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 . 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':
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 . http://www.phpit.net/demo/php on the fly/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':
// Get numbers
$num1 = intval($_GET['num1']);
$num2 = intval($_GET['num2']);
// Return answer
echo ($num1 + $num2);
?>
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.
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.
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
Quick Intro to PHP Development
By Alan Grissett
Chances are that if you've been around the Internet long enough, you've heard of server-side scripting languages such as PERL, ASP and ColdFusion. These are all popular languages that are used to add interactivity to Web sites, but one stands out from the crowd in terms of usability, power, and, yes, price: the PHP scripting language. Initially developed in 1995 by North Carolina programmer Rasmus Lerdorf, PHP has since blossomed into one of the leading open-source, cross-platform scripting languages available. This is due, in large part, to the worldwide community of coders that contributes to its development. Unlike proprietary scripting languages like ASP and ColdFusion, PHP's source code is freely available for peer review and contributions. This is, of course, the essence of open-source software development, but why is it that PHP in particular has gained such popularity among Web developers when there are other open-source alternatives, such as good old-fashioned PERL CGI scripts?
One very strong reason is that PHP, unlike PERL CGI scripts, is scalable and fast. Instead of requiring the server to start a new process in the operating system's kernel for each new request, which uses both CPU time and memory, PHP can run as a part of the Web server itself, which saves a considerable amount of processing time when dealing with multiple requests. This decreased processing time means that PHP can be used for high-traffic sites that cannot afford to have their performance hampered by relatively slow CGI scripts.
In addition to its scalability and speed, another usability factor that sets PHP apart is its ease of use. The PHP language is considered to be a mix between C and PERL, and it draws from the best features of each parent language, while adding unique features of its own. For example, PHP code can be embedded within standard HTML documents without using additional print statements or calling separate scripts to perform the processing tasks. In practice, this allows for very flexible programming practices. Although a working knowledge of HTML is a prerequisite for PHP development, PHP's basic functions can be learned quickly and applied to a wide range of common Webmaster-related projects, such as order forms, e-mail responses, and interactive Web pages.
Contributing to the power of the PHP language, is its native support for leading relational database platforms, including MySQL, Oracle and PostgreSQL. Platform-specific functions are built into the language for 12 databases in all. This native support for database platforms is a boon to any site that needs to track user information, store product data, or collect sales information.
Last but not least, because PHP is open-source, it is essentially free to use. Almost all professional Unix-based Web hosts offer PHP as an included option with hosting accounts. Be sure to check with your host to see if it is available to you.
This article is meant to be an introduction to the PHP language and not a tutorial, but have no fearhere are several first-rate sites that have articles that will guide you along in beginning your PHP development projects:
About the Author
Alan is the lead developer for InfoServe Media, LLC ( http://www.infoservemedia.com ), a Web development company that specializes in Web site design, hosting, domain name registration, and promotion for small businesses.
Mastering Regular Expressions in PHP
By Dennis Pallett
What are Regular Expressions?
A regular expression is a pattern that can match various text strings. Using regular expressions you can find (and replace) certain text patterns, for example "all the words that begin with the letter A" or "find only telephone numbers". Regular expressions are often used in validation classes, because they are a really powerful tool to verify e-mail addresses, telephone numbers, street addresses, zip codes, and more.
In this tutorial I will show you how regular expressions work in PHP, and give you a short introduction on writing your own regular expressions. I will also give you several example regular expressions that are often used.
Regular Expressions in PHP
Using regex (regular expressions) is really easy in PHP, and there are several functions that exist to do regex finding and replacing. Let's start with a simple regex find.
Have a look at the documentation of the preg_match function . As you can see from the documentation, preg_match is used to perform a regular expression. In this case no replacing is done, only a simple find. Copy the code below to give it a try.
<?php
// Example string
$str = "Let's find the stuff <bla>in between</bla> these two previous brackets";
// Let's perform the regex
$do = preg_match("/<bla>(.*)<\\/bla>/", $str, $matches);
// Check if regex was successful
if ($do = true) {
// Matched something, show the matched string
echo htmlentities($matches['0']);
// Also how the text in between the tags
echo '' . $matches['1'];
} else {
// No Match
echo "Couldn't find a match";
}
?>
After having run the code, it's probably a good idea if I do a quick run through the code. Basically, the whole core of the above code is the line that contains the preg_match. The first argument is your regex pattern. This is probably the most important. Later on in this tutorial, I will explain some basic regular expressions, but if you really want to learn regular expression then it's best if you look on Google for specific regular expression examples.
The second argument is the subject string. I assume that needs no explaining. Finally, the third argument can be optional, but if you want to get the matched text, or the text in between something, it's a good idea to use it (just like I used it in the example).
The preg_match function stops after it has found the first match. If you want to find ALL matches in a string, you need to use the preg_match_all function . That works pretty much the same, so there is no need to separately explain it.
Now that we've had finding, let's do a find-and-replace, with the preg_replace function . The preg_replace function works pretty similar to the preg_match function, but instead there is another argument for the replacement string. Copy the code below, and run it.
<?php
// Example string
$str = "Let's replace the <bla>stuff between</bla> the bla brackets";
// Do the preg replace
$result = preg_replace ("/<bla>(.*)<\\/bla>/", "<bla>new stuff</bla>", $str);
echo htmlentities($result);
?>
The result would then be the same string, except it would now say 'new stuff' between the bla tags. This is of course just a simple example, and more advanced replacements can be done.
You can also use keys in the replacement string. Say you still want the text between the brackets, and just add something? You use the $1, $2, etc keys for those. For example:
<?php
// Example string
$str = "Let's replace the <bla>stuff between</bla> the bla brackets";
// Do the preg replace
$result = preg_replace ("/<bla>(.*)<\\/bla>/", "<bla>new stuff (the old: $1)</bla>", $str);
echo htmlentities($result);
?>
This would then print "Let's replace the <bla>new stuff (the old: stuff between)</bla> the bla brackets". $2 is for the second "catch-all", $3 for the third, etc.
That's about it for regular expressions. It seems very difficult, but once you grasp it is extremely easy yet one of the most powerful tools when programming in PHP. I can't count the number of times regex has saved me from hours of coding difficult text functions.
An Example
What would a good tutorial be without some real examples? Let's first have a look at a simple e-mail validation function. An e-mail address must start with letters or numbers, then have a @, then a domain, ending with an extension. The regex for that would be something like this: ^[a-zA-Z0-9_\\.\\-]+@[a-zA-Z0-9\\-]+\\.[a-zA-Z0-9\\-\\.]+$
Let me quickly explain that regex. Basically, the first part says that it must all be letters or numbers. Then we get the @, and after that there should be letters and/or numbers again (the domain). Finally we check for a period, and then for an extension. The code to use this regex looks like this:
<?php
// Good e-mail
$good = "john@example.com";
// Bad e-mail
$bad = "blabla@blabla";
// Let's check the good e-mail
if (preg_match("/^[a-zA-Z0-9_\\.\\-]+@[a-zA-Z0-9\\-]+\\.[a-zA-Z0-9\\-\\.]+$/", $good)) {
echo "Valid e-mail";
} else {
echo "Invalid e-mail";
}
echo '';
// And check the bad e-mail
if (preg_match("/^[a-zA-Z0-9_\\.\\-]+@[a-zA-Z0-9\\-]+\\.[a-zA-Z0-9\\-\\.]+$/", $bad)) {
echo "Valid e-mail";
} else {
echo "Invalid e-mail";
}
?>
The result of this would be "Valid E-mail. Invalid E-mail", of course. We have just checked if an e-mail address is valid. If you wrap the above code in a function, you've got yourself a e-mail validation function. Keep in mind though that the regex isn't perfect: after all, it doesn't check whether the extension is too long, does it? Because I want to keep this tutorial short, I won't give the full fledged regex, but you can find it easily via Google.
Another Example
Another great example would be a telephone number. Say you want to verify telephone numbers and make sure they were in the correct format. Let's assume you want the numbers to be in the format of xxx-xxxxxxx. The code would look something like this:
<?php
// Good number
$good = "123-4567890";
// Bad number
$bad = "45-3423423";
// Let's check the good number
if (preg_match("/\\d{3}-\\d{7}/", $good)) {
echo "Valid number";
} else {
echo "Invalid number";
}
echo '';
// And check the bad number
if (preg_match("/\\d{3}-\\d{7}/", $bad)) {
echo "Valid number";
} else {
echo "Invalid number";
}
?>
The regex is fairly simple, because we use \\d. This basically means "match any digit" with the length behind it. In this example it first looks for 3 digits, then a '-' (hyphen) and finally 7 digits. Works perfectly, and does exactly what we want.
What exactly is possible with Regular Expressions?
Regular expressions are actually one of the most powerful tools in PHP, or any other language for that matter (you can use it in your mod_rewrite rules as well!). There is so much you can do with regex, and we've only scratched the surface in this tutorial with some very basic examples.
If you really want to dig into regex I suggest you search on Google for more tutorials, and try to learn the regex syntax. It isn't easy, and there's quite a steep learning curve (in my opinion), but the best way to learn is to go through a lot of examples, and try to translate them in plain English. It really helps you learn the syntax.
In the future I will dedicate a complete article to strictly examples, including more advanced ones, without any explanation. But for now, I can only give you links to other tutorials: The 30 Minute Regex Tutorial Regular-Expressions.info
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.webdev-articles.com
Track your visitors, using PHP
By Dennis Pallett
There are many different traffic analysis tools, ranging from simple counters to complete traffic analyzers. Although there are some free ones, most of them come with a price tag. Why not do it yourself? With PHP, you can easily create a log file within minutes. In this article I will show you how!
Getting the information
The most important part is getting the information from your visitor. Thankfully, this is extremely easy to do in PHP (or any other scripting language for that matter). PHP has a special global variable called $_SERVER which contains several environment variables, including information about your visitor. To get all the information you want, simply use the following code:
As you can see the majority of information comes from the $_SERVER variable. The mktime() and getHostByAddr() functions are used to get additional information about the visitor.
Logging the information
Now that you have all the information you need, it must be written to a log file so you can later look at it, and create useful graphs and charts. To do this you need a few simple PHP function, like fopen and fwrite .
The below code will first create a complete line out of all the information. Then it will open the log file in "Append" mode, and if it doesn't exist yet, create it.
If no errors have occurred, it will write the new logline to the log file, at the bottom, and finally close the log file again.
// Write to log file:
$logfile = '/some/path/to/your/logfile.txt';
// Open the log file in "Append" mode
if (!$handle = fopen($logfile, 'a+')) {
die("Failed to open log file");
}
// Write $logline to our logfile.
if (fwrite($handle, $logline) === FALSE) {
die("Failed to write to log file");
}
fclose($handle);
Now you've got a fully function logging module. To start tracking visitors on your website simply include the logging module into your pages with the include() function:
include ('log.php');
Okay, now I want to view my log file
After a while you'll probably want to view your log file. You can easily do so by simply using a standard text editor (like Notepad on Windows) to open the log file, but this is far from desired, because it's in a hard-to-read format.
Let's use PHP to generate useful overviews for is. The first thing that needs to be done is get the contents from the log file in a variable, like so:
// Open log file
$logfile = "/some/path/to/your/logfile.txt";
if (file_exists($logfile)) {
$handle = fopen($logfile, "r");
$log = fread($handle, filesize($logfile));
fclose($handle);
} else {
die ("The log file doesn't exist!");
}
Now that the log file is in a variable, it's best if each logline is in a separate variable. We can do this using the explode() function, like so:
// Seperate each logline
$log = explode("\n", trim($log));
After that it may be useful to get each part of each logline in a separate variable. This can be done by looping through each logline, and using explode again:
// Seperate each part in each logline
for ($i = 0; $i < count($log); $i++) {
$log[$i] = trim($log[$i]);
$log[$i] = explode('|', $log[$i]);
}
Now the complete log file has been parsed, and we're ready to start generating some interesting stuff.
The first thing that is very easy to do is getting the number of pageviews. Simply use count() [http://www.phpit.net/count] on the $log array, and there you have it;
echo count($log) . " people have visited this website.";
You can also generate a complete overview of your log file, using a simple foreach loop and tables. For example:
You can also use custom functions to filter out search engines and crawlers. Or create graphs using PHP/SWF Charts . The possibilities are endless, and you can do all kinds of things!
In Conclusion...
In this article I have shown you have to create a logging module for your own PHP website, using nothing more than PHP and its built-in functions. To view the log file you need to parse it using PHP, and then display it in whatever way you like. It is up to you to create a kick-ass traffic analyzer.
If you still prefer to use a pre-built traffic analyzer, have a look at HotScripts .
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
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