Transcript WWW & Internet Fundamentals

Internet & WWW Details
Client-Server Architecture
Browser-WebServer Details
Part 0: Your Project
• Your project is to create a working ecommerce website.
• Here are some feasible project ideas…
Part 1: Internet History & Details
Timeline:
• Innovation Phase: 1961-1974
• Institutional Phase: 1980-1993
• E-commerce Phase: 1995-today
Internet Characteristics
• Analogy: Human Characteristics that really
matter:
– Humans walks on two legs
– Humans have a 3lbs brain.
– Humans communicate with speech and
written words
Internet Characteristics
• Internet characteristics that really matter:
– Internet uses packet switching –
• data is broken into little packets that have to reassembled
– Internet uses TCP/IP protocol –
• robust protocol for sending everything from email
to video
– Internet used IP addresses
Innovation Phase: 1961-1974
• All the technology was invented
– Paul Baran proposed the idea of packet
switching for network communication (1962)
– Vinton Cerf Proposed TCP/IP Protocol in 1974
Institutional Phase: 1980-1993
• ARPANet: A purely military network got turned
over to Scientists working on Defense
Department Projects
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National Labs – National Science Foundation
NASA
Department of Energy
Leading Universities
• Over in Europe another large network emerged.
– CERN – Leading particle physics lab (Geneva,
Switzerland)
Institutional Phase: 1980-1993
• ARPANet and CERN’s network officially
became 100% TCP/IP in 1982
• Standardization – commitment to this
standard protocol allowed software
developers to coordinate networking
efforts.
• In many ways, this marks the birth of the
Internet we now know.
Side Topic
• Didn’t Al Gore invent the Internet?
Side Topic
• Didn’t Al Gore invent the Internet?
– Al Gore never made this claim…it’s a complete
misquote
• Gore’s High Performance Computing and
Communication Act of 1991 (Gore Bill) passed in
1991 and led to the National Information
Infrastructure.
• This directly led to the commercialization of the
Internet.
– The term Internet started to become widely used.
– Gore may have been the first to use the term
“information superhighway.”
E-commerce Phase: 1995-today
• Prior to 1995, the Internet facilitated B2B ecommerce (which is really e-business).
– But the systems developed were very specialized and
isolated.
• True E-commerce wasn’t realized until the end
consumer got Internet access.
• In 1995, we saw the explosion of Internet
Service Providers (ISPs)
– AOL
– Dialup Providers
ISPs of Today
• Telephone companies own most of the
infrastructure. They are the global players
– They farm it out to local ISPs
• Cable TV providers are now the biggest
local players.
• Dialup Still exists
– AOL
– Netzero
Part 1: Internet History & Details
• Network of networks built on standardized
technology and protocols.
• Until the Internet emerged…different
groups were using all different kinds of
protocols.
• Key Term: Protocol
– a set of rules governing the format of
messages that are exchanged between
computers
Packet Switching
• PAD – Packet assembler/dissembler
Why is Packet Switching
important?
• Otherwise you need a direct, uninterupted
connection, which is not feasible.
– Network goes down all the time.
– Traffic gets re-routed on the fly
• Also, its higher performance.
– Your packets could take numerous paths in
parallel.
TCP/IP
• Transmission control protocol
• Internet Protocol
Why is TCP/IP so important
• The Internet would never have expanded
so rapidly without a commitment to Global
Standardization
• Its hard to get experts to agree on a single
Protocol
• TCP/IP is very robust and allows for
numerous levels of sub-networks.
IP Address
• 32-bit number
– Uniquely identifies devices on the Internet
• 192.168.120.227
– 4 billion unique devices.
• There are already more than 4 billion
devices:
– Sub-netting –
• one IP address gets you to a subnet
• Subnet uses its own internal IP address.
Sub-Networks
• IP Addresses are a commodity, limited supply.
• Controlled by ICANN, which indirectly came from
the Gore Bill.
• Siena gets Internet Access from Time Warner
Cable…we probably pay for 20-40 IP Addresses,
which are reserved for key server
– Web server
– Blackboard server
– Mail server.
• How do the other 4000 computers
communicate?
Internal Sub-netting
Internet
(All Real IPs in
the World)
• Outside of Siena, you can’t reach
computer A and B directly.
• Instead, you contact the router
(Real IP) and also indicate
A or B’s Internal IP.
Time Warner
(Real IP)
Siena Gateway Router (Real IP)
A
B
Internal IP
Internal IP
Internal Sub-netting
Internet
(All Real IPs in the
World)
C
• Siena’s router is programmed so that
A and B can directly communicate
using Internal IPs (sub-net).
Time Warner
• If A needs to reach a computer C
(Real IP)
outside of Siena, then the router
modifies the packet headers
to indicate the Siena Router’s
Real IP address and
Siena Gateway Router (Real IP)
the Internal IP of A.
A
• Thus, C will know
Internal IP
how to reach A.
B
Internal IP
Part 1: Activities
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Traceroute
Lookup
Whois
Ping
Finger
Port Scan
Part 2: World Wide Web (WWW)
• Remember: There are companies that use
the Internet to connect two computers, yet
these computers are not part of the WWW.
• To be part of the world wide web, you
need a URL
– Uniform Resource Locator (not universal)
URL examples
• mailto:[email protected]
• http://www.cs.siena.edu
• ftp://ftp.mit.edu/public/data.db
URL Concept
• Internet IP Address are meaningless
– There is no organization
– No geographic significance
– No organizational significance
• Create a meaningful name that is an alias
for an IP Address
– Given a URL create a system to find the IP
Address (DNS lookup).
URL Breakdown
Main Network – Domain Name
SubNetwork
(optional)
• http://www.cs.siena.edu
Server
Name
Top Level Domain Name
Protocol
Top-level Domain Names
Top Level Domains
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.com
.net
.org
.edu
.mobi
.gov
.mil
• U.S. - centric
• Country Domains
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.cn
.ca
.de
.au
• Combinations
• .com.au
• .edu.au
Domain Name Hierarchies
root Name Server (NS)
.com NS
.edu NS
.net NS
siena.edu NS mit.edu NS harvard.edu NS
imail.siena.edu
www.siena.edu
turing.cs.siena.edu
cs.siena.edu NS
www.cs.siena.edu
sos.siena.edu NS
ares.cs.siena.edu
Domain Name Hierarchies
ICANN
• Internet Corporation for Assigned
Numbers and Networks.
• Global coordinator of IP Address and
Domain names.
• Registrars like GoDaddy are “licensed” by
ICANN to register domain names.
• Large Internet Providers (ISPs) also
“secure” IP addresses and farm them out
to smaller ISPs.
Map of the Internet (US)
• http://www.cs.siena.edu/~ebreimer/course
s/csis-116-s07/Internet_map_labels.pdf
• The above is a partial map as seen from
one location (Lumeta.com).
USA: Pioneers of the Internet
• The United States pioneered the Internet, and
thus, “owns” the largest chunk of the
infrastructure.
• Western Europe, Japan, and Australia were
quick to follow.
• Eastern Europe, Russia and China are just
getting established
• Parts of Asia are next: India
• South America is coming along
• Africa may be decades away
Part 2: Activities
• Do some surfing and try to find a URL with
a sub-domain.
• How much does it cost to register a
domain name for .com, .net, .us?
• Thinking of registering a domain name for
your project? See if the one you want is
available?
Client Server Model
• The WWW uses this model exclusively.
Protocols of the WWW
• HTTP / HTTPS – Hypertext Transfer
Protocol (Secure)
• FTP / SFTP – (Secure) File Transfer
Protocol
• SMTP – Simple Mail Transfer Protocol
• POP – Post Office Protocol
• IMAP – Internet Message Access Protocol
• Telnet – Terminal Emulation
Big Picture
Albany
Other
countries?
Clients / Visitors
Potential Customers
Potential Revenue
Host Monster
Web Server
Utah
Internet
USA
HTTP / HTTPS
You – The Developer
/ The Designer
FTP / SFTP
Big Picture
Clients / Visitors
Potential Customers
Potential Revenue
•HTML Documents (Production)
•Application Support Services
•Message Board Service
•Payment Systems, Chat Server,
Internet
Host Monster
Web Server
Utah
•HTML Documents (Development)
You – The Developer /
The Designer
•HTML Editor
•Image Editor
HTTP / HTTPS
•Other Development Software
FTP / SFTP
Big Picture
Hostmonster Server
•HTML Documents (Development)
•Steal other websites designs
•HTML Editor
•Dreamweaver
Internet
•Image Editor
•Fireworks
•Other Development Software
•Flash
You – The Developer /
The Designer
•Word
•Excel
Hostmonster Control Panel
FTP, SFTP, or SCP Client
HTTP / HTTPS
FTP / SFTP
Key Technologies
• Hypertext –
– HTML – Hypertext Markup Language
• Markups are used to structure a web page
– CSS – Cascading Style Sheets
• Styles are defined that decorate each structural
element
DNS
Domain Name System
• The WWW is supported by a network of
DNS servers
• These server help translate URLs into IP
Addresses.
• Domain Names are a fundamental
concept that is connected to E-commerce.
Why are Domain Name so
important?
Setting up a web server
The old way
• Buy a computer (The Web Server)
• Get an static IP Address from your ISP
• Install Web Server software
• Register a domain name with ICANN
• Have your ISP update their DNS server.
Setting up a web server
The NEW way
• Buy a computer (for creating web pages)
• Pay for hosting service (Web Server +
DNS services).
– Get the name of the DNS server.
• Register a domain name with Registrar
– Tell the registrar the name of the DNS server
that your hosting service is using.
DNS Services vs. Hosting
DNS Services
• ICANN coordinates this
effort (1st party)
• Companies (2nd party)
need domain names.
• 3rd parties registrars
actually manage domain
name registration.
• Registrars: goDaddy,
Network Solutions, Yahoo
• Hosting Services