SLIDE 1
Forms, CGI
Forms, CGI
Objectives
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 1 / 19
Forms, CGI
Forms, CGI
Objectives
◮ The basics of HTML forms
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 1 / 19
Forms, CGI Objectives DD1335 (Lecture 5) Basic Internet - - PowerPoint PPT Presentation
Forms, CGI Objectives DD1335 (Lecture 5) Basic Internet - - PowerPoint PPT Presentation
Forms, CGI Forms, CGI Objectives DD1335 (Lecture 5) Basic Internet Programming Spring 2010 1 / 19 Forms, CGI Forms, CGI Objectives The basics of HTML forms DD1335 (Lecture 5) Basic Internet Programming Spring 2010 1 / 19 Forms, CGI
SLIDE 2
SLIDE 3
Forms, CGI
Forms, CGI
Objectives
◮ The basics of HTML forms ◮ How form content is submitted
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 1 / 19
SLIDE 4
Forms, CGI
Forms, CGI
Objectives
◮ The basics of HTML forms ◮ How form content is submitted
◮ GET, POST DD1335 (Lecture 5) Basic Internet Programming Spring 2010 1 / 19
SLIDE 5
Forms, CGI
Forms, CGI
Objectives
◮ The basics of HTML forms ◮ How form content is submitted
◮ GET, POST
◮ Elements that you can have in forms
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 1 / 19
SLIDE 6
Forms, CGI
Forms, CGI
Objectives
◮ The basics of HTML forms ◮ How form content is submitted
◮ GET, POST
◮ Elements that you can have in forms ◮ Responding to forms
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 1 / 19
SLIDE 7
Forms, CGI
Forms, CGI
Objectives
◮ The basics of HTML forms ◮ How form content is submitted
◮ GET, POST
◮ Elements that you can have in forms ◮ Responding to forms
◮ CGI – the Common Gateway Interface DD1335 (Lecture 5) Basic Internet Programming Spring 2010 1 / 19
SLIDE 8
Forms, CGI
Forms, CGI
Objectives
◮ The basics of HTML forms ◮ How form content is submitted
◮ GET, POST
◮ Elements that you can have in forms ◮ Responding to forms
◮ CGI – the Common Gateway Interface ◮ Later: Servlets DD1335 (Lecture 5) Basic Internet Programming Spring 2010 1 / 19
SLIDE 9
Forms, CGI
Forms, CGI
Objectives
◮ The basics of HTML forms ◮ How form content is submitted
◮ GET, POST
◮ Elements that you can have in forms ◮ Responding to forms
◮ CGI – the Common Gateway Interface ◮ Later: Servlets
◮ Generation of dynamic Web content
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 1 / 19
SLIDE 10
Forms, CGI
HTML forms
◮ In most internet programming, you need the user to enter data
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 2 / 19
SLIDE 11
Forms, CGI
HTML forms
◮ In most internet programming, you need the user to enter data ◮ HTML forms offer the basic user interface elements inside HTML
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 2 / 19
SLIDE 12
Forms, CGI
HTML forms
◮ In most internet programming, you need the user to enter data ◮ HTML forms offer the basic user interface elements inside HTML ◮ Forms have a method which corresponds to the HTTP command that will
be sent when the form is submitted
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 2 / 19
SLIDE 13
Forms, CGI
HTML forms
◮ In most internet programming, you need the user to enter data ◮ HTML forms offer the basic user interface elements inside HTML ◮ Forms have a method which corresponds to the HTTP command that will
be sent when the form is submitted
◮ Forms have an action which denotes the URL loaded when the form is
sent.
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 2 / 19
SLIDE 14
Forms, CGI
HTML forms
◮ In most internet programming, you need the user to enter data ◮ HTML forms offer the basic user interface elements inside HTML ◮ Forms have a method which corresponds to the HTTP command that will
be sent when the form is submitted
◮ Forms have an action which denotes the URL loaded when the form is
sent.
◮ The action URL is typically a CGI or a servlet DD1335 (Lecture 5) Basic Internet Programming Spring 2010 2 / 19
SLIDE 15
Forms, CGI
HTML forms
◮ In most internet programming, you need the user to enter data ◮ HTML forms offer the basic user interface elements inside HTML ◮ Forms have a method which corresponds to the HTTP command that will
be sent when the form is submitted
◮ Forms have an action which denotes the URL loaded when the form is
sent.
◮ The action URL is typically a CGI or a servlet
◮ Inside the form you can have normal HTML and inputs (user interface
elements)
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 2 / 19
SLIDE 16
Forms, CGI
Form example
<html> <body> <form action="http://localhost/response.html" method="get"> your name: <input name="someText" type="text" value="change me!" /> <br /> your password: <input name="somePass" type="password" /> <br /> <input name="theButton" type="submit" value="click me" /> <br /> </form> </body> </html>
We submit the form to the SimpleHttpServer that we wrote last time (an improved version to also accommodate POST)
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 3 / 19
SLIDE 17
Forms, CGI
Form example . . .
your name: change me! your password: click me!
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 4 / 19
SLIDE 18
Forms, CGI
Form submission
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 5 / 19
SLIDE 19
Forms, CGI
Form submission
◮ Upon submission, the form will generate the following HTTP:
GET/response.html?someText=change+me%21&somePass= sddsfs&theButton=click+me%21 HTTP/1.1 Host: localhost Connection: Keep-Alive . . . and other headers
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 5 / 19
SLIDE 20
Forms, CGI
Form submission
◮ Upon submission, the form will generate the following HTTP:
GET/response.html?someText=change+me%21&somePass= sddsfs&theButton=click+me%21 HTTP/1.1 Host: localhost Connection: Keep-Alive . . . and other headers
◮ The data of the form is thus sent in the HTTP command, after form’s
action and ?
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 5 / 19
SLIDE 21
Forms, CGI
Form submission
◮ Upon submission, the form will generate the following HTTP:
GET/response.html?someText=change+me%21&somePass= sddsfs&theButton=click+me%21 HTTP/1.1 Host: localhost Connection: Keep-Alive . . . and other headers
◮ The data of the form is thus sent in the HTTP command, after form’s
action and ?
◮ The format of the data (inputName=value&...) is called a query string
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 5 / 19
SLIDE 22
Forms, CGI
Form submission
◮ Upon submission, the form will generate the following HTTP:
GET/response.html?someText=change+me%21&somePass= sddsfs&theButton=click+me%21 HTTP/1.1 Host: localhost Connection: Keep-Alive . . . and other headers
◮ The data of the form is thus sent in the HTTP command, after form’s
action and ?
◮ The format of the data (inputName=value&...) is called a query string ◮ In the GET method the query string is limited to 65535 chars
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 5 / 19
SLIDE 23
Forms, CGI
Form submission
◮ Upon submission, the form will generate the following HTTP:
GET/response.html?someText=change+me%21&somePass= sddsfs&theButton=click+me%21 HTTP/1.1 Host: localhost Connection: Keep-Alive . . . and other headers
◮ The data of the form is thus sent in the HTTP command, after form’s
action and ?
◮ The format of the data (inputName=value&...) is called a query string ◮ In the GET method the query string is limited to 65535 chars ◮ The GET query string is visible in the browser. Beware of passwords!
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 5 / 19
SLIDE 24
Forms, CGI
POST form
Simply indicate the method POST
<html> <body> <form action="http://localhost/response.html" method="post"> your name: <input name="someText" type="text" value="change me!" /> <br /> your password: <input name="somePass" type="password" /> <br /> <input name="theButton" type="submit" value="click me!" /> <br /> </form> </body> </html>
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 6 / 19
SLIDE 25
Forms, CGI
POST form submission
POST /response.html HTTP/1.1 Content-Type: application/x-www-form-urlencoded Content-Length: 59 ... Host: localhost someText=change+me%21&somePass=sdfdsf&theButton=click+me%21
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 7 / 19
SLIDE 26
Forms, CGI
POST form submission
POST /response.html HTTP/1.1 Content-Type: application/x-www-form-urlencoded Content-Length: 59 ... Host: localhost someText=change+me%21&somePass=sdfdsf&theButton=click+me%21
◮ When sending data with the POST method, the query string is sent after the
HTTP empty line marking the end of the HTTP header. – So the query string is HTTP content
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 7 / 19
SLIDE 27
Forms, CGI
POST form submission
POST /response.html HTTP/1.1 Content-Type: application/x-www-form-urlencoded Content-Length: 59 ... Host: localhost someText=change+me%21&somePass=sdfdsf&theButton=click+me%21
◮ When sending data with the POST method, the query string is sent after the
HTTP empty line marking the end of the HTTP header. – So the query string is HTTP content
◮ By doing that, the POST method lets you send content with any length (e.g.
upload large files)
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 7 / 19
SLIDE 28
Forms, CGI
POST form submission
POST /response.html HTTP/1.1 Content-Type: application/x-www-form-urlencoded Content-Length: 59 ... Host: localhost someText=change+me%21&somePass=sdfdsf&theButton=click+me%21
◮ When sending data with the POST method, the query string is sent after the
HTTP empty line marking the end of the HTTP header. – So the query string is HTTP content
◮ By doing that, the POST method lets you send content with any length (e.g.
upload large files)
◮ The POST query string is not visible in the browser!
– You can have both GET-style and POST query strings by <form action="someScript?p1=v1&p2=v2" method="post">
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 7 / 19
SLIDE 29
Forms, CGI
Form <input>
◮ For all HTML inputs you can indicate CSS styles, etc
– http://www.htmlhelp.com/reference/html40/forms/input.html
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 8 / 19
SLIDE 30
Forms, CGI
Form <input>
◮ For all HTML inputs you can indicate CSS styles, etc
– http://www.htmlhelp.com/reference/html40/forms/input.html
◮ type="text" and type="password" was demonstrated
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 8 / 19
SLIDE 31
Forms, CGI
Form <input>
◮ For all HTML inputs you can indicate CSS styles, etc
– http://www.htmlhelp.com/reference/html40/forms/input.html
◮ type="text" and type="password" was demonstrated ◮ type="submit" creates a submit button.
If you don’t set any value, it will be "submit query"
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 8 / 19
SLIDE 32
Forms, CGI
Form <input>
◮ For all HTML inputs you can indicate CSS styles, etc
– http://www.htmlhelp.com/reference/html40/forms/input.html
◮ type="text" and type="password" was demonstrated ◮ type="submit" creates a submit button.
If you don’t set any value, it will be "submit query"
◮ Most inputs have a name= (not necessarily needed for type=submit)
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 8 / 19
SLIDE 33
Forms, CGI
Form <input>
◮ For all HTML inputs you can indicate CSS styles, etc
– http://www.htmlhelp.com/reference/html40/forms/input.html
◮ type="text" and type="password" was demonstrated ◮ type="submit" creates a submit button.
If you don’t set any value, it will be "submit query"
◮ Most inputs have a name= (not necessarily needed for type=submit) ◮ Most inputs have a type= that determines the user interface element type
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 8 / 19
SLIDE 34
Forms, CGI
Form <input>
◮ For all HTML inputs you can indicate CSS styles, etc
– http://www.htmlhelp.com/reference/html40/forms/input.html
◮ type="text" and type="password" was demonstrated ◮ type="submit" creates a submit button.
If you don’t set any value, it will be "submit query"
◮ Most inputs have a name= (not necessarily needed for type=submit) ◮ Most inputs have a type= that determines the user interface element type ◮ Most inputs have a value= to indicate initial value
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 8 / 19
SLIDE 35
Forms, CGI
Form <input>
◮ For all HTML inputs you can indicate CSS styles, etc
– http://www.htmlhelp.com/reference/html40/forms/input.html
◮ type="text" and type="password" was demonstrated ◮ type="submit" creates a submit button.
If you don’t set any value, it will be "submit query"
◮ Most inputs have a name= (not necessarily needed for type=submit) ◮ Most inputs have a type= that determines the user interface element type ◮ Most inputs have a value= to indicate initial value ◮ type="reset" creates a button that brings all inputs to their initial values
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 8 / 19
SLIDE 36
Forms, CGI
Form <textarea> and <select>
Dedicated input elements:
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 9 / 19
SLIDE 37
Forms, CGI
Form <textarea> and <select>
Dedicated input elements:
◮ <textarea name="aText">
initial text multiline </textarea> http://www.htmlhelp.com/reference/html40/forms/textarea.html
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 9 / 19
SLIDE 38
Forms, CGI
Form <textarea> and <select>
Dedicated input elements:
◮ <textarea name="aText">
initial text multiline </textarea> http://www.htmlhelp.com/reference/html40/forms/textarea.html
◮ <select name="aChoice" >
<option value="1">option title</option> <option value="two">second</option> </select> http://www.htmlhelp.com/reference/html40/forms/select.html
To indicate an initial value, options can be declared <option selected ...> If the select is declared <select multiple ...>, multiple options can be sent
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 9 / 19
SLIDE 39
Forms, CGI
Form <textarea> and <select>
Dedicated input elements:
◮ <textarea name="aText">
initial text multiline </textarea> http://www.htmlhelp.com/reference/html40/forms/textarea.html
◮ <select name="aChoice" >
<option value="1">option title</option> <option value="two">second</option> </select> http://www.htmlhelp.com/reference/html40/forms/select.html
To indicate an initial value, options can be declared <option selected ...> If the select is declared <select multiple ...>, multiple options can be sent
◮ The query string looks like aChoice=1&aChoice=two etc, i.e. the name repeats
for each value
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 9 / 19
SLIDE 40
Forms, CGI
Checkboxes and radio buttons
◮ <input type="checkbox" name="x" value="y" />
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 10 / 19
SLIDE 41
Forms, CGI
Checkboxes and radio buttons
◮ <input type="checkbox" name="x" value="y" />
◮ Typically you will have more checkboxes with the same name DD1335 (Lecture 5) Basic Internet Programming Spring 2010 10 / 19
SLIDE 42
Forms, CGI
Checkboxes and radio buttons
◮ <input type="checkbox" name="x" value="y" />
◮ Typically you will have more checkboxes with the same name ◮ All of the checked boxes will be sent in the query string, with the same name
and the respective values, as for <select multiple >
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 10 / 19
SLIDE 43
Forms, CGI
Checkboxes and radio buttons
◮ <input type="checkbox" name="x" value="y" />
◮ Typically you will have more checkboxes with the same name ◮ All of the checked boxes will be sent in the query string, with the same name
and the respective values, as for <select multiple >
◮ <input type="radio" name="x" value="y"/>
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 10 / 19
SLIDE 44
Forms, CGI
Checkboxes and radio buttons
◮ <input type="checkbox" name="x" value="y" />
◮ Typically you will have more checkboxes with the same name ◮ All of the checked boxes will be sent in the query string, with the same name
and the respective values, as for <select multiple >
◮ <input type="radio" name="x" value="y"/>
◮ Typically you will have more radio buttons with the same name DD1335 (Lecture 5) Basic Internet Programming Spring 2010 10 / 19
SLIDE 45
Forms, CGI
Checkboxes and radio buttons
◮ <input type="checkbox" name="x" value="y" />
◮ Typically you will have more checkboxes with the same name ◮ All of the checked boxes will be sent in the query string, with the same name
and the respective values, as for <select multiple >
◮ <input type="radio" name="x" value="y"/>
◮ Typically you will have more radio buttons with the same name ◮ Normally only one radio button can be checked DD1335 (Lecture 5) Basic Internet Programming Spring 2010 10 / 19
SLIDE 46
Forms, CGI
Common Gateway Interface (CGI)
◮ CGI is a standard that allows us to write programs that respond to forms
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 11 / 19
SLIDE 47
Forms, CGI
Common Gateway Interface (CGI)
◮ CGI is a standard that allows us to write programs that respond to forms ◮ A standard HTTP server responds to every request
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 11 / 19
SLIDE 48
Forms, CGI
Common Gateway Interface (CGI)
◮ CGI is a standard that allows us to write programs that respond to forms ◮ A standard HTTP server responds to every request ◮ For some requests (typically starting with /cgi-bin/ ) the server will start a program
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 11 / 19
SLIDE 49
Forms, CGI
Common Gateway Interface (CGI)
◮ CGI is a standard that allows us to write programs that respond to forms ◮ A standard HTTP server responds to every request ◮ For some requests (typically starting with /cgi-bin/ ) the server will start a program ◮ CGI is the interface between the HTTP server and our program
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 11 / 19
SLIDE 50
Forms, CGI
Common Gateway Interface (CGI)
◮ CGI is a standard that allows us to write programs that respond to forms ◮ A standard HTTP server responds to every request ◮ For some requests (typically starting with /cgi-bin/ ) the server will start a program ◮ CGI is the interface between the HTTP server and our program ◮ CGI lets us to find out what has been in the HTTP request that the server got
http://hoohoo.ncsa.uiuc.edu/cgi/overview.html http://www.cgi-resources.com
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 11 / 19
SLIDE 51
Forms, CGI
The input/output paradigm
◮ Normally in DOS or Unix a program reads an input stream (so-called
standard input) and writes to an output stream (so-called standard output)
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 12 / 19
SLIDE 52
Forms, CGI
The input/output paradigm
◮ Normally in DOS or Unix a program reads an input stream (so-called
standard input) and writes to an output stream (so-called standard output)
◮ A DOS or Unix program also reads its command line arguments, and its
environment variables
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 12 / 19
SLIDE 53
Forms, CGI
The input/output paradigm
◮ Normally in DOS or Unix a program reads an input stream (so-called
standard input) and writes to an output stream (so-called standard output)
◮ A DOS or Unix program also reads its command line arguments, and its
environment variables
◮ In DOS you can set an env variable like set varName=value DD1335 (Lecture 5) Basic Internet Programming Spring 2010 12 / 19
SLIDE 54
Forms, CGI
The input/output paradigm
◮ Normally in DOS or Unix a program reads an input stream (so-called
standard input) and writes to an output stream (so-called standard output)
◮ A DOS or Unix program also reads its command line arguments, and its
environment variables
◮ In DOS you can set an env variable like set varName=value ◮ In Unix, it depends on your shell (command line interpreter), DD1335 (Lecture 5) Basic Internet Programming Spring 2010 12 / 19
SLIDE 55
Forms, CGI
The input/output paradigm
◮ Normally in DOS or Unix a program reads an input stream (so-called
standard input) and writes to an output stream (so-called standard output)
◮ A DOS or Unix program also reads its command line arguments, and its
environment variables
◮ In DOS you can set an env variable like set varName=value ◮ In Unix, it depends on your shell (command line interpreter), ◮ In bash export varName=value DD1335 (Lecture 5) Basic Internet Programming Spring 2010 12 / 19
SLIDE 56
Forms, CGI
The input/output paradigm
◮ Normally in DOS or Unix a program reads an input stream (so-called
standard input) and writes to an output stream (so-called standard output)
◮ A DOS or Unix program also reads its command line arguments, and its
environment variables
◮ In DOS you can set an env variable like set varName=value ◮ In Unix, it depends on your shell (command line interpreter), ◮ In bash export varName=value ◮ In csh setenv varName value DD1335 (Lecture 5) Basic Internet Programming Spring 2010 12 / 19
SLIDE 57
Forms, CGI
The input/output paradigm
◮ Normally in DOS or Unix a program reads an input stream (so-called
standard input) and writes to an output stream (so-called standard output)
◮ A DOS or Unix program also reads its command line arguments, and its
environment variables
◮ In DOS you can set an env variable like set varName=value ◮ In Unix, it depends on your shell (command line interpreter), ◮ In bash export varName=value ◮ In csh setenv varName value ◮ For example the PATH environment variable tells the system where to find
programs
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 12 / 19
SLIDE 58
Forms, CGI
The input/output paradigm
◮ Normally in DOS or Unix a program reads an input stream (so-called
standard input) and writes to an output stream (so-called standard output)
◮ A DOS or Unix program also reads its command line arguments, and its
environment variables
◮ In DOS you can set an env variable like set varName=value ◮ In Unix, it depends on your shell (command line interpreter), ◮ In bash export varName=value ◮ In csh setenv varName value ◮ For example the PATH environment variable tells the system where to find
programs
◮ So for input there are: standard input, command line arguments and
environment variables
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 12 / 19
SLIDE 59
Forms, CGI
The input/output paradigm
◮ Normally in DOS or Unix a program reads an input stream (so-called
standard input) and writes to an output stream (so-called standard output)
◮ A DOS or Unix program also reads its command line arguments, and its
environment variables
◮ In DOS you can set an env variable like set varName=value ◮ In Unix, it depends on your shell (command line interpreter), ◮ In bash export varName=value ◮ In csh setenv varName value ◮ For example the PATH environment variable tells the system where to find
programs
◮ So for input there are: standard input, command line arguments and
environment variables
◮ The standard output is the only place for program output
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 12 / 19
SLIDE 60
Forms, CGI
CGI program input/output
◮ Input: a number of environment variables set by the WWW server
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 13 / 19
SLIDE 61
Forms, CGI
CGI program input/output
◮ Input: a number of environment variables set by the WWW server ◮ One of the variables (the QUERY_STRING) contains arguments in the
form arg1=value1&arg2=value2&...
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 13 / 19
SLIDE 62
Forms, CGI
CGI program input/output
◮ Input: a number of environment variables set by the WWW server ◮ One of the variables (the QUERY_STRING) contains arguments in the
form arg1=value1&arg2=value2&...
◮ In the GET method the query string is read from the URL, after the ’?’ sign
http://yourServer:port/cgi-bin/scriptName?arg1=value1&arg2=value2
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 13 / 19
SLIDE 63
Forms, CGI
CGI program input/output
◮ Input: a number of environment variables set by the WWW server ◮ One of the variables (the QUERY_STRING) contains arguments in the
form arg1=value1&arg2=value2&...
◮ In the GET method the query string is read from the URL, after the ’?’ sign
http://yourServer:port/cgi-bin/scriptName?arg1=value1&arg2=value2
◮ In the POST method the standard input gives the query string DD1335 (Lecture 5) Basic Internet Programming Spring 2010 13 / 19
SLIDE 64
Forms, CGI
CGI program input/output
◮ Input: a number of environment variables set by the WWW server ◮ One of the variables (the QUERY_STRING) contains arguments in the
form arg1=value1&arg2=value2&...
◮ In the GET method the query string is read from the URL, after the ’?’ sign
http://yourServer:port/cgi-bin/scriptName?arg1=value1&arg2=value2
◮ In the POST method the standard input gives the query string
◮ Output: the standard output of the CGI program will be sent back to the
browser!
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 13 / 19
SLIDE 65
Forms, CGI
CGI program input/output
◮ Input: a number of environment variables set by the WWW server ◮ One of the variables (the QUERY_STRING) contains arguments in the
form arg1=value1&arg2=value2&...
◮ In the GET method the query string is read from the URL, after the ’?’ sign
http://yourServer:port/cgi-bin/scriptName?arg1=value1&arg2=value2
◮ In the POST method the standard input gives the query string
◮ Output: the standard output of the CGI program will be sent back to the
browser!
◮ Both the HTTP headers and content DD1335 (Lecture 5) Basic Internet Programming Spring 2010 13 / 19
SLIDE 66
Forms, CGI
CGI program input/output
◮ Input: a number of environment variables set by the WWW server ◮ One of the variables (the QUERY_STRING) contains arguments in the
form arg1=value1&arg2=value2&...
◮ In the GET method the query string is read from the URL, after the ’?’ sign
http://yourServer:port/cgi-bin/scriptName?arg1=value1&arg2=value2
◮ In the POST method the standard input gives the query string
◮ Output: the standard output of the CGI program will be sent back to the
browser!
◮ Both the HTTP headers and content ◮ Headers, empty line, content DD1335 (Lecture 5) Basic Internet Programming Spring 2010 13 / 19
SLIDE 67
Forms, CGI
CGI program input/output
◮ Input: a number of environment variables set by the WWW server ◮ One of the variables (the QUERY_STRING) contains arguments in the
form arg1=value1&arg2=value2&...
◮ In the GET method the query string is read from the URL, after the ’?’ sign
http://yourServer:port/cgi-bin/scriptName?arg1=value1&arg2=value2
◮ In the POST method the standard input gives the query string
◮ Output: the standard output of the CGI program will be sent back to the
browser!
◮ Both the HTTP headers and content ◮ Headers, empty line, content ◮ Content is typically HTML but not necessarily DD1335 (Lecture 5) Basic Internet Programming Spring 2010 13 / 19
SLIDE 68
Forms, CGI
CGI environment variables
◮ SERVER_SOFTWARE: type of the server
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 14 / 19
SLIDE 69
Forms, CGI
CGI environment variables
◮ SERVER_SOFTWARE: type of the server ◮ SERVER_NAME: e.g. www.nada.kth.se
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 14 / 19
SLIDE 70
Forms, CGI
CGI environment variables
◮ SERVER_SOFTWARE: type of the server ◮ SERVER_NAME: e.g. www.nada.kth.se ◮ SERVER_PORT: e.g. 80
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 14 / 19
SLIDE 71
Forms, CGI
CGI environment variables
◮ SERVER_SOFTWARE: type of the server ◮ SERVER_NAME: e.g. www.nada.kth.se ◮ SERVER_PORT: e.g. 80 ◮ REQUEST_METHOD: GET or POST
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 14 / 19
SLIDE 72
Forms, CGI
CGI environment variables
◮ SERVER_SOFTWARE: type of the server ◮ SERVER_NAME: e.g. www.nada.kth.se ◮ SERVER_PORT: e.g. 80 ◮ REQUEST_METHOD: GET or POST ◮ PATH_INFO: path to your program in the URL, like /cgi-bin/prog
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 14 / 19
SLIDE 73
Forms, CGI
CGI environment variables
◮ SERVER_SOFTWARE: type of the server ◮ SERVER_NAME: e.g. www.nada.kth.se ◮ SERVER_PORT: e.g. 80 ◮ REQUEST_METHOD: GET or POST ◮ PATH_INFO: path to your program in the URL, like /cgi-bin/prog ◮ PATH_TRANSLATED: path of the program on disk
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 14 / 19
SLIDE 74
Forms, CGI
CGI environment variables
◮ SERVER_SOFTWARE: type of the server ◮ SERVER_NAME: e.g. www.nada.kth.se ◮ SERVER_PORT: e.g. 80 ◮ REQUEST_METHOD: GET or POST ◮ PATH_INFO: path to your program in the URL, like /cgi-bin/prog ◮ PATH_TRANSLATED: path of the program on disk ◮ SCRIPT_NAME: name of the CGI program
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 14 / 19
SLIDE 75
Forms, CGI
CGI environment variables
◮ SERVER_SOFTWARE: type of the server ◮ SERVER_NAME: e.g. www.nada.kth.se ◮ SERVER_PORT: e.g. 80 ◮ REQUEST_METHOD: GET or POST ◮ PATH_INFO: path to your program in the URL, like /cgi-bin/prog ◮ PATH_TRANSLATED: path of the program on disk ◮ SCRIPT_NAME: name of the CGI program ◮ QUERY_STRING: actual path of the program
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 14 / 19
SLIDE 76
Forms, CGI
CGI environment variables
◮ SERVER_SOFTWARE: type of the server ◮ SERVER_NAME: e.g. www.nada.kth.se ◮ SERVER_PORT: e.g. 80 ◮ REQUEST_METHOD: GET or POST ◮ PATH_INFO: path to your program in the URL, like /cgi-bin/prog ◮ PATH_TRANSLATED: path of the program on disk ◮ SCRIPT_NAME: name of the CGI program ◮ QUERY_STRING: actual path of the program ◮ REMOTE_HOST: host where the request comes from
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 14 / 19
SLIDE 77
Forms, CGI
CGI environment variables
◮ SERVER_SOFTWARE: type of the server ◮ SERVER_NAME: e.g. www.nada.kth.se ◮ SERVER_PORT: e.g. 80 ◮ REQUEST_METHOD: GET or POST ◮ PATH_INFO: path to your program in the URL, like /cgi-bin/prog ◮ PATH_TRANSLATED: path of the program on disk ◮ SCRIPT_NAME: name of the CGI program ◮ QUERY_STRING: actual path of the program ◮ REMOTE_HOST: host where the request comes from ◮ AUTH_TYPE: authentication if the user logged-in (e.g. BASIC)
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 14 / 19
SLIDE 78
Forms, CGI
CGI environment variables
◮ SERVER_SOFTWARE: type of the server ◮ SERVER_NAME: e.g. www.nada.kth.se ◮ SERVER_PORT: e.g. 80 ◮ REQUEST_METHOD: GET or POST ◮ PATH_INFO: path to your program in the URL, like /cgi-bin/prog ◮ PATH_TRANSLATED: path of the program on disk ◮ SCRIPT_NAME: name of the CGI program ◮ QUERY_STRING: actual path of the program ◮ REMOTE_HOST: host where the request comes from ◮ AUTH_TYPE: authentication if the user logged-in (e.g. BASIC) ◮ REMOTE_USER: username if the user logged-in
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 14 / 19
SLIDE 79
Forms, CGI
CGI environment variables
◮ SERVER_SOFTWARE: type of the server ◮ SERVER_NAME: e.g. www.nada.kth.se ◮ SERVER_PORT: e.g. 80 ◮ REQUEST_METHOD: GET or POST ◮ PATH_INFO: path to your program in the URL, like /cgi-bin/prog ◮ PATH_TRANSLATED: path of the program on disk ◮ SCRIPT_NAME: name of the CGI program ◮ QUERY_STRING: actual path of the program ◮ REMOTE_HOST: host where the request comes from ◮ AUTH_TYPE: authentication if the user logged-in (e.g. BASIC) ◮ REMOTE_USER: username if the user logged-in ◮ CONTENT_TYPE: the content-type HTTP header
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 14 / 19
SLIDE 80
Forms, CGI
CGI environment variables
◮ SERVER_SOFTWARE: type of the server ◮ SERVER_NAME: e.g. www.nada.kth.se ◮ SERVER_PORT: e.g. 80 ◮ REQUEST_METHOD: GET or POST ◮ PATH_INFO: path to your program in the URL, like /cgi-bin/prog ◮ PATH_TRANSLATED: path of the program on disk ◮ SCRIPT_NAME: name of the CGI program ◮ QUERY_STRING: actual path of the program ◮ REMOTE_HOST: host where the request comes from ◮ AUTH_TYPE: authentication if the user logged-in (e.g. BASIC) ◮ REMOTE_USER: username if the user logged-in ◮ CONTENT_TYPE: the content-type HTTP header ◮ CONTENT_LENGTH: the content-length HTTP header (useful in POST)
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 14 / 19
SLIDE 81
Forms, CGI
CGI at NADA
◮ Put your CGI program in your CGI dir at NADA (if it’s activated)
/afs/nada.kth.se/public/www.student/cgibin/yourUserName/yourProgram
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 15 / 19
SLIDE 82
Forms, CGI
CGI at NADA
◮ Put your CGI program in your CGI dir at NADA (if it’s activated)
/afs/nada.kth.se/public/www.student/cgibin/yourUserName/yourProgram
◮ Make sure that the file has execution rights
chmod uo+x yourProgram cd /afs/nada.kth.se/public/www.student/cgi-bin/yourUserName/ fs setacl . system:anyuser rl
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 15 / 19
SLIDE 83
Forms, CGI
CGI at NADA
◮ Put your CGI program in your CGI dir at NADA (if it’s activated)
/afs/nada.kth.se/public/www.student/cgibin/yourUserName/yourProgram
◮ Make sure that the file has execution rights
chmod uo+x yourProgram cd /afs/nada.kth.se/public/www.student/cgi-bin/yourUserName/ fs setacl . system:anyuser rl
◮ You should first test your program without a browser
Set the CGI variables by hand using setenv (csh) or export (bash) setenv QUERY_STRING a=b&c=d call yourProgram
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 15 / 19
SLIDE 84
Forms, CGI
CGI at NADA
◮ Put your CGI program in your CGI dir at NADA (if it’s activated)
/afs/nada.kth.se/public/www.student/cgibin/yourUserName/yourProgram
◮ Make sure that the file has execution rights
chmod uo+x yourProgram cd /afs/nada.kth.se/public/www.student/cgi-bin/yourUserName/ fs setacl . system:anyuser rl
◮ You should first test your program without a browser
Set the CGI variables by hand using setenv (csh) or export (bash) setenv QUERY_STRING a=b&c=d call yourProgram
◮ When it works, test it with a browser
http://cgi.student.nada.kth.se/cgibin/yourUserName/yourProgram
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 15 / 19
SLIDE 85
Forms, CGI
CGI at NADA
◮ Put your CGI program in your CGI dir at NADA (if it’s activated)
/afs/nada.kth.se/public/www.student/cgibin/yourUserName/yourProgram
◮ Make sure that the file has execution rights
chmod uo+x yourProgram cd /afs/nada.kth.se/public/www.student/cgi-bin/yourUserName/ fs setacl . system:anyuser rl
◮ You should first test your program without a browser
Set the CGI variables by hand using setenv (csh) or export (bash) setenv QUERY_STRING a=b&c=d call yourProgram
◮ When it works, test it with a browser
http://cgi.student.nada.kth.se/cgibin/yourUserName/yourProgram
◮ You can check the server error log and try to find your error between other
people’s errors
http://cgi.student.nada.kth.se/cgi-bin/get-errlog
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 15 / 19
SLIDE 86
Forms, CGI
A CGI example in PERL
◮ PERL = the Practical Extraction and Report Language
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 16 / 19
SLIDE 87
Forms, CGI
A CGI example in PERL
◮ PERL = the Practical Extraction and Report Language
◮ www.perl.com ◮ http://broadcast.oreilly.com/2008/09/
a-beginners-introduction-to-pe.html
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 16 / 19
SLIDE 88
Forms, CGI
A CGI example in PERL
◮ PERL = the Practical Extraction and Report Language
◮ www.perl.com ◮ http://broadcast.oreilly.com/2008/09/
a-beginners-introduction-to-pe.html
◮ An interpreted programming language inspired by C and shellscript (bash, csh)
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 16 / 19
SLIDE 89
Forms, CGI
A CGI example in PERL
◮ PERL = the Practical Extraction and Report Language
◮ www.perl.com ◮ http://broadcast.oreilly.com/2008/09/
a-beginners-introduction-to-pe.html
◮ An interpreted programming language inspired by C and shellscript (bash, csh) ◮ Available on many platforms but inspired by and started on Unix
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 16 / 19
SLIDE 90
Forms, CGI
A CGI example in PERL
◮ PERL = the Practical Extraction and Report Language
◮ www.perl.com ◮ http://broadcast.oreilly.com/2008/09/
a-beginners-introduction-to-pe.html
◮ An interpreted programming language inspired by C and shellscript (bash, csh) ◮ Available on many platforms but inspired by and started on Unix ◮ Very strong pattern matching
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 16 / 19
SLIDE 91
Forms, CGI
A CGI example in PERL
◮ PERL = the Practical Extraction and Report Language
◮ www.perl.com ◮ http://broadcast.oreilly.com/2008/09/
a-beginners-introduction-to-pe.html
◮ An interpreted programming language inspired by C and shellscript (bash, csh) ◮ Available on many platforms but inspired by and started on Unix ◮ Very strong pattern matching ◮ Easy to use e.g. to make a simple CGI
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 16 / 19
SLIDE 92
Forms, CGI
A CGI example in PERL
◮ PERL = the Practical Extraction and Report Language
◮ www.perl.com ◮ http://broadcast.oreilly.com/2008/09/
a-beginners-introduction-to-pe.html
◮ An interpreted programming language inspired by C and shellscript (bash, csh) ◮ Available on many platforms but inspired by and started on Unix ◮ Very strong pattern matching ◮ Easy to use e.g. to make a simple CGI ◮ But not for larger applications
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 16 / 19
SLIDE 93
Forms, CGI
A CGI example in PERL
◮ PERL = the Practical Extraction and Report Language
◮ www.perl.com ◮ http://broadcast.oreilly.com/2008/09/
a-beginners-introduction-to-pe.html
◮ An interpreted programming language inspired by C and shellscript (bash, csh) ◮ Available on many platforms but inspired by and started on Unix ◮ Very strong pattern matching ◮ Easy to use e.g. to make a simple CGI ◮ But not for larger applications ◮ We just illustrate the CGI principle with PERL
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 16 / 19
SLIDE 94
Forms, CGI
A CGI example in PERL
◮ PERL = the Practical Extraction and Report Language
◮ www.perl.com ◮ http://broadcast.oreilly.com/2008/09/
a-beginners-introduction-to-pe.html
◮ An interpreted programming language inspired by C and shellscript (bash, csh) ◮ Available on many platforms but inspired by and started on Unix ◮ Very strong pattern matching ◮ Easy to use e.g. to make a simple CGI ◮ But not for larger applications ◮ We just illustrate the CGI principle with PERL ◮ Java is not a good language to write CGI in, because CGI makes one
process/HTTP access and a Java Virtual Machine has a large footprint (30 Meg)
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 16 / 19
SLIDE 95
Forms, CGI
A CGI example in PERL
◮ PERL = the Practical Extraction and Report Language
◮ www.perl.com ◮ http://broadcast.oreilly.com/2008/09/
a-beginners-introduction-to-pe.html
◮ An interpreted programming language inspired by C and shellscript (bash, csh) ◮ Available on many platforms but inspired by and started on Unix ◮ Very strong pattern matching ◮ Easy to use e.g. to make a simple CGI ◮ But not for larger applications ◮ We just illustrate the CGI principle with PERL ◮ Java is not a good language to write CGI in, because CGI makes one
process/HTTP access and a Java Virtual Machine has a large footprint (30 Meg)
◮ Servlets are the solution in Java
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 16 / 19
SLIDE 96
Forms, CGI
A form to respond to
<FORM ACTION="/cgi-bin/test.pl" METHOD="GET"> Write a message: <INPUT TYPE="text" NAME="message" SIZE=20 MAXLENGTH=40 VALUE=""> <INPUT TYPE = "submit" VALUE= "Send it!"> <INPUT TYPE= "reset" VALUE= "Remove it!" > </FORM>
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 17 / 19
SLIDE 97
Forms, CGI
Responding to a form in a PERL CGI
#!/usr/local/bin/perl print "Content-type: text/html\\n\\n"; ## CGIs must print HTTP headers AND empty line! $REQUEST_METHOD = $ENV\{’REQUEST_METHOD’\}; $QUERY_STRING = $ENV\{’QUERY_STRING’\}; ## Reading environment variables if($REQUEST_METHOD ne "GET") \{ print"Sorry, i can only do <code>GET</code><br />Bye!"; exit(0); \} ($COMMAND, $MESSAGE) = split(/=/, $QUERY_STRING); ## Split the query string via PERL pattern matching. if($COMMAND eq "message") \{ print "<h1>You sent:</h1>"; print "Message: $MESSAGE"; exit(0); \} exit(0);
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 18 / 19
SLIDE 98
Forms, CGI
Dynamic Web content
◮ Content generated by CGI is different from normal HTTP serving
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 19 / 19
SLIDE 99
Forms, CGI
Dynamic Web content
◮ Content generated by CGI is different from normal HTTP serving ◮ It’s not a static file or image that’s being served
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 19 / 19
SLIDE 100
Forms, CGI
Dynamic Web content
◮ Content generated by CGI is different from normal HTTP serving ◮ It’s not a static file or image that’s being served ◮ Instead, a dynamic content is generated
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 19 / 19
SLIDE 101
Forms, CGI
Dynamic Web content
◮ Content generated by CGI is different from normal HTTP serving ◮ It’s not a static file or image that’s being served ◮ Instead, a dynamic content is generated ◮ You can use CGI to generate dynamic content even if you don’t respond
to a form
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 19 / 19
SLIDE 102
Forms, CGI
Dynamic Web content
◮ Content generated by CGI is different from normal HTTP serving ◮ It’s not a static file or image that’s being served ◮ Instead, a dynamic content is generated ◮ You can use CGI to generate dynamic content even if you don’t respond
to a form
◮ Or you can use Java servlets for the same purpose
DD1335 (Lecture 5) Basic Internet Programming Spring 2010 19 / 19