Lecture for Introduction to programming

1. Networks, Internet and Internet
Protocols

3. Cont.
• The term network is defined as a set of computers of
different types, terminals, telephones, and other
communication equipments, connected by data
communication links, which allow the network
components to work together.
• The network components may be located within a small
area or spread over many remote locations. In any case,
data communications hold the network together.

5. The following are the potential needs for
computer networks.
• Information exchange -To exchange data and
information between different individual users, it is
necessary to interconnect the individual user’s computers
• Resource sharing - The cost of computer has corne
down. However, the cost of a laser printer, bulk storage,
and large enterprise software remains high. When
computers are interconnected, there is a possibility that,
users connected to the network may share the above
mentioned resources.

6. Network Architecture
• 1. Client/Server
• 2. Peer-to-Peer

7. Client/Server
• Client/server describes the relationship between two
computer programs in which one program, the client,
makes a service request from another program, the
server, which fulfils the request.

9. Cont.
• Example - To check your bank account from your
computer, a client program in your computer forwards
your request to a server program at the bank.

10. Peer-to-Peer
• A peer-to-peer (P2P) network is created when two or
more PCs are connected and share resources without
going through a separate server computer.

12. ADVANTAGES OF NETWORKING
• Easy Sharing of Data
• Easy Sharing of Hardware Resource
• Easy Sharing Software
• Easy to Decentralize Data Processing
• Easy to Communicate
• Facility of Technical Support

13. DISADVANTAGES OF NETWORKING
• Purchasing the network cabling and file servers can be
expensive
• Managing a large network is complicated
• If the file server breaks down the files on the file server
become inaccessible
• Viruses can spread to other computers throughout a
computer network.

14. Cont.
• A computer attached to the LAN: In home or in a small
office, computers can make peer to peer network with
each other and share data and resources with each other.

15. NETWORK DEVICES
• Hardware devices that are used to connect computers,
printers, fax machines and other electronic devices to a
network are called network devices
• These devices transfer data in a fast, secure and correct
way over same or different networks.
• Network devices may be inter-network or intra-network.
– Inter means between or among two or more entities or units.
– Intra mean within the same entity or unit.

16. Modem
• Modem is a device that enables a computer to send or
receive data over telephone or cable lines. The data
stored on the computer is digital whereas a telephone line
or cable wire can transmit only analog data.
• The main function of the modem is to convert digital
signal into analog and vice versa.
• The modulator converts digital data into analog data when
the data is being sent by the computer.
• The demodulator converts analog data signals into digital
data when it is being received by the computer

18. Types of Modem
• Simplex − A simplex modem can transfer data in only
one direction, from digital device to network (modulator) or
network to digital device (demodulator).
• Half duplex − A half-duplex modem has the capacity to
transfer data in both the directions but only one at a time.
• Full duplex − A full duplex modem can transmit data in
both the directions simultaneously.

19. RJ45 Connector
• RJ45 is the acronym for
Registered Jack 45. RJ45
connector is an 8-pin jack
used by devices to
physically connect to
Ethernet based local area
networks (LANs).
• Ethernet is a technology
that defines protocols for
establishing a LAN.

20. Ethernet Card
• Ethernet card, also known as
network interface card (NIC),
is a hardware component
used by computers to connect
to Ethernet LAN and
communicate with other
devices on the LAN.
• The NIC has RJ45 socket
where network cable is
physically plugged in.

21. Router
• A router is a network layer
hardware device that
transmits data from one
LAN to another if both
networks support the
same set of protocols. So
a router is typically
connected to at least two
LANs and the internet
service provider (ISP).

22. Switch
• Switch is a network device
that connects other
devices to Ethernet
networks through twisted
pair cables.
• The switch maintains a list
of network addresses of all
the devices connected to
it.

23. Wi-Fi
• Wi-Fi is the acronym for
wireless fidelity. Wi-Fi
technology is used to achieve
wireless connection to any
network. Wi-Fi card is a card
used to connect any device
to the local network
wirelessly
• The physical area of the
network which provides
internet access through Wi-Fi
is called Wi-Fi hotspot.

24. COMPUTER NETWORKING
TERMINOLOGY

25. COMPUTER NETWORKING
TERMINOLOGY
• WAN
It stands for Wide Area Network and covers a wide area such as a city.
• LAN
It stands for Local Area Network and covers a small area such as a small office
or home. It physically connects all the computers located in the premises.
• Internet
It is a computer network system that connects the computers of the world. It is
normally connecting through WAN and LAN.

26. • Intranet
It is a close room computer network system, as it covers a
small area and only authorized people can access it.
• Extranet
It is also a sort of Internet access to which is granted only to
a few.
• World Wide Web (WWW)
It is the service that is used on Internet to view and search
contents (in the form of web-pages).

27. • Instant messaging (IM)
It is an online facility that facilitates us to chat or talk. Such service is provided
by Skype, Google Talk, Windows Live Messenger, Yahoo Messenger, etc.
• Voice over Internet Protocol (VoIP)
It is a Protocol, which is used especially for voice transfer over IP network.
Likewise, it facilitates users to make phone-calls by using internet.
• Really Simple Syndication (RSS)
It is a technique, which is used for the dissemination of information, articles, etc.
Users normally subscribe to the RSS channel in order to receive news.

28. • Web log
It is a sort of online inventory (normally on a specialized topics) that consists of a series
of entries. These entries are arranged in opposite chronological order. The person who
maintains the weblog regularly update it with a new information.
• Podcast
It is a digital file that normally contains audio or video record and is available on the
Internet as well.
• Social networking websites
It refers to the websites that facilitate users with a common platform where they can
share their message (in text, audio, or even video form), images, videos, etc

29. • Upload
It is a process that transfers the saved data from a personal
computer to Internet server.
• Dial-up
It is a technique in which a phone line is used in order to connect
to the Internet.
• Broadband
It is a wide bandwidth data transmission that transports multiple
signals and traffic types swiftly.

30. • Chat Rooms
It is a dedicated area on the Internet that facilitates users to
communicate.
• Download
It is a process that saves data from Internet onto a personal
computer.

31. • Public Switched Telephone Network (PSTN)
It is a technical expression for public telephone system.
• Integrated Services Digital Network (ISDN)
It is a set of communication standards that transmits voice,
video, data, and other network services simultaneously.
• Asymmetric Digital Subscriber Line (ADSL)
It is a sort of digital subscriber line (DSL) technology that
facilitates faster data transmission.

32. INTERNET CONCEPT
• The Internet is essentially a global network of computing
resources. You can think of the Internet as a physical
collection of routers and circuits as a set of shared
resources

33. Internet-Based Services
• Email − A fast, easy, and inexpensive way to
communicate with other Internet users around the world.
• Telnet − Allows a user to log into a remote computer as
though it were a local system.

34. Cont.
• FTP − Allows a user to transfer virtually every kind of
file that can be stored on a computer from one Internet-
connected computer to another.
• UseNet news − A distributed bulletin board that offers
a combination news and discussion service on thousands of
topics.
• World Wide Web (WWW) − A hypertext interface to
Internet information resources.

35. What is WWW?
• WWW stands for World Wide Web. A technical definition
of the World Wide Web is − All the resources and users
on the Internet that are using the Hypertext Transfer
Protocol (HTTP).

36. What is HTTP?
• HTTP stands for Hypertext Transfer Protocol. This is the
protocol being used to transfer hypertext documents that
makes the World Wide Web possible.
• A standard web address such as Yahoo.com is called a
URL and the prefix http indicates its protocol

37. What is URL?
• URL stands for Uniform Resource Locator, and is used to
specify addresses on the World Wide Web.
• A URL will have the following format −
(protocol://hostname/other_information)
https://medium.com/kayvan-kaseb

38. What is Website?
• It is a collection of various pages written in HTML markup
language
• Each page available on the website is called a web page
and first page of any website is called home page for that
site.

39. What is Web Server?
• Every Website sits on a computer known as a Web
server.
• This server is always connected to the internet. Every
Web server that is connected to the Internet is given a
unique address made up of a series of four numbers
between 0 and 256 separated by periods.
• For example, 68.178.157.132 or 68.122.35.127.

40. What is Web Browser?
• Web Browsers are software installed on your PC. To
access the Web you need a web browsers, such as
Netscape Navigator, Microsoft Internet Explorer or Mozilla
Firefox.
• On the Web, when you navigate through pages of
information this is commonly known as browsing or
surfing.

41. What is SMTP Server?
• SMTP stands for Simple Mail Transfer Protocol Server.
This server takes care of delivering emails from one
server to another server. When you send an email to an
email address, it is delivered to its recipient by a SMTP
Server.

42. What is ISP?
• ISP stands for Internet Service Provider. They are the
companies who provide you service in terms of internet
connection to connect to the internet.

43. What is HTML?
• HTML stands for Hyper Text Markup Language. This is
the language in which we write web pages for any
Website.

44. What is Hyperlink?
• A hyperlink or simply a link is a selectable element in an
electronic document that serves as an access point to
other electronic resources. Typically, you click the
hyperlink to access the linked resource. Familiar
hyperlinks include buttons, icons, image maps, and
clickable text links.

45. What is DNS?
• DNS stands for Domain Name System.
• When someone types in your domain name,
www.example.com, your browser will ask the Domain
Name System to find the IP that hosts your site.

46. What is W3C?
• W3C stands for World Wide Web Consortium which is an
international consortium of companies involved with the
Internet and the Web
• The W3C was founded in 1994 by Tim Berners-Lee, the
original architect of the World Wide Web. The
organization's purpose is to develop open standards so
that the Web evolves in a single direction rather than
being splintered among competing factions. The W3C is
the chief standards body for HTTP and HTML.

47. The Web physically consists of the following
components
• Your personal computer − This is the PC at which you
sit to see the web.
• A Web browser − A software installed on your PC
which helps you to browse the Web.
• An internet connection − This is provided by an ISP
and connects you to the internet to reach to any Website.
• A Web server − This is the computer on which a
website is hosted.
• Routers & Switches − They are the combination of
software and hardware who take your request and pass to
appropriate Web server.

48. Cont
• The Web is known as a client-server system. Your
computer is the client and the remote computers that
store electronic files are the servers.

49. How the Web Works

50. THE WORLD WIDE WEB
• WWW stands for World Wide Web.
• A technical definition of the World Wide Web is : all the
resources and users on the Internet that are using the
Hypertext Transfer Protocol (HTTP).
• A broader definition comes from the organization that
Web inventor Tim Berners-Lee helped found, the World
Wide Web Consortium (W3C):The World Wide Web is the
universe of network-accessible information, an
embodiment of human knowledge.

51. Cont.
• In simple terms, The World Wide Web is a way of
exchanging information between computers on the
Internet, tying them together into a vast collection of
interactive multimedia resources.

52. NOTE!
• Internet and Web is not the same thing: Web uses
internet to pass over the information.

53. Evolution
• World Wide Web was created by Timothy Berners Lee in
1989 at CERN in Geneva.
• World Wide Web came into existence as a proposal by
him, to allow researchers to work together effectively and
efficiently at CERN. Eventually it became World Wide
Web.

54. The following diagram briefly defines evolution
of World Wide Web:

55. WWW Architecture

56. Identifiers and Character Set
• Uniform Resource Identifier (URI) is used to uniquely
identify resources on the web
• and UNICODE makes it possible to built web pages that
can be read and write in human languages.

57. Syntax
• XML (Extensible Markup Language) helps to define
common syntax in semantic web.

58. Data Interchange
• Resource Description Framework (RDF) framework helps
in defining core representation of data for web. RDF
represents data about resource in graph form.

59. Taxonomies
• RDF Schema (RDFS) allows more standardized
description of taxonomies and other ontological
constructs.

60. Ontologies
• Web Ontology Language (OWL) offers more constructs
over RDFS. It comes in following three versions:
• • OWL Lite for taxonomies and simple constraints.
• • OWL DL for full description logic support.
• • OWL for more syntactic freedom of RDF

61. Rules
• RIF and SWRL offers rules beyond the constructs that are
available from RDFs and OWL. Simple Protocol and RDF
Query Language (SPARQL) is SQL like language used for
querying RDF data and OWL Ontologies.

62. Proof
• All semantic and rules that are executed at layers below
Proof and their result will be used to prove deductions.

63. Cryptography
• Cryptography means such as digital signature for
verification of the origin of sources is used.

64. User Interface and Applications
• On the top of layer User interface and Applications layer is
built for user interaction.

65. WWW Operation
• WWW works on client- server approach. Following steps
explains how the web works:

66. INTERNET ETIQUETTES

67. Internet etiquettes are also called as "Netiquette".
Netiquettes are basic rules or techniques which are
accepted worldwide. For effective communication through
the internet, these are to be mandatorily followed.

68. • REMEMBER THE HUMAN- People communicating online
should remember that they’re dealing with other human
beings, and should treat them the same way they would in
person.
• STANDARDS OF BEHAVIOR- It can seem easy to get
away with moral and ethical infractions or with law-
breaking online. People should always behave the same
way online that they would in the real world.

69. • KNOW WHERE YOU ARE- Just as in real life, different
spaces on the internet have different social mores and
codes of conduct. What might be acceptable in an online
message board is not when posting professional blog
content.
• RESPECT OTHER PEOPLE’S TIME- The internet is full
of content and communications seeking the user’s
attention. Being respectful by being brief and concise or
by not expecting an immediate response is likely to be
appreciated.

70. • MAKE YOURSELF LOOK GOOD- Avatars, word choice,
bios and other such things should always convey the right
message. Politeness is important.
• SHARE EXPERT KNOWLEDGE- When sharing
information online, it’s important to ensure that the
information is of good quality, is true and is helpful.

71. • KEEP FLAME WARS UNDER CONTROL- In general,
protracted arguments (“flame wars”) can make
participants seem impulsive or rude; avoiding them is
usually the best course of action.
• RESPECT OTHER PEOPLE’S PRIVACY- People online
should not share other people’s personal information or
seek it out. It’s typically unethical and often illegal.

72. • DON’T ABUSE YOUR POWER- Those with power or
privilege over others should do their best not to use either
unethically.
• BE FORGIVING OF OTHER’S MISTAKES- Those
communicating online should bear in mind that netiquette
is a constant process for everyone, and give others the
benefit of the doubt when possible.

73. EMAIL OPERATIONS

74. • Composing and Sending Email
• Reading Email
• Replying Email
• Forwarding Email
• Deleting Email

75. E-MAIL ETIQUETTES
Here are set of guidelines that should be followed while working with
email:
• Try to make your message as short as possible. It will make
your message easy to read and understood.
• Be careful about spelling and grammar while typing a
message.
• Use emoticons, smiles when required.
• Email address entered must be correct.
• The subject heading of a message should be clear and
descriptive.

76. • Follow the same rules as if you are writing a letter or a
memo.
• Sending a message that has already been forwarded
or replied many times may contain many angled brackets. It
is better to remove the angled brackets from the message.
• While sending mails to multiple persons, specify their
email addresses in the BCC: field so that the spammers
cannot come to know about addresses of other recipients to
whom you have sent a copy.

77. • Keep size of attachment as small as possible.
• Always add your signature at the end of email.
• Before you send, make it sure everything is fine
because you cannot call back a sent mail.

78. DOWNLOADING AND
UPLOADING

79. • While exploring the Internet, you’ve probably encountered
the terms downloading and uploading.
• Downloading means receiving data or a file from the
Internet on your computer.
• Uploading means sending data or a file from your
computer to somewhere on the Internet.