Internet and WWW

Internet

• A way to send an array of bytes from any machine to any other machine

Internet

How to identify the machine to send to

• By address (IP Address - 4 bytes)

Internet

128.78.22.32233.21.1.45

117.211.23.22 233.12.32.111

How to identify the machine to send to

• By name (domain name)

Internet

Croatian.cs.byu.eduIcie.cs.byu.edu

Myhome.isp.com Yahoo.com

Domain Name - a pathname in a tree

EDU COM GOV

BYU

CS

WWW ICIE

EE

MIT Utah Microsoft

research

Yahoo

whitehouse

LOC

Icie.cs.byu.edu

EDU COM GOV

BYU

CS

WWW ICIE

EE

MIT Utah Microsoft

research

Yahoo

whitehouse

LOC

Servers

• Computers that store information or services

Internet

Icie.cs.byu.edu

Yahoo.com

Clients

• Programs that help users get access to info

Internet

Netscape

Instant messenger

Protocol

• Language for computers to talk with each other

Internet

Netscape

Instant messenger

HTTP

IRC

Review

• Internet– Array of bytes between computers– By address 128.23.12.1– By name icie.cs.byu.edu

• Server - delivers info on request• Client - helps user access server info• Protocol - language for computers to talk with

each other

URL (Uniform Resource Locator)

• http://www.yahoo.com/

• http://www.espn.com/nba

• http://icie.cs.byu.edu/cs100/schedule.html

URL - Protocol

• http://icie.cs.byu.edu/cs100/schedule.html

• ftp://netscape.com/downloads/msng.exe

• mailto:george.w.bush@whitehouse.gov

URL - Domain Namename of the server to access

• http://icie.cs.byu.edu/cs100/schedule.html

• ftp://netscape.com/downloads/msng.exe

URL - page name

• http://icie.cs.byu.edu/cs100/schedule.html

• ftp://netscape.com/downloads/msng.exe

URL - page name

• http://icie.cs.byu.edu/cs100/schedule.html• http://icie.cs.byu.edu/cs100/Lectures/server.gif• http://icie.cs.byu.edu/cs100/Lectures/L1.ppt• http://icie.cs.byu.edu/cs456/Homework/Program1• http://icie.cs.byu.edu/cs456/Homework/Program2

– -

URL - page name

• http://icie.cs.byu.edu/cs100/schedule.html• http://icie.cs.byu.edu/cs100/Lectures/server.gif• http://icie.cs.byu.edu/cs100/Lectures/L1.ppt• http://icie.cs.byu.edu/cs456/Homework/Program1• http://icie.cs.byu.edu/cs456/Homework/Program2

– Page names are pathnames in a tree

URL - page name

• cs100/schedule.html

• cs100/Lectures/ server.gif

• cs100/Lectures/L1.ppt

• cs456/Homework/Program1

• cs456/Homework/Program2

cs100

schedule.html

Lectures

server.gif L1.ppt

cs456

Homework

Program1

Program2

Hypertext

• How to link together many documents so that users can get whatever information they want.

Links

Linkshttp://nasa.gov/home.html

http://nasa.gov/security.html

http://nasa.gov/NTV.html

Search Engines

Links

Search Engines

??

Search Engines

Pathname in a category tree