Servlet TechnologyWeb Application Development

Zsolt Tóth

University of Miskolc

2017

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Back-end Programming Languages

1 Back-endProgramming LanguagesApplication Servers

2 Web ApplicationsStructureDeployment Descriptor

3 J2EEHttpServletFilter

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Back-end Programming Languages

Common Gateway Interface

CGI Program / ScriptPHP, CGenerate HTML

Started by the Web ServerCreate process for eachHTTP RequestCostly

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Back-end Programming Languages

Script Languages

PHPMost popular

Local companies use it.Frameworks

YiiContent ManagementSystems

JoomlaWordPress

Easy–to–startSupported by web serverhosting companiesWikipedia

PythonHigh–level, general purposelanguagePopular but not in MiskolcEasy–to–LearnGoogle, Youtube

RubyRuby on Rails FrameworkNot popular in MiskolcTwitter

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Back-end Programming Languages

Object Oriented Languages

Web ApplicationsComplex,Reliable,Stable

Expensive InfrastructureComponents can beseparated easilyGood, well-tested code(hopefully ,)

DevelopmentSlowStandardized

Fixed rolesMethodologies

DifficultIf you do it well ,Lots of technology

Both Java and C# are used bylocal companies

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Back-end Application Servers

Overview

ApplicationMiddlewareSoftware FrameworkEnvironment for DynamicWeb ApplicationsContains

Servlet ContainerJSPEnterprise JavaBeans

ServersGlassFish, WildFly,Geronimo

$ WebSphere, WebLogic,JBoss

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Back-end Application Servers

Common Tasks

Admin ConsoleDeploymentScaling

Manage NodesClustering

MonitoringServerApplicationsResources

Resource ManagementJDBCJNDIJMS

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Back-end Application Servers

Installation

Java ApplicationPlatforms

UnixLinuxWindows

No install.exe

Extract and runScript files

bin/startup.shbin/shutdown.sh

Hints for DevelopersYour are not a SystemAdministrator.You should not operate anApplication Server.Logging is essential.Log files grow quickly.Never run as root!

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Back-end Application Servers

Usage as a Developer

Local DeploymentManual TestingDemonstration

≈ Test Server

IDE IntegrationEclipseIntelliJ IDEANetBeans

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Back-end Application Servers

Tomcat

Apache Software FoundationLightweightServlet ContainerVersions

8.0Servlet 3.1JSP 2.3

8.5HTTP/2OpenSSL

Popular among developers!

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Back-end Application Servers

Tomcat

Directoriesbin

Script filesstartup.shshutdown.sh

confXMLserver.xmltomcat-users.xml

webapps

.+-- bin+-- conf+-- lib+-- LICENSE+-- logs+-- NOTICE+-- RELEASE-NOTES+-- RUNNING.txt+-- temp+-- webapps\-- work

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Back-end Application Servers

Tomcat for Developers

IDEIntelliJ IDEAEclipse

Multiple ServersLocal Configuration

Workspace

Start/Stop ServerDeploymentRefresh / Restart

TasksRun LocallyTest Manually

See alsoDatabase ManagementSoftware TestingOperation Systems

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Web Applications Structure

1 Back-endProgramming LanguagesApplication Servers

2 Web ApplicationsStructureDeployment Descriptor

3 J2EEHttpServletFilter

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Web Applications Structure

Structure

Web AppExpected Directory StructureStandard LocationsDeployed from Web ARchive

Root DirectoryStatic ContentDirect Access

+-- images+-- index.jsp+-- META-INF| \-- context.xml+-- WEB-INF| +-- jsp| | +-- 401.jsp| | +-- 403.jsp| | +-- 404.jsp| | \-- sessions.jsp| \-- web.xml

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Web Applications Structure

Web ARchive

ZIP File

*.war ExtensionContains Web ApplicationCreation

jar cvf ...Maven Packaging

Can be Deployed

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Web Applications Structure

WEB-INF

Cannot be Accessed Directly!

classes

*.class filesCompiled Servlet ClassesPackage Structure

lib

*.jar Files3rd Party Dependencies

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Web Applications Deployment Descriptor

Deployment Descriptor

WEB-INF/web.xml

Details of Web ApplicationNameDescriptionServlet DefinitionURL MappingListenersFilters. . .

1 <web-app xmlns="..."><servlet>

3 <servlet-name>greetings

5 </servlet-name><servlet-class>

7 org.dummy.Greetings</servlet-class>

9 </servlet><servlet-mapping>

11 <servlet-name>greetings

13 </servlet-name><url-pattern>/</url-pattern>

15 </servlet-mapping></web-app>

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Web Applications Deployment Descriptor

Servlet Mapping

servlet tagIdentified by nameservlet-class

Instanceinit-param

Initialization

load

servlet-mapping

Key Value pairExtends application’s URL* wild card

http://host:port/WebAppName/path

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Web Applications Deployment Descriptor

Filters

filter

filter-name Identifierfilter-class

Similar to ServletPreprocessingForwarding / Rejection

filter-mapping

filter-name

Selectionurl-patternservlet-name

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Web Applications Deployment Descriptor

Context-Param

Context InitializationKey-Value ParisAvailable in JavaPredefined Keys

contextConfigLocation

<context-param><param-name>contextConfigLocation

</param-name><param-value>/dispatcher-servlet.xml/applicationContext.xml

</param-value></context-param>

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J2EE HttpServlet

1 Back-endProgramming LanguagesApplication Servers

2 Web ApplicationsStructureDeployment Descriptor

3 J2EEHttpServletFilter

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J2EE HttpServlet

Servlet

javax.servlet

InterfaceGeneric Methods

initservicedestroy

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J2EE HttpServlet

HttpServlet

javax.servlet.http

Implements ServletRun in Servlet ContainerMethods

doGetdoPostdoPutdoDelete

doGet(2 HttpServletRequest req,

HttpServletResponse resp){4 //do something

}

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J2EE HttpServlet

HttpServletRequest

Request InformationgetCookies

getSession

getHeaders

getParameter

getQueryString

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J2EE HttpServlet

HttpServletResponse

Servlet ResponseHTTP HeaderCookiesadd*

sendError

getWriter

getOutputStream

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J2EE Filter

Filter

PreprocessingMethods

initdoFilterdestroy

TypesAuthentication FiltersLogging and Auditing FiltersImage conversion FiltersData compression FiltersEncryption FiltersTokenizing FiltersFilters that trigger resourceaccess eventsXSL/T filtersMime-type chain Filter

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