52 Internet Concepts The
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Title Slide
Internet Concepts
Web Browsers
By
Ralph B. Bisland, Jr.
Hypertext
• Hypertext: Coined by Ted Nelson
about 1969
• Normal text is designed to be read
sequentially.
• Some text is not designed to be
read sequentially.
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Hypertext (ctd)
• Examples:
– Dictionary
– Encyclopedia
– Reference books
– Footnotes
• Hypertext contains links that point to
other, possibly, supporting information
• Supporting information may be text,
pictures, sounds, etc.
• Usually follow associative paths through
information
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World Wide Web (WWW)
• An attempt to provide access to the widest range
of information by linking documents created in
HTML (HyperText Markup Language), FTP, some
Oracle databases, etc.
• The WWW was originally at CERN, a high energy
physics research center in Switzerland, by Tim
Berners-Lee.
– Note: CERN = Conseil European pour la Recherche Nucleaire =
European Laboratory for Particle Physics, located in Geneva,
Switzerland.
• To access the WWW a Web Browser is needed.
• Internet
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Types of Browsers
• Text processing
– mainframe oriented
– Basically out of date
– Best: Lynx (University of Kansas)
• Graphics oriented
– Designed for PCs with PPP access
– Majority of browsers are graphics oriented
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Daemons
• A program that runs on a UNIX-based
computer system.
• Provides a single task.
• “Wakes up” periodically, performs its
function, then goes back to sleep.
• There many different types of daemons on
UNIX-based computer systems.
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URLs
• Addresses on WWW are called
Universal Resource Locators
• The URL consists of a:
– Scheme
– The name of the computer
– The domain name
– An optional port number
– An optional path (subdirectory) name
– An optional file name
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Scheme
• What you want the browser to do.
• The scheme can be any of the following:
– http: HyperText Transfer Protocol (default)
– telnet: Connect to another computer syste
– ssh: Secure shell
– file: A file on your local system or a file on
an anonymous FTP site
– ftp: FTP site
– news: A USENET Newsgroup
• The scheme is separated from the other
components with ://
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Host and Domain
• This is the DNS name of the computer
where the web page file is located.
• Example: orca.st.usm.edu
• The domain is whose computer account
do you want to connect to.
• Usually the person’s login name on the
computer proceeded by a tilde symbol
(~).
• Example:
orca.st.usm.edu/~bisland
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Port Number
• Where the request for service is routed.
• Generally the port number can be omitted.
(Default WWW port is generally 80)
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The Path and Filename
• A subdirectory within the computer
account (login id)
• The default directory is:
<login-id name>/public_html
• The name of the file containing the web
page commands.
• The default file name is index.html or
index.shtml
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Example URLs
http://orca.st.usm.edu
orca.st.usm.edu
orca.st.usm.edu/~bisland
orca.st.usm.edu/~bisland/golfstuff/golfl.html
telnet://orca.st.usm.edu
ssh://orca.st.usm.edu
ftp://ftp.usm.edu
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Home Pages or Web Pages
• WWW Home Page - Analogous to a
main menu item
– Note: A page is not really a page as it may
extend for several printed pages. A page is
actually a file which contains commands to
produce the output shown on your screen.
• When you first connect to a Web site,
the first screen that you see is called the
home page.
• Normally other links are attached to the
Home Page
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Home Pages or Web Pages (ctd)
• USM WWW address:
– http://www.usm.edu
– www.usm.edu
• There are many links that this connects
to
• A page is created by HTML (Hypertext
Markup Language) commands stored in
a text file.
• The HTML commands “render” the
page.
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Example Web Page File
<HTML>
<HEAD>
<TITLE>Sample Web Page</TITLE>
</HEAD>
<BODY BACKGROUND=YELLOW>
<FONT FACE=ARIAL COLOR=BLUE SIZE=+2>
This is a sample web page
</FONT>
</BODY>
</HTML>
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Home Page Architecture
Your Home
Page
Page1
Page4
Page2
Page5
Page6
Hyperlinks
Page3
Page7
Page8
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More on Web Browsers
• Web browsers are programs used to
access information on the WWW.
• Browsers normally run as client
programs on PCs.
• Make request to servers that sent the
file containing HTML code to your
server.
• The browser “renders” the commands
on your screen.
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Common Web Browsers
• Mosaic (NCSA)
• Netscape Navigator/Communicator
(Netscape Communications)
• Mozilla
• Internet Explorer (Microsoft)
• Opera
• Hot Java
• Others
– AOL
– Compuserve
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Mozilla
• Netscape was a web browser developed by
Netscape Communications.
• Major competitor of Internet Explorer.
• On January 22, 1998, Netscape announce
plan to make the code for Netscape
available to the public free of charge.
• This made the code “open source”.
• This was done to deny Microsoft a
monopoly.
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Mozilla (ctd)
• In July 2004 the Mozilla Foundation was
formed with the help of America
Online’s Netscape Division.
• The Mozilla Foundation exists to
“provide organizational, legal, and
financial support for the Mozilla open
sourece project.”
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Mozilla (ctd)
• Mozilla was rated the best web browser in 2003
by:
– PC World Magazine
– LinuxJournal Magazine
– Time Magazine
• Features
– Free to download (www.mozilla.org or ftp.usm.edu)
– Handles over 50 languages (Afikaans to Zulu)
– Internalization
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Mozilla Features
•
•
•
•
•
Navigator (web browser)
Mail and Newsgroups
Chat
Composer (web page development)
Calendar
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Using A Browser
• To use a browser, you must enter a a
scheme and a URL to link to.
• You must either know the URL and enter it
directly or select it from a set of saved
addresses (bookmarks/favorites/etc.)
• Enter the URL in the window atop the
browser page or pull down the “File” menu
and select “Open Location”.
• Use a search engine and search for
whatever you wish.
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Using A Browser (ctd)
• Browser links are usually displayed in a
different color and underlined
• To hyperlink to a link, move the cursor
to the link and double click on the left
mouse button.
• You may jump from one link to another.
• Browser Status Line: Line at the bottom
of the page telling you what the browser
is currently doing.
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Browser Connections
• Browsers transfer to links, download the
page into the browser, interpret the code,
and render the material on your screen.
• Once the material has been downloaded the
connection is broken.
• If you want to go to another hyperlink on the
same page, the browser must reconnect to
the URL. (Not always!)
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Cashe
• Netscape keeps the “N” most recently accessed
pages in a special area of the computer called
cache. This enhances performance.
• Two types of cache:
– Memory Cache: A special section of very fast
memory chips set aside tostore the information
most frequently accessed from Random Access
Memory (RAM).
– Disk Cache: A special area of very fast disk
used to store pages.
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Cashe (ctd)
• Memory cache is faster than disk cache.
• Disk cache is faster than retrieving
pages from the net.
• Disk cache has the advantage of
persistence.
• Sometimes you will see the message
“Reorganizing Cache” in the Status
Line. (Macintosh versions only)
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Disposition Of Web Pages
• Whenever a file is rendered on your
screen, the file can be:
– Saved to your PC disk.
– Printed on your PC printer.
– E-mail the code that produced the page to
whatever address you wish.
• All of these options are listed under the
“File” pull down menu.
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Saving Web Pages
• Web pages can be saved in two different
forms:
– Text: A text rendering of the page (no graphics).
– Source: HTML code that renders the page.
• Note that you may store the page anywhere
you wish (desktop, diskette, etc.)
• Once the file is stored as HTML, it can be
opened as a local file.
• Pull down the File Menu and then select
Open File from the menu
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Saving Web Pages
(ctd)
• Use whatever command(s) to place
the page you wish to save on your
screen (the current page).
• Pull down the File Menu.
• Select “Save As” from the menu..
• Select where you wish to save file
and the file name
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E-mailing Web Pages
• You may either E-mail the entire page
or the link to the page.
• To do either pull down the file menu and
select either:
– Send as Page
– Send as Link
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Plug-ins
• Sets of code used to assist a browser to
execute such things as Java (a
programming language used to enhance the
browser) and VRML (Virtual Reality
Modeling Language) a language used to
produce animation and 3-dimensional
pictures.
• When a browser is downloaded, a default
plug-in(s) is/are included.
• Other plug-ins can be added to further
enhance the program.
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Internet Explorer
•
•
•
•
•
Microsoft Product
Usually comes with Windows OS
Compatible with Netscape (well almost)
Smaller than Mozilla
Getting bigger with each new release
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Search Engines
• Very powerful feature of the WWW
• Start up your browser.
• Enter the URL of the search engine in your
Location Window.
• To use a search engine, you enter some
descriptive text of what you are looking for ,
then click the search button.
• The search engine will create a dynamic web
page that has hyperlinks to pages that have
that text string(s) somewhere on the page.
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How Search Engines Work
• Systematically logons to every web site
in the world and creates a KWIC index.
• The key words are then indexed along
with their URLs.
• When a query is entered, the index is
searched and a dynamic web page is
created which includes the URLs of the
various indexed locations.
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Differences In Search Engines
Size of the index
Frequency of update of the index
Organization of the index
User interface
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Some Search Engines
•
•
•
•
•
•
•
Google (google.com)
Altavista (altavista.com)
Lycos (lycos.com)
Dogpile (dogpile.com)
Hotbot (hotbot.com)
AskJeeves (ask.com)
Infoseek (infoseek.com)
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Types Of Searches
• Simple Query: Search for simple text strings
– May also do:
•
•
•
•
•
Translations
Browse By Subject
People Search
Business Search
Many, many others
• Advanced Query: Can and/or strings together
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Google Search Engine
• Most used search engine.
• Uses very high quality hardware and
software to drive it.
• Uses an algorithm called PageRank to
search indexes and assign weights to
the results. This algorithm was
developed by the two creators of
Google.
• This supposedly produces the best
ranking of query results.
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Google Search Basics
• Just enter a few related key words and press
the Enter key or click the “Google Search”
button.
• Google returns pages that contain ALL the
words.
• I’m Feeling Lucky: Opens the first link
generated.
• You can refine your search by adding
additional words to the search string.
• Click on a hyper link to go to that URL.
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Google Search Basics (ctd)
• You may not find what you want at first. Try
going to a page, reading it, looking for
additional/other key words, then enter them
as keywords in another search.
• Capitalization is irrelevant. (“George
Washington” = “george washington”)
• Plurals are irrelevant.
• If Google determines that the word that you
have entered is misspelled, it corrects your
spelling. “Did you mean ---?”
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Natural Language Searches
• Google queries can be entered in natural
language.
• Example: What is the weather in
Hattiesburg, MS?
• Google will parse the query and extract the
key words and use them in the query.
• Note: Ask Jeeves (ask.com) does a
particularily good job at this.
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Selecting Keywords
• Choose keywords wisely.
• Try the obvious first. Try “Picasso” instead of
“painters” (too broad).
• Use words likely to appear on the site.
Choose “luxury hotel hattiesburg” rather than
“really nice places to spent the night in
Hattiesburg”.
• Make keywords as specific as possible. Ex.
“antique lead soldiers” rather than “old metal
toys”.
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Automatic “and” Queries
• Google automatically “ands” together all
key words entered.
• There is no reason to insert the word
“and” between words.
• The order in which you enter the key
words will affect the search results.
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Automatic Exclusion Of Common Words
• Google excludes common words such as
“where” and “how” as well as single digits
and single letters. (Reason: It slows down
the search.) Google informs you that a word
has been omitted by displaying details in the
results page below the search box.
• If the common word is important to the
search, either put the search string in double
quotes (“) or place a space plus sign (“ +”)
before the word/digit.
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Examples
To search for Star Wars Episode I enter:
“Star Wars Episode I”
Or
Star Wars Episode +I
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Word Variations (stemming)
• Google now uses stemming technology.
• When appropriate, it will not only search for
your search items, but also for words similar
to some or all of those words.
• Example:
“pet lemur diet needs”
“pet lemur dietary needs”
• Any variants of your terms that were
searched for will be highlighted in the
snippet text that accompanies the results.
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Search By Category
• The Google directory
(directory.google.com) is a good place
to start if you are not sure what keywords to
use in your search.
• Example:
– Searching for “Saturn” within the Science >
Astronomy category yields information on the
planet Saturn.
– Searching for “Saturn” under the Automotive
category yield information on cars.
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Advanced Searches
• Used to increase the accuracy in your
searches.
• Click on “Advanced Search Page” from the
Google Home page.
• Category restrictions:
–
–
–
–
–
–
–
Find Results
Language
File Format
Date
Occurrences
Domain
Safe Search
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Find Results
• To perform an Advanced Search just fill
in the blanks.
– With all the words
– With the exact phrase
– With at least one of the words
– Without the words
• These things can also be performed
in simple searches by using
operators.
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The + Operator
• Used to make sure that a word normally
omitted is included in the search.
• Example:
Star Wars Episode +I
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The - Operator
• Used to exclude words from the search.
• Example: the word “bass” can be a music
term and a fishing term. To make sure that
you got to the bass that referred to fish,
you could specify the following search
string:
bass -music
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The ~ Operator
• Used to search not only for the word,
but any of its synonyms.
• Example: To search not only for food
facts, but nutrition and cooking
information, you may want to use the
search string:
~food ~facts
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Phrase Searches
• To search for certain words in a
particular order (a phrase), enter the
search string in double quotes (“).
• This is convenient when searching for
proper names or quotations.
• Example: To search for information on
the Emancipation Proclamation, you
might enter:
“Emancipation Proclaimation”
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The OR Operator
• Normally all words are “and”ed together.
• To “or” words insert the word OR (all
caps) between the words you wish to or.
• Example: To check out information on
vacations in London or Paris, you might
enter the search string:
vacation london OR paris
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Alternate Query Types
• This feature allows Google to further restrict
query results.
• The alternate query type name must be
followed with a colon (:) followed by a value
with no embedded spaces.
• Example: define:google
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Alternate Query Types (ctd)
• Cashe:Shows the version of the page Google
has in cashe. (No argument to this type.)
• Link: Lists the webpages that have links to
the specified page
(link:orca.st.usm.edu/~bisland)
• Related: Lists the web pages that are similar
to the web page listed
• Info: Will present some information that
Google has about the specified page
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Other Information Needs
• Define: Define the word specified.
define:pettifogger
• Stocks: Treats any symbols after this
word as stock symbols . It will show
stock information on these stocks.
(Actually it goes to Yahoo Finance and it
looks up the stock for you.)
stocks:IBM
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Query Modifiers
• Site: Restricts the search to a particular
domain.
Ex. help site:www.google.com
• Allintitle: Restricts the results to those with
all the query words in the title.
Ex. allintitle:google search
• Intitle: Restricts the search to the one query
word in the title.
Ex. Intitle:google search
Searches for “google” in the title and
“search” anywhere else.
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Query Modifiers (ctd)
• Allinurl: Restrict the search results to those
with all of the query words in the URL.
Ex. Allinurl:google search
Returns all documents with the words
“google” and “search” in the URL.
• A backslash (\) is not a valid character to
search for. The query
allinurl:foo\bar
will return all the documents with “foo” and
‘bar” in the URL, but not “foo\bar”, or “foo”
necessarily followed by “bar”.
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Query Modifiers (ctd)
• Inurl: Restricts the results to documents
containing that word in the URL.
Ex. Inurl:google
Restricts the results to the
documents with the word “google” in the
URL.
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Other Neat Features Of Google
• Calculator: Use Google to evaluate math
expressions.
• To use the calculator, simply enter the
expression into the search string box. (Ex.
2+2) the press the Enter key.
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Calculator Operators
•
•
•
•
•
•
•
•
•
+ = Addition (2+2)
- = Subtraction (5-3)
* = Multiplication (5*4)
/ = Division (3/2)
^ = Exponentiation (3^2)
% = Modulo division (5%3)
Choose = Permutations (18 choose 4)
th root of = nth root of (5th root of 32)
% of = Percentage (10% of 156)
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Calculator Functions
•
•
•
•
•
•
•
Sqrt = Square root {sqrt (10)}
Sin = Sine function {sin(1.0)}
Cos = Cosine function {cos(1.0)}
Tan = Tangent function {tan(1.0)}
Ln = Logarithm base e {ln(10)}
Log = Logarithm base 10 {log10)}
! = Factorial (5!)
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Things To Know
• You can force the result immediately by
placing an equals sign after the expression
(1+1=).
• Addition and subtraction are low priority
operators. You may change priority with
parenthesis.
2+2*3 = 8
(2+2)*3 = 12
• Google shows you how the expression was
evaluated.
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Things To Know (ctd)
• The in operator is used to specify what units
you want used to express your answer.
Ex. 5 kilometers in miles
• You can use Google to express numbers in
hexadecimal, octal, or binary. Use the
prefixes: 0x, 0o, or 0b
Ex. 0b101011 + 0b111100
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Things To Know (ctd)
• The calculator understands many different units, as
well as many physical and mathematical constants.
You may use them in computations.
• You may use some abbreviations for some
constants. (Ex. Km for kilometer, e for the speed of
light, etc)
– 25 in roman numerals
– Sine(30 degrees)
– e^pi
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Other Search Features
• Froogle: Searches for products for sale
online.
• Search by number: Searches for such things
as:
–
–
–
–
–
–
–
UPS Tracking numbers
Fed Ex Tracking numbers
USPS Tracking numbers
Vechicle ID numbers (VIN)
UPC Codes
Patent Numbers
FCC Airplane Registration Numbers
• Street Maps
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People Searches
• Type the person’s name into the query string.
• Formats:
–
–
–
–
–
–
–
First name (or initial), Last name, city
First name (or initial), Last name, state
First name (or initial), Last name, area code
First name (or initial), Last name, zip code
Phone number (including area code)
Last name, city, state
Last name, zip code
• You may even get a map to the persons residence.
• Try: switchboard.com or whitepages.com
for phone numbers
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Yahoo!
•
•
•
•
•
Yahoo’s search engine is organized by topics
Select the most likely category and click on it
Proceed until you find what you want
May use Search boxes
People Search is also nice
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Bookmarks
• Some browsers call them favorites.
• Bookmarks are a user named location on
the web.
• Mozilla allows a mechanism for recording
bookmarks.
• Automatic recording of bookmarks.
– When you are viewing a page that you like and want to
make a bookmark for, simply pull down the "Bookmark"
menu and select the "Add Bookmark“ option.
• Recording the information yourself.
– Pull down the "Bookmarks" menu and select the
“Properties " option and fill in the blanks.
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Bookmarks (ctd)
• To delete or rename a bookmark select
“Manage Bookmarks”, then select the
specific bookmark and then select either
delete or rename.
• To edit a bookmark, select the
bookmark, select properties, then
perform the edit.
• To use a bookmark, select the
"Bookmarks" pull down menu, then
select the name of the bookmark that
you desire to use, then click on it.
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