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Web Browsers. CS 3505. Wb_webBrowsers-I.ppt. Vendors. Major web browsers: Netscape and Microsoft IE, Firefox , Opera 8 AOL uses a browser that’s re-branded IE (I think). They’re free A few others out there: lynx (text-based), etc. URLs. The URL: http://www.microsoft.com/office

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web browsers

Web Browsers

CS 3505

Wb_webBrowsers-I.ppt

vendors
Vendors
  • Major web browsers: Netscape and Microsoft IE, Firefox , Opera 8
  • AOL uses a browser that’s re-branded IE (I think).
  • They’re free
  • A few others out there: lynx (text-based), etc
slide3
URLs
  • The URL: http://www.microsoft.com/office
    • http is the protocol
    • www.microsoft.com is the server name
    • /office is the file on that server
slide4
URLs
  • ftp://ftp. nps.navy.mil/
    • ftp is the protocol
    • ftp.nps.navy.mil is the server
    • Logs you onto the ftp server as user “anonymous” with ?? As password.

NPS FTP does not work well try ftp://ftp.microsoft.com

slide5
URLs
  • news://news.mbay.net
    • news/nntp is the protocol
    • news.mbay.net is the news server
    • Launches news reader
  • gopher:// hardly ever used these days
  • https:// is secure http (more later)
what the url means
What the URL means
  • Http: “Using the http protocol”
  • machine name: “Connect to this machine”
  • file name: “starting from the default point for documents on this web server, retrieve this document”
url example
URL Example
  • Example: http://www.nps.navy.mil/cs/Faculty.asp
  • On the site www.nps.navy.mil, the Web server will look for the file
    • CS/Faculty.asp
default index file
Default index file
  • Usually you can just specify the directory you want to look in. By default the server will look for a file usually called “index.html” within that directory.
  • Index.html or default html is usually the top file of a web site
  • Also htm and html are alternative dialects
other types of files
Other types of files
  • You can configure your web browser to cooperate with types of files other than html
  • You can configure it to launch a “helper application” or “plugin” when it encounters a file. A plugin is a program that runs inside of your browser. A helper application launches external to the web browser.
plug ins and helper applications
Plug-ins and Helper Applications
  • View plug-ins:

Tools->Internet Options->

_General->Settings->View objects_

  • Programs tab
  • File extension mechanism
slide11
PDF
  • Adobe Portable Document Format
  • Postscript-like control of graphics in the document
  • Free viewer from adobe
  • Can either be viewed as a plugin or an external viewer
slide12
VRML
  • 3D environments
  • Usually done as a plugin
  • .wrl extension
browser features
Browser Features
  • Top tool bar
    • Back , forward
    • Refresh , update local copies
    • Home ; set home page Tools->Internet Options
bookmarks
Bookmarks
  • An easy way to save a place on the web
  • Called “Favorites” in Internet Explorer
  • “History” provides a list of sites visited
    • Today,Last week, 2 weeks,3weeks
cache and refresh
Cache and Refresh
  • Browsers copy html files to local disk and retrieve from the stored copy
  • Change Cache settings

Tools->Internet Options-> temporary internet files-> settings

  • Location example:

C:\Documents and Settings\userID\Local Settings\Temporary Internet Files

searching the web
Searching the web
  • Click “Search” on IE
    • Enter key words on pop up
    • Uses MS Search engine
  • Go to A search engine
    • Yahoo.com, AltaVista.com, Google.com
    • Enter key words
key word searches
Key word searches
  • Return all key words
  • Example:Terrain Images
  • Will return references to all indexed pages which contain the word
    • Terrain
    • Images
  • Lots of “hits”
  • Presented in an order as determined by the search engines “evaluator rules”
  • Often paid advertisements are the primary order
    • Yahoo was “pure” until recently
advanced boolean searches
Advanced Boolean searches
  • Most search engines have Boolean rules usually available through a help or advanced search button
  • Typical Advances search options
    • Match all words(AND)
    • Match any words(OR)
    • Group whole phrase(“ “)
    • Do not include (NOT)
  • Example Yahoo the OR is implicitly coded as a blank
  • Natural gas prices in Washington State
  • Will get hits on all words except articles(in, a, of..)
  • Reduce the search by applying rules
  • “Natural gas prices” “Natural gas cost” Washington NOT DC
search trick
Search Trick

* Often the whole or part of a web page has been indexed thus one is searching for a phrase in a page.

* Think how the question would be answered not how it would be asked

* NOT

“What is the capital of Ohio”

*Instead

“The capital of Ohio is”

saving and viewing information
Saving and Viewing Information
  • View->refresh
  • File ->Print
  • File->save As
  • Save Image
    • Right click on image, save as
  • View->source
secure transmission
Secure Transmission
  • Recall that messages and files sent across the internet are plain text and can be intercepted
  • SSL uses encryption to send files and messages across the net. This is done with secure http, https.
  • A bit slower than http, but fast enough
  • https and a little icon of a lock show you’re secure
example amazon com
Example: Amazon.com
  • Https:// and lock icon when using secure server, http:// and no lock icon or unlocked lock icon for unsecure server
  • Warning
cookies
Cookies
  • Cookies are used to implement things like shopping carts
  • Web servers can’t remember information from one transaction to the next easily.
  • Cookies are just a place for a web server to store data
  • Location example:

C:\Documents and Settings\userID\cookies

  • Control Coockies:

tools->internet options->

Security-> custom level

slide24
HTTP
  • Http is the protocol used by browsers and servers on the web
  • Very simple request response sequence
  • RFC 2616: Hypertext Transfer Protocol -- HTTP/1.1

http

WWW Server

(apache)

Browser

(netscape)

request

response

http cont

Status line

Headers

A blank line

Body if required

HTTP(cont)
  • Request

Method

URL

HTTP Version

Main Methods: GET, HEAD, POST

Others; Put, Patch, copy, move, delete, link, unlink, option

  • Response
  • Mime like
  • Status codes

Example: 302-moved

http example
HTTP example

client

server

GET /usr/bin/image1 HTTP1.1

Accept: image/gif

HTTP/1.1 200 OK

Date: mon, 07-jan-02 13:15:14: GMT

Server: Challanger

MIME-Version: 1.0

Content-Length:2048

( body of document)

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