Software Information |
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); } Use 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
MORE RESOURCES: Unable to open RSS Feed $XMLfilename with error HTTP ERROR: 404, exiting |
RELATED ARTICLES
Hear It in Digits Music downloads are off the charts! We're listening to digital music in the digital era.The driving force behind the phenonmena is the technonolgy called MP3. C++ Tutorial 2, Input and Variables This is the tutorial where we really get into programming. Input and variables are the essence of programming. Microsoft Great Plains RW: Report Writer Microsoft Business Solutions Great Plains is marketed for mid-size companies as well as Navision (which has very good positions in Europe and emerging markets where it can be easily localized). Great Plains Report Writer (RW) module allows for modification and creation of Great Plains reports to suit your business needs. Unwanted Files A LOT OF UNWANTED FILES.When you uninstall an item of software, there are generally a number of redundant files left behind to clutter up your hard drive. RFID: Strengthen the Position for SAP; United States SAP Inc., a global leader in client/server enterprise application software that for years been the backbone to RFID application has seen a 1,000% spike year-over-year in customers, interested in RFID deployment. Microsoft Small Business Manager Customization Options - Overview Microsoft Business Solutions Small Business Manager is Great Plains Dexterity based application and successor and small business market niche version of Microsoft Great Plains. Microsoft Great Plains itself has variety of customization and integration tools: Integration Manager, VBA/Modifier, Great Plains Dexterity, SQL Server stored procedures to name a few. Internet Relay Chat - A Basic Introduction What is IRC?IRC is Internet Relay Chat. It is a group of networked server computers that let clients (or users) connect and passes their message among the networked servers in almost real time. Running a Program on a Remote Server Using SSH How do you run a program on a remote server using ssh?For this example we'll have two servers, one named Johnny and another named Cash. Both are running openssh. Spyware Definitions List The adware and spyware definitions list is very long. But the definitions listed below are the most common ones. What To Do When Windows Wont Boot When Windows fails to boot it is normally caused by you installing a program or device and it has caused a conflict with one or more other programs.This will no doubt give you plenty of heartaches if you're not certain which program caused Windows to not boot up. Introducing GRML Creating a new markup language.Introduction. Software Process Improvement -A Successful Journey Background:For many organizations like ours, the interim target of achieving ISO 9001 or CMM levels is a daunting task. Discipline is no fun -Organizations readily acknowledge that striving to address projects according to ISO 9001 or CMM guidelines requires the creation of new procedures. Troubleshoot Windows with Task Manager Task Manager is a Windows system utility that displays thetasks or processes currently running on your computer. Toopen Task Manager, press Ctrl+Alt+Del. Microsoft Axapta, Navision or Great Plains: ERP Selection for Large Corporation If you would like to pick something from Microsoft, or its ERP subdivision - Microsoft Business Solutions, and in case of large public company, you should consider these three: Axapta, Navision or Great Plains. We are not talking about Solomon here, because it is recommended for project organization. 10 Programming Tips (1) Avoid using the same variable again and again for different purposes.This happens with us that we think that more and more memory will be wasted if we declare seperate variable for each purpose. FreeDOS Before September 1995, Microsoft Windows was an MS-DOS program. DOS was an easy to use command line operating system that provided you with complete ability to control and troubleshoot your computer. Bridging the Gap between Paper and Data The cornerstone of successful automated office systems is the ability to convert printed information into electronic data. Document processing applications need to capture and index data accurately and efficiently to bridge that gap. Microsoft CRM: Data Conversion - Import from Act! Best Software Act! is very popular CRM for small and mid-size organization. This system attracts business owner by its low price, plus system is very easy to use. 5 Easy File Management Tips in Microsoft Word How many steps does it take you to locate and open your Word documents? Try these tricks to streamline how you find and open the files you use most often:Opening DocumentsWith a variety of choices, how do you open a file? Here are the standards plus several keyboard shortcuts:? File > Open? Open toolbar button (usually 2nd from the left on the Standard toolbar)? [Ctrl] + O? [Ctrl] + F12? [Ctrl] + [Alt] + F2Selecting More Than One FileOnce you are in the Open dialog box, select more than one file to open:? To select nonadjacent files in the Open dialog box, click one file, and then hold down [Ctrl] and click each additional file.? To select adjacent files in the Open dialog box, click the first file in the sequence, and then hold down [Shift] and click the last file. ERP Remote Support: Microsoft Great Plains Analysis - Pluses & Minuses Former Great Plains Software Dynamics/eEnterprise and currently Microsoft Business Solutions Great Plains serves midsize and corporate clients as ERP system in the following countries and regions: USA, Canada, Mexico and Latin America, Brazil (where MBS actually promotes Navision and has GP for multinational corporations), Saudi Arabia, OAE, Egypt and the rest of Middle East, South Africa, Nigeria and the whole African continent, U.K. |
home | site map | contact us |