the internet : a world wide combination of wans and lans involving millions of machines u.s....
TRANSCRIPT
The Internet: a world wide combination of WANs and LANs involving millions of machines• U.S. Department of Defense research initiative
– drive was partially military…• secure connections between major military sites (MILNET)
– …partially economic• get most economical use out of scarce computer resources
– December 1969: startup of 4-node ‘ARPANET’– 1980s: evolved into ‘The Internet’
• consisting of thousands of hosts and millions of users
– 1990: ARPANET replaced by NSFnet• NSFnet still major internet backbone in the USA
1
2
Connecting to the Internet
• Many home and small business users connect to the Internet via high-speed broadband Internet service
Discovering Computers 2012: Chapter 2Page 76
DSL Fiber to the Premises (FTTP) Fixed wireless Cellular Radio
NetworkWi-Fi (wireless
fidelity)Satellite Internet
Service
Evolution of the Internet
• Each organization is responsible only for maintaining its own network– The World Wide Web Consortium (W3C) oversees
research and sets guidelines and standards
• Internet2 – A not-for-profit research– To develop and test advanced network technologies
require that will benefit Internet users in the short-term future
– connect more than 200 universities and 115 companies via a high-speed private network
4
Internet Protocol Address (IP Address)
• An IP address is a number that uniquely identifies each computer or device connected to the Internet
• A domain name is the text version of an IP address– Top-level domain (TLD)
• A DNS server translates the domain name into its associated IP address
74.125.230.210
6
• http://en.utrace.de/?query=www.psu.ac.th• http://www.whois.net/• http://whatismyipaddress.com/
Internet Architecture
• Domain names must be registered (at ICANN)– so everybody knows where each domain resides
• Hierarchical structure of networks of networks…
• Internet service provider (ISP) provides Internet access for you
Internet Corporation for Assigned Names
and Numbers
7
The Internet: Addressing
• Machines in the Internet have unique addresses:– IP-address (32 bits (4 groups)) consisting of two parts
• Domain name: ‘network address’ (given by ICANN)• Machine name: ‘host address’ (given by network operator)
– In dotted decimal form, example: 74.125.95.103
– As registered domain name: google.co.th
– Top-Level Domain (TLD): domain’s classification– In each domain list of IP-addresses is maintained
• publicly accessible through name server
8
010000011
9
• Generic top-level domains• USA top-level domains• Country code top-level domains• Internationalized country • code top-level domains
List of Internet top-level domains
The Internet: Killer Applications
• The internet originally intended for:– remote login & file transfer (does work)– distributed computing (still a promise only)
• However:– 1980s: e-mail– 1990s: web-browsing– 2000s: search engines– 2010s: Grid computing?
10
The World Wide Web
• Software infrastructure on top of the Internet• Developed at CERN High-Energy Physics
laboratories in Geneva, Switzerland (1991)• Hypertext (HTML):
– ‘mouse-clickable’ access to files on other computers
• Requires special software:– web browser (client)– web server
11
12
The World Wide Web
• The World Wide Web, or Web, consists of a worldwide collection of electronic documents (Web pages)
• A Web site is a collection of related Web pages and associated items
• A Web server is a computer that delivers requested Web pages to your computer
• Web 2.0 refers to Web sites that provide a means for users to interact
13
The World Wide Web
• A Web browser, or browser, allows users to access Web pages and Web 2.0 programs
Internet Explorer Firefox Opera
Safari Google Chrome
To find documents on the World Wide Web
• Each document has unique address:– URL (uniform resource locator)
14
protocol
domain name
path
Web page name
HyperText Transfer Protocol: HTTP) คื�อโพรโทคือลในระดั บชั้ �นโปรแกรมประยุ�กต์�เพ��อการแจกจ�ายุและการท�างานร�วมก นก บสารสนเทศ
ของส��อผสม ใชั้%ส�าหร บการร บทร พยุากรท'� เชั้��อมโยุงก บภายุนอก ซึ่*�งน�าไปส,�การจ ดัต์ �ง
เว-ลดั�ไวดั�เว.บ
Homework (What is it?)
FTP (File Transfer Protocol) เป/นโปรโต์คือล มาต์รฐานในอ-นเต์อร�เน.ต์ ซึ่*�งเป/นว-ธี'ท'�ง�ายุท'�ส�ดัใน
การแลกเปล'�ยุนไฟล� ระหว�างคือมพ-วเต์อร�บน อ-นเต์อร�เน.ต์
Hypertext Transfer Protocol (HTTP) ท'�ใชั้%ในการส�ง เว.บเพ.จและไฟล�ท'�เก'�ยุวข%อง
Simple Mail Transfer Protocol (SMPT) ท'�ใชั้%ส�ง ผ�าน e-mail
POP3 (Post Office Protocol version 3)
IMAP (Internet Mail Access Protocol)
MIME (Multipurpose Internet Mail Extensions)• VoIP (Voice over Internet Protocol)
15
HTML – HyperText Markup Language
16
HTML is the main markup language for web pages. HTML elements are the basic building-blocks of webpages.
• XML is a markup language that defines a set of rules for encoding documents in a format that is both human-readable and machine-readable.
17
XML – Extensible Markup Language
18
jass.xml
jw.css
Linking to jw.css style sheet
jass.xml document formatted with jw.css style sheet
the cascading style sheet stored in the jw.css file
How messages are transferred over the Internet.
• This transfer process requires – the cooperation of all the computers in the system,
and – software for controlling this process (resides on
every computer in the Internet).
19
Networking Software
• Provide the infrastructure required for transferring messages from one machine to another.
• In the Internet, this message-passing activity is accomplished by means of a hierarchy of software units, which perform tasks analogous to those that would be performed if you were to send a gift in a package from the South to a friend on the North.
20
Gift Package-Shipping Example
• You are not concerned with the details of the shipping company, and the
• shipping company is not concerned with the internal operations of the airline.)
21
You are not concerned with the details of the shipping company, and the shipping company is not concerned with the internal operations of the airline.
The Internet Software Layers
22
Network Protocols
• Define details of all network activities, a.o.:– encoding of messages– addressing of messages– splitting and merging of (large) messages– deciding who has the right to send messages, etc…
• In other words, protocols ensure that messages:– arrive at the right place– in the right order– without errors– and are understood by the receiver as well
23
Following a Message Through the Internet
24
Network Protocol Summary
• Interaction between four software layers– Application:
• deals with messages and addressing
– Transport:• deals with message ↔ packets conversion
– Network:• deals with ‘hopping’ packets through the internet
– Link:• deals with the transmission of packets as bit streams
25
Multiple Implementations: TCP versus UDP
26
Towards ‘The Grid’
• The Internet:– a network with static compute and data resources in which
information flows from the producer to the consumer (and sometimes back).
– user personally decides what data to access and what servers to use
• The Grid:– dynamic computing utility over a distributed set of compute
and data resources– automatic resource detection, automatic error recovery,
automatic performance optimization, etc…27
The Grid: Large Scale Problem Solving
• Utilize (a) large number or (b) very high-end, specialized resources over large distances
Identifying brain disorders
California: earthquake simulations
Telescope data analysis
Finding E.T.???28
Cloud Computing
29
Cloud computing is Internet- ("cloud-") based development and use of computer technology ("computing").
Cloud computing is about hardware-based services (involving computing, network and storage capacities), where:• Services are provided on-demand; customers can pay for them as
they go, without the need to invest into a datacenter.• Hardware management is abstracted from the customers.• Infrastructure capacities are elastic and can easily scale up and
down.
Web 2.0
• The term "Web 2.0" is commonly associated with web applications that facilitate interactive information sharing, interoperability, user-centered design and collaboration on the World Wide Web.
• Examples of Web 2.0 include – web-based communities - hosted services– web applications - social-networking sites– video-sharing sites - wikis – blogs - mashups – folksonomies 30
31