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thickbugSoftware and s/w Development

Oct 28, 2013 (4 years and 10 days ago)

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© Minder Chen, 1996
-
2013

Web Architecture
-

1

The Architecture of Internet and WWW

Web

Browser

Client

Web

Server

End User

HTTP

TCP/IP

HTML

documents

Internet

or

Intranet

Benefits of the Web as a delivery mechanism:

•
Thin clients

•
Platform independence

•
Easy for deployment/upgrade

•
Based on standards




© Minder Chen, 1996
-
2013

Web Architecture
-

2

Internet: The Virtual Network & Internal Structure

Computer

Router

A Regional Network

Internet

NAP

ISP

LAN

NAP: National Access Point ISP: Internet Service Provider

TELCO

© Minder Chen, 1996
-
2013

Web Architecture
-

3

Hosts on the Internet

•
IP Datagram

–
Datagram Header

•
Source: 15.127.9.12 (IP Address)

•
Destination: 254.231.15.129

•
American Registry for Internet Numbers https://www.arin.net/

Router

Total about 4.3 billion IP addresses.

© Minder Chen, 1996
-
2013

Web Architecture
-

4

Domain Name

•
DNS (Domain Name Server): Mapping the four octets (32
-
bit numeric)
IP address (such as 217.156.3.14) to a domain name such as
student.csuci.edu

•
http://www.godaddy.com

for domain name registration


edu

uiuc

csuci

cs

vax

The name of a host computer
with an IP address

student

First Level

Second
Level

CSUCI.EDU

Top
country
domain
name

.us

.tv (30M)

.md

© Minder Chen, 1996
-
2013

Web Architecture
-

5

Key Elements of Web

•
Hypertext
: Non
-
linear links to anchors of the
same document, or to different documents on
the same or different web site.

–
Using HTML (HyperText Markup Language) links and
anchors

–
Relying on URL (Uniform Resource Locators)
addressing scheme

•
Multimedia: graphics, video, sound, etc.

–
Web browser can access networked hypermedia.

–
Hypermedia access of the web browser is facilitated
by helper applications, plug
-
ins, or document
viewers.

•
Network: Global reach and "Universal" access

–
Based on HTTP which is built on top of the TCP/IP
protocol.

© Minder Chen, 1996
-
2013

Web Architecture
-

6

Client
-
Server Model of http

Web Server

Web Client

•
Requesting a
document via a
URL address

•
Connection open

•
Returning MIME
-
compliance document

•
Connection close

helper app

helper app

helper app

helper app

helper app

Web contents

•
HTML documents

•
Images

•
Animation

•
Video clips

•
Sound bites

•
Java applets

•
Java Scripts

•
CGI scripts

•
JSP

•
Database access

•
ASP/ASPX/PHP

•
JSP

Web Site

Internet or

Intranet

1

2

Static

Dynamic

MIME: Multipurpose Internet Mail Extension

© Minder Chen, 1996
-
2013

Web Architecture
-

7

HTTP

•
HTTP: HyperText Transfer Protocol

•
Characteristics:

–
Runs on top of TCP/IP (Transmission Control
Protocol/Internet Protocol)

–
Has a comprehensive addressing scheme, i.e. URL

–
An extensible and open representation for data type,
using MIME header

–
Has a
stateless

protocol. There is no
memory
between client connections.


Cookies are used to
track users.

–
Is efficient

–
Is portable

–
Possible extensions, Secure HTTP (SHPPT), SSL.
(
https
://URL)

© Minder Chen, 1996
-
2013

Web Architecture
-

8

The Extended Framework of WWW

Web

Browser

Client



HTML
Authoring

Tools/Editors

End User

Web Master

Web Designer

& Publisher

External Applications

Non
-
HTTP objects

•
ColdFusion,

•
CGI (Perl)

•
ASP & ASP.NET

•
JAVA Servlet

•
Java Server
Pages

•
Java Applet

•
JavaScript

Internet


Global Reach

Broad Range

Web Programmer

Web

Server



<html>

<head>

<title> HTML Sampler Web Page </title>

</head>

<body>

<h1>HTML Sampler</h1>

<img src="eyes.gif"><br>

<b> List: </b>

<ul>

<li> Item 1

<li> <font size=+2>Item 2</font>

<li> <i>Item 3</i>

</ul>

<table border=1>

<tr> <th> Name</th> <th>Speciality </th> </tr>

<tr> <td> Minder Chen</td> <td>MIS </td> </tr>

<tr> <td> Justin Chen</td> <td>Aerospace </td> </tr>

</table>

<p>

A sample of a form:

<form method="post"

action="http://hoohoo.ncsa.uiuc.edu/cgi
-
bin/post
-
query" >

Name: <input type="text" size=20> <br>

<input type="checkbox" name="html" value="YES"> Know HTML <br>

<b><input type="submit" value="Submit your data"></b>

</form>

<hr> Developed by

<a href="http://www.erols.com/aitc/"> Advanced IT Consulting</a>

</body></html>

© Minder Chen, 1996
-
2013

Web Architecture
-

10

HTTP (Web) Cookie

•
First party and third party Cookies at http://on.wsj.com/LamyJX


This is how most web sites used to track
you and maintain online sessions.

© Minder Chen, 1996
-
2013

Web Architecture
-

11

Clickstream

•
Hit
–

any Web server request that generates a log file entry. A
page has many elements (html, gifs), each generating a hit.

•
Page
–

Web server file that is sent to client user agent, usually a
browser.

•
Session
–

all actions (i.e. requests, resets) made in single visit,
from entry until logout or time out (e.g., 20 minutes of no
activity).

•
Visitor
–

a user or bot/spider/crawler that makes requests at a
site. Can be new, returning, registered, anonymous

•
Buyer
–

visitor that purchases something

•
Customer
–

a visitor that registers (sometimes defined as buyer)

•
Conversion
–

rate at which visitors transition to desired state

•
(buyers, customers, registered, started checkout)

•
Host
–

remote machine, identified by IP address, used for visit.

•
Referrers
–

page that provides a link to another page. Can be
internal or external

© Minder Chen, 1996
-
2013

Web Architecture
-

12

Web Log Analysis

•
Number of visits and number of unique visitors

•
Visits duration and last visits

•
Authenticated users, and last authenticated visits

•
Days of week and rush hours

•
Domains/countries of host's visitors.

•
Hosts list

•
Number total pageviews

•
Most viewed, entry and exit pages

•
Files type

•
OS

used

•
Browsers

used

•
Robots

•
HTTP referrer

•
Search engines
, key phrases and keywords used to find the analyzed web
site

•
HTTP errors

•
Some of the log analyzers also report on who's on the site, conversion
tracking, visit time and page navigation.