Transcript 5.4 Common Network environment

Internet
 The internet is a world wide collection of computer using the same protocol (
TCP/IP)
 The Internet is a network of networks.
 It gives users access to a wide variety of information from millions of different
sources.
 It also gives users access to electronic mail (email).
 To access the Internet users need:
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A computer.
A modem.
A telephone line or broadband connection.
An Internet Service Provider (ISP). What is the Internet?
 Once a user is ‘online’ they can access information produced by content
providers.
 A content provider can vary from a large company that sells its products online
to an individual who has a single page website.
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Advantages of Internet
 It can be accessed from anywhere.
 It provides access to huge amounts of information (e.g.
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encyclopaedias, dictionaries, online newspapers, online
magazines, online books).
Information can be accessed immediately (e.g. finding
information in a book may take some considerable time).
The information is up-to-date (unlike books that can take
months between being written and being published).
The information can include multimedia (e.g. video clips,
animations, sound).
Search engines can help users find the information they need.
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Disadvantages of Internet
 The hardware and software required to use the Internet can be expensive
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(e.g. buying a computer and modem, paying for an Internet Service Provider
[ISP], paying for a dial-up or broadband connection).
Users must know how to use search engines properly in order to access the
information they actually want.
Information may not always be accurate or true.
the information may not be up-to-date if the web-site is not frequently
updated.
there may be too much information available (search engines return
thousands of links) so it may be difficult to find exactly what is wanted.
not available if there is no computer connected to the Internet.
data may not be secure if transferred over the Internet.
many viruses are spread using the Internet.
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Aspects of the Internet
World Wide Web
- view information stored on participating computers
- documents called pages with links to other Web pages
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Service provider
gives access to net and to private services
 Usenet newsgroups
most devoted to specific areas of interest
 Internet Relay Chat (IRC)
live conversations
 Videoconferencing
you can see the person at the other end of the line
 E-mail
send and receive messages
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(C) Uniform Resource Locator (URL)
To access resources on the Internet, you need to use a URL
 first part of the URL shows what protocol to use
 last part is the path name where resource is located on the Web server
 The standard address used to find a page, Web server or other device on the Web or
the Internet. A typical address or URL is
http://www.usa.edu.pk
First part of a URL specifies the protocol used for connection to the server.
 Protocols
- http://
- https://
- ftp://
- Localhost://
Hypertext Transfer Protocol, for Web sites
Hypertext Transfer Protocol, secure
File Transfer Protocol
Information from a local Web server
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(d) Domain Name
– The next part of the URL specifies the name of the server on which the web resource is held
which is Domain Name.
– Is a string of identifier separated by full stops ( called ‘dot’ when you are reading out an
address).
– Identify the type of organization and often the country in which the server is located.
– People prefer to use names for things
– Domain Name Server (DNS) coverts names to numbers.
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International codes include:
.ac
.co
.com
.edu
.gov
.nato
.net
.org
.tm
an academic institution
a company that trades in a single country
a commercial organisation that trades internationally
an educational establishment
a government department or other related facility
a NATO installation
an organisation or company that provides Internet access
a non-commercial organisation, such as a charity
a trade-marked business name
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Domain Name Contd.
 UK-specific codes include
.ltd
.sch
a UK Limited company
a school
 A 2-character country code may follow – there are hundreds of these including
au
es
sg
uk
ch
Pk
Australia
Spain
Singapore
UK
Switzerland
Pakistan
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HTTP ( Hyper text Transfer Protocol)
 The HTTP, (hypertext transfer protocol) , is one method by
which pages are transferred from web servers to the
browser on your local machine.
 It is thus a client server model making use of the TCP/IP
protocol.
 Some URL's (uniform resource locator) start https in this
instance the s stands for secure, which will allow you to
contact another computer, (such as on-line banking) with
128 -bit encryption through a secure port .
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FTP ( File Transfer Protocol )
 The file transfer protocol (FTP) allows users to transfer files from one
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computer to another in a client server network.
It is ideal for transferring files on LANs and WANs which make use of the
TCP/IP protocol.
Using FTP you can download files from the Web FTP files have ftp as the
first part of the address instead of http
You can also use FTP to upload pages onto a Web site
It is currently the most common way to publish a site because files can
easily be uploaded to an FTP server, from the computer where the site
was developed.
You can use specific software such as CuteFTP to do this or some
WYSIWYG HTML editors such as Dreaweaver have inbuilt tools which
support this.
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(2) Service Provider
 To access the Internet you are a basic choice
1. Internet service provider
2. Online Services.
Internet Service Provider
 An ISP provides you with a connection to the net and the software you will need
to navigate.
 Example:
 AOL ( American Online ) started out as an online service provider but now the
biggest ISP in the world
Online Service Provider
 An online service provider will give you access to the net and to their own
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private network of services.
Examples:
Databases of information
On line editions
Cinema , listings, travel information, shopping , user forms, chatting.
The difference between OSP and ISP are very less they are so like.
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Newsgroups
 A newsgroup is a repository usually within the Usenet system, for messages
posted from many users at different locations
 Newsgroups are Internet-based discussion groups devoted to
discussing specific topics or interests (e.g. rock bands, world
politics, hobbies or sports).
 Usenet was created in 1979 by a group of American
Computer science graduates.
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Newsgroups revolve around specific topics, such as wireless technology or organic
gardening. You can read what others have written and reply your own thoughts.
 These are the bulletin boards of the Internet
 There are currently over 5,000 newsgroups.
 They were originally developed so that scientists could post questions (and
answers) to each other
 To share their knowledge of the bugs.
 Newsgroups have also been hit by bulk junk mail messages (
known as SPAM ) which makes certain newsgroups unusable.
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IRC
 IRC stands for Internet Relay Chat.
 This is a 'real time' chat system built around internet technology.
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There are IRC clients available for every operating system.
IRC make use of 'channels' to set up a conversation between two
or more people. It is still used today to chat on the internet, but
'Instant Messaging' systems such as MSN and ICQ and AOL have
become more popular.
IRC are live. Whatever you say on the channel is instantly
broadcast to everyone on the same channel.
Chat rooms are pages on a website or online service where users
can ‘chat’ with other users.
This is done by typing messages that are displayed on the
screens of others users who are logged-on to the ‘chat room’.
Chat rooms are also called ‘online forums
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Email
 Emails are messages sent via a computer network to
individuals or groups of individuals.
 Although emails are usually text, users can attach files
that include graphics, sound, and video.
 Email addresses include the @ symbol, such as
[email protected].
 Emails can be created online (i.e. whilst connected to
the Internet – ideal for users who have broadband
Internet connection) or offline (i.e. before connecting
to the Internet – ideal for users who have expensive
dial-up Internet connection).
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Facilities of e-mail
 send a message anywhere in the world
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for the price of a local call;
attach files
documents, photographs, maps, programs;
keep an address book
of people you regularly e-mail;
send the same letter to a group
of people simultaneously;
reply to an e-mail
simply by clicking on the reply button;
forward a received message with comments
to an individual or group;
Pick up your mail from anywhere in the world
with special software.
Join a mailing list
get free information sent to you regularly
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Example of Email
The email addresses of
people who are to be sent
a copy of the email (Cc =
carbon copy) are typed in
or selected from the
address book.
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Advantages of e-mail
 Cheaper than fax or phone
for messages sent over long distances
 No need to worry about time-zones
message will be picked up at a convenient time
 You receive an answer quicker than by mail
and you know it has been received
 Easy to use, friendly and direct
you don’t have to be formal in a business e-mail
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Disadvantages of e-mail
 Easy to offend people without meaning to
hard to convey mood
 Busy people may be overloaded with e-mail
and junk mail can be a problem
 Viruses can be spread in e-mail attachments
always virus-check attached files before opening
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Video Conferencing
 Meetings may be held with participants from all over the world. Each
person has a computer linked to the Internet (or telephone system).
 A camera and microphone are used to input pictures and sound which
are then transmitted between the computers.
 It is possible, with appropriate hardware and an ISDN line
 It enables users to see and hear each other, and with the right software
and hardware share an interactive whiteboard, graphics tablets etc.
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Intranets
 An intranet is a network similar to the Internet but only accessible from
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within a site (school, company, government department etc).
Browsers are used to display web pages which have hyperlinks to other
pages.
An Intranet is a company-wide network run along the lines of the World
Wide Web
This makes it possible to share documents, databases and applications
This saves wasting time browsing aimlessly through thousands of files
and also enables unsuitable material to be screened out.
Example: A school may have an intranet which pupils can access for
information from any networked computer. Nobody outside the school
can look at the intranet
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TELNET
 Telnet is a protocol enabling users to manage a remote computer
connected to the Internet.
 Once you have logged on it is as though you were sitting at the keyboard
of the remote computer. The telnet console operates in a very similar
way to conventional DOS-based window.
 Web servers can be remotely administered by using Telnet.
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VCN( VIRTUAL NETWORK CONNECTION)
 To remotely administer a server using a GUI environment software such
as Virtual Network Connection, (VNC) can be used.
 For this appropriate client server software would need to be
installed,then you can run software on the remote machine as if you
were actually sitting at it.
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JAVA
 Java programming language organized from the computer company SUN
 Small java programs and applications called applets ,can be executed
through web browser.
 browsers contain software called Java Virtual Machine (JVM)
 Applets have the suffix .class for example MYApp.class.
Java Script
 Java script is cut down version of java which is easier to learn and use..
 It creates fast connection of web pages.
 Using a java or java script applet , you can create interaction between the
user and your web page.
 Example:
 If u have a user information form , you can use an applet to check that
the user has filled and display message prompt to do so if they have no
 You can use a java applet to make a button change appearance.
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What the following term mean
Web server: a system on the internet
containing one or more web site
Web site: a collection of one or more web
pages
Web pages: single disk file with a single
file name
Home pages: first page in website
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What is HTML?
 Telling the browser what to do, and what props to use.
 A serises of tags that are integrated into a text document.
Tags are ;
 surrounded with angle brackets like this
 <B> or <I>.
 Most tags come in pairs
 exceptions: <P>, <br>, <li> tags …
 The first tag turns the action on, and the second turns it off.
 The second tag (off switch) starts with a forward slash.
 For example ,<B> text </B>
 can embedded, for instance, to do this:
 <HEAD><TITLE> Your text </HEAD></TITLE> it won't work.
 The correct order is <HEAD><TITLE> Your text
</TITLE></HEAD>
 not case sensitivity.
 Many tags have attributes.
 For example, <P ALIGN=CENTER> centers the paragraph following it.
 Some browsers don't support the some tags and some attributes.
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Basic HTML Document Format
<HTML>
<HEAD>
<TITLE>WENT'99</TITLE>
</HEAD>
<BODY>
Went'99
</BODY>
</HTML>
See what it
looks like:
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How to Create and View an HTML document?
1.Use an text editor such as Editpad to write the document.
2.Save the file as filename.html on a PC. This is called the Document
Source.
3.Open Netscape (or any browser) Off-Line
4.Switch to Netscape
5.Click on File, Open File and select the filename.html document that
you just created.
6.Your HTML page should now appear just like any other Web page
in Netscape.
7.You may now switch back and forth between the Source and the HTML
Document
 switch to Notepad with the Document Source
 make changes
 save the document again
 switch back to Netscape
 click on RELOAD and view the new HTML Document
 switch to Notepad with the Document Source......
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Tags in head
 <HEAD>...</HEAD>-- contains information about the document
 <TITLE>...</TITLE>-- puts text on the browser's title bar.
 Tags in Body
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Let's talk Text
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Heading: <H1> </H1>
Center:<Center> </Center>
Line Break <P> ,<Br>
Phrase Markups: <I></I> ,<B></B>
Create a List
 Unordered list : <UL><li>
 Ordered list: <OL><li>
 Nested
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Add Images
 Use <IMG SRC=imagefilename> tags
 How to specify Relative pathnames
 Attributes of IMG tag
-width,height
-Alt
-Align
-<Img src=my.gif width=50 height=50 align=right
alt=“My image”>
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 How to make colors changes?
 Hexadecimal number :
 Color names : <Font color=white>
 Changing the Background color
<BODY BGCOLOR=#19378a>
 Changing Text color
<BODY BGCOLOR=#19378a TEXT=#ffffff LINK=#ffff66
VLINK=#66ffff>
 Spot color
<FONT COLOR=#66ffcc>WENT'99</FONT>
 Image Background
<BODY BACKGROUND=bgimg.gif >
 Add some Link
 Use <A href=filename|URL></a>tags
 How to specify Relative pathnames
 Kinds of URLs
 e.g. <A HREF=”http://www.bbc.co.uk”> yourtext </A>
-http://www.women.or.kr
- ftp://ftp.foo.com/home/foo
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Example of HTML for Webpage Advertising
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