Intro Ppt Internet Computing

8/3/2019 Intro Ppt Internet Computing

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History

Internet Basics

Internet Services

Client/Server


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The renaissance of interest in the web that we call Web 2.0 hasreached the mainstream.

Tim OReilly

Billions of queries stream across the servers of these Internetservicesthe aggregate thoughtstream of humankind, online.

John Battelle, The Search

People are using the web to build things they have not built orwritten or drawn or communicated anywhere else.

Tim Berners-Lee

Some people take what we contribute and extend it and contributeit back [to Ruby on Rails]. That's really the basic open sourcesuccess story.

David Heinemeier Hansson, interviewed by Chris Karr atwww.Chicagoist.com


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Software Instructions to command the computer to perform actions and make

decisions)

JavaScript and PHP are popular software development languages for web-

based applications.

Computer development

Computer use increasing in most fields

Computer costs and size decreasing

Abundance of silicon drives down prices of silicon-chip technology Allows development of applications with graphical user interfaces (GUIs)

Multimedia capabilities

Integration with the Internet and World Wide Web


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Computer

Device capable of Performing computations Making logical decisions

Works billions of times faster than human beings Fastest supercomputers today

Perform hundreds of billions of additions per second

Programs Sets of instructions that process data Guide computer through orderly sets of actions specified by

computer programmers

Computer system Comprised of various hardware devices

Keyboard Screen Disks Memory DVD drives Processing Units


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Every computer divided into six units

1. Input unit Receiving section of computer Obtains data from input devices

Usually a keyboard, mouse, disk, scanner, uploads (photos and videos)and networks (Internet)

Places data at disposal of other units

2. Output unit Shipping section of computer Puts processed info on various output devices

Screens, paper printouts, speakers Makes info available outside the computer (e.g., Internet)

3.Memory unit Rapid access, low capacity warehouse Retains information entered through input unit Retains info that has already been processed until can be sent to

output unit Often called memory, primary memory, or random access memory

(RAM)


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4. Arithmetic and Logic Unit Manufacturing section of computer Performs calculations (addition, subtraction, multiplication and

division) Contains decision mechanisms and can make comparisons

5. Central Processing Unit (CPU) Administrative section of computer Coordinates and supervises other sections Multiple CPUs (multiprocessors)

6. Secondary storage unit

Long-term, high-capacity warehouse Stores programs or data not currently being used by other units on

secondary storage devices (like CDs and DVDs) Takes longer to access than primary memory


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Internet is an opensystem:

all specifications are available to the general public,

any company can build a compatible technology.

A communication protocol is an agreement thatspecifies a common language two computers use to

exchange messages. TCP/IP


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A network of thousands of networks. Heterogeneous computers running different operating systems,

but the same network protocol. Open architecture. Peer-to-peer Technology (does not distinguish among the

connected computers).

Unlimited Expandability (can add a new network to the Interneteasily) Multiple Connectivity (capable of having more than one

connection to Internet) Flexibility: (IP)

independent of network speed LAN, WAN technology no packet loss

Reliability: TCP constantly monitors conditions on the Internetand automatically adapts.

Efficiency: does not require extensive computation to

send/receive packet, runs on small computers too.


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E-mail

Newsgroups

BBS (Bulletin Board Service)

FTP (File Transfer)

Telnet (Remote System Access) rsh (Remote Shell)

rlogin (Remote login)

rcp (Remote file copy)

Information Browsing and Content Search (Gopher, WAIS, WWW) nslookup (Network Server Lookup)


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The Early Years of Internet (1960-70)

Developed by DoDs ARPA (Advanced ResearchProjects Agency),

ARPANET is the backbone of the Internet

Two important developments of Internet: (1982)

IP (Internet Protocol) provides the basiccommunication,

TCP (Transmission Control Protocol) providesadditional facility for the applications.

TCP/IP.


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The growth

ARAP expanded the Internet to include all the militarysites that connected to the ARPANET in 1983.

Internet meets Unix: TCP/IP was included in the BSD

Unix.

The Internet doubles in size in one year (early 80s).Exponential growth.


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Internet

Computer


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Every Computer is assigned a unique address(Internet Address, or IP Address). IP Address Syntax: 255.255.255.255

The address is not random. Fortunately, wedont have to memorize the IP address. We can

use domain name such as www.cs.uh.edu[129.7.240.13].


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C:\D\USER>tracert www.uh.edu

Tracing route to www.uh.edu [129.7.235.44]

over a maximum of 30 hops:

1 2 ms 2 ms 2 ms Charybdis-VLAN03.cs.uh.edu[129.7.240.126]

2 * * * Request timed out.

3 1 ms 1 ms


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Computer names must be unique on the Internet. Name = "machine (subdomain) name" . "domain name"

. "type" . ["country"]

A domain name identifies the organization that ownsthe computer and the type of the organization.

A fully qualified name is translated to an equivalent IPaddress by the DNS (Domain Name Server).


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There are many DNS on the Internet. A computer hasto know the location of one DNS.

IP Addresses and Domain Names are unrelated eventhough they looks the same. www.cs.uh.edu 129.7.240.13


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The Internet domain name-space is tree-structured,

with top-level domains such as:

COM commercial establishments

EDU educational institutions

GOV government agencies

MIL MILNET hosts


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nslookup www.uh.eduServer: dns.cs.uh.edu

Address: 129.7.240.1

Non-authoritative answer:Name: www.uh.edu

Address: 129.7.235.44

Most network applications involve a server and aclient.


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A Server process provides a specific service on ahost machine that offers such as service.

Each network-wide service has its own unique portnumber that is identical across all hosts.

Examples: ftp (port 21), www (port 80). The first 512 ports (port 0 to 511) are reserved for

network-wide applications registered by the InterNIC. The next 512 ports are semi-official and are used for

standard services such as remote UNIX login at

513, and remote printing at 515. Higher numbered ports are used for local

applications.


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>more services

tcpmux 1/tcp

echo 7/tcp

echo 7/udp

discard 9/tcp sink null

discard 9/udp sink null

systat 11/tcp users

daytime 13/tcp

daytime 13/udp

netstat 15/tcp

chargen 19/tcp ttytst source

chargen 19/udp ttytst source

ftp-data 20/tcp

ftp 21/tcp

telnet 23/tcp


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A client process on a host connects with a server on

another host to obtain its services.

Different client programs are required for differentservices.


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Client

TCP IP Driver

Server

Driver IP TCP

Host A Host B

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Intro Ppt Internet Computing