1. Simple PHP application

2. A simple application
We are going to develop a simple PHP application with a Web interface.
The user enters two numbers and the application returns the two multiplied to together
Start

3. UML Interaction Diagram
Interaction diagrams describe the communication between objects, but we will use them to describe interation between programs even if they are not objects

4. Simple interaction diagram
Simple example and explanation
Ref to UML

5. User-script interaction
Browser
Web server
multiply.php
PHP processor
Click link
page
get form.htm
Locate file
Enter data
Display form.htm
Calculate button
get multiply.php?x=5&y=6
Locate file and run as PHP
x=5 y=6
5 * 6 = 30 HTML
MIME
run script
“5 * 6 = 30”
Read output
Display generated HTML

6. User-browser interaction
Click link
page
Enter data
Display form.htm
Calculate button
Read output
Display generated HTML

7. User – Browser interaction
User locates desired link
<a href=form.htm> Multiply numbers</a>
Browser retrieves the form from the server
Form is displayed
User fills in the fields on the form
User clicks submit button
Magic stuff happens
User reads the result and goes back to the form to change the values in the form

8. form.htm <!-- this is not XHTML standard because it lacks headers
but it does have all attribute values in quotes and all tags are terminated
-->
<form method="get" action="multiply.php">
x = <input type=text name="x" size="5"/>
y = <input type=text name="y" size="5"/>
<input type="submit" value="Calculate"/>
</form>

9. Browser-Server interaction
Web server
Click button
get multiply.php?x=5&y=6
Locate file and run as PHP
5 * 6 = 30

10. Browser-Server interaction
Parameters passed as data couplets (name/value pairs) either
Attached to URL (and visible to user in the address line)
Values must be URL-Encoded
space to +
punctuation to %hex e.g. ? to %3f
METHOD=GET in an HTML Form
appended to the ACTION URL
Explicitly added to the base URL e.g.
<a href=“multiply.php?x=5&y=6”>5 * 6</a>
A separate document (invisible to user)
METHOD=POST in an HTML Form
Result passed back in a MIME wrapper
MIME tells browser what kind of file it is (HTML,JPEG, XML, Flash.. )
Content-type: image/jpeg

11. Server-script interaction
Web server
multiply.php
get multiply.php?x=5&y=6
Locate file and run as PHP
x=5 y=6
run script
“5 * 6 = 30”

12. User-script interaction
Browser
Web server
multiply.php
PHP processor
Click link
page
get form.htm
Locate file
Enter data
Display form.htm
Calculate button
get multiply.php?x=5&y=6
Locate file and run as PHP
x=5 y=6
5 * 6 = 30 HTML
MIME
run script
“5 * 6 = 30”
Read output
Display generated HTML

13. form.htm <!-- this is not XHTML standard because it lacks headers
but it does have all attribute values in quotes and all tags are terminated
-->
<form method="get" action="multiply.php">
x = <input type=text name="x" size="5"/>
y = <input type=text name="y" size="5"/>
<input type="submit" value="Calculate"/>
</form>

14. Browser-Server interaction
Web server
Click button
get multiply.php?x=5&y=6
Locate file and run as PHP
5 * 6 = 30 HTML
MIME

15. URL Relative URL Absolute URL multiply.php?x=5&y=6
(my Home machine running IIS)
(the development server)
(the public production server)

16. Server-script interaction
Web server
multiply.php
PHP processor
get multiply.php?x=5&y=6
Locate file and run as PHP
x=5 y=6
run script
“5 * 6 = 30”

17. Server-PHP interaction
Parameters
GET and POST Parameters available as
variables of the same name $x, $y (deprecated but used in my code )
in an array $_GET[‘x’]
depends on the setup
Parameter values are URL-Decoded
Implicit Parameters
In addition to the user-defined parameters, other data is available about the client and about the server
$PHP_SELF is the program name
$HTTP_USER_AGENT is the browser
Reply
HTML goes through to output
<?php … ?> script is executed as PHP
Print or echo statements add to output
All output returned to Server
Other kinds of output (JPEG, GIF.. ) require different headers to be output

18. Multiply.php script <?php /*
function: to multiply the two input numbers and display the result
input:
x, y : numbers
author:
Chris Wallace
9 Oct 204 */
// calculate the result
// no typing or declaring new variable
// also implicit conversion of string to number
$prod = $x * $y;
// values of variables interpolated into the string
print "$x * $y = $prod";
?>

19. The generated HTML
5 * 6 = 30
This simple text is not XHTML compliant of course.
HTML to provide a readable page can be added around the PHP
<a href=multiply2.php?x=5&y=6>5 * 6</a>
Note that we have added the name/value pairs to the URL – not very useful here obviously.
some pairs can be in the action URL of a form, some in input fields
The script multiply2.php includes the original PHP script within an HTML page

20. Multiply2.php Program composition with ‘require’
<html>
<title>PHP introduction - multiply script</title>
</head>
<body>
<img src="cems-banner.gif">
<h1>PHP introduction</h1>
<table><tr><td><img src="multiply.jpg"></td><td width="5%"</td><td><font color="red" size="+4">
<?php include "multiply.php“; ?>
</font></td><tr></table>
</body>
</html>

21. ‘Sticky Forms’
Poor interface -user must to go back to original form to change the data and re-calculate.
Key idea:
Combine form and calculator into one script
Do calculation (if required) first
Put inputs as defaults in form
Simple combination of form and script
<a href=multiply3.php> Calculate Product </a>

23. multiply3.php Combined form and calculator
// first compute the output, but only if data has been input
if( isset($calc)) { // data was submitted
$prod = $x * $y; }
else { // set defaults
$x=0;$y=0;$prod=0;
?>
<form method="get" action="<?php print $PHP_SELF; ?>">
x = <input type=text name="x" size="5" value="<?php print $x?>"/>
y= <input type=text name="y" size="5" value="<?php print $y?>"/>
x * y = <?php print $prod ?>
<br/><input type="submit" name="calc" value="Calculate"/>
</form>

24. Initial Form <form method="get" action=“scripts/multiply3.php">
x = <input type=text name="x" size="5" value="0"/>
y= <input type=text name="y" size="5" value="0"/>
x * y = 0<br/><input type="submit" name="calc" value="Calculate"/>
</form>

25. Form with Entered Values
<form method="get" action=“scripts/multiply3.php">
x = <input type=text name="x" size="5" value="654321"/>
y= <input type=text name="y" size="5" value="9"/>
x * y = <br/><input type="submit" name="calc" value="Calculate"/>
</form>

26. Forms processing Interface and presentation can be easily improved
<a href=multiply4.php> Calculate Product </a>
Script can do validation and add error messages to the form where fields are missing or invalid.
Where to do the processing?:
on Client in Javascript
on Server in PHP or Java
What factors do you need to consider to decide?

28. SMS version
Now nearly the same application with an SMS presentation layer.
For variety, I’ve generalised to allow any number of numbers to be multiplied together
Text
MUL num1 num2 num3 …
To:
Eg.
MUL
Reply
34 x 56 x 78 =

29. SMS to script interface
Script ‘plugs’ into SMS server
Must obey the protocol:
Parameters
Text
From
Code
Reply text:
Reply: <message to send back>
Entry required in routing file:
MUL

30. smsmult.php
<?php
$text=trim($text); // to remove trailing whitespace
$nums = split(" +",$text); // split the string apart on spaces
// + means 1 or more occurances
$prod=1;
foreach ($nums as $number){
$prod=$prod*$number; // accumulate the product }
$numlist = join(" x ",$nums); // join the numbers with ' x '
print "Reply: $numlist = $prod";
?>