Web Technology – A computer Science perspective

7/29/2019 Web Technology A computer Science perspective

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Web Technology A computer

Science perspective

Pradeep Pocha11th Feb 2012


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What is a protocol?

Protocol An agreement about how to do something

This enables computers and software built by different

people to be able to communicate in the same language

Examples that we have seen: Hyper Text Transfer Protocol (HTTP) Web Browser

File Transfer Protocol (FTP) File transfer

Simple Mail Transfer Protocol (SMTP) Email

Internet Protocol (IP) Packets across the Internet

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Contents!

Human Protocols

Sending a letter via the postal service

Shayne Evans

5501 Sennott Sq.

Pittsburgh, PA. 15260

Kim Morrison

123 Somewhere St.

Someplace, PA. 15555

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Computer Protocols

Sending a packet via the network

To: 192.168.1.1 on port 23

From: 192.168.1.110 on port 6710

Payload: The contents of the message belong

here.

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Contents!!!

Visual Comparison

To: 192.168.1.1 on port 23

From: 192.168.1.110 on port 6710

Payload: The contents of themessage belong here.

Contents!

Shayne Evans5501 Sennott Sq.


Kim Morrison

123 Somewhere St.


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Textual Comparison

The address of the letter is the destination of

the packet

The return address of the letter is the source

of the packet

The content of the envelope is the payload of

the packet

In both protocols, if you disobey the rules your

message will not be received

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Protocol Layers

Protocols can be layered on top of other

protocols to enable new ways of

communicating

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Example: Writing a letter

A common protocol that is followed when

writing a letter is:

[Date]

Dear [Recipient],

[Body of message goes here]

[Closing][Sender signature]

[Sender name]

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A common protocol that is followed when

writing a letter is:

04/01/2008

Dear Kim,

Hey there! Whats up? Im good. Thanks.

Sincerely,Shayne EvansShayne Evans

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04/01/2008

Dear Kim,

Hey there! Whats up? Im good. Thanks.

Sincerely,

Shayne EvansShayne Evans

Example: Writing a Letter

After following the protocol for writing a

letter, I can use the protocol for sending a

letter via the postal service:

Shayne Evans

5501 Sennott Sq.


Kim Morrison123 Somewhere St.


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Thus, I have layered two protocols on top of

each other.

The lower protocol provides a service used by

the higher protocols.

Letter Writing Protocol

Sending a Letter via USPS Protocol

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Protocol Layering:

The Internet is build this way

Internet Protocol (IP) provides a way to deliver

packets to a destination

TCP

Internet Protocol

SSH, FTP, HTTP, SMTP

UDP

DNS, VoIP

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TCP uses packets to maintain connections

across a network, and thus is layered above IP

TCP

Internet Protocol


UDP

DNS, VoIP

Protocol Layering:


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UDP just sends or receives raw packets with a

best-effort approach, also layered above IP

TCP

Internet Protocol


UDP

DNS, VoIP

Protocol Layering:


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SSH, FTP, HTTP, SMTP and many more

applications use TCP connections to

communicate data back and forth

TCP

Internet Protocol


UDP

DNS, VoIP

Protocol Layering:


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DNS, VoIP, and many more applications use

UDP packets to communicate data

TCP

Internet Protocol


UDP

DNS, VoIP

Protocol Layering:


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CS 640 17

HTTP Request Messages

GETretrieve document specified by URL

PUTstore specified document under given URL

HEADretrieve info. about document specified by URL

OPTIONSretrieve information about available options

POSTgive information (eg. annotation) to the server

DELETEremove document specified by URL

TRACEloopback request message

CONNECTfor use by caches


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CS 640 18

HTTP Response Codes

1xxInformationalrequest received, processing

2xxSuccessaction received, understood, accepted

3xxRedirectionfurther action necessary 4xxClient Errorbad syntax or cannot be fulfilled

5xxServer Errorserver failed


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URI,URN,URL

Uniform Resource Identifier

Information about a resource

Uniform Resource Name The name of the resource with in a namespace

Uniform Resource Locator

How to find the resource, a URI that says how to find

the resource


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Using HTML/XHTML

XHTML is relatively simple. You do most of yourwork with about twenty tags.

XHTML is orderly and structured Good references and tutorial sites are available

Follow the standards and your work will be muchsimpler, more consistent, and your results more

reliable Plus your co-workers will like you more


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Device Independence

Your audience may view your site with many

different devices and browser types.


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The Browser

The browser is not print!


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The Browser Is Not Print

No fixed page size

No fixed page length

User can change the font size User can link to her/his own local style sheet

Screen size can be tiny or huge


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The Adjustable Document


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The Birth of HTML

Created by Tim Berners-Lee at CERN

Open standard developed under supervision of the

World Wide Web Consortium (www.w3.org) Works to ensure the full potential of the Web for

shared, integrated functionality is realized
http://www.w3.org/http://www.w3.org/


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The History of HTML/XHTML

1992HTML first defined

1994HTML 2.0

1995Netscape specific non-standard HTML

1996HTML 3.2, compromise version

1997HTML 4.0, separates content from presentation

1998XML standard for writing Web languages

2000XHTML 1.0, XML compliant HTML

2002XHTML 2.0


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Problems With HTML

Competing versions of browsers introducedfeatures beyond the standards

Inconsistent implementations of display enginesand scripting

Content and presentation mixed together Layout often done with tables

Each element had many presentation attributes,resulting in laborious maintenance

The Slop Code Era


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XHTML

XHTML is a version of HTML modified to conform to theXML standard

Designed to separate content from presentation

Content in XHTML Presentation controlled by Cascading Style Sheets (CSS)

ExtensibleAdditional elements can be defined

XML CompatibleOther XML based languages can be

embedded in XHTML documents Like a programming language Specific syntax to use

Validators help you get it right


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XHTML Differences

Case is significant

All elements must have begin tags and end tags

Hello

Empty elements contain their own end tag

Attribute values must be enclosed in quotation

marks More specfics available at

http://www.w3.org/TR/xhtml1/#diffs


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A Simple XHTML File

My Home Page

My Home Page

Welcome to my home page


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Hierarchical Structure

Well formed xhtml forms a hierarchy


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Content Types

Documents are made up of logical types of content.


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Semantic Structure

Content of the same type usually is formatted to look thesame.


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Semantic Markup

HTML markup is based on logical content types


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Hierarchy

The resulting hierarchy


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The DOCTYPE Statement

Declares the specific version of HTML orXHTML being used on the page

Used by the browser to decide how to process thepage

Three types Transitional - Forgiving

StrictRequires adherence to standards FramesetUse if page has frames

Always first in file


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Strict DOCTYPE

Enter exactly as below


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Elements

Consist of three parts

Begin tag, which can contain attributes

Contents End tag

Example:

Welcome

W3schools specifications for

http://www.w3schools.com/tags/tag_p.asp


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Attributes

Always only used in the element begin tag

Three types Optional attributes: Varies with element type

Standard attributes: id, class, title, style, dir, lang,xml:lang

Event attributes: onclick, ondblclick, onmousedown,onmouseup, onmouseover, onmousemove, onmouseout,

onkeypress, onkeydown, onkeyup Used in scripting


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Empty Elements

Some elements have no content and therefore alsohave no end tag


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, , , etc.

Headings on the page

Represent the main topic, subtopics, subsubtopics,

etc. of the page Important to use they in a logical manner, which

greatly helps assistive technology like voice

browsers present the page content intelligibly


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Paragraph

Important for presentation control to put text in an

element. When in doubt, put text in a paragraph Blockquotes () except they have

wider left and right margins


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Lists

Unordered lists (bulleted lists)

One

Two

Ordered lists (numbered lists)

One

Two


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Text Markup

Bolding text

text

Italics text

text

Other

text subscript text superscript

text deleted text


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Tables

People on the team

Name

Position

Mary

Analyst

John

Technician


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Graphics

Graphics are placed by using an img element

The alt attribute provides alternative text

describing the graphic in case the graphic itselfcannot be shown or the user cannot see the graphic


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Anchors

Anchors can link your page to any file on the Web

University of Washington


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Divs

Divs enclose a set of elements

News

Budget

Investment


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Spans

Spans enclose objects (text, graphics) within an

element

Call me Ishmael. Some years agonever mind how long

preciselyhaving little or no money in my purse,

and nothing particular to interest me on shore,


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Cascading Style Sheets

Are used to control how elements are presented in

the Web page

Use a different syntax that HTML/XHTML Work with the common visual browsers (Internet

Explorer, FireFox, Opera)

Used properly, can great simplify visual design,

site management and content maintenance


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A Style

Selector Property Value

p { font-family: times; }

Note the punctuation: The property is followed by

a colon (:) and the value is followed by a

semicolon(;)


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Using CSS

Styles can be set in a stylesheet, in a style element inthe head or in a style attribute


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Selectors

Simple selectors

p { color: blue }

h1, h2, h3, h4 { font-style: italic; }

Contextual selectors

ul li { font-weight: bold; }

#main img { border: solid black 5px; }

p.intro { font-family: verdana, sans-serif;}


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The Box Model

Each element has padding, border, and margin


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Vertical Margins

The larger of the two vertical margins will determinethe distance between elements


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Visual Formatting Model

Pages are built as a series of blocks stacked from thetop down


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Controlling Layout

Styles can control size and placement of elements

Example:

#nav { width: 12em; float: left; }#news { width: 12em; float: right; }

#main { margin: 1em 13em 1em 13em;


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Nav Div Float Left


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Nav Div Float Right


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Nav Across Top

Items in the Nav bar are anchors within a div


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HTML-Kit

HTML-Kit (Windows) is free editor that makes iteasy to make standards compliant XHTML


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HTML-Kit Has Tidy

Press F9 and your XHTML is validated and tidiedfor easy reading


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Resources

HTML-Kit editorhttp://chami.com/

Amaya editorhttp://www.w3c.org/Amaya

W3schools XHTML and CSS tutorialshttp://www.w3schools.com/

Web Head Start tutorialshttp://www.webheadstart.org/

Tidy Web Interface - http://www.washington.edu/webinfo/tidy.cgi

CSS Validator - http://jigsaw.w3.org/css-validator/

Dave Raggett XHTML and CSS tutorials -http://www.w3.org/MarkUp/Guide/Overview.html

Web Accessibility in Mind (WebAIM) - http://www.webaim.org/

Color contrast analyzer -http://www.visionaustralia.org.au/info.aspx?page=628

Stylin With CSS, A Designers Guide, Second Edition by CharlesWyke-Smith


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Web Application

64


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Model 1 Architecture

Model 1Architecture


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Model 2Architecture

Model 2Architecture


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Model-View-Controller


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Servlet

A servlet is a JavaTM technology-based Web

component, managed by a container, that

generates dynamic content. --- Servlet API

Specification, Version 2.4

The servlet containeris a part of a Web server or

application server that provides the network

services over which requests and responses aresent, decodes MIME-based requests, and formats

MIME-based responses. A servlet container also

contains and manages servlets through their

lifecycle


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Web Server Machine

Client

Web

Server

App

(e.g.

Apache)

Web

Container

App

(e.g.

Tomcat)

Servlet

Web App Processing with Servlet

Request

URL


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Web Server Machine

Client

Web

Server

App

(e.g.

Apache)

Web

Container

App

(e.g.

Tomcat)

Servlet


Request

URL

Apache forwards HTTP request to

Tomcat Using AJP protocol


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Web Server Machine

Client

Web

Server

App

(e.g.

Apache)

Web

Container

App

(e.g.

Tomcat)

Servlet


Request

Tomcat uses the mapping info in a

configuration file called web.xml of the

web application to find the right servlet


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Web Server Machine

Client

Web

Server

App

(e.g.

Apache)

Web

Container

App

(e.g.

Tomcat)

Servlet


Response

Tomcat uses the mapping info in a

configuration file called web.xml of the

web application to find the right servlet


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Web Server Machine

Client

Web

Server

App

(e.g.

Apache)

Web

Container

App

(e.g.

Tomcat)

Servlet


Response


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Web Server Machine

Client

Web

Server

App

(e.g.

Apache)

Web

Container

App

(e.g.

Tomcat)

Servlet


Response


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What Container Provides?

Communication Support(to web server; no socket code)

Lifecycle Management of Servlet(loading; instantiating; initializing; invoking; garbage collection; fault

tolerance) Multithread Support

(create threat for each servlet request)

Declarative Security(use XML deployment descriptor to configure/modify security withouthaving to hard-code it into servlet code)

JSP Support(translating that JSP code into real java)


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What a Simple Servlet looks Like?import javax.servlet.*;

import javax.servlet.http.*;import java.io.*;

public class SimpleServlet extends HttpServlet {

public void doGet (HttpServletRequest request, HttpServletResponse response) throwsIOException {

PrintWriter out = response.getWriter();java.util.Date today = new java.util.Date();

out.println("This is a simple web page generated by SimpleServletwith date info.
Today is "+today+"");

}

}


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What a Servlet Code looks Like?package com.example.web;

import com.example.model.*;import javax.servlet.*;

import javax.servlet.http.*;

import java.io.*;

import java.util.*;

public class BeerSelect extends HttpServlet {

public void doPost (HttpServletRequest request,HttpServletResponse response)

throws IOException, ServletException {

String c = request.getParameter("color");

BeerExpert be = new BeerExpert();

List result = be.getBrands(c);

request.setAttribute("styles", result);RequestDispatcher view =

request.getRequestDispatcher("result.jsp");

view.forward(request, response);

}

}


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How Does Container Find Right Servlet?

Using the Deployment Descriptor web.xml

CS301 Simple Servlet

SimpleServlet

CS301 Simple Servlet /s1

This mapping improves flexibility and security. How?


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A Simple Web Application Following Model-

View-Controller Design Pattern

Servlet

Controller

e.g. BeerSelect.java

Class Beer{

//Business

//Logic

}

Model

e.g., BeerExpert.java

View

e.g. result.jsp

Fil St t i A J W b D l t
http://cs.uccs.edu/~cs301/mvc/beerV1/src/com/example/web/BeerSelect.javahttp://cs.uccs.edu/~cs301/mvc/beerV1/src/com/example/model/BeerExpert.javahttp://cs.uccs.edu/~cs301/tomcatChow/webapps/Beer-v1/result.jsp.htmlhttp://cs.uccs.edu/~cs301/tomcatChow/webapps/Beer-v1/result.jsp.htmlhttp://cs.uccs.edu/~cs301/mvc/beerV1/src/com/example/model/BeerExpert.javahttp://cs.uccs.edu/~cs301/mvc/beerV1/src/com/example/web/BeerSelect.javahttp://cs.uccs.edu/~cs301/java/mvc/beerV1/http://cs.uccs.edu/~cs301/java/mvc/beerV1/


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File Structure in A Java Web Development

Environment

beerV1

srcetc lib classes web

web

com

example

model

BeerSelect.javaBeerExpert.java

Web.xml

File Structure in a tomcatChow
http://cs.uccs.edu/~cs301/java/mvc/beerV1/http://cs.uccs.edu/~cs301/java/mvc/beerV1/http://cs.uccs.edu/~cs301/java/mvc/beerV1/http://cs.uccs.edu/~cs301/tomcatChow/webapps/Beer-v1/result.jsp.htmlhttp://cs.uccs.edu/~cs301/tomcatChow/webapps/Beer-v1/result.jsp.html


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Java Web

Deployment

Environment Beer-v1

WEB-INF

libclasses

web

com

example

model

BeerSelect.javaBeerExpert.java

Web.xml

webapps

Form.html

Servlet with JDBC demo
http://cs.uccs.edu/~cs301/tomcatChow/webapps/Beer-v1/result.jsp.htmlhttp://cs.uccs.edu/~cs301/tomcatChow/webapps/Beer-v1/result.jsp.htmlhttp://blanca.uccs.edu:8080/sql/join.jsp.htmlhttp://java.sun.com/docs/books/tutorial/jdbc/basics/index.htmlhttp://windom.uccs.edu:9888/sql/testDBServlet.htmlhttp://windom.uccs.edu:9888/sql/testDBServlet.htmlhttp://java.sun.com/docs/books/tutorial/jdbc/basics/index.htmlhttp://blanca.uccs.edu:8080/sql/join.jsp.html


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Servlet with JDBC demo

import java.sql.*;

import javax.sql.*;

public class InventoryDBServlet extends HttpServlet {

Driver D;

Connection con;

Statement stmt;

PrintWriter out = response.getWriter();

try {

Class.forName("org.gjt.mm.mysql.Driver").newInstance();

} catch(java.lang.ClassNotFoundException e) {

System.err.print("ClassNotFoundException: +e.getMessage());

}

String url="jdbc:mysql://blanca.uccs.edu:3306/"+database+"?user="+user+"&password="+passwd;

con = DriverManager.getConnection(url);

stmt = con.createStatement();

String sqlcmd = "select * from inventory";

ResultSet rs = stmt.executeQuery(sqlcmd);while (rs.next()) {

StringBuffer itemName = new StringBuffer(rs.getString(1));

StringBuffer amount = new StringBuffer(rs.getString(2));

out.println(""+itemName+""+amount+"");

}

}
http://blanca.uccs.edu:8080/sql/join.jsp.htmlhttp://java.sun.com/docs/books/tutorial/jdbc/basics/index.htmlhttp://windom.uccs.edu:9888/sql/testDBServlet.htmlhttp://windom.uccs.edu:9888/sql/testDBServlet.htmlhttp://java.sun.com/docs/books/tutorial/jdbc/basics/index.htmlhttp://blanca.uccs.edu:8080/sql/join.jsp.html


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JSP with JSTL SQL Tag Demo

select price.item, price.unitPrice, inventory.amount from price, inventory where price.item =inventory.item

DBcatalog DB Catalog Retrieval Results

itemunitPriceamount

${row.item} ${row.unitPrice}${row.amount}
http://cs.uccs.edu/~cs301/tomcatChow/webapps/sql/join.jsp.htmlhttp://windom.uccs.edu:9888/sql/catalogDB.jsphttp://windom.uccs.edu:9888/sql/catalogDB.jsphttp://cs.uccs.edu/~cs301/tomcatChow/webapps/sql/join.jsp.html


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JSP with SQL:UPDATE Parameter Access

Demo http://windom.uccs.edu:9888/sql/passwd.jsp

Source

Note that we really do not need to set login/password variable. Just use directly in and in
http://windom.uccs.edu:9888/sql/passwd.jsphttp://cs.uccs.edu/~cs301/tomcatChow/webapps/sql/passwd.jsp.htmlhttp://cs.uccs.edu/~cs301/tomcatChow/webapps/sql/passwd.jsp.htmlhttp://windom.uccs.edu:9888/sql/passwd.jsp


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JDBC

Load the driver class

Get a connection

Create a statement Execute the query, returns ResultSet

Iterate through ResultSet

JDBC Example


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JDBC Example

// Load the Oracle JDBC driver

Class.forName ("oracle.jdbc.driver.OracleDriver"); //Connect to DB server as authorized user

Connection conn = DriverManager.getConnection("jdbc:oracle:thin:@orion.towson.edu:1521:cosc", account,

password);

// Create a JDBC Statement to hold SQL queryStatement stmt = conn.createStatement ();ResultSet rset = stmt.executeQuery ("select ticker fromstocks");

// Iterate through the result and print the employee names

while (rset.next ()) {out.println (rset.getString (1));}


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Storing and Sharing Data

Persistent Temporary

Server side

Database,

Flat files

Class level variable,

Session,Application context

Client side

Persistent

cookie

Session cookie


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HTTP State and Session

What is a session? A serial of consecutive and related requests from and responses to a

single client, in a certain duration and scope

What is state? State is the information to describe or identify a session at a certain

point of time

Stateful: each request/response can maintain its state at different pointsof times

Phone calls are stateful

Stateless: each request/response cannot maintain its state at differentpoints of times HTTP protocol is stateless, i.e., HTTP itself does not provide mechanisms

to maintain state information for each request/response. In other words,HTTP does not remember.


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Applications

Where is session/state needed?

User sign-in status

A transaction involving multiple steps

(requests/responses), such as

shopping (cart)

multi-page survey or multi-page test

auto insurance quote

User preferences, personalization, customization


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Making HTTP Stateful

HTTP itself is not stateful. Application level

statement management is needed.

How to manage state (with Java platform)?

Cookie (persistent cookie and session cookie)

Java session API

URL rewriting Using form hidden variables


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Cookies

Cookie is a small piece of textual information stored on theclient computer which web servers can interact with

Cookie facts Cookie is pure text information Cookie is sent with HTTP headers

Cookie has restrictions (number, size, domain, path)

For more cookie informaiton http://wp.netscape.com/newsref/std/cookie_spec.html

http://www.w3.org/Protocols/rfc2109/rfc2109.txt

http://kristol.org/cookie/
http://wp.netscape.com/newsref/std/cookie_spec.htmlhttp://www.w3.org/Protocols/rfc2109/rfc2109.txthttp://kristol.org/cookie/http://kristol.org/cookie/http://www.w3.org/Protocols/rfc2109/rfc2109.txthttp://wp.netscape.com/newsref/std/cookie_spec.html


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Client Computer

Cookie Life Cycle

Server side

Servlets

or

JSPs

Persiste

ntCookie

Response to set cookies

Subsequent requests:

Cookie is sent with HTTP header

Cookie expires at certain duration

Response to set cookies

SessionCookie


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Java Cookie API

javax.servlet.http.Cookie

Creating a cookie

Cookie cookie=new Cookie(cookieName, cookieValue);

cookie.setMaxAge(int seconds); //only for persistent cookie

response.addCookie(cookie); //sending cookie to client

Reading a cookie Cookie cookies[]=request.getCookies()

getName() and getValue()

See example cookieset.jsp, cookieread.jsp and Listing 8.2


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Session Cookie

Session cookie is not saved to the disk; it onlyexist in the memory for the duration of the

browser

Session cookie expires when the browser window isclosed

Dont set maxAge when creating a sessioncookie

Note: a session cookie JSESSIONID isautomatically set by the server

See example cookieset.jsp and cookieread.jsp


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Cookie Practices

Cookies only handle simple data Numbers, characters, strings

Persistent cookies save data on client computers for acertain period of time A unique feature that can be utilized

Often used to save user preferences or convenience information

See example cookieset.jsp and cookieread.jsp

Client computers might block cookies See IE privacy settings

How to detect that? See section 8.3


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Web Application Server Session

State information can also be saved on the server side (inserver memory)

How to relate each visit/client with a specific session(server memory storage)? Each visit/session is identified by a unique ID (session id), which

is passed with every request

What are the ways to pass this ID to server?

Session duration On the server side, session duration is set by the server. Session

expires when there is no activity for a certain amount of time.


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Client Browser

Session Life Cycle

Server side

1strequest

ServerMemory

Servletsor

JSPs

Session Created

Put data into memory

Read data from memory

SessionCookie

First response: session id is set

Subsequent requests:

session id is sent to server

Session ends

after browser is closed*

Session ends

after a certain idle period


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Servlet Session API

Session class javax.servlet.http.HttpSession object represents a session

To get a session object ServletSession session=request.getSession();

JSP: session is given as an implicit object

Properties Session ID: session.getId()

Creation time

Is it a new session?

See example sessioninfo1.jsp and sessioninfo2.jsp; or Listing 9.1


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Using Session API

Web server settings Session is automatically created by web server

Session ID is automatically generated by web server

Session ID is sent to client (either as session cookie or URLparameter) automatically

Store data in session session.setAttribute()

Read data from session session.getAttribute()

needs type casting if an object is stored in the session

See example sessioninfo1.jsp and sessioninfo2.jsp; or Listing 9.1


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Session Practice

What data to put in session? Information that should be shared during a users visit

of multiple requests User preferences, choices

User status, e.g. login information Shopping cart information

Temporary data between page transition

How much data to put in session? Use session only for necessary and frequently accessed

data


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Servlet Class Variables

Class level variable is accessed and shared by allrequests to the same servlet (JSP page) For JSP page, it is the variable defined in the

declaration element

The value of the variable remains in the memoryuntil the servlet is reloaded

Example Counter of the servlet/JSP page

How to prevent count cheating?

See example classvariable.jsp


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Application Context API

To share the data application wide (across allsessions), use the ServletContext classjavax.servlet.ServletContext class

To get the application context object Servlet

ServletContext application=this.getServletContext();

JSP: application is given as an implicit object

Usage A counter of user visits (sessions)


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Web Application Events

A J2EE web application (context), and everysession, has its own life cycle

Usage How to count website (application) visits?

How to perform some operations every time a userissues the first request (for any file)

For more information http://www.stardeveloper.com/articles/display.html?article=2001111901
http://www.stardeveloper.com/articles/display.html?article=2001111901http://www.stardeveloper.com/articles/display.html?article=2001111901


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Summary: Data Sharing and Access

ServletContext /applicationJSP/Servlet

Computer A

JSP/Servlet JSP/Servlet

Computer B

Session / session cookie

shares information only

for that session

Request/Response

Class Level Variable

shares information

across all computers,

but within thatJSP/servlet

Persistent cookie shares

information for all

sessions on one computer


105/105

References:

www.cs.pitt.edu/~sevans/cs110/protocols.ppt(#1) XHTML and CSS:Rick Ells UW Technology

http://staff.washington.edu/rells/

Java Web Application Framework (WAF)

Melek OKTAY 50050403 [email protected]

Servlet and JSP C Edward Chow

Data Sharing and State Management -Jack G. Zheng
http://www.cs.pitt.edu/~sevans/cs110/protocols.ppt(http://staff.washington.edu/rells/mailto:[email protected]:[email protected]://staff.washington.edu/rells/http://staff.washington.edu/rells/http://www.cs.pitt.edu/~sevans/cs110/protocols.ppt(http://www.cs.pitt.edu/~sevans/cs110/protocols.ppt(