www forms and search. forms url - always fetch a particular page what if the information we want...
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WWW Forms and Search
Forms
• URL - always fetch a particular page
• What if the information we want varies from time to time and from user to user?
Forms
Forms - requests to a web-site
• How to get information from the user
• When to send the request
• Where to send the request
• How to send the user’s information with the request
<body><h1>Example form</h1>
<form action="http://icie.cs.byu.edu/cgi/findMe">
First name <input name=firstName size=20 value="Phred">
<p>Last name<input name=lastName size=20 value="Phinster">
<p><input type="submit" value="Find Me">
</form></body>
Labels
<body>
<h1>Example form</h1><form action="http://icie.cs.byu.edu/cgi/findMe">
First name
<input name=firstName size=20 value="Phred"><p>
Last name<input name=lastName size=20 value="Phinster">
<p><input type="submit" value="Find Me">
</form></body>
Labels
How to get info from the user
<body><h1>Example form</h1><form action="http://icie.cs.byu.edu/cgi/findMe">
First name
<input name=firstName size=20 value="Phred"><p>
Last name
<input name=lastName size=20 value="Phinster"><p>
<input type="submit" value="Find Me"></form></body>
Parts to an input tag
• <input name=“N” size=20>
• Name - the name that this input information will be given
• Size - the number of characters that the user can type
When to send the request
<body><h1>Example form</h1><form action="http://icie.cs.byu.edu/cgi/findMe">
First name <input name=firstName size=20 value="Phred">
<p>Last name<input name=lastName size=20 value="Phinster">
<p>
<input type="submit" value="Find Me"></form></body>
When to send the request
Where to send the request
<body><h1>Example form</h1>
<form action="http://icie.cs.byu.edu/cgi/findMe">First name <input name=firstName size=20 value="Phred">
<p>Last name<input name=lastName size=20 value="Phinster">
<p><input type="submit" value="Find Me">
</form></body>
How to send the user informationin a URL
<body><h1>Example form</h1><form action="http://icie.cs.byu.edu/cgi/findMe">
First name <input name=firstName size=20 value="Phred">
<p>Last name<input name=lastName size=20 value="Phinster">
<p><input type="submit" value="Find Me">
</form></body>
http://icie.cs.byu.edu/cgi/findMe?firstName=Phred&lastName=Phinster
How to send the user informationin a URL
<body><h1>Example form</h1><form action="http://icie.cs.byu.edu/cgi/findMe">
First name <input name=firstName size=20 value="Phred">
<p>Last name<input name=lastName size=20 value="Phinster">
<p><input type="submit" value="Find Me">
</form></body>
http://icie.cs.byu.edu/cgi/findMe?firstName=Phred&lastName=Phinster
How to send the user informationin a URL
<body><h1>Example form</h1><form action="http://icie.cs.byu.edu/cgi/findMe">
First name <input name=firstName size=20 value="Phred">
<p>Last name<input name=lastName size=20 value="Phinster">
<p><input type="submit" value="Find Me">
</form></body>
http://icie.cs.byu.edu/cgi/findMe?firstName=Phred&lastName=Phinster
Forms - How does the server respond?
• Not every URL refers to a page
• CGI - Common Gateway Interface
• You can give a server a program and place it at a URL.
• The server will then run the program and return its result rather than fetch a page
Search
• How do we describe the page that we want?
Search
• How does Google know where that page is?
• Find as many web pages as you can
• For each web page 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
How does your browser ask for the search
CS 100 - Which page?
CS 100 - the winner
• Why? Both have the words CS 100
• CS 100 in <title>
• CS 100 in text
Problems with word searches
• Search for “doctor”
• What about pages with the word “doctors”?• What about pages with the word “physicians”?• What about pages about “witch doctors”?• What if the page only has a picture of a doctor?• What if the only use of the word doctor is in a
picture?
Blocking pornography
• The reverse of the search problem
• I don’t want pages that have this– How do you describe what you don’t want?
Blocking pornography
• 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?