Internet Basics
web server, Client HTTP etc.
Need to be refined
Learning Objectives
• Learn about the Internet and the World Wide
Web
• Start the Internet Explorer app and the Internet
Explorer desktop application
• Develop search techniques for locating
information on the web
• Use a search engine to conduct a search
• Find and evaluate information on the web
• Learn about copyright laws
• Document web resources
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Terms
• Internet, web servers, browsers
Outlines
• How Internet Works?
Scope
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What is the World Wide Web?
What makes the Web work?
How does the World Wide Web work?
What is a web server?
What is a web browser?
What is a web page?
How does a web page work?
What is a home page?
What is a web site?
Learning outcomes
• Demonstrate an understanding of the concepts, terms,
and technology behind the World Wide Web
• Describe how the World Wide Web works
• List several web servers
• Identify different web browsers
• Define what is a web page
• Differentiate a home page from a web site
• Understand how a web page works
What is the World Wide Web?
• a hypertext based system for providing, organizing and
accessing information that allows users to jump from one
information space to another
• comprises servers and client computers on the Internet
that communicate using the hypertext transfer protocol
(http)
• a way to access and provide information in various media
via the Internet
What is the World Wide Web?
World Wide Web
• information resource consisting of web pages that
organize and present vast amount of information (mostly
text embedded with images, audio, video, or animation),
and other resources (databases, interactive multimedia,
virtual environments, etc.)
• body of information available on the Web
What makes the Web work?
• Hypertext - provides easy navigation among documents and
resources
• Protocols - set of standards used to access resources via the
Web
• Universal Resource Locator (URL) - uniform naming scheme for
Internet resources
• Client and server computers - Web access is based on
client/server technology
What makes the Web work?
Hypertext
– presents and relates information as hyperlinked
documents that point to other documents or
resources
– is usually embedded in the text, on a highlighted word
or phrase, or on a symbol, an icon, or other graphic
elements are hypertext documents on the Internet
mostly created using HTML
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What makes the Web work?
HyperText Markup Language (HTML)
• the publishing language of the World Wide Web; the
standard used to create web pages.
• markup language that defines the structure of
information by using a variety of tags and attributes,
which is designed to display text and other
information on a screen and provide hyperlinks to
other Web documents.
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What makes the Web work?
Protocols
• standard set of rules that governs how computers
communicate with each other, i.e. SMTP, FTP, HTTP is the
underlying protocol used to transmit information over
the Web
• the Web supports several Internet protocols aside from
HTTP such as SMTP, FTP, allowing access to huge
collection of information and services.
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Important protocols
• HTTP
• SMTP
• FTP
What makes the Web work?
Uniform Resource Locator (URL)
• uniform naming scheme that specifies unique
addresses for web servers, documents, and other
resources, no matter what its access protocol
• the URL points to where the data or service is located
(the host computer and the directory in which it
resides) on the Internet
• web documents and resources are located and linked
through their URL’s
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What makes the Web work?
Anatomy of a URL
protocol
host computer
directory path
file name
Note: Not all URLs will have the directory and filename
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What makes the Web work?
Client and server computers
• computers on the Internet communicate and share
resources
• servers are computers that host web documents and
provide information through a web server program
• client computers access web documents using an
application program called web browsers
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How the Web works
client – server framework
5. User receives file displayed by
the browser
4. Server sends requested files to browser to
be interpreted
Browser
1. User sends request
2. Browser interprets user’s
selection and makes request from
appropriate server
3. Server accepts
and processes
request from
browser
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How the Web works
• A user runs a Web browser on a client computer that
makes requests to a server machine, which is
running a web server program that sends the
requested item or an appropriate error message back
to the browser, which displays the item or error sent
back by the server to the user.
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What is a Web Server?
• Client/Server, the Internet, and WWW
– ttp://www.robelle.com/www-paper/paper.html
• How Web servers and the Internet Work
– http://www.howstuffworks.com/web-server.htm
• Program that understands the HTTP protocol and
generates appropriate responses
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Clients “connect” to the machine
Clients send a “request”
Server reads request, generates “response”
Client interprets response appropriately
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What is a web server?
Web server
• computer running application software that listens and
responds to a client computer’s request made through
a web browser
• machine that hosts web pages and other web
documents
• provides web documents and other online services
using HTTP
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Web servers
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Apache - most popular open source server software on the Web
iServer – application / web server written entirely in Java
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Microsoft Internet Information Server - IIS is fully integrated into the
Windows NT / 2000 server package
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Macromedia ColdFusion – application / web server focuses on serving
dynamic pages supporting other Macromedia products like Flash and
Ultradev
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IBM Web Sphere Studio – combination of content creation software
with web application
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Apple Webobject - application / web server for Mac
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What is a web browser?
Web browser
• application software that is used to locate and issue a
request for the page on the web server that hosts the
document
• It also interpret the page sent back by the web server
and display it on the monitor of the client computer
• computer program that lets you view and explore
information on the World Wide Web
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Web browsers
• Microsoft Internet Explorer – browser integrated with the
Windows operating system. Mac versions are available.
• Netscape Navigator - available for Windows, Mac, and Unix
platforms.
• Opera – one of the alternatives to the two most popular
browser mentioned above
• Mozilla – open source web browser software
• Lynx - popular Unix text-based browser
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Activity
Explore these pages that contain links to several
web servers and browsers :
• World Wide Web Server Software
– http://www.w3.org/Servers.html
• Browsers
– http://www.webreference.com/internet/software
/browsers/
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What is a Web page?
Web page
• electronic document that typically contains several
types of information accessible via the World Wide
Web
• set of information created, and organized, using HTML
and/or other web page authoring and development
tools
• Interpreted and displayed on the screen according to
the instructions of the web page authoring tool
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How web page works
Sample web page and its source.
• The source contains the instructions
that define the contents, layout, and
structure of a web page.
• The instructions are written in HTML
or another web authoring tool used in
creating the page.
• The browser uses these instructions to
interpret and display the web page on
the screen.
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How web page works
• The user requests a web page by entering its
URL on the address location bar of a web
URL
browser.
• The browser transmits the request to a web
server through http.
• The web server processes the request, locates Navigationa
l tools
and sends back the requested web document
also using http.
• The web browser interprets the file sent by the
server and displays it on the monitor.
• The same process happens when the user
selects any of the hyperlinks or navigational
tools on the page.
Navigationa
l tools
Graphics /
Hyperlinks
Hyperlinks
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What is a web site?
Web site
• a collection of related web pages of a certain individual,
group, or organization, connected through a system of
hyperlinks, hosted in a particular domain
• can be a single web page that contains links to related
information located on several web sites
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What is a home page?
Home page
• the main page of a web site that typically serves as
an index or table of contents to other web pages
• usually the first web page or the welcome page the
users see when they visit a web site
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A Simplified Web Server
• Client asks for file
• Server finds appropriate file
• Server sends back a response header followed
by the requested file’s data
• Server closes connection
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How Do You Identify Machines
• Domain names/IP address and ports
• http://www.oneonta.edu implies a machine
named www.oneonta.edu and a default port
of 80.
• http://127.0.0.1:8080/index.html
– Refers to local box (127.0.0.1 is me)
– Port # is 8080 (used for this project)
– File is named index.html
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How Do You Identify Files?
• File name is specified in Request Message
• Server maps that name to a real file
– Mapping can be done in whichever way server
wants
– For example, /~vivek/index.html is actually
/n/fs/fac/vivek/public_html/index.html
– In your web server, you can choose your own
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What’s In A Request Message?
GET /index.html HTTP/1.0\r\n
Connection: Keep-Alive\r\n
User-Agent: Mozilla/4.72 [en] (X11..)\r\n
Host: 127.0.0.1:31415\r\n
Accept: image/gif, image/jpeg, */*\r\n
Accept-Encoding: gzip\r\n
Accept-Language: en\r\n
Accept-Charset: iso-8859-1,*,utf-8\r\n
\r\n
Fun Fun Project One
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What Do You Care About?
GET /index.html HTTP/1.0
In particular, just index.html
Assume “/” means “/index.html”
Fun Fun Project One
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What Could They Want?
• An honest-to-goodness file (me.jpg)
• An indirect request for such a file (such as “/”
meaning index.html)
• An implied directory with index (/home/vivek
instead of /home/vivek/)
• Just a directory listing
• A query (we don’t care about these)
• An invalid/nonexistent file
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What’s In A Response Message?
HTTP/1.0 200 OK\r\n
Date: blah-blah-blah\r\n
Server: blah-blah-blah\r\n
Content-Type: important\r\n
Content-Length: 12345\r\n
Last-Modified: blah-blah-blah\r\n
\r\n
Raw data
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What’s a Minimal Response?
HTTP/1.0 200 OK\r\n
Content-Type: stuff\r\n
\r\n
Data
HTTP/1.0 404 Not Found\r\n
\r\n
HTTP/1.0 302 Moved\r\n
Location: newurl\r\n
\r\n
But also
Connection: close\r\n
Content-Length: yyy\r\n
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Response when…
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File exists?
Send it
Directory without “/” suffix? Redirect
Directory with index.html?
Send it
Directory with no index.html? List it
– For each list entry, add “/” if needed
• Failure(Not Found)?
• Bad Request?
Send 404
Send 400
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How to Test Your Server?
• Use a browser(Netscape/IE)
• Use “wget”
– Support HTTP protocol
– http://www.gnu.org/manual/wget
– create directory hierarchy for retrieving
• Include some big images
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What is Content-Type?
text/html
image/gif
image/jpeg
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Visual Overview
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Microsoft Internet Explorer 10
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Understanding the Internet and the
World Wide Web
• The web (World Wide Web) is a collection of
electronic documents or files – called
webpages – that are available through the
Internet.
• The Internet is a worldwide collection of
computer networks.
• Webpages are stored on web servers, which
are the computers connected to the Internet.
• A website is a collection of related webpages.
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Starting the Internet Explorer App
• Click on the Internet Explorer tile to open the home
page
• To display a specific web page, you can enter its URL
in the Address bar.
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Clicking Links
• When you click on a link, a new webpage
appears, replacing the previous page
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Understanding Search Engines
• If you don’t know the URL of a site you want to
visit you can use a search engine to locate
information.
• Search engines use a program called a spider or
bot to compile databases that are indexed by
keywords
• When you enter a keyword in a search engine, it
searches the database to find webpages that
include those keywords
• Results are displayed as a list of links to the
webpages
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Finding Information on the Web
• Formulating a Search Strategy
– Identify your topic
– List keywords that represent your topic
– Refine your keywords list
– Develop your search query
• A search query is the translation of your original
question into a form that a search engine can
understand.
– Refine your search query
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Starting the Internet Explorer Desktop
Application
• To start the Internet Explorer Desktop
application:
1. Click on the Start screen
2. Click on the Desktop tile
3. Click on the Internet Explorer button
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Using the Bing Search Engine from the
Address Bar
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Using Page Tabs
• Tabbed browsing displays multiple webpage
in the same browser window.
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Using the History List
• The History list tracks the webpages you visit
over a certain time period.
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Evaluating the Search Results
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Identify the author
Check for objectivity/bias
Verify currency
Assess accuracy
Determine validity
Consider relevancy
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Webpage Evaluated for Usefulness
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Saving Webpages as Favorites
• A Favorites list is a feature you can use to store and
organize a list of webpages you want to revisit.
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Pinning Webpages
• You can pin a page to the taskbar so you open the
webpage directly from the desktop without first
starting Internet Explorer.
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Using the Information you Find
• The content found on the web is a form of
intellectual property.
– Intellectual property includes all creations of the
human mind presented in a form that can be
shared with others.
• A copyright is a protection granted by law to
the author or creator of an original work who
creates a tangible expression of that work or
creation.
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Determining Fair Use
• U.S. copyright law allows portions of copyrighted
works to be used without obtaining permission if
that use is a fair use.
• Four factors usually determine fair use:
– The purpose and character of the new work
– The nature of the copyrighted work
– The amount and substantiality of the portion used in
relation to the copyrighted work as a whole
– The effect of the use on the potential market, or
value, of the copyrighted work
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Identifying Works in the Public Domain
• When the term of the copyright has expired, the
work moves into the public domain and can be
copied without requesting permission.
• New print editions or audio recordings of public
domain work can be copyrighted and protected
under current copyright laws.
• Authors or creators can place their own work into
the public domain voluntarily at any time.
• The source of public domain work must be
acknowledged to avoid plagiarism.
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Avoiding Plagiarism
• Failure to cite the source of material you use is
called plagiarism.
• Claiming someone else’s work as your own is a
serious legal violation.
• Be sure to properly reference the sources of
works that you use.
• You must obtain the copyright holder’s
permission to use work in a way that falls
outside of fair use.
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Documenting Web Resources
• Material protected by copyright or in the
public domain needs to be properly cited.
• For academic research, the two most widely
used standards for citation are:
– American Psychological Association (APA)
– Modern Language Association (MLA)
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Webpage Citations
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Previewing and Printing a Webpage
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Saving a Webpage
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Objectives
• Learn about the Internet and the World Wide
Web
• Start the Internet Explorer app and the Internet
Explorer desktop application
• Develop search techniques for locating
information on the web
• Use a search engine to conduct a search
• Find and evaluate information on the web
• Learn about copyright laws
• Document web resources
New Perspectives on Microsoft
Office 2013
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URL
Domain name
Tcp/ip
protocols
• http
• ftp
• Smtp