Day 2 1 Modified Fundamentals 1 PDF

Preview

Summary

web programming lectures ...

Description

Topics   History

of the Internet   History of the World Wide Web   Network communication over Internet   Client-server architecture by Web browser and Web server   MIME structure: the formats of web control messages   The HyperText Transfer Protocol

1

Slides references:   wikipedia.com   online

images   Dr. Fancott lecture slides – SOEN287 2009 fall version   Dr. Jose Vidal (SCU) – CSCE242 2008 version

How do we connect to Internet? How do we use Internet?

2

The Internet: A network of networks Mobile network Global ISP

Home network Regional ISP

Institutional network

3

An Image of the Internet

image from wikipedia!

4

Internet History 1961-1972: Early packet-switching principles!   1967:

ARPAnet conceived by Advanced Research Projects Agency   1969: first ARPAnet node operational

  1972:      

ARPAnet public demonstration first e-mail program ARPAnet has 15 nodes

•  communication •  file/program sharing •  remote access 5

Internet History 1972-1980: Internetworking, new and proprietary nets!   1970:

ALOHAnet satellite network in Hawaii   1974: Cerf and Kahn architecture for interconnecting networks   1976: Ethernet at Xerox PARC   late70’s: proprietary architectures: DECnet, SNA, XNA   late 70’s: switching fixed length packets (ATM precursor)   1979: ARPAnet has 200 nodes

Cerf and Kahn’s internetworking principles:   decentralized control   stateless routers   minimalism, autonomy no internal changes required to interconnect networks   best effort service model define today’s Internet architecture

6

Internet History 1980-1990: new protocols, a proliferation of networks!   1983:

deployment of TCP/IP   1982: smtp e-mail protocol defined   1983: DNS defined for name-to-IP-address translation   1985: ftp protocol defined   1988: TCP congestion control

  new

national networks: Csnet, BITnet, NSFnet, Minitel   100,000 hosts connected to confederation of networks

7

Internet History 1990, 2000’s: commercialization, the Web, new apps!   Early

1990’s: ARPAnet decommissioned   1991: NSF lifts restrictions on commercial use of NSFnet (decommissioned, 1995)   early 1990s: Web    

hypertext [Bush 1945, Nelson 1960’s] HTML, HTTP: Berners-Lee

8

Tim Berners-Lee and WWW Origins: Tim Berners-Lee at CERN proposed the Web in 1989

  WWW        

CERN: Conceil Eurropean pour la Recherce Nucleaire A new protocol: HTTP Hypermedia – more than just text – images, sound, etc. Exchange documents

  The

ENQUIRE system   The first Web server (CERN HTTPD)   The first browser

9

Tim Berners-Lee and WWW (2) "I just had to take the hypertext idea and connect it to the Transmission Control Protocol and domain name system ideas and — ta-da! — the World Wide Web”!   The

founder of the World Wide Web Consortium (since 1994)   the founder of the World Wide Web Foundation (since 2008)   MIT Computer Science and Artificial Intelligence Laboratory   a member of the United States National Academy of Sciences,

2005!

10

WWW History 1990, 2000’s: commercialization, the Web, new apps!   early

1990s: Berners-Lee   1994: Mosaic

11

WWW History 1990, 2000’s: commercialization, the Web, new apps!   early

1990s: Berners-Lee   1994: Mosaic, later Netscape

12

WWW History 1990, 2000’s: commercialization, the Web, new apps!   early

1990s: Berners-Lee   1994: Mosaic, later Netscape   1994: Yahoo (Jerry Yang and David Filo)

13

WWW History 1990, 2000’s: commercialization, the Web, new apps!   early

1990s: Berners-Lee   1994: Mosaic, later Netscape   1994: Yahoo (Jerry Yang and David Filo)   1996: BackRub (Larry Page and Sergey Brin)

14

WWW History 1990, 2000’s: commercialization, the Web, new apps!   early

1990s: Berners-Lee   1994: Mosaic, later Netscape   1994: Yahoo (Jerry Yang and David Filo)   1996: BackRub (Larry Page and Sergey Brin), later Google

15

Internet History 1990, 2000’s: commercialization, the Web, new apps! Late 1990’s – 2000’s:   more killer apps: instant messaging, P2P file sharing   network security to forefront   est. 50 million host, 100 million+ users   backbone links running at Gbps 16

Internet History 2007:   ~500 million hosts   Voice, Video over IP   P2P applications: BitTorrent (file sharing) Skype (VoIP), PPLive (video)   more applications: YouTube, gaming, Gmail, Firefox   social net software   wireless, mobility

17

More Web applications at work Performance   Email   Enterprise Mgmt   Transportation Mgmt   Customer Service   Talent Mgmt &Support   Travel Booking System   Sales   Team Collaboration   Accounting   Sourcing & E-Procurement   Supply Chain   Web Conferencing Planning   E-learning   Employee Self-Service   Recruitment   Warehouse Mgmt   Mktg Automation Google I/O 2010, Keynote Day 1, pt. 8!  

Social Software

  Emplyee

18

The Growth of the Internet

19

The Web Platform

From Brad Beuberg: Introduction to HTML5 at Yahoo Theatre!

20

Network Communication over Internet

21

Internet structure: network of networks   a

packet passes through many networks! local ISP

Tier 3 ISP

local ISP

Tier-2 ISP

local ISP

local ISP Tier-2 ISP

Tier 1 ISP

Tier 1 ISP Tier-2 ISP local local ISP ISP

Tier 1 ISP Tier-2 ISP local ISP

Tier-2 ISP local ISP 22

Two hosts and two routers

23

The Abstraction Layers & Protocols

Application.

Application.

Transport. TCP, UDP.

Transport. TCP, UDP.

Internet. IP.

Internet. IP.

Link.

Link. Host-to-network. Ethernet, FDDI.

24

The Abstraction Layers Data! Segment! Datagram Packet! Frame!   The

Open Systems Interconnection (OSI) 7-level model is overkill.   Encapsulation of application data descending through the protocol stack.   A gateway (router) connects two local networks. 25

TCP/IP Function of the bits in an IP datagram packet.! 0

4

8

12

Version

Header Length

Type of Service

16

20

24

28

Datagram Length

Identification

Flags

Fragment Offset

TTL Protocol Source address IP Destination address IP Options

Header checksum

TCP: Source Port TCP: Sequence Number TCP: Acknowledgment Number

TCP: Destination Port

26

TCP and UDP   The

transport layer is implemented by either TCP or UDP.  

 

The Transmission Control Protocol make sure that all packets are received, and in order. It uses numbering and re-sending. RFC 761 User datagrams allow lost and unordered packets. It is thus faster than TCP. RFC 768

27

Internet Protocol Defines IP Addresses   Every  

Form: 32-bit binary number  

 

node has a unique numeric address

Concordia.ca: 132.205.7.63

New standard, IPv6, has 128 bits (1998)

  Organizations

are assigned groups of IPs for their

computers

28

iClicker Question:   Which

A.  B.  C.  D. 

of the following IP address is possibly valid?

256.0.2.4 127.0.0.1 192.1.2 134.789.5.6

Answer: B! 29

Domain names   Form:  

host-name.domain-names

For example: concordia.ca, users.encs.concordia.ca

  First

domain is the smallest; last is the largest   Last domain specifies the type of organization   Fully qualified domain name - the host name and all of the domain names   DNS servers - convert fully qualified domain names to IPs

30

Distributed, Hierarchical Database Root DNS Servers

com DNS servers yahoo.com amazon.com DNS servers DNS servers

org DNS servers pbs.org DNS servers

edu DNS servers poly.edu umass.edu DNS serversDNS servers

Client wants IP for www.amazon.com; 1st approx:   client

queries a root server to find com DNS server   client queries com DNS server to get amazon.com DNS server   client queries amazon.com DNS server to get IP address for www.amazon.com 31

DNS: Root name servers   contacted

by local name server that can not resolve name   root name server (13 root servers (each a cluster of replicated servers)):      

contacts authoritative name server if name mapping not known gets mapping returns mapping to local name server a Verisign, Dulles, VA c Cogent, Herndon, VA (also LA) d U Maryland College Park, MD g US DoD Vienna, VA h ARL Aberdeen, MD j Verisign, ( 21 locations)

e NASA Mt View, CA f Internet Software C. Palo Alto,

k RIPE London (also 16 other locations) i Autonomica, Stockholm (plus 28 other locations) m WIDE Tokyo (also Seoul, Paris, SF)

CA (and 36 other locations)

b USC-ISI Marina del Rey, CA l ICANN Los Angeles, CA

13 root name servers worldwide! 32

  The

Web uses one of the protocols, http: hyper text transfer protocol ftp: File transfer protocol smtp: Simple Mail Transfer Protocol nntp: Newsgroups Protocol

33

Internet structure: network of networks   roughly

hierarchical   at center: “tier-1” ISPs (e.g., Verizon, Sprint, AT&T, Cable and Wireless), national/international coverage   treat

each other as equals

Tier-1 providers interconnect (peer) privately

Tier 1 ISP

Tier 1 ISP

Tier 1 ISP

34

Tier-1 ISP: e.g., Sprint

35

Internet structure: network of networks   “Tier-2”  

ISPs: smaller (often regional) ISPs

Connect to one or more tier-1 ISPs, possibly other tier-2 ISPs

Tier-2 ISP pays tier-1 ISP for connectivity to rest of Internet   tier-2 ISP is customer of tier-1 provider

Tier-2 ISP

Tier-2 ISP

Tier 1 ISP

Tier 1 ISP Tier-2 ISP

Tier 1 ISP

Tier-2 ISPs also peer privately with each other.

Tier-2 ISP

Tier-2 ISP 36

Internet structure: network of networks   “Tier-3”  

ISPs and local ISPs

last hop (“access”) network (closest to end systems) local ISP

Local and tier3 ISPs are customers of higher tier ISPs connecting them to rest of Internet

Tier 3 ISP

local ISP

Tier-2 ISP

local ISP

local ISP Tier-2 ISP

Tier 1 ISP

Tier 1 ISP

Tier-2 ISP local local ISP ISP

Tier 1 ISP Tier-2 ISP local ISP

Tier-2 ISP local ISP 37...