Web Application Success through JavaServer Pages

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Web Application Success through JavaServer Pages

• Vezen Wu
• vw89_at_columbia.edu

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Success Model for Web Applications
Simple to Use
Success
High Performance
Ease of Development
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Key Facts on JavaServer Pages (JSP)

• Server-side Java technology for dynamic content
• Specification, not a product
• Element-driven and scripting-based syntax
• Supports Model-View-Controller (MVC) design

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Case Study

• CTA program requests a web-based application for
  students to check their information
• Design a portal that requires students to enter a
  valid Student ID for access
• Requirement for dynamic content

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Query Screen
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Dynamic Content
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Validation
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Error Page
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Technologies for Dynamic Web Content

• Active Server Pages (ASP)
• PHP
• Common Gateway Interface (CGI)
• ColdFusion
• Java Servlets
• JavaServer Pages (JSP)

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Java Servlet

• public class StudentServlet extends HttpServlet
• public void doGet(HttpServletRequest request,
  HttpServletResponse response)
• throws ServletException, IOException
• response.setContentType(text/html)
• Printwriter out response.getWriter()
• if (isValid() true)
• out.println(lthtmlgt)
• out.println( ltheadgt lttitlegtCTA Student
  Serviceslt/titlegt lt/headgt)
• out.println( ltbodygt)
• out.println( lth1gtCTA Student Services
  Portallt/h1gt)
• out.println( ltp align\center\gtWelcome
  , ltfont color\red\gt getStudentName()
  lt/fontgt.)
• out.println( Click lta
  href\profile.jsp\gtherelt/agt to access your
  profile.lt/pgt)
• out.println( lt/bodygt)
• out.println(lt/htmlgt)
• private boolean isValid()
• private String getStudentName()

HTML
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The JSP Advantage
JSP Element

• lt_at_ page language"java" contentType"text/html"
  gt
• lthtmlgt
• ltheadgt
• lttitlegtCTA Student Serviceslt/titlegt
• lt/headgt
• ltbodygt
• ltjspuseBean id"studentBean" scope"request"
  class"mybeans.StudentBean" /gt
• lth1gtCTA Student Services Portallt/H1gt
• ltp align"center"gt
• Welcome, ltfont color"red"gtlt
  studentBean.getStudentName() gtlt/fontgt.
• Click lta href"profile.jsp"gtherelt/agt to
  access your profile.
• lt/pgt
• lt/bodygt

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HTTP Request/Response Model
Request
Client Web Browser
Server Web Server
Resource studentlookup.jsp
Response
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JSP Processing
II Read
studentlookup.jsp
I GET /studentlookup.jsp
Client Web Browser
Server with JSP Container
III Generate
studentlookupServlet.java
VI HTTP/1.0 200 OK
Translation Phase (II, III, IV)
IV Compile
V Execute
V Execute
studentlookupServlet.class
Request Processing Phase (V)
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Model-View-Controller (MVC) Design
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MVC Design for the CTA Application
Request 1
View studentlookup.jsp studentconfirmation.jsp
Response 1
Response 2
Model StudentBean.java DatabaseBean.java
Client Web Browser
Forward
Controller studentvalidate.jsp
Request 2
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JSP Anatomy
JSP Element

• lt_at_ page language"java" contentType"text/html"
  gt
• lthtmlgt
• ltheadgt
• lttitlegtCTA Student Serviceslt/titlegt
• lt/headgt
• ltbodygt
• ltjspuseBean id"studentBean" scope"request"
  class"mybeans.StudentBean" /gt
• lth1gtCTA Student Services Portallt/H1gt
• ltp align"center"gt
• Welcome, ltfont color"red"gtlt
  studentBean.getStudentName() gtlt/fontgt.
• Click lta href"profile.jsp"gtherelt/agt to
  access your profile.
• lt/pgt
• lt/bodygt

Template Text
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JSP Elements

• Directive
• lt_at_ page gt
• Action
• ltjspuseBeangt
• ltjspsetPropertygt
• ltjspgetPropertygt
• ltjspforwardgt
• ltjspparamgt
• Scripting
• lt gt Scriptlet
• lt gt Expression

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Controller JSP

• lt_at_ page language"java" gt
• ltjspuseBean id"studentBean" scope"request"
  class"mybeans.StudentBean"gt
• ltjspsetProperty name"studentBean"
  property"" /gt
• lt/jspuseBeangt
• lt if (studentBean.isValid()) gt
• ltjspforward page"studentconfirmation.jsp" /gt
• lt else gt
• ltjspforward page"studentlookup.jsp" /gt
• lt gt

Directive Element
Scripting Element
Action Element
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JavaBeans

• Reusable software component
• Conform to a design pattern
• Model tier in MVC design
• Value Beans and Utility Beans
• IDE Support

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JavaBean

• public class StudentBean implements Serializable
  
• private String studentID
• private String studentName
• public StudentBean()
• public String getStudentID()
• return studentID
• public void setStudentID(String studentID)
• this.studentID studentID
• public boolean isValid()

Properties
Getter/Setter Methods
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JSP The Winning Choice

• Familiar interface
• Access to benefits of the Java language
• Streamlined development