CMPT 165 Intro to Internet & WWW

Sept. 10th 2015

Admin

• Survey on TA office hours

• Course website

CMPT 165 D1 (Fall 2015) 2

My objectives • I aim to teach you concepts that will stay with you for

a long, long time.. (hopefully really long time!)

– Good (or bad) news: we won’t test you on definitions

• How to know if you truly understand concepts?

– Try the 5W’s: • What

• Who

• When

• Where

• Why

• How

CMPT 165 D1 (Fall 2015) 3

e.g. What is a modem made of?

Who uses modems?

When is it (un)necessary?

Where can it (not) be installed?

Why would one choose a modem over a wireless router?

How does a modem work really?

Today’s agenda

• Preliminaries

• Internet & its structure

– Network devices: modems, router, etc.

• Learn few terms & concepts:

– Client/Server communication

– How data is transmitted over the internet

– Connection and network types

– IP address…

4 CMPT 165 D1 (Fall 2015)

In-class Exercise #1 Instructions:

1. Get into groups of 3

2. Find a piece of paper

3. Write your student IDs on top-right corner

4. Delegate one student to write down answers

5. Answers derived from group discussions only; no other tools allowed.

At the end of 30min. session

• We will have your answer sheets marked after

• Marker: write your student IDs on top-left corner

• When answering questions:

– Use bullet points

– Be as precise as possible

• Your group scores will be kept on file for future reference

CMPT 165 D1 (Fall 2015) 5

Questions 1. What is a computer?

2. What does binary mean?

3. What is a software?

4. What are differences between software and hardware?

5. What is malware?

6. What is physical memory?

7. What does upload means?

8. How is download differ from upload?

9. What does a modem do?

10. What is a network? How is Facebook related to the term network?

11. What is an ADSL?

12. What is a command prompt?

13. What is ipconfig?

14. What is an “IP”?

6 CMPT 165 D1 (Fall 2015)

Preliminaries

Computer: device that is programmed (instructed) to perform some operations automatically

Hardware: physical items that you buy at a store

e.g. motherboard, hard drive, memory card, etc.

7 CMPT 165 D1 (Fall 2015)

Preliminaries

8

http://en.wikipedia.org/wiki/Motherboard

CMPT 165 D1 (Fall 2015)

Preliminaries

9 http://en.wikipedia.org/wiki/Hard_disk_drive

CMPT 165 D1 (Fall 2015)

Preliminaries

Computer: device that is programmed (instructed) to perform some operations automatically

Hardware: physical items that you buy at a store

e.g. motherboard, hard drive, memory card, etc.

Software: instructions stored and run by hardware

• 3 common types: – Application: Browser (“FireFox”), Word, PowerPoint, Paint,

Acrobat Reader, Notepad++, …

– System:

• Operating system: e.g. OS X of Mac, Windows of PC

• Devices drivers (for printer, monitor, scanners, etc.)

– Malware: malicious software

10 CMPT 165 D1 (Fall 2015)

Preliminaries Data

• Computers do not read text like humans do

• They are programmed to interpret streams of “bits” only, e.g.

… 00100010 00000110 11101011 …

• Bits (binary digits): 2 states “binary”

• 8 bits = 1 byte Example above: “3 bytes of data”

Memory storage

• Physical: data is stored permanently on device

– E.g. Hard drive, USB “local” storage

• Virtual: data is lost after computer is shut off

Modem: “modulator-demodulator”

• Encode/decode data for communication between devices

– streams of bits signals

– signals streams of bits

11

CMPT 165 D1 (Fall 2015)

Preliminaries – Summary • Hardware

• Software

– Application software

– Operating system

– Malware

• Data

– Bits

– Bytes

• Memory storage

– Virtual

– Physical

• Modem

12 CMPT 165 D1 (Fall 2015)

Internet & its Structure

13

What is the Internet? Inter-connected network

Computer network: computers connected together

– Connected:

• Communication channels established

• Data transferred between individual network entities

– Illustration: (links/lines as connections between endpoints)

“Internet”: typically used to refer to its global nature

• Billions of computers world wide interconnected via some infrastructure

14

https://thesprawl.org/media/projects/opte2kml.png

CMPT 165 D1 (Fall 2015)

CMPT 165 D1 (Summer 2005)

15

Illustration of the 2005 Internet Dark blue: .net .ca .us Green: .com .org Red: .mil .gov .edu Yellow: .jp .cn .tw ... Magenta: .uk .it .fr ... …

http://www.opte.org/the-internet/

CMPT 165 D1 (Summer 2005)

Illustration of the 2010 Internet

16 http://www.opte.org/the-internet/

Warmer color indicates denser connections

Internet vs. World Wide Web

• Consists of a set of software services running on the Internet + webpages (connected documents)

• World Wide Web Consortium (W3C)

– made up of member organizations, each with staff working on developing “standards for the WWW”

– Has 397 members as of April 2015 [wiki]

CMPT 165 D1 (Summer 2005) 17

A dichotomy of the network

18

Structure of a simple network Home#1: consists of laptop, tablet, computer, router

Home#2: computer, …, modem

Home#3 (or office/lab): printer, …, modem

19

Internet Service

Providers (Gateways)

Networking devices

Web servers (computers with sophisticated hard/software)

Greg Baker ©

CMPT 165 D1 (Fall 2015)

Simple computers that serve to relay data

Data transmission process:

Suppose you request to view the “www.sfu.ca” webpage on your tablet…

1. Client (B): requests the webpage for “www.sfu.ca”

2. Networking device (D): relays request to the correct path

3. Server (L): receives + processes request + send data back

Establishing connection (communication)

20

? ?

?

? ?

“SFU web server” hosting www.sfu.ca

Greg Baker ©

CMPT 165 D1 (Fall 2015)

Related Internet terminologies

Upload vs. download data

Local area network vs. wide area network

21

Greg Baker ©

CMPT 165 D1 (Fall 2015)

Networking devices Devices L + S have 2 communication pathways

- Uses these devices to relay data so they go through “best” path

- E.g. Router, Hub, Switch

22

Greg Baker ©

CMPT 165 D1 (Fall 2015)

Common connection types

Greg Baker ©

23

Wired: Wireless:

CMPT 165 D1 (Fall 2015)

Common connection types

Ethernet: connects devices with wire

Dial-up: connects via phone line

Cannot surf while on phone

ADSL (Asymmetric Digital Subscriber Line): copper wire phone line

Faster than Dial-Up

Download faster than upload

TV cable

Modem:

e.g. “001001” electrical signals

Wi-Fi “wireless fidelity” network

e.g. 802.11b, 802.11g

Radio waves to transmit data

Bluetooth

Radio waves of shorter wavelengths

Meant for shorter distances

…

Wireless router:

“001001” radio wave signals

Wired:

24

Wireless:

CMPT 165 D1 (Fall 2015)

Other types of network

Mobile

• Phones use either wifi or mobile network, if wifi N/A

• Data is transmitted wirelessly to phone towers

• Slowest to fastest: GSM, EDGE, 3G, HSPA, LTE

Fiber optic

• Strands of glass or plastic, slightly thicker than hair

• Transmit data as pulses of light

• Works very well even over long-distance

25 CMPT 165 D1 (Fall 2015)

Quick recap

• Computer: defined

• Different types of computers: routers, modems, tablet

• Roles of computers: Clients vs. Servers

• What is a connection

– What is involved in the communication

– Data transfer process

• How connections are established between them

– Physical vs. non-physical

26 CMPT 165 D1 (Fall 2015)

Next week

• Finish off last 3 questions

• Start on Unit 2

27 CMPT 165 D1 (Fall 2015)