PHP On-The-Fly!

Introduction

PHP can be used for a lot of different things, and is one of the most powerful scripting languages available on the web. Not to mention it's extremely cheap and widely used. However, one thing that PHP is lacking, and in fact most scripting languages are, is a way to update pages in real-time, without having to reload a page or submit a form.

The internet wasn't made for this. The web browser closes the connection with the web server as soon as it has received all the data. This means that after this no more data can be exchanged. What if you want to do an update though? If you're building a PHP application (e.g. a high-quality content management system), then it'd be ideal if it worked almost like a native Windows/Linux application.

But that requires real-time updates. Something that isn't possible, or so you would think. A good example of an application that works in (almost) real-time is Google's GMail (http://gmail.google.com). Everything is JavaScript powered, and it's very powerful and dynamic. In fact, this is one of the biggest selling-points of GMail. What if you could have this in your own PHP websites as well? Guess what, I'm going to show you in this article.

How does it work?

If you want to execute a PHP script, you need to reload a page, submit a form, or something similar. Basically, a new connection to the server needs to be opened, and this means that the browser goes to a new page, losing the previous page. For a long while now, web developers have been using tricks to get around this, like using a 1x1 iframe, where a new PHP page is loaded, but this is far from ideal.

Now, there is a new way of executing a PHP script without having to reload the page. The basis behind this new way is a JavaScript component called the XML HTTP Request Object. See http://jibbering.com/2002/4/httprequest.html for more information about the component. It is supported in all major browsers (Internet Explorer 5.5+, Safari, Mozilla/Firefox and Opera 7.6+).

With this object and some custom JavaScript functions, you can create some rather impressive PHP applications. Let's look at a first example, which dynamically updates the date/time.

Example 1

First, copy the code below and save it in a file called 'script.js':

var xmlhttp=false;

/*@cc_on @*/

/*@if (@_jscript_version >= 5)

// JScript gives us Conditional compilation, we can cope with old IE versions.

// and security blocked creation of the objects.

try {

xmlhttp = new ActiveXObject("Msxml2.XMLHTTP");

} catch (e) {

try {

xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");

} catch (E) {

xmlhttp = false;

}

}

@end @*/

if (!xmlhttp && typeof XMLHttpRequest!='undefined') {

xmlhttp = new XMLHttpRequest();

}

function loadFragmentInToElement(fragment_url, element_id) {

var element = document.getElementById(element_id);

element.innerHTML = 'Loading ...';

xmlhttp.open("GET", fragment_url);

xmlhttp.onreadystatechange = function() {

if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {

element.innerHTML = xmlhttp.responseText;

}

}

xmlhttp.send(null);

}

Then copy the code below, and paste it in a file called 'server1.php':

And finally, copy the code below, and paste it in a file called 'client1.php'. Please note though that you need to edit the line that says 'http://www.yourdomain.com/server1.php' to the correct location of server1.php on your server.

Example 1

function updatedate() {

loadFragmentInToElement('http://www.yourdomain.com/server1.php', 'currentdate');

}

The current date is .

Now go to http://www.yourdomain.com/client1.php and click on the button that says 'Update date'. The date will update, without the page having to be reloaded. This is done with the XML HTTP Request object. This example can also be viewed online at http://www.phpit.net/demo/php%20on%20the%20fly/client1.php.

Example 2

Let's try a more advanced example. In the following example, the visitor can enter two numbers, and they are added up by PHP (and not by JavaScript). This shows the true power of PHP and the XML HTTP Request Object.

This example uses the same script.js as in the first example, so you don't need to create this again. First, copy the code below and paste it in a file called 'server2.php':

And then, copy the code below, and paste it in a file called 'client2.php'. Please note though that you need to edit the line that says 'http://www.yourdomain.com/server2.php' to the correct location of server2.php on your server.

Example 2

function calc() {

num1 = document.getElementById ('num1').value;

num2 = document.getElementById ('num2').value;

var element = document.getElementById('answer');

xmlhttp.open("GET", 'http://www.yourdomain.com/server2.php?num1=' + num1 + '&num2=' + num2);

xmlhttp.onreadystatechange = function() {

if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {

element.value = xmlhttp.responseText;

}

}

xmlhttp.send(null);

}

U se the below form to add up two numbers. The answer is calculated by a PHP script, and not with JavaScript. What's the advantage to this? You can execute server-side scripts (PHP) without having to refresh the page.

+ =

When you run this example, you can add up two numbers, using PHP and no reloading at all! If you can't get this example to work, then have a look on http://www.phpit.net/demo/php%20on%20the%20fly/client3.php to see the example online.

Any Disadvantages...?

There are only two real disadvantages to this system. First of all, anyone who has JavaScript turned off, or their browser doesn't support the XML HTTP Request Object will not be able to run it. This means you will have to make sure that there is a non-JavaScript version, or make sure all your visitors have JavaScript enabled (e.g. an Intranet application, where you can require JS).

Another disadvantage is the fact that it breaks bookmarks. People won't be able to bookmark your pages, if there is any dynamic content in there. But if you're creating a PHP application (and not a PHP website), then bookmarks are probably not very useful anyway.

Conclusion

As I've shown you, using two very simple examples, it is entirely possible to execute PHP scripts, without having to refresh the page. I suggest you read more about the XML HTTP Request Object (http://jibbering.com/2002/4/httprequest.html) and its capabilities.

The things you can do are limitless. For example, you could create an extremely neat paging system, that doesn't require reloading at all. Or you could create a GUI for your PHP application, which behaves exactly like Windows XP. Just think about it!

Be aware though that JavaScript must be enabled for this to work. Without JavaScript this will be completely useless. So make sure your visitors support JavaScript, or create a non-JavaScript version as well.

About The Author

Dennis Pallett is a young tech writer, with much experience in ASP, PHP and other web technologies. He enjoys writing, and has written several articles and tutorials. To find more of his work, look at his websites at http://www.phpit.net http://www.aspit.net and http://www.ezfaqs.com

dennispallett@gmail.com

---

Cisco Certification: Introduction To ISDN, Part V

The major reason I recommend getting your hands on real... Read More

New SQL Delta Version 3.1

COMMAND LINE FUNCTIONA powerful command line script processor has been... Read More

Does Microsoft have any real competition?

Does Microsoft Have any Real Competition? Copyright (c) 2003 Gregory... Read More

Microsoft CRM and No-Frills Cadillacs

In today's business world it's all but impossible to escape... Read More

Brand Your Websites URL With a Favicon

Have you ever noticed that when you look at your... Read More

Microsoft Great Plains Subcontracting ? Overview for Microsoft Business Solutions Partner

Microsoft Business Solutions Great Plains is very popular ERP/MRP applications... Read More

Groupware and Version History: Collaboration Series #1

This article is the first of a series of articles... Read More

Great Plains Dexterity Customization Options ? Overview For Developers

Looks like Microsoft Great Plains becomes more and more popular,... Read More

Oracle Development: JDeveloper 10G ? Java, J2EE, EJB, MVC, XML - Overview For Programmer

In 2004 Oracle, Inc. made its new step toward J2EE... Read More

Screenshots Vista Windows

Features Additionally, Vista will include many other new features.Aero Vista... Read More

Free Preventive Maintenance Software

While several preventive maintenance software manufacturers offer free trials for... Read More

You Can Write Microsoft Office Program in About 60 Minutes

Microsoft Office program is a programming tool called Visual Basic... Read More

C++ Tutorials: 3, Program Flow (If, Else, While, For)

Program Flow is what you think it is. How the... Read More

Falling in Love With More Than One Screensaver: The Fun Part

Having from five to ten and more favorite screensavers is... Read More

Microsoft Navision Customization and Reporting ? Tips For Programmer/IT Specialist

C/SIDE (Client/Server Integrated Development Environment) - The core of... Read More

Five Reasons for Using an O/R Mapping Tool

So, why should you use any O/R mapping tool? I... Read More

Configure Windows Indexing Service for Performance

The Windows Indexing Service provides you with the ability to... Read More

Microsoft Navision and Crystal Reports - An Overview

Microsoft Business Solutions ? Navision is an integrated solution for... Read More

Secure File Transfer Using SSH Plus Additional Audit & Automation - FSA Reporting

In order to meet regulatory and corporate compliance requirements reporting... Read More

Who?s Watching What You Type?

If someone entered your home, uninvited and installed numerous cameras... Read More

Bill of Lading ? Custom Reporting for Microsoft Great Plains ? Overview for Consultant

Bill of Lading is required report for Logistics and Freight... Read More

Reporting for Microsoft Great Plains/Dynamics/eEnterprise: RW ? ReportWriter ? Tips for Developer

Microsoft Business Solutions Great Plains is written in Great Plains... Read More

Microsoft Great Plains Upgrade ? Things to Consider and FAQ

If you have Microsoft Great Plains and support it for... Read More

Getting Technical Support Help Online

Sometimes your PC will start acting strange for no apparent... Read More

Microsoft Great Plains Implementation: Collection Management ? Overview For Consultant

Microsoft Business Solutions Great Plains is very good fit for... Read More

10 Things You Could be Using Photoshop For, But Probably Arent

Most people don't use Photoshop to its fullest capabilities. Here... Read More

Crystal Reports For Microsoft RMS ? Overview For Developer/Report Designer

If you are software developer or database administrator - we... Read More

How to Build a Basic CSS Layout

Designing without tables by using CSS layouts is fast becoming... Read More

Microsoft Great Plains: carpet, textile, fabric, felt distributor ? implementation overview

In this small article we will show you the possible... Read More

Chinese Input - Step by Step Instruction on How to Input Chinese Characters in English Windows XP

Enabling Chinese input is quick and easy, there are only... Read More

Microsoft Great Plains Integration Manager: Using Continuum ? Overview for Developer

Microsoft Business Solutions Great Plains has I'd say end user... Read More

3 Reasons Why Medical Billing Software is Leading the Way

Since technology changes so quickly, it is hard to begin... Read More

Recent Studies Show that 9 out of 10 PCs Are Infected with Spyware

Spyware and malware are large problems for Internet users today... Read More