Transcript Lecture #7 -- Chapter 8

Welcome to CMPE003
Personal Computer
Concepts: Hardware and
Software
Winter 2003
UC Santa Cruz
Instructor: Guy Cox
Assignments
nd
2
Homework
Due Now!!
No late assignments will be accepted
January 19, 2003
2
The Internet:
A Resource for All of Us
Chapter 8
Part A
Objectives
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Describe some of the history of the Internet
Explain what is needed to get on the Internet
Describe generally what an Internet service
provider does
Describe the rudimentary functions of a browser
Describe how to search the Internet
List and describe the non-Web parts of the
Internet
Explain some of the ongoing problems
associated with the Internet
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History of the Internet


Government and Universities over 30 years
Who’s connected today?
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Individuals
Educational institutions
Government/Military/Police
Research
Medical
Businesses
Everyone!
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The Early Years


1969 – US Department of Defense and Rand
Corporation
Origins

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
Cold War – fear that a bomb could demolish computing
capabilities
Several computers, geographically dispersed, networked
together
Plan – if one computer was disabled, others could carry on
using alternative communication routes
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The Early Years

Many WANs and LANs were installed, but
machines on the WANs could not access
information on the LANs..
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
Remote access was separated from local access
A single cohesive network was desirable.
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The Early Years
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US Department of Defense had a similar
scenario – lots of autonomous networks that
could not interoperate
The DoD funded network research in the
early ’70s through (D)ARPA creating various
network technologies, including a research
WAN called ARPANET.
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The Early Years

ARPANET allowed researchers the
opportunity to build a working test-bed for
networking ideas.

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Solved incompatibility issues
Solved interoperability issues
Created an internetwork of LANs and the WANs
The Internet is born
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The Early Years
G2
G1
UCB
LAN
UCLA
LAN
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ARPANET
Backbone
G4
G3
MIT
LAN
DARPA
LAN
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The Early Years…
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Internet Software

Internet Protocol (IP)
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Transmission Control Protocol (TCP)
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Provides basic communication
Handles the addressing and routing
Provides services for applications to communicate
Packetizes message, reassembles message at the
destination
The “TCP/IP Internet Protocol Suite”
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aka TCP/IP
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The Early Years
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ARAPA placed the research and software into
the public domain.
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All information was freely available to any person
or vendor, allowing them to create devices or
networks that would interoperate with the Internet
technology.
Improvements were documented and made
publicly available.
This philosophy is called an Open System
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The Early Years

Internet documentation


On-line and accessible from the Internet
Reports for improvements to the Internet were initially a
two step process

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
Request for comments (RFC) went out first
Internet Engineering Note came out with the comments
as the final report.
Today the RFC remains as the definitive documentation for
the Internet

On-line at www.faqs.org/rfcs/
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Also www.ietf.org/rfc.html
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The Early Years

The UNIX operating system
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Built at Bell Labs in the early ’70s
UNIX given to universities to study
UC Berkeley team added LAN software
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Distributed to others via the Berkeley Software
Distribution (BSD) and became known as BSD UNIX
(The ancestor of today’s Free BSD)
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The Early Years

ARPA negotiated with UCB to add the TCP/IP
suite to the BSD UNIX release.
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Gave large number of universities access to
study networking, and deploy it in their
departments.
1982 the US Military chose the Internet as its
primary communication system.
1983 the ARPANET began running TCP/IP
exclusively.
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The Early Years

Incredible growth from day one..
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In 1982 ~200 machines were connected
By 1983 the number had doubled
With growth comes the problems..
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Static lists of machines need updated
Limited memory space …
Software updates..
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The Early Years
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The Computer Science Network (CSNET)
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Sponsored by NSF in early `80s
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Goal was to connect every Computer Scientist in the
country over one network.
CSNET was deployed using TCP/IP and the Internet
By mid 1980s most major university and research labs
were connected to the Internet
Graduate students began to investigate the details of
these new technologies, and include them in their
research topics.
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Developed new applications
Extended the technology
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The Early Years
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The IAB (Internet Activities Board)
(Now known as the Internet Architecture
Board)

Original controlling body to coordinate TCP/IP
research and Internet development.
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Chairman – Internet Architect
RFC Editor
Formed volunteer task forces to solve problems

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Task forces generated new RFCs
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The Early Years
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The IETF (Internet Engineering Task Force)
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Originally chartered for short-term Internet
development.
Now is responsible for most of the Internet
technical development

Working groups meet and create the RFCs

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Manet, ipsec, tcp…
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The Early Years
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NSFNET
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NSF recognized the importance of the Internet to
the scientific community.
Interconnected the supercomputer centers
around the US with a TCP/IP WAN
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Proved useful, but small
NSF looked for ways to improve the ARPA Internet
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The Early Years
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The NSFNET Backbone

1988 WAN established as main backbone of the
Internet
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MCI – long distance transmission lines
IBM – dedicated computers and software
MERIT – network operation
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The Early Years
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The ANS Backbone (Advanced Networks and
Services)
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Consortium of MCI, IBM & MERIT
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Allowed the government to begin privatization of the
Internet
1992 – WAN was built to serve as the Internet
backbone
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ANSNET, 30 times NSFNET capacity
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The Early Years

Exponential growth …….
80000000
70000000
60000000
50000000
40000000
30000000
20000000
Computers
Connected
10000000
0
1983 1987 1991 1995 1999
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The Early Years
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By 1999, the Internet was growing so fast that,
on average, a computer was added to the
Internet every second – and the rate continues
to increase.
An interesting fact:
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At any time from 1983 through 1999, approximately
half the growth of the Internet occurred in the previous
12 months…
So, after you have been “on” the Internet for
only one year, you will have had more
experience than half the other users….
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The Early Years

Growth – Good and Bad
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Good for vendors
Bad for the IETF

Predictions of imminent collapse

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March 1993, Summer ’97
Technology improvements have kept up with
bandwidth and switching speeds required.
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The Early Years
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The Hard limit – Address space

The IP protocol is limited to a number contained in
4 bytes (32 bits)…
Byte 3
Byte 2
Byte 1
Byte 0
•This limits the number of possibilities to 232 = 4,294,967,296
•There are solutions – IPv6, NAT
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The Early Years
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Summary
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The Internet began as an ARPA research project.
The TCP/IP protocol software was developed to
make the Internet operational.
The Internet is an Open System, with the
technology freely available to all.
The Internet documentation is available on-line in
the form of reports known as RFCs.
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The Early Years
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Summary (continued)
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BSD UNIX distributed TCP/IP suite freely to
universities in the early 80s
1982 US Military adopted TCP/IP as primary
communication standard
Exponential growth from its inception
IAB formed to coordinate development
IETF - major technical development body
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Working groups
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The Early Years
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Summary (Continued)
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1988 – NSFNET Backbone
1992 – Privatization (ANSNET)
Exponential growth from its inception
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Half of the users today have been there less than one
year……
IP Address 32 bit limitation
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Tim Berners-Lee
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1990
Perceived a spider’s web of computers with links
from computer to computer
CERN site
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Dr. Berners-Lee’s physics laboratory
Birthplace of the World Wide Web
Easy movement due to links
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Hypertext
Hyper-region
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Marc Andreessen
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1993
Created browser software
Mosaic – first graphical browser
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Became Netscape (now owned by AOL)
Provided attractive images and a graphical interface
permitting users to click on pictures as well as text
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Internet Explosion
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September 2002
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Over 600 million users worldwide
Part of our daily lives
Four factors
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TCP/IP standard
Ability to link from site to site
Ease of use of browser
Growth of PC and LANs that can connect
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Global Internet Usage
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URL
Uniform Resource Locator
http://domain-name.top-level-domain/last-section
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Unique address of a web page or file on the
Internet
Case-sensitive
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http
hypertext transfer protocol
http://domain-name.top-level-domain/last-section
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Protocol – rules
Communication using links
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Domain name
http://domain-name.top-level-domain/last-section
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Address of the ISP
Domain names are registered
Ongoing fee is paid for each domain
name
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Top-level Domain
Represent the purpose of the organization of entity
.com
.gov
.edu
.org
.net
May be a two-letter country code
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Last section
http://domain-name.top-level-domain/last-section
Directories and file names that specify a
particular web page
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Getting Started
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Computer with a modem or NIC
Internet service provider (ISP)
Browser client
Other related software
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Internet Service Provider
Vehicle to access the Internet
 Provides

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Server computers
 Email,
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News, etc..
Software to connect
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Wireless Internet Access
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Supports mobile handheld devices
Text pagers
 PDAs
 Pocket computers
 Web-enabled cellular phones
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Applications
E-mail
 Checking weather
 Making airline reservations

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Wireless Internet Access
 Need
Account with wireless access provider
Cellular modem card or adapter

 Slow
download speeds
 Wireless Application Protocol (WAP)
Convert web pages into format for mobile devices
Resized for limited display area
Fewer graphics transmitted

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Browser
Netscape Communicator
Microsoft Internet Explorer
Mozilla
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Browser
Used to explore the Internet
 Dials the ISP
 Display web pages

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Browser
Welcome
Parts of the window
Banner
Menu
Bar
Buttons
Bookmarks
“Hot List”
Status
Line
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URL
Textbox
Control
Panel
Browser
Logo
Scroll
Bar
Display
Window
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Browser
Functions and Features
 Browser
display window
Displays contents of web page from each Internet
site visited
Screen limits how much of the site you can view at
a time. The page can be scrolled using the scroll
bar to see its entire contents

line – progress of data being
transferred and other messages
 Status
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Browser
Functions and Features
 Welcome
banner on title bar
 Browser logo – animation indicates you are
in the process of moving to a new site
 Hot list
Bookmark
Favorites
Store your favorite URLs

 Browser
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control panel – menus and buttons
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Browser
Menus and Buttons
 Pull-down
menu
 Buttons
Convenient shortcuts for commonly used functions
Click button rather than locate command from pulldown menu
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Browser Support: Frames
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Divides page into
rectangular
sections
Each section
displays web pages
independently
Several small pages
on one screen
Can be scrolled
independently
 Can be replaced
with other pages
independently


Not all browsers
support frames
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Plug-ins
 Software
that increases the functionality of
a browser
Audio-video
Image viewing

 Download
from web sites
 Install
 Example
Adobe Acrobat Reader
Shockwave

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Programming
Java
 Write software that is machine independent
 Programming language
Dancing icons
 Sound clips
 Flashing messages
 Banners that scroll


Applets – Permits dynamic web pages
Display animations
 Receive input
 Perform calculations

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Programming
ActiveX Controls
Capabilities similar to Java
Browser must be enabled to support applets /
ActiveX Controls
Security issues
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Moving Between Sites
 Clickable
categories in the browser
Sports
Weather
News
Technology
Comic strips

 Enter
the URL in the address text box and
press <Enter>
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URL
Uniform Resource Locator
http://domain-name.top-level-domain/last-section
Unique address of a web page or file on the
Internet
 Case-sensitive

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Processing Requests
URL
 User
enters a URL
 User computer sends request to the ISP
server
 ISP server sends request across networks of
TCP/IP computers
 Destination site is reached
 Content is transmitted back to your computer
(process in reverse)
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Searching the Internet
Search engine
 User specifies a search request
 Browser links to Search Engine
 Request returns matching pages based upon the
Search Engine’s database
 Results presented
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Processing Requests: Search
Engine Database

Search Engine builds database
Searchable terms
 Related web sites


Spider, robot, bot
Follows links across the web
 Automatically indexes pages to a database

 One
word
 All words

Pages may be submitted by the owner
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Processing Requests: Search Engine
Database
 Request
same search using different
engines yields different results
 Databases built independently
Size
Content
Search methodology

– atomically puts the same
request to several search engines
 Metasearch
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Processing Requests
Directory vs. Search Engine

Directory
Human involvement
 Sites organized by content category
 May concentrate on specific content areas
 Subjective decisions regarding inclusion and
importance


Search Engine
Spider, robot, or bot automatically builds database
 Index on a few keywords
 Index on all words on web page

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Processing Requests: Search
Engine Limitations
 Index
only a fraction of the Web
 Approximately 20% to 33% of sites
 More web pages added daily
 Solution
Same request to several search engines
Metasearch

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Search Tools
Directories


Yahoo!
NetGuide
Metasearch Sites


MetaCrawler
Dogpile
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Search Engines
AltaVista
 Excite
 Google
 HotBot
 Infoseek
 Lycos
 Northern Light

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Refine the Search
 Add
words
 Enclose words in “quotes”
 Use Boolean logic
 Examples
“World Trade Center”
Jordan AND NOT Michael

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Other Uses of the Internet
 Newsgroups
 FTP
 Telnet
 E-mail
 Internet
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Relay Chat (IRC)
63
Newsgroups / Usenet
Large bulletin board divided by category
 Posting and reading of messages that focus on
specific topics
 Over 20,000 newsgroups
 Functions

Conversation
 File download


Newsreader software required (included with
most browsers)
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Newsgroup Operations
 Lurking
 Posting

material
Inappropriate material
 Flame
 Flame

January 19, 2003
war
Moderated newsgroup
65
FTP Client
File Transfer Protocol
 Download
files to your local computer
 Upload files to another computer
 Requirements to download file
Permission to download from a site
File is available for copying

FTP – do not need to identify
yourself to the remote computer
 Anonymous

(But we do know your IP address)
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Public Archives
Free files provided by educational institution or
the government
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Telnet/SSH
Use your PC as a terminal providing remote access
to another computer
 Permits

Log on to a host
 Use as if you are sitting at a local terminal

Need account on the host system
 Telnet software required (provided with most
browsers)
 SSH available free on-line – must be installed

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e-mail client
Send/receive written messages
 Most used feature of the Internet
 Mail server – Collects and stores e-mail
 Mailbox – Assigned to each user
 E-mail address

User name
@
 Domain of the mail server
 [email protected]

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e-mail
Client Software Functions
Retrieve
Create
Send
Store
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Print
Delete
Address book
Attach files
Filters
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IRC: Internet Relay Chat
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Not Quite Perfect Yet
 Unregulated
 Useless
web sites
 Misinformation and misstatements on web
sites
 Concern over government censorship
 Security & Privacy Issues
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Not Quite Perfect Yet: Social
Issues
 Behavior
problems
Who is out there?
What are they doing?

 Netiquette
Suggestions for appropriate behavior
Example: TYPING IN CAPS is shouting

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Midterm #1

Wednesday – January 29
Chapters 1 – 4 and 8
 ~50 questions
 Multiple choice


Bring Scantron form
 #F-1712-ERI-L


(big & pink)
Bring #2 pencil
Bring your student ID

January 19, 2003
Required to take exam
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