset="utf-8"Content-Length: nnnnSOAPAction: "Some-URI"<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"> <SOAP-ENV:Body> <m:GetLastTradePrice xmlns:m="Some-URI"> <symbol>DIS</symbol> </m:GetLastTradePrice> </SOAP-ENV:Body></SOAP-ENV:Envelope>

Example SOAP ResponseHTTP/1.1 200 OKContent-Type: text/xml; charset="utf-8"Content-Length: nnnn

<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"

SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"/>

<SOAP-ENV:Body> <m:GetLastTradePriceResponse xmlns:m="Some-URI"> <Price>34.5</Price> </m:GetLastTradePriceResponse> </SOAP-ENV:Body></SOAP-ENV:Envelope>

ASP.NETASP =>

Active Server PagesPut most of the

computation in the server

Very simple model to use

ADO.NET is the database connection part

Calling Web Services Any class can be converted into an XML Web Service with just a

few lines of code, and can be called by any SOAP client. 

Take-away lessonsVM’s are important

Even Microsoft thinks soDistributed apps are important, but to do so

requires standard protocolsWays of serializing dataWays of doing RPC

Limitations of the .NET FrameworkWhat if you’re not on the network?

Maybe that’s not an issue?Mapping between XML and any object is

hardAny object is controlled by compiler.

XML can be written by anybody with a text editor.

There’s a whole bunch of class support for modified serializers and compilers