Foundations of Computing

1
Discussion 15 WWW Forms I and Search
2
HTML Tags
Review

• ltagt - Anchor
• ltbgsoundgt - Audio Sound
• ltblinkgt - Blink text
• ltbodygt - Document body
• ltcentergt - Center text
• ltfieldsetgt - Item grouping
• ltfontgt - Font Specification
• lth1gt-lth6gt - Headings
• lthrgt - Horizontal Line
• ltimggt - Image
• ltlegendgt - Fieldset caption

3
HTML Tags
Review

• ltmarqueegt - Marquee
• ltpregt - Preformatted Text
• lttitlegt - Document title
• ltligt - List item
• ltolgt - Ordered List
• ltulgt - Unordered List
• lttablegt - Tables
• lttdgt - Table Data Cell
• ltthgt - Table Header
• lttrgt - Table Row

4
Linking w/in a Document
Review

• The first ltagt tag specifies a named fragment the
  second ltagt tag links back to the named fragment.
• This is the default input type.
• Examples
• lta name"fragmentname"gtText lt/agt
• lta href"fragmentname"gtLink to Text lt/agt

5
WWW Forms and Search
6
Web Access

• URL - always fetch a particular page?
• What if the information we want varies from time
  to time and from user to user?

7
Web-site Requests

• How does the web-site get information from the
  user?
• When does a user send the request?
• Where does the user send the request?
• How does the user send the information with the
  request?

8
HTML Forms

• ltbodygt
• lth1gtExample formlt/h1gt
• ltform action"http//students.cs.byu.edu/cgi/findM
  e"gt
• First name
• ltinput type"text" name"firstName"
• size"20" value"Phred" /gt
• ltp /gt
• Last name
• ltinput type"text" name"lastName"
• size"20" value"Phinster" /gt
• ltp /gt
• ltinput type"submit" value"Find Me" /gt
• lt/formgt
• lt/bodygt

9
Labels

• ltbodygt
• lth1gtExample formlt/h1gt
• ltform action"http//students.cs.byu.edu/cgi/findM
  e"gt
• First name
• ltinput type"text" name"firstName"
• size"20" value"Phred" /gt
• ltp /gt
• Last name
• ltinput type"text" name"lastName"
• size"20" value"Phinster" /gt
• ltp /gt
• ltinput type"submit" value"Find Me" /gt
• lt/formgt
• lt/bodygt

10
User Input

• ltbodygt
• lth1gtExample formlt/h1gt
• ltform action"http//students.cs.byu.edu/cgi/findM
  e"gt
• First name
• ltinput type"text" name"firstName"
• size"20" value"Phred" /gt
• ltp /gt
• Last name
• ltinput type"text" name"lastName"
• size"20" value"Phinster" /gt
• ltp /gt
• ltinput type"submit" value"Find Me" /gt
• lt/formgt
• lt/bodygt

Default value
Name of variable to contain the information
Maximum number of characters allowed
11
Send the Request

• ltbodygt
• lth1gtExample formlt/h1gt
• ltform action"http//students.cs.byu.edu/cgi/findM
  e"gt
• First name
• ltinput type"text" name"firstName"
• size"20" value"Phred" /gt
• ltp /gt
• Last name
• ltinput type"text" name"lastName"
• size"20" value"Phinster" /gt
• ltp /gt
• ltinput type"submit" value"Find Me" /gt
• lt/formgt
• lt/bodygt

What to do with the information
Caption on input button
12
Where to Send Request

• ltbodygt
• lth1gtExample formlt/h1gt
• ltform action"http//students.cs.byu.edu/cgi/findM
  e"gt
• First name
• ltinput type"text" name"firstName"
• size"20" value"Phred" /gt
• ltp /gt
• Last name
• ltinput type"text" name"lastName"
• size"20" value"Phinster" /gt
• ltp /gt
• ltinput type"submit" value"Find Me" /gt
• lt/formgt
• lt/bodygt

13
Browser Request for the Search
14
How does the Server Respond?
Static HTML Page
Server
Client

• CGI - Common Gateway Interface
• URL specifies to the server a program.
• The program generates an HTML page.

15
Search

• How do we search on the internet?
• How do we describe the page that we want?

16
Search

• How does Google know where that page is?
• Pro-active web sites
• Contract w/Google
• Pay per click
• Google finds as many web pages as it can.
• Web crawler
• Web sniffing
• For each web page found
• Prepare a list of words on that page
• For each word in all of the web keep a list of
  pages that have that word

17
CS 100 - Which page?
18
CS 100 - the winner

• Why? Both have the words CS 100
• CS 100 in lttitlegt
• CS 100 in text

19
Problems with word searches

• Search for a medical doctor
• What about pages with the word doctors?
• What about pages with the word physicians?
• What about pages about witch doctors?
• What about pages with college professors?
• What if the page only has a picture of a doctor?
• What if the only use of the word doctor is in a
  picture?

20
Blocking pornography

• The reverse of the search problem.
• I dont want pages that have this
• How do you describe what you dont want?
• Keep a list of all bad sites
• If site is on the black list then refuse to make
  an Internet connection
• What if someone creates a new site?
• Keep a list of bad words and block any URL or
  page that has those words
• What about Middlesex, England?
• What about breast cancer?
• What about slang words?
• What about pictures?