mark dixon page 1 18 – web applications: server-side code (php)

Mark Dixon

18 – Web applications:Server-side code (PhP)

Mark Dixon

Session Aims & Objectives• Aims

– To introduce the fundamental ideas involved in server-side code

• Objectives,by end of this week’s sessions, you should be able to:

– create an asp web-page, including:• HTML, and• server-side PhP

Mark Dixon

Example: Logon (analysis)SPECIFICATION

• User Requirements – protection from fraud and invasion of privacy

• Software Requirements– Functional:

– logon page, user must type name and password–following pages can only be accessed after

successful logon– Non-functional

should be very difficult to hack

hotmail, Amazon, University portal, utility bills (gas, electricity, phone, internet), Travel (flights, ferry, car rental)

Mark Dixon

Example: Logon (design)• Restrict access to

home page

Mark Dixon

Example: Logon (code v1)• Using Client-side VB Script

<html> <head><title></title></head> <body> Please logon:<br /> <input id="txtUserName" type="text" /><br /> <input id="txtPassWord" type="text" /><br /> <input id="btnLogon" type="submit" value="Logon" onclick="btnLogon_onClick()" /> <p id="msg"></p> </body></html>

<script language="javascript"> function btnLogon_onClick(){ var un; var pw; un = txtUserName.value; pw = txtPassWord.value; if(un == "mark" && pw == "soft131"){ window.navigate("home.htm"); }else{ msg.innerText = "Login details incorrect."; } }</script>

Logon.htm

<html> <head><title>My Home page</title></head> <body> <p> Welcome to my home page.<br /> <img src="YouAreHere.jpg" /> </p> </body></html>

Home.htm

Mark Dixon

Example: Login (Problem)• View Source – shows client-side script:

Reveals bothusername & password

Mark Dixon

networkconnection

Web Hardware and Software

ClientServer

BrowserApplication(MS Explorer,FireFox, Opera)

Web-serverApplication

(MS IIS,Apache)

Mark Dixon

BrowserApplication

(MS Explorer, Firefox)

Request-Response Cycle


(MS IIS, Apache)

Logon.htm

Request

<html> <head><title></title></head> <body> Please logon:<br /> <input id="txtUserName" type="text" /><br /> <input id="txtPassWord" type="text" /><br /> <input id="btnLogon" type="submit" value="Logon" onclick="btnLogon_onClick()" /> <p id="msg"></p> </body></html>

<script language="javascript"> function btnLogon_onClick(){ var un; var pw; un = txtUserName.value; pw = txtPassWord.value; if(un == "mark" && pw == "soft131"){ window.navigate("home.htm"); }else{ msg.innerText = "Login details incorrect."; } }</script>

Response

Client-side code:Code sent to ClientInterpreted by browser

Mark Dixon

Server-side Script (what)

• PhP – HyperText PreProcessor pages– code not sent to client

• code secure (can't be viewed by client)

– executed on server• takes time – request-response cycle• requires server software (e.g. Apache)

• PhP pages will NOT work by double clicking on file

Mark Dixon

Example: Date• php code:

– .php (not .htm)– php (not javascript)

– variables have $(no declaration)

– date is current date and time (on server)

– use . instead of +

<?php $d = "The date today is "; $d = $d . date("D d M Y"); $t = "The time now is "; $t = $t . date("H:i");?>

<html> <head><title>Today's Date</title></head> <body> <?php echo $d . "<br />" . $t; ?> </body></html>

Date.php

Mark Dixon

Request-Response CycleBrowser

Application(MS Explorer, Firefox)


(MS IIS, Apache)

date.php

Request

<html> <head><title>Today's Date</title></head> <body> The date today is Mon 15 Feb 2010<br /> The time now is 20:28 </body></html>

Response

<?php $d = "The date today is "; $d = $d . date("D d M Y"); $t = "The time now is "; $t = $t . date("H:i");?>

<html> <head><title>Today's Date</title></head> <body> <?php echo $d . "<br />" . $t; ?> </body></html>

Server-side code: run on server(never sent to Client)

Mark Dixon

View Source• Code executed at server

– code is never sent to client

• View, Source – does not show code:

Mark Dixon

Example: AddNum (client-side)<html> <head><title></title></head> <body> <input id="txtN1" type="text" /><br /> <input id="txtN2" type="text" /><br /> <input id="btnAdd" type="submit" value="Add" onclick="btnAdd_onClick()" /> <p id="parRes"></p> </body></html>

<script language="javascript"> function btnAdd_onClick(){ var N1; var N2; N1 = parseFloat(txtN1.value); N2 = parseFloat(txtN2.value); parRes.innerText = N1 + N2; }</script>

AddNum.htm

Mark Dixon

Example: AddNum (server-side)

• input tags inside form

• submit button:refreshes page (sending data to server)

<?php $Res = ""; if(isset($_POST["btnAdd"])){ $N1 = $_POST["txtN1"]; $N2 = $_POST["txtN2"]; $Res = $N1 + $N2; }?>

<html> <head><title></title></head> <body> <form method="post"> <input name="txtN1" type="text" /><br /> <input name="txtN2" type="text" /><br /> <input name="btnAdd" type="submit" value="Add" /> <?php echo $Res; ?> </form> </body></html>

AddNum.php

• If btnAdd clicked

• $_POSTreads data from form

Mark Dixon

<?php $Res = ""; if(isset($_POST["btnAdd"])){ $N1 = $_POST["txtN1"]; $N2 = $_POST["txtN2"]; $Res = $N1 + $N2; }?>

<html> <head><title></title></head> <body> <form method="post"> <input name="txtN1" type="text" /><br /> <input name="txtN2" type="text" /><br /> <input name="btnAdd" type="submit" value="Add" /> <?php echo $Res; ?> </form> </body></html>

AddNum.php<html> <head><title></title></head> <body> <input id="txtN1" type="text" /><br /> <input id="txtN2" type="text" /><br /> <input id="btnAdd" type="submit" value="Add" onclick="btnAdd_onClick()" /> <p id="parRes"></p> </body></html>

<script language="javascript"> function btnAdd_onClick(){ var N1; var N2; N1 = parseFloat(txtN1.value); N2 = parseFloat(txtN2.value); parRes.innerText = N1 + N2; }</script>

AddNum.htm

Client-side vs. Server-side Code

Both use same concepts (variables, conditionals …)

Mark Dixon

Example: Apples

<?php $s = ""; if(isset($_POST["btnGo"])){ $s = $s . "<img src='Apple.gif' />"; }?>

<html> <head><title>Apples</title></head> <body> <form method="post"> <input name="btnGo" type="submit" value="Go" /> <?php echo $s; ?> </form> </body></html>

Apples.php

Mark Dixon

Errors<?php $d = "The date today is "; $d = $d . date("D d M Y"); $t = "The time now is "; $t = t . date("H:i");?>

<html> <head><title>Today's Date</title></head> <body> <?php echo $d . "<br />" + $t; ?> </body></html>

use . instead of + for strings

variables need $ in front

Mark Dixon

Running your PhP pages• using Apache

– makes PC a server– page available to all computers on internet

• edit page within NetBeans– Run (play) button– uses Apache

Mark Dixon

Apache: Exposing pages• Put php pages in:

– C:\wamp\www (this part of hard disk exposed to outside world)

• Execute pages by putting:– localhost:8080

(in web browser, e.g. IE, means local machine)(8080 is port number, usually 80, changed in labs to run IIS and Apache together)

• PhP pages don't work by double-clicking

Mark Dixon

PhP Tutorials• w3schools php tutorial:

http://www.w3schools.com/php/default.asp

Mark Dixon

Tutorial Exercise: Login (client-side)• LEARNING OBJECTIVE:

see how vulnerable client-side code is

• Task 1: Get the Login (v1) example from the lecture working.

• Task 2: Use view source – you should be able to see the code.

Mark Dixon

Tutorial Exercise: Date• LEARNING OBJECTIVE:

create a PhP page, including HTML and server-side Script

• Task 1: Get the Date example from the lecture working.

• Task 2: Add code that displays good morning/afternoon/evening/night, depending on the time of day.

Mark Dixon

Tutorial Exercise: Student Loan• LEARNING OBJECTIVE:

create an PhP page, including HTML and server-side Script from scratch to solve a problem

• Task 1: Create a web page that allows the user to enter their salary and the computer calculates the annual and monthly payments for their student loan. Hint: Use your client-side code (from term 1), and the AddNum example from the lecture.

Mark Dixon

Tutorial Exercise: Login (client-side)• LEARNING OBJECTIVE:

create an PhP page, including HTML and server-side Script from scratch to solve a problem

• Task 1: Create a login page that uses server-side code to check the username and password entered by the user. Hint: Use the AddNum example as inspiration. Hint2: Use the following code to send the user to the homepage: header("Location: Home.htm");

• Task 2: Use view source – you should NOT be able to see the code.

Mark Dixon

Tutorial Exercise: Apples• LEARNING OBJECTIVE:

use loops in PhP code

• Task 1: Get the apples example (from the lecture) working.

• Task 2: Modify your program so that the user enters a number, and the code adds that number of apple images.

• Task 3: Modify your program so that the user enters another number, and the code adds a new line tag for that number of apples. Hint: Within the loop divide the number of apples by the second number, if the result is a whole number add a new line tag.

mark dixon page 1 18 – web applications: server-side code (php)

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