JSP.pptx ROOPAM

8/8/2019 JSP.pptx ROOPAM

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JSPJSP

JavaServerJavaServer

PagesPages


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PagesPages The Typical WebThe Typical Web

server, differentserver, differentclients connectingclients connecting

via the Internet tovia the Internet to

a Web server. Ina Web server. In

this example, thethis example, theWeb serverisWeb serveris

running on Unixrunning on Unix

and is the veryand is the very

popular Apachepopular ApacheWeb serverWeb server..


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First static web pages were displayed.First static web pages were displayed.

Afterwards Perl and C were languages used onAfterwards Perl and C were languages used on

the web server toprovide dynamiccontent.the web server toprovide dynamiccontent.Soon most languages includingSoon most languages including VisualbasicVisualbasic,,

Delphi, C++ and Java could be used to writeDelphi, C++ and Java could be used to write

applications that provided dynamiccontent usingapplications that provided dynamiccontent using

data from text files or database requests.data from text files or database requests.

These were known as CGI server sideThese were known as CGI server side

applications.applications.

ASP was developed by Microsoft to allow HTMLASP was developed by Microsoft to allow HTMLdevelopers to easilyprovide dynamiccontentdevelopers to easilyprovide dynamiccontent

supported as standard by Internet Informationsupported as standard by Internet Information

Server (IIS).Server (IIS).

JSP was developed by Sun Microsystems.JSP was developed by Sun Microsystems.


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Introduction to Java ServerIntroduction to Java Server

PagesPages

JavaServerJavaServer Pages (JSP) is a technologyPages (JSP) is a technology

based on the Java language and enablesbased on the Java language and enables

the development ofdynamic web sites.the development ofdynamic web sites.JSP was developed by Sun MicrosystemsJSP was developed by Sun Microsystems

to allow server side development. JSPto allow server side development. JSP

files are HTML files with special Tagsfiles are HTML files with special Tags

containing Java source code that providecontaining Java source code that providethe dynamiccontent.the dynamiccontent.


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JSP source code runs on the web serverin the JSP Servlet Engine. The JSP

Servlet engine dynamically generates the HTML and sends the HTML output to

the client's web browser


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Why use JSP?Why use JSP?

JSP is easy to learn and allows developers toJSP is easy to learn and allows developers to

quicklyproduce web sites and applications in anquicklyproduce web sites and applications in an

open and standard way. JSP is based on Java,open and standard way. JSP is based on Java,

an object oriented language. JSP offers a robustan object oriented language. JSP offers a robustplatform for web development.platform for web development.

Main reasons to use JSPMain reasons to use JSP::Multiplatform (windows nMultiplatform (windows n unixunix))

Component reuse by usingComponent reuse by using JavabeansJavabeans and EJB.and EJB.

Advantages ofJava.Advantages ofJava.


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What are Java ServerWhat are Java Server

Pages?Pages?Conceptually seen as scriptsConceptually seen as scripts

Adopt more procedural style ofcodingAdopt more procedural style ofcoding

OO techniques are still possibleOO techniques are still possibleAdopt a modern web development styleAdopt a modern web development style

Simplified syntaxSimplified syntax

Many builtMany built--in shortin short--cutscuts

Text files containingText files containing

HTMLHTML

Java codeJava code


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You can take one JSP file and move it to another platform, webYou can take one JSP file and move it to another platform, web

server or JSPserver or JSP ServletServlet engine.engine.

Moving JSP file from one platform to another.Moving JSP file from one platform to another.


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HTML and graphics displayed on the web browser are classed as theHTML and graphics displayed on the web browser are classed as the

presentation layer..presentation layer..

JavaServer Pages

JSP

Implementation

Javadevelopers

presentation

web designers


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Advantages ofAdvantages of ServletsServlets

EfficientEfficient: threads instead ofOS processes, one: threads instead ofOS processes, oneservletservlet copy, persistencecopy, persistence

ConvenientConvenient: lots ofhigh: lots ofhigh--levellevel utilitiesutilities

PowerfulPowerful: talking to server, sharing data, pooling,: talking to server, sharing data, pooling,persistencepersistence

PortablePortable: run on virtually all operating systems: run on virtually all operating systemsand serversand servers

SecureSecure: no shell escapes, no buffer: no shell escapes, no bufferoverflowsoverflowsInexpensiveInexpensive: inexpensive plug: inexpensive plug--ins ifins ifservletservletsupport not bundledsupport not bundled


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Pro l ithPro l ith r l tr l t

r l tr l t d lopment requires highdevelopment requires high--level oflevel of

understanding ofmanyconceptsunderstanding ofmanyconcepts

Too much overhead in development cycleToo much overhead in development cycle(implementation n design concatenated)(implementation n design concatenated)

Limited uiltLimited uilt--in productivitymechanismsin productivitymechanisms

Clunkysyntax (Clunkysyntax (unorganisedunorganised))


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Advantages f J PAdvantages f J P

Versus ASP: better language for dynamicpart,Versus ASP: better language for dynamicpart,

portableportable

Versus PHP: better language for dynamicpartVersus PHP: better language for dynamicpart

Versus pureVersus pure servletsservlets: more convenient tocreate: more convenient tocreate

HTMLHTML

Versus SSI: much more flexible and powerfulVersus SSI: much more flexible and powerful

Versus JavaScript: serverVersus JavaScript: server--sideside,, richerricher languagelanguageVersus static HTML: dynamicfeaturesVersus static HTML: dynamicfeatures


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JSP orJSP or ServletsServlets: How do I choose?: How do I choose?

Servlets JSP

Servlets usageMinimal HTML generation

Somewhat constant logic

Complex Java logic

JSP usageComplex HTML

Dynamic logic

simple Java logic

Servlet disadvantages

Nopre-built set ofreusable

componentsHard to maintain when HTML

intensive

Require Java expertise

Development cycle

JSP disadvantages

Can get messy

Can be misused

Servlet benefits

Complete controlAdvanced development

Flexible

JSP benefits

Pre-built componentsExpression language

Convenience features

Requires minimal Java knowledge

Development cycle

Flexible


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JSP rchitect reJSP rchitect re

JSPs re b ilt on topofSUN'sJSPs re b ilt on topofSUN's servletservlet technology.technology.

JSPs reessential an HTML page with special JSP tagsJSPs areessential an HTML page with special JSP tags

embedded. TheseJSP tags can contain Java code.embedded. TheseJSP tags can contain Java code.

TheJSPfileextension is .TheJSPfileextension is .jspjsp rather than .rather than .htmhtm or .html.or .html.TheJSPengineparses the .TheJSPengineparses the .jspjsp and creates aJavaand creates aJava

servletservlet sourcefile. It then compiles the sourcefileintoasourcefile. It then compiles the sourcefileintoa

class file, this is done thefirst timeand this why theJSPclass file, this is done thefirst timeand this why theJSP

is probably slower thefirst timeit is accessed.is probably slower thefirst timeit is accessed.

Any timeafter this the special compiledAny timeafter this the special compiled servletservlet isis

executed and is therefore returns faster.executed and is therefore returns faster.


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Steps required for a JSP request:Steps required for a JSP request:

1.1. The user goes to a web site made using JSP. The user goes to aThe user goes to a web site made using JSP. The user goes to a

JSP page (ending with .JSP page (ending with .jspjsp). The web browser makes the request). The web browser makes the request

via the Internet.via the Internet.

2.2. The JSP request gets sent to the Web server.The JSP request gets sent to the Web server.

3.3. The Web serverThe Web server recognisesrecognises that the file required is special (.that the file required is special (.jspjsp),),therefore passes the JSP file to the JSPtherefore passes the JSP file to the JSP ServletServlet Engine.Engine.

4.4. Ifthe JSP file has been called the first time, the JSP file is parsed,Ifthe JSP file has been called the first time, the JSP file is parsed,

otherwise go to step 7.otherwise go to step 7.

5.5. The next stepis to generate a specialThe next stepis to generate a special ServletServlet from the JSP file. Allfrom the JSP file. All

the HTML required is converted tothe HTML required is converted toprintlnprintln statements.statements.6.6. TheThe ServletServlet source code is compiled into a class.source code is compiled into a class.

7.7. TheThe ServletServlet is instantiated, calling the init and service methods.is instantiated, calling the init and service methods.

8.8. HTML from theHTML from the ServletServlet output is sent via the Internet.output is sent via the Internet.

9.9. HTML results are displayed on the user's web browser.HTML results are displayed on the user's web browser.


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Installing a softwareInstalling a software

Java 2 Standard addition SoftwareJava 2 Standard addition Software

Development Kit(J2SE SDK)Development Kit(J2SE SDK)

Apache Jakarta TomcatApache Jakarta Tomcat Tomcat is known asTomcat is known as servletservlet container. In java,container. In java,

world,world, servletservlet containeris responsible forcontaineris responsible for

receiving web requests and passing them toreceiving web requests and passing them to

the java web application.the java web application.


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JSP Syntax TagsJSP Syntax Tags

6 primary JSP syntax tags6 primary JSP syntax tagsCommentComment

Server side comment styleServer side comment style

Single or multiSingle or multi--lineline

DirectiveDirective

Used to describe page characteristicsUsed to describe page characteristics

Provides execution information tocontainerProvides execution information tocontainer

DeclarationDeclaration

Used to declare variables or methodsUsed to declare variables or methods

Can inadvertentlycreate a nonCan inadvertentlycreate a non--thread safe JSPthread safe JSP


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JSPSyntax Tags [cont.]JSPSyntax Tags [cont.]

6 primaryJSPsyntax tags6 primaryJSPsyntax tags

ScriptletScriptlet

Used to apply business logic to HTML generationUsed to apply business logic to HTML generationTypicallyintermixed with HTML throughout pageTypicallyintermixed with HTML throughout page

ExpressionExpression

Used to convert Java value into HTML textUsed to convert Java value into HTML text

Easy way to write out a valueEasy way to write out a value

JSPactionJSPaction

Predefined executable tagsPredefined executable tags

SimplifiesJSPsyntaxSimplifiesJSPsyntax


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JSP evelopmentJSP evelopment

Like writing an HTML documentLike writing an HTML document

JSPhas its own set of tagsJSPhas its own set of tags

Contains HTML presentation logicContains HTML presentation logic

Includes conditional Java logicIncludes conditional Java logic

CanincludeJavaScript or XMLCanincludeJavaScript or XML

Normally stored in a .Normally stored in a .jspjsp filefile

Handles requestHandles request

Generates responseGenerates response


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FreeFree ServletServlet and S Softwareand S Software

Tomcat: http://jakarta.apache.org/

JSWDK:

http://java.sun.com/products/servlet/download.ht

ml

JRun: http://www.allaire.com/products/jrun/

ServletExec: http://newatlanta.com/

LiteWebServer: http://www.gefionsoftware.com/Java Web Server:

http://www.sun.com/software/jwebserver/try/


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Thank YouThank You

Queries???Queries???

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