Doing this using Legacy FBML code is very simple. The following code will display different HTML content based on whether the user Likes the page or not. If the user doesn’t like the page, a message to Like the page will be displayed. If the user Likes the page already, the full content will be displayed.

<fb:visible-to-connection>
    Show content to the user
    <fb:else>
        <div style="position:absolute; top:0; left:0;">
               Like the page inorder to view the content.
        </div>
    </fb:else>
</fb:visible-to-connection>

But the case is not that simple because Facebook has deperecated the use FBML since March 2011. This is what Facebook has to say.

While looking at alternate methods to get this feature working, I came across a very easy solution. If you are good with a server-side scripting language like PHP, this solution is for you. Of course you should build your own Facebook application and create a custom Tab in your application which could be added to a Page.

Goto the Facebook Developers Page and create a new application. Fill in the necessary fields and Save the changes. The URL entered on the ‘Tab URL’ field is the location where Facebook will fetch the content when the Tab is clicked. Technically this is where your script will be hosted. Now add the App you created to your Facebook Page. You will see the Tab visible on your page. Create a PHP page with a Hello World message in the URL you provided as Tab URL. When you cick on the Tab, if you see the Hello World message, then its time to write our script.

When Facebook requests our script, we need to extract the signed_request that comes along with the request. To do that we will need the Facebook php-sdk. Download, extract it and copy the src directory to the location where your script is. Here is the script that will provide content based on whether the user Likes the Page or not.

<?php
require 'src/facebook.php';
 
// Create our Application instance (replace this with your appId and secret).
$facebook = new Facebook(array(
  'appId' => '2324983201930103',
  'secret' => 'f5wjeu72hmxjf981da84jpwo02sdvge3',
));
 
$theRequest = $facebook->getSignedRequest();
 
if($theRequest["page"]["liked"] == 1){
    echo "The real content";
}
else{
    echo "Like our page to view";
}
?>

Happy Coding!

<meta name="generator" content="WordPress 2.8.4">

To hide/remove the above, simply include the line below in the functions.php found in your theme files.

<?php
remove_action('wp_head', 'wp_generator');
?>

It’s that simple..

Replace the appID with yours.

<div id="fb-root"></div>
<script type="text/javascript"> 
  window.fbAsyncInit = function() {
        FB.init({appId: '123456789123', status: true, cookie: true, xfbml: true});
        window.setTimeout(function() {
            FB.Canvas.setAutoResize();
        }, 250);
  };
  (function() {
        var e = document.createElement('script'); e.async = true;
        e.src = document.location.protocol + '//connect.facebook.net/en_US/all.js';
        document.getElementById('fb-root').appendChild(e);
  }());
</script>

After more research, I realized that this problem isn’t specific to Facebook, but iframes. Since the iframe was loading a web page from a different domain, IE8′s default settings prevented loading of 3rd party cookies. To get this working, I had to setup a P3P Cookie Privacy Policy according to P3P Specifications. In PHP, this can be done by sending this header on top of the script.

<?php
header('P3P: CP="CAO PSA OUR"');
?>

That’s it. All problems automagically solved..

Prior to WordPress 3.1, query_posts() can only be used to search a single key or value using meta_key and meta_value parameters. meta_compare parameter can be used to specify the comparison between them.

<?php
query_posts( array(
                            'meta_key' => 'price',
                            'meta_value' => '22',
                            'meta_compare' => '<=',
                            'post_type' => 'product'
                          )
                );
?>

With the release of WordPress 3.1, the introduction of meta_query parameter to query_posts() allows developers to extend the search across multiple Custom Fields.

<?php
$args = array(
	'post_type' => 'product',
	'meta_query' =>
		array(
			'key' => 'color',
			'value' => 'blue',
			'compare' => 'NOT LIKE'
		),
		array(
			'key' => 'price',
			'value' => array( 20, 100 ),
			'type' => 'numeric',
			'compare' => 'BETWEEN'
		)
)
query_posts( $args );
?>

Happy Coding!

When executed, the following PHP script will optimize the tables which requires optimization in your WordPress database. Place this file in your WordPress’s root directory.

You can run this manually or the ideal scenario would be to setup a cron job to execute it in a given time interval based on your requirement..

<?php            
include("wp-config.php");
mysql_connect(DB_HOST, DB_USER, DB_PASSWORD);
mysql_select_db(DB_NAME);
$selQuery = "SHOW TABLE STATUS FROM `".DB_NAME."`";
$resSel = mysql_query($selQuery) or die(mysql_error());
while($row = mysql_fetch_assoc($resSel)){
    if($row["Data_free"] > 0){    
        echo date("Y-m-d H:i:s")." - Optimized : "
                .$row["Name"]." ( ".$row["Data_free"]." )\n";
        $optQuery = "OPTIMIZE TABLE `".$row["Name"]."`";
        mysql_query($optQuery) or die(mysql_error());
    }
}
echo "---------------\n\n";
?>

Maintaining and monitoring your WordPress site requires performing certain tasks on a regular basis. The term regular will depend on how often your Website gets updated. Depending on the frequency you will need to plan this out. If you run a Website that gets updated daily (eg: news), then taking daily backups is a high priority. Performing these tasks manually can become a tedious process. There are plenty of tools and techniques available to automate them.

Monitoring a Website

You might want to use a Website Monitoring Service to check whether your website is up and running. There are plenty of services over the Internet if you Google for it. These services offer monitoring your Web Server (HTTP), FTP, Mail Server (POP & SMTP), SSL, DNS and custom TCP ports on regular intervals. If any of these don’t respond, the service will alert you via Email or SMS. Most of them offer limited options for free while you need to pay based on the additional services you require. This type of monitoring is not WordPress specific and can apply to any Wesbite.

If you are a developer you can code your own monitoring system which will be cost efficient and can be expandable according to your monitoring requirements. Using socket functions and tools like curl can assist in doing that.

In any of the case above, you will need to specify the port of the service you wish to monitor. In certain cases, the port can occasionally differ from the default port that particular service would run depending on how it is configured on your Server. So you need to specify the correct one.

There is one instance that most of the Bloggers/Web Developers fail to address. While your Web Server/Apache might run smoothly, there is a possibility that your database might not respond. This can happen when your DB gets corrupted, privileges get messed up or your MySQL Server crashes for some reason. In this case WordPress will send you this ugly message on a plain white page.

It’s not suitable to show an error message of this nature to your visitors. Most importantly the HTTP status code for this response is 200, which means Search Engines will pick it up as your content for the site. If this message hangs on for long, you will get indexed on Google with this Error Message.

Here is how you can display a custom error message with your design template and get notified at the same time when your DB doesn’t respond.

Create a file called db-error.php and store that file under the wp-contents folder.
The contents of the file should be..

header("HTTP/1.0 500 Internal Server Error");
mail("webmaster@mydomain.com", "DB fail", "Down at : ".date("Y-m-d H:i:s"));
echo "<html>Your customer error message with yout HTML template</html>";

It’s that simple..!

WordPress will execute the above script when the DB doesn’t respond. The first line will send the HTTP response code 500 (Internal Server Error) so that Search Engines won’t index it. The next line will send an email to you, notifying the time the DB went down. Third line will output the HTML of your template where you can include a custom error message. You can extend this piece of code to fit into your needs. Instead of Email, you could use SMS/Twitter to get instantly notified.

Backup

Taking regular backups of your WordPress installation and most importantly the database regularly will help to restore your Website within minutes if any data loss occurs. A hard disk crash, server failure or even a hacker wiping out all your data can be some of the reasons how a data loss could occur. While your hosting provider might do the backup for you, its always good to have your own. If you take regular backups, you are never a loser.

One of the important folders to backup is the wp-contents folder, but I would advise you to backup the whole WordPress installation directory. You will also need to backup the MySQL database. A simple MySQL dump would do. If you are the average blogger, then there are quite a lot of WordPress plugins for backup which would do the job for you. If you have shell access, I would advice you to write a shell script that would backup the files and database. Add a cron job to execute the script based on how frequent you wish to take backups. If you don’t have shell access, you can try using the options in your Web Hosting Control Panel.

Security

When it comes to security, applying the correct patches and upgrading to the newest version of the core and plugins of WordPress will prevent the hackers from trying to exploit the vulnerabilities in your Website. While this can be automated, it is advisable you do this process manually to reduce complications that may arise after an upgrade. It will depend on the plugins you use and the purpose you use it for. Golden rule before upgrade is to backup your WordPress files and DB so that you can restore it if something goes wrong.

Before choosing the right plugin to use, make sure to check the compatibility of the plugin with the version of WordPress you are running. Also make sure to check the ratings of the plugin. All these information is available on the plugin’s page.

Good luck..!!

You can follow InduNan who live tweeted from the event. Thanks to Thilina and Malinthe for live blogging from the event. Photos will be uploaded to Refresh Colombo Facebook page soon. See you all at the next event.

Arm your vuvuzelas: WordPress 3.0, the thirteenth major release of WordPress and the culmination of half a year of work by 218 contributors, is now available for download (or upgrade within your dashboard). Major new features in this release include a sexy new default theme called Twenty Ten.Theme developers have new APIs that allow them to easily implement custom backgrounds, headers, shortlinks, menus (no more file editing), post types, and taxonomies. (Twenty Ten theme shows all of that off.) Developers and network admins will appreciate the long-awaited merge of MU and WordPress, creating the new multi-site functionality which makes it possible to run one blog or ten million from the same installation. As a user, you will love the new lighter interface, the contextual help on every screen, the 1,217 bug fixes and feature enhancements, bulk updates so you can upgrade 15 plugins at once with a single click, and blah blah blah just watch the video:) (In HD, if you can, so you can catch the Easter eggs.)

Source : http://wordpress.org/development/2010/06/thelonious/