Web Programming introduction

Engr. Abdul-Rahman Mahmood
DPM, MCP, QMR(ISO9001:2000)
armahmood786@yahoo.com alphasecure@gmail.com
alphapeeler.sf.net/pubkeys/pkey.htm http://alphapeeler.sourceforge.net
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abdulmahmood-sss alphasecure mahmood_cubix 48660186
armahmood786@hotmail.com alphapeeler@icloud.com
http://alphapeeler.sf.net/me http://alphapeeler.sf.net/acms/
Web Programming

Course portal
 http://alphapeeler.sf.net/me

Outline
 History & Internet Technologies
 Internet Hardware, Various technical terms
 Network Protocols
 TCP/IP, DNS
 Who manages the Internet?
 Who defines the Internet Standards?
 Web Programming Languages
 Markup Languages
 HTML, WML, XML, XHTML
 Client-side & Server-side Scripting
 JavaScript, VBScript, Java Servlets, ASP, JSP

6
Introduction
 This is an introductory course to the latest
technologies for creating and processing the Web
content.
 Enough examples will be provided to you to clarify the
principle concepts.
 You are advised to get more information from the
bookstore, the library and the online materials.

Internet History
 The first node of ARPAnet was established at
UCLA in 1969.
 In the late 1970s and 1980s, many networks were
developed (BITNET, CSNET, NSFnet) locally.
 Internet is a huge collection of computers
connected in a communications network.

Estimation of Users connected to
the Internet

Estimation of Devices connected
to the Internet

Network Protocols
 TCP
 IP
 HTTP
 SNMP
 Netconf
 ICMP
 DHCP
 FTP
 BGP

Internet Protocol Address
 The Internet devices are identified by numeric
addresses for computers
 The IP address is a unique 32-bit number
 Divided into 4 parts (1 byte each)
 191.57.126.0
 Next generation : IPv6 – 128-bit

Domain Name & DNS
 People have difficulty dealing with and
remembering numbers, machines on the Internet
also have textual names.
 www.cuhk.edu.hk
 It is the machine providing web services on the CUHK
domain.
 There are name servers on the Internet that
provide Domain Name Services (DNS).
 ns.cuhk.edu.hk, 137.189.6.6
 It replies the name or IP address of any machine in the
CUHK domain.

The World Wide Web
 Generally called “The Web”
 It is a collection of information stored on the
networked computers over the world.
 The WWW was proposed in 1989 by Tim Berners-Lee
at CERN.

How does the Web work?
 The web information is stored in the Web pages.
 In HTML format.
 Web pages are stored in the computers called Web servers.
 In the Web server file system.
 The computer reading the pages is called web clients with
specific web browser.
 Most commonly Internet Explorer or Netscape.
 The web server waits for the request from the web clients
over the Internet.
 Internet Information Server (IIS) or Apache.

Web or Internet?
 They are not the same things.
 The Internet is a collection of computers or
networking devices connected together.
 They have communication between each other.
 Decentralized design that there is no centralized body
controls how the Internet functions.
 The Web is a collection of documents that are
interconnected by hyper-links.
 These documents are accessed by web browsers and
provided by web servers.

Internet Terminology
 Client
 Any computer on the network that requests services
from another computer on the network.
 Server
 Any computer that receives requests from client
computers, processes and sends the output.
 Web Page
 Any page that is hosted on the Internet.
 Web Development
 The process of creating, modifying web pages.

Web Browser (Web Client)
 It is a program that retrieves information from the
Web.
 Microsoft Internet Explorer
 Most commonly used browsers
 Netscape, Mosaic
 Many different computing platforms
 Opera
 The fastest browser on Earth
 Lynx
 Text based web client

Lynx – UNIX based
 Text
mode
browser,
fast!

Web Server
 It is a program that waits for requests from the web
browser.
 It provides four major functions
 Serving web pages
 Running gateway programs (CGI) and returning output
 Controlling access to the server
 Monitoring and logging all access
 E.g. Apache, IIS, Tomcat, …

HTTP Request/Response Model
Client Server
Request
Response
HTML Codes
<html>
…
</html>
Program /
Scripts

Valid HTTP Request/Response
messages
 Provides additional information
GET /index.html HTTP/1.0
Host: www.anyhost.com
User-Agent : Mozilla/4.5 [en] (WinNT;
I)
Accept : image/gif, image/jpeg, */*
Accept-language : en
Accept-charset : iso-8859-1, *, utf-8
HTTP/1.0 200 OK
Last-Modified: Mon, 20 Dec 1999 …
Date: Tue, 11 Jan 2002 …
Status: 200
Content-Type: text/html
Servlet-Engine: Tomcat Web Server
Content-Length: 59
<html>
…
</html>

Universal Resource Locators
(URL)
 It is also called “Uniform Resource Locators” which
is used to identify resources on the Internet.
 It has the following general format:
 Scheme:object-address
 Schemes can be
 http, ftp, gopher, telnet, file, mailto, news
 Object-address
 //fully-qualified-domain-name/document-path
 E.g. http://www.cse.cuhk.edu.hk/index.html

Who manages the Internet?
 There is no such a central authority manages the whole
Internet.
 The Internet is managed in a hierarchical fashion with
several organizations on the top.
 Internet Assigned Numbers Authority (IANA)
 Regional Internet Registry for Europe (RIPE)
 Asian Pacific Network Information Center (APNIC)
 American Registry for Internet Numbers (ARIN)

Top-Level Domains
Country code
domain
Generi
domain

INE2720 – Web Application
Software Development All copyrights reserved by C.C. Cheung 2003. 29
IP Address Space

30
Who defines the Web
standards?
 The Web standards are not defined or setup by the
browser companies or Microsoft, but the World Wide
Web Consortium (W3C).
 The specifications form the Web standards.
 HTML, CSS, XML, XHTML, …

W3C
 Quoted from W3C:
 W3C's long term goals for the Web are:
1. Universal Access: To make the Web accessible to all by promoting
technologies that take into account the vast differences in culture,
languages, education, ability, material resources, and physical
limitations of users on all continents;
2. Semantic Web : To develop a software environment that permits
each user to make the best use of the resources available on the
Web;
3. Web of Trust : To guide the Web's development with careful
consideration for the novel legal, commercial, and social issues
raised by this technology.

The History of Markup
 In the early 1970s
 GML (the Generalized Markup Language)
 “:h1.The Content is placed here”
 Since the 1980s
 SGML (the Standard GML)
 HTML
 Currently
 XML
 Not intended to replace HTML!
 XHTML does by providing better data description, …

SGML, HTML and XML
Meta
Language
Language
Usage of the
Language
SGML XML
HTML
Web pages
XHTML
simplifies
defines
XML
Definitions
XML
Documents
Meta
Data
Data

HTML
 Hyper Text Markup Language
 Use to describe the general form and layout of
documents to be displayed by the browser.
 Compose of “Content” and “Controls”
 The Difference Between XML and HTML.
 XML and HTML were designed with
different goals: XML was designed to carry data - with
focus on what data is. HTML was designed to display data -
with focus on how data looks.

WML
 Wireless Markup Language
 Formerly called HDML (Handheld Devices Markup
Languages)
 Allows the text portions of web pages to be displayed on
cell phones or PDAs via wireless media.
 It is part of the Wireless Application Protocol (WAP).

XML
 eXtensible Markup Language (XML)
 It provides a standard way to represent
information so as to allow information to be stored
and interchanged among any Internet-connected
devices.
 It is not a markup language.
 It is a meta-markup language that specifies rules for
creating markup languages.
 Browsers use XML parsers to isolate and extract the
information from XML documents.

All copyrights reserved by C.C. Cheung 2003. 39
MathML Example
 E = mc2
MathML Presentation Markup Example
<mrow>
<mi>E</mi><mo>=</mo><mi>m</mi>
<msup>
<mi>c</mi>
<mn>2</mn>
</msup>
</mrow>

XHTML
 The eXtensible HyperText Markup Language
 A Reformulation of HTML 4 in XML 1.0
 Consists all HTML 4.0.1 predefined components
combined with XML standards
 A way of making XML documents that look and
act like HTML documents.
 Using XHTML helps you strengthen the structure
and syntax of your markup.

HTML – OK, XHTML - !OK
<HTML>
<HEAD>
<TITLE>My Title</TITLE>
<body></HEAD>
<td>It is an acceptable HTML, but
an unacceptable XHTML
</BODY>
…
<table WIDTH=80%>  Incorrect
<table width=“80%”>  Correct

HTML 5
 HTML5 is the latest version of Hypertext Markup
Language, the code that describes web pages. It's
actually three kinds of code: HTML, which provides
the structure; Cascading Style Sheets (CSS), which
take care of presentation; and JavaScript, which makes
things happen.

Cascading Style Sheets (CSS)
 Provides a powerful and flexible way to control the
details of web documents.
 HTML is more concerned about the content, CSS
is used to impose a particular style on the
document.
 Named cascading style sheets because they can be
defined at three different levels to specify the style
of a document.
 Inline, document level, external.

Using Stylesheets to add
presentation
HTML Page
CSS stylesheet
Web browser Displayed page

Client-Side and Server-side
Programming
 Client-side code
 ECMAScript
 JavaScript
 VBScript – Microsoft
 Embedded in <script> elements and execute in the browser,
provides immediate feedback to the user.
 Reduces the load on a server, reduces network traffic.
 Server-side code
 Execute on the server
 CGI/Perl, ASP, PHP, ColdFusion, JSP
 The code remains hidden from users, and browser independent.
 Can be combined with good results.

Client-side & Server-side
Technologies
Client-Side Server-Side
HTML, XML, XHTML
Cascading Style Sheets (CSS)
Scripting languages
- JavaScript, VBScript
Java Applets
ActiveX controls
Plug-ins and Helpers application
CGI/Perl
PHP
ColdFusion
Scripting Languages
- ASP, JSP, Java Servlets
ISAPI/NSAPI programs

JavaScript
 There is no relationship between Java and JavaScript –
misleading!
 They both contain “Objects”.
 It provides a computational capability in web
documents.
 It is used in creating, accessing, modifying a
document.

What can JavaScript do?
 Control document appearance and content
 Control the browser
 Interact with the user
 Read and Write Client State with Cookies
 my.yahoo.com
 Interact with Applets
 What it cannot do?
 Read/write files
 Protect your system

DHTML
 It is used to describe a set of animated web documents
that built from HTML, style sheets and scripts.
 There are three main parts of DHTML
 Positioning
 Style modifications
 Event handing
 It relies on the browser for the display and
manipulation of the web pages.

VRML
 Virtual Reality Modeling Language (VRML) is a
language for the animation and 3D modeling on the
Internet.
 The user can connect the online VRML website and
move around the “3D world”.

Server Slide Include (SSI)
 Some pages end with the .shtml extension
instead of the .html or .htm
 The web server reads the document and parses it
for directives.
 
 
 Follows the instructions and creates an enhanced
document.
 The new document is sent to the client browser.

CGI/Perl
 When the page is loaded by a browser, the tag of the
webpage call the script and then execute by the server.
 It is different from the Java applets or JavaScript which
are executed by the client’s system.

CGI / Perl
 Common Gateway Interface (CGI) is a standard way in
which a browser communicate to run a program on the
server and return the output to the browser.
 It can be written in any programming language (most
common is Perl).
 It is a powerful string pattern-matching language.

Using Scripts
HTML Page
CSS stylesheet
Web browser Displayed page
Database
File stored
scripts

VBScript
 VBScript is the short form for Visual Basic Scripting
from Microsoft.
 Try to edit a file “hello.vbs”
 Msgbox “Hello world”

ASP
 Active Server Page was developed by Microsoft and
it is a popular technology for developing dynamic
web sites.
 It allows the author includes scripting code (VBScript or
JScript) in regular web pages.
 In complex code, COM (ActiveX) components are used.
 Must run on an active server pages server
 IIS, Personal Web Server, …
 The latest version is ASP.NET

How to load an ASP page?
Client Server
Request
Reply with
HTML page
ASP
Server
Component
Hands request to
Hands HTML page
Translates
Script
Into
HTML

PHP
 It is not an acronym for anything.
 An open source web scripting language.
 A PHP page is always interpreted by the server when it is
requested.
 The latest version is PHP 7.
 Have to learn an entirely new language.
 Reference: http://www.php.net/

PHP Popularity
http://www.veon.in/sugarcrm/php-face-of-modern-web-app/

INE2720 – Web Application
Software Development
PHP Example

ColdFusion
 It is a Web application development environment
produced initially by the Macromedia Corporation.
Client
Web Server
Request *.cfm
Reply Web Page
CF Page
Cold Fusion
Application
Server
Web Page

JAVA / Java applet
 Instead of running a program on the web server, a
special kind of Java program (applet) is downloaded to
the browser.
 JavaScript is less powerful than Java.
 JavaScript code is physically part of an HTML
document, but applets are stored separately from the
HTML files.

Java 2 Platforms
 J2EE
 J2SE
 J2ME

Java Servlets
 They are Java application programs that are resident
on the server and are alternatives to CGI programs.
 Java Servlets allow you to build
 Web page based on the user’s input data
 Web page that changes frequently
 More efficient, easier to use, more powerful and
portable.

Servlets Advantages
 Platform and vendor independence
 Supported by all the major web servers
 Integration
 Take advantages of all the Java technologies, JDBC,
Enterprise JavaBeans (EJB).
 Efficiency
 A single process that runs until the servlet-based
application is shut down.
 Scalability – extremely scalable.
 Robustness and security
 A strongly typed programming language.

What is JSP?
 It is JavaServer Pages that built on top of Java servlets in
late 1999.
 In the early days of the Web, the only tool for developing
dynamic web content was CGI. For every request, the web
server creates a process (not efficient).
 The Java Servlet API has introduced in 1997, however,
HTML code has to be embedded inside programs. (lot of
“out.println()”)
 JSP provides a development model for the web authors to
experience all the server-side technologies.

69
Processing phase
Translation phase
JSP page translation and
processing phases
Client Server
Request
Response
Hello.jsp
helloServlet.class
helloServlet.java
Read
Generate
Execute

70
Example Java Servlet & JSP
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class HelloWorld extends HttpServlet {
public void doGet(HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException {
res.setContentType("text/html");
PrintWriter out = res.getWriter();
out.println("<HTML>");
out.println("<HEAD><TITLE>Hello World</TITLE></HEAD>");
out.println("<BODY>");
out.println("<BIG>Hello World</BIG>");
out.println("</BODY></HTML>");
}
}
<HTML>
<HEAD>
<TITLE>Hello</TITLE>
</HEAD>
<BODY>
<H1>
<%
if (request.getParameter("name") == null)
{
out.println("Hello World");
} else {
out.println("Hello, " +
request.getParameter("name"));
}
%>
</H1>
</BODY>
</HTML>

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