The Internet 1 Communicating with Others Dr John Cowell phones off (please) 1CSCI1412-I-1.
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CSCI1412 Lecture 4 The Internet 1 Communicating with Others Dr John Cowell phones off (please) 1 CSCI1412-I-1
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Transcript of The Internet 1 Communicating with Others Dr John Cowell phones off (please) 1CSCI1412-I-1.
CSCI1412Lecture 4
The Internet 1Communicating with Others
Dr John Cowell
phones off (please)
1CSCI1412-I-1
OverviewThe Internet
history and organisationThe world wide web
web pages (HTTP and HTML)browsing the internet
Web authoringdesign issues, authoring tools
Other Internet featuressearch enginesemail, ftpfuture of the Internet?
CSCI1412-I-1 2
The Internet
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The Development of the InternetStarted as US Department of Defence network
Advanced Research Projects Agency (ARPAnet), distribute US military computing capability
resist (nuclear) attacks / natural disastersA 4 node Arpanet working - November 1969First network email – 1971First Arpanet connection outside the US (to
Norway) 1973First File Transfer (FTP) – 1973All links converted to TCP/IP 1983Administered by the US government until 1992
Internet Penetration
World Internet Usage
Internet Languages
Internet AdministrationThe Internet Society (ISOC)
Nonprofit organisation founded in 1992 to provide leadership in Internet related standards, education, and policy.
A global clearing house for Internet information and education
Coordinator of Internet-related initiatives around the world.
Includes: Internet Engineering Task Force (IETF) governs
administrative and technical activities. Adopts some Requests for Comments (RFCs) as Internet Standards
The Internet Architecture Board (IAB). technical activities of the Internet including writing spec’s and protocols .
Full details at - http://www.isoc.org
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Internet DomainsInternet sites need two pieces of information
domain name from domain name service (DNS) registered by Internet Corporation for Assigned Names
and Numbers InterNICIP address, such as 123.123.123.123
Domains are hierarchicaltop/primary level - WWW.DMU.AC.UKsecondary level - WWW.CSE.DMU.AC.UK
Political, commercial and organisational domains.GOV, .COM, .ORG, .BIZ, .TV
ISO country names.UK, .NL, .AU
Domains within countries.AC, .CO
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The World Wide Web
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The World Wide WebA part of the Internet
open information sharinginterconnected pages of information
‘Governed’ by WWW Consortium (W3C.ORG)Pages/sites are interconnected by hypertext links
non-linear documents first proposed by Ted Nelson in 1963
links point to other documents selecting the link
requests web-page and/or moves to that point within current document
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WWW BrowsersBrowsers are not all the same
different versionsdifferent sets of commandsDifferent things happen if the XHTML is invalid
Mosaicwritten by students at University of Illinois
Marc Andreesen and Jim Clark founded NetscapeNetscape 7.0Mozilla - Firefox 2.0Microsoft’s Internet Explorer 7Opera 9
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How the Web WorksUser types uniform resource locator (URL)
maps to IP address using DNSBrowsers use hypertext transfer protocol (HTTP)HTTP requests document from host system
returns documentor error message
not found (404) no permission to access (403)
Browser reads tags in documenttags control layout of document objectslink tags are used to request further objects
e.g. graphic, sound, video filesCSCI1412-I-1 13
HypertextHypertext mark-up language (HTML)
uses tags to control layout of objects on web-pageReplaced in 2000 by XHTML. Similar in appearance
to HTMLTags appear between angled brackets
<br />Most tags work in pairs
<html> </html><a> </a>
View the source code of any web-pageunless facility has been disabledNetscape: View|Page SourceExplorer: View|SourceCSCI1412-I-1 14
Example XHTML<?xml version="1.0" encoding="ISO-8859-1"?><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN""http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"><html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Home page</title> <link href="style.css" type="text/css" rel="stylesheet" /> </head> <body><p>This is my home page</p> </body></html>
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Web Authoring
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Web-Site DesignSite design must be fluid
adopt a prototyping design approachif building a site for a client
get them involved listen to their ideas display your work regularly
Four considerationsaimstarget audiencepurposecontent
These issues may change as web-site developsCSCI1412-I-1 17
Aims and Target Audience Aims
what goals do you intend your web-site to achieve? your hobbies, interests? commercial sites
new products details easy ordering
Target audiencewho do you expect to visit your site?
general groupswhat are their motivations?what will be their expectations?
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Purpose and ContentPurpose
what is the reason for building the web-site?what should your visitors be able to achieve?
purchasing contact complaints
Contentwhat is the page content / layout?
use storyboarding for initial design cascading style sheets? frames?
where do text / graphics come from?CSCI1412-I-1 19
Authoring ToolsHTML editors
NotepadProducts such as "Enhanced HTML"
allows direct entry of HTML tags wizards may do the more complex bits
WYSIWYG authoring packageNetscape ComposerFrontPageDreamWeaverFlash, Director
On-line authoring; for example:www.Angelfire.com
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Web-Site MaintenanceKeep site up to date
there is nothing worse than visiting a web-site that hasn’t been touched for two years and is now totally out of date!
Add a ‘last updated’ text object to pageCheck to see that all links (on- and off-site) are
still activeask your visitors to let you know of any broken links
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Other Internet Features
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Search EnginesSearch engines use their own database of entries
web authors upload key words/phrasesSingle
UK Excite, Lycos
world wide Yahoo, AltaVista,Google
MultipleAskJeevesCopernic - searches within results, stores web pages,
customisedhttp://www.copernic.com/en/products/agent/index.html
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Other Internet FacilitiesWWW is just one part of the internet
many other top layer protocols/featuresemail, FTP, telnet
Allows one computer to connect to another and act as a terminal of that computer. Superseded by remote login.
archie Developed at the Computer Science Department at McGill University in
Montreal, - a public domain tool for finding files on anonymous ftp sites. The Archie database currently indexes more than 2,100,000 files contained in more than 1000 anonymous ftp sites around the world. See http://www.acad.bg/beginner/gnrt/specialist/archie.html
ping signal sent out by one server to another, asking for a response, checks latency
and presence of serverstraceroute
tracks & displays route packets take between client and host
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emailSimple Mail Transfer Protocol (SMTP)
all outgoing email sent by this protocolPOP3 / IMAP
mail receiving systemsPost Office Protocol
mail is stored, copied to PC when on-line, read off-line Eudora, Outlook Express, Pegasus Mail, Netscape Messenger
interactive Mail Access Protocol log on to remote server, read mail on-line
Yahoo, Hotmail
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email FeaturesAddress books
typing first few characters of an address will access the relevant record in the address book
Contact groupslist of email addresses
mail the contact list name - mail goes to all members of list
Attachmentssingle or multiple documents attached to email
get a ‘piggyback’ ride to recipient(s)CSCI1412-I-1 26
FTPFile Transfer Protocol
allows easy transfer of files between remote systems whole directory trees in single transaction
other file maintenance facilities directory / folder management
create, change, remove, etc file management
delete, move, copy, etc.superior error recovery than browser downloads
DMU FTP server is ftp.cms.dmu.ac.ukInstructions page
http://www.cse.dmu.ac.uk/~cfi/Reference/UseFTP.htm
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CORE-FTPShareware - drag & drop
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Future of the Internet?Multimedia, speeds need to be increasedIncreasingly used for social activities, YouTube,
FacebookVirtual living – Second LifeVirtual Reality Modelling Language (VRML)
three-dimensional graphics on web pages http://www.ocnus.com/vrml.html
Stargazing web-sitehttp://internetbrothers.com/futureshock.htm
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SummaryThe Internet
history and organisationThe world wide web
web pages (HTTP and HTML)browsing the internet
Web authoringdesign issues, authoring tools
Other Internet featuressearch engines
http://searchenginewatch.com/webmasters/article.php/2168031email, ftp future of the Internet?
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