1. Clone the trunk

   git svn clone http://svn.wp-plugins.org/web-invoice/trunk/
   

2. Make your changes
3. Commit changes locally

   git commit -a
   

4. Pull new changes (e.g. new release). Git is very good at merging, you will not have conflicts unless you edit exact same lines in the local version. Still a manual merge shouldn’t be too complicated

   git svn rebase
   

In the example I have taken the svn trunk of Web Invoice WordPress plugin. Hope you find this information useful next time you hack a WordPress plugin.

If you have a Dialog Family package please go through your bills for February and March (April if you have already got it) 2009 and you will see the difference. Please post a comment if you are affected and even if you are not affected leave a comment then we might be able to find a pattern . It might not affect you if your primary connection makes more than Rs. 250 worth of local calls, not the case with me.

If you want to see my bills please leave a comment, it’s 8 pages, little too much to post in a blog.

I believe this is clearly deceiving the public. Shame on you Dialog GSM.

As I promised, here is the post that will discuss in detail how I configured my cluster of 2 nodes to host my sites.

Setting up SSH tunnels

You have to setup a SSH tunnel between the nodes. In order to do that you need to allow restricted root logins into your nodes. Using your favourite text editor edit /etc/ssh/sshd_config and change the line PermitRootLogin to PermitRootLogin forced-commands-only.

Then generate SSH authentication keys for all your nodes and add the public keys to /root/.ssh/authorized_keys on other nodes. Keys can be generated by running ssh-keygen. By default your private key is stored in /root/.ssh/id_rsa and public key in /root/.ssh/id_rsa.pub. Your public key will look similar to bellow (Key shortened for brevity)

ssh-rsa AAAA...w== root@example.com

To enable tunnel only access via root you need to add tunnel="0",command="/sbin/ifdown tun0;/sbin/ifup tun0" before your public key in /root/.ssh/authorized_keys. Your /root/.ssh/authorized_keys will look something like bellow.

tunnel='0',command='/sbin/ifdown tun0;/sbin/ifup tun0' ssh-rsa AAAA...w== root@example.com

Now setup the actual tunnel. Add following lines to /etc/network/interfaces in the “server”

auto tun0
iface tun0 inet static
address 10.100.2.1
netmask 255.255.255.0
pointopoint 10.100.2.2

and the following in the “client”

auto tun0
iface tun0 inet static
pre-up ssh -S /var/run/ssh-myvpn-tunnel-control -M -f -w 0:0 example.com true
pre-up sleep 5
address 10.100.2.2
pointopoint 10.100.2.1
netmask 255.255.255.0
up route add -net 10.100.2.0 netmask 255.255.255.0 gw 10.100.2.0 tun0
post-down ssh -S /var/run/ssh-myvpn-tunnel-control -O exit example.com

Now you only have to restart networking to enable the tunnel. Now your nodes will be in their own VPN.

Setting up document root replication (rsync)

Share /var/www via rsync. You need to install rsync and add following to /etc/rsyncd.conf if they are not already there.

max connections = 2
log file = /var/log/rsync.log
timeout = 300

[www]
comment = DOC Root
path = /var/www
read only = yes
list = yes
uid = www-data
gid = www-data
auth users = replicator
secrets file = /etc/rsyncd.secrets

Add following cron jobs to www-data crontab (crontab -e)

1/10 *  *   *   *    test -r /tmp/rsync.docroot.lock || touch /tmp/rsync.docroot.lock && rsync -aP rsync://replicator@10.100.2.2/www/ /var/www/ --password-file=/etc/rsync.secrets  --contimeout=30  > /dev/null 2>1 && rm /tmp/rsync.docroot.lock

1/10 *  *   *   *    test -r /tmp/rsync.docroot.lock || touch /tmp/rsync.docroot.lock && rsync -aP rsync://replicator@10.100.2.1/www/ /var/www/ --password-file=/etc/rsync.secrets  --contimeout=30 > /dev/null 2>1 && rm /tmp/rsync.docroot.lock

Setting up session_mysql

Next let us setup session_mysql such that we can forget about replicating PHP session .

Install php5-dev and libmysql++-dev, download session_mysql and extract it, running following commands as root within the extracted location.

export PHP_PREFIX='/usr'
$PHP_PREFIX/bin/phpize
./configure --enable-session-mysql --with-php-config=$PHP_PREFIX/bin/php-config --with-mysql=$PHP_PREFIX
make
make install

Create the database to store the session data with the following SQL

create database phpsession;
grant all privileges on phpsession.* to phpsession identified by 'phpsession'; -- CHANGE DEFAULT PASSWORD
create table phpsession(
sess_key char(64) not null,
sess_mtime int(10) unsigned not null,
sess_host char(64) not null,
sess_val mediumblob not null,

index i_key(sess_key(6)),
index i_mtime(sess_mtime),
index i_host(sess_host)
);

Add the following to your php.ini (or /etc/php5/conf.d/session_mysql.ini)

session.save_handler = 'mysql'
session_mysql.db='host=localhost db=phpsession user=phpsession pass=phpsession'

Do not forget to change the default password. Restart Apache or Lighttpd (or any other web server you are using).

MySQL asynchronous two way replication

I’m sure some of you are asking why I went for asynchronous replication. Main reasons being flexibility and lack of nodes (My cluster is just 2 nodes).

Stop MySQL from listening only to local connections. Remember to review your user table (mysql.user) to make sure you don’t grant wild card access like 'user'@'%'. Comment out bind-address in/etc/mysql/my.cnf in all nodes. Then add following to node1

server-id               = 1
replicate-same-server-id = 0
auto-increment-increment = 2
auto-increment-offset   = 1
log_bin                 = /var/log/mysql/mysql-bin.log
expire_logs_days        = 10
max_binlog_size         = 100M

master-host = 10.100.2.2
master-user = slave_user_0
master-password = your$password
master-connect-retry = 60

and following to node2

server-id               = 2
replicate-same-server-id = 0
auto-increment-increment = 2
auto-increment-offset   = 2
log_bin                 = /var/log/mysql/mysql-bin.log
expire_logs_days        = 10
max_binlog_size         = 100M

master-host = 10.100.2.1
master-user = slave_user_1
master-password = your$password
master-connect-retry = 60

Now create the users only granting them with replication rights. Also make sure you specify the hostname or the IP to make sure someone is not offloading your data . Following SQL will create the users given in the example. You will have to run the command in both nodes as the data in either node is identical.

CREATE USER 'slave_user_1'@'10.100.2.1' IDENTIFIED BY 'your$password';

GRANT REPLICATION SLAVE ON * . * TO 'slave_user_1'@'10.100.2.1' IDENTIFIED BY 'your$password' WITH MAX_QUERIES_PER_HOUR 0 MAX_CONNECTIONS_PER_HOUR 0 MAX_UPDATES_PER_HOUR 0 MAX_USER_CONNECTIONS 0 ;

CREATE USER 'slave_user_2'@'10.100.2.2' IDENTIFIED BY 'your$password';

GRANT REPLICATION SLAVE ON * . * TO 'slave_user_2'@'10.100.2.2' IDENTIFIED BY 'your$password' WITH MAX_QUERIES_PER_HOUR 0 MAX_CONNECTIONS_PER_HOUR 0 MAX_UPDATES_PER_HOUR 0 MAX_USER_CONNECTIONS 0 ;

Now start MySQL and run following in mysql prompt on each of the nodes.

reset master;
stop slave;
start slave;

Finally

Now you have a cluster of 2 nodes where you can run your PHP site. Your databases are replicated, your user session data is replicated and your document root is replicated. Have fun, if you have issues please post it as a comment.

Until recently I used one Linode VPS for hosting all my sites. On 26th March, there was a DDoS attack on one of the Linode customers in the Fremont Datacenter (where my node was as well). This made my sites inaccessible for couple of hours. This got me thinking, what could be done to mitigate such downtime. Answer of course is having a load balanced and high availability cluster. However I couldn’t afford 2 dedicated servers to do this, but I of course can afford 2 Linodes . I’ll try to explain how I set up a load balanced, high availability and shared nothing cluster using Linodes (you can use any VPS or dedicated server). I used two Linode 540 s for the job.

All of my web sites are either using PHP, Python or Perl. All of them are using MySQL as the database. Problems I had to solve were;

1. replicate files across the nodes
2. replicate databases across the nodes
3. replicate session (PHP session variables) across the nodes

All the replication needs to be done securely, so I went for a SSH tunnel between the nodes of the cluster. Over which I’ll;

1. use rsync to replicate/synchronize the document root
2. use MySQL asynchronous replication (not a NDBCLUSTER) to synchronize data across the nodes
3. use session_mysql PECL extension to store PHP session in MySQL database transparent to all applications

Check back next week when I’ll post with configuration examples on how I configured my server. If you are in a hurry above pointers are good enough to get you started.

Now to get to the point, the e-mail templates are found in ‘Web Invoice’ -> ‘E-mail templates’.  There are three templates,

• Invoice e-mail – First e-mail your client receives about the invoice
• Reminder e-mail – E-mail sent when send reminder(s) is selected
• Receipt e-mail – Sent when the client makes a payment. You also need to set ‘Send Payment Confirmation’ to yes in Settings

All variables are of the format %variable_name. Bellow you will find the list of variables available in the current version.

• %call_sign – First name + Last name of the client
• %business_name – Business name as set in the ‘Settings’
• %recurring – Recurring or not
• %amount – Amount, with currency symbol and currency formatted
• %link – Link to the invoice
• %business_email – Business e-mail as set in the ‘Settings’
• %subject – Invoice subject
• %description – Invoice description

You can definitely use the default templates as a guideline for your templates. IMHO, default templaes are awesome

Don’t go away, there is more. You can write your own plugin to add more variables. e.g. you want to use web invoice along with a booking system. In your plugin add a filter for web_invoice_email_variables and add to the global array (variable) $web_invoices_email_variables.

I want to hear what you think about this feature or Web Invoice in general. Please post your ideas and comments in the Web Invoice community forum. Do not forget to subscribe to my RSS feed to get latest news about WordPress plugins and all things web

Web Invoice is ideal for web developers, SEO consultants, general contractors, or anyone with a WordPress blog and clients to bill. If you come under any of the above, you should give Web Invoice a try.

Download or read more about Web Invoice.

• Send invoice reminders to customers with a secured link back to the
  web invoice
• Moneybookers, AlertPay or PayPal available if you don’t have a
  credit card processing account
• Setup recurring billing using Authorize.net’s ARB (Automatic Recurring Billing) feature or Moneybookers
• Automatically mark invoices paid via Moneybookers as paid (Requires
  merchant status)
• Automatically mark invoices paid via AlertPay as paid (Requires
  business status)
• Split gateway support (Your client is given the option of choosing the preferred gateway from the list of gateways you support). e.g PayPal and Moneybookers
• All user interfaces are internationalized

If you are already using WP-Invoice and would like to leverage these new features, it’s simple. Follow the 3 step process to switch from WP-Invoice to Web Invoice.

1. Rename the tables invoice_log to web_invoice_log, invoice_main to web_invoice_main, invoice_meta to web_invoice_meta. (Assuming $table_prefix is empty)
2. Download Web Invoice WordPress plugin and upload it to your server
3. Activate Web Invoice

That’s all, you can use Web Invoice without losing that you generated with WP-Invoice.

If you already using SyntaxHighlighter WordPress plugin and using XHTML, you should upgrade to SyntaxHighlighter2 because SyntaxHighlighter uses invalid XHTML. Bellow you will find the sample WordPress configuration file with SyntaxHighlighter2 .

<?php
/**
 * The base configurations of the WordPress.
 *
 * This file has the following configurations: MySQL settings, Table Prefix,
 * Secret Keys, WordPress Language, and ABSPATH. You can find more information by
 * visiting {@link http://codex.wordpress.org/Editing_wp-config.php Editing
 * wp-config.php} Codex page. You can get the MySQL settings from your web host.
 *
 * This file is used by the wp-config.php creation script during the
 * installation. You don't have to use the web site, you can just copy this file
 * to "wp-config.php" and fill in the values.
 *
 * @package WordPress
 */

// ** MySQL settings - You can get this info from your web host ** //
/** The name of the database for WordPress */
define('DB_NAME', 'putyourdbnamehere');

/** MySQL database username */
define('DB_USER', 'usernamehere');

/** MySQL database password */
define('DB_PASSWORD', 'yourpasswordhere');

/** MySQL hostname */
define('DB_HOST', 'localhost');

/** Database Charset to use in creating database tables. */
define('DB_CHARSET', 'utf8');

/** The Database Collate type. Don't change this if in doubt. */
define('DB_COLLATE', '');

/**#@+
 * Authentication Unique Keys.
 *
 * Change these to different unique phrases!
 * You can generate these using the {@link https://api.wordpress.org/secret-key/1.1/ WordPress.org secret-key service}
 *
 * @since 2.6.0
 */
define('AUTH_KEY', 'put your unique phrase here');
define('SECURE_AUTH_KEY', 'put your unique phrase here');
define('LOGGED_IN_KEY', 'put your unique phrase here');
define('NONCE_KEY', 'put your unique phrase here');
/**#@-*/

/**
 * WordPress Database Table prefix.
 *
 * You can have multiple installations in one database if you give each a unique
 * prefix. Only numbers, letters, and underscores please!
 */
$table_prefix  = 'wp_';

/**
 * WordPress Localized Language, defaults to English.
 *
 * Change this to localize WordPress.  A corresponding MO file for the chosen
 * language must be installed to wp-content/languages. For example, install
 * de.mo to wp-content/languages and set WPLANG to 'de' to enable German
 * language support.
 */
define ('WPLANG', '');

/* That's all, stop editing! Happy blogging. */

/** WordPress absolute path to the Wordpress directory. */
if ( !defined('ABSPATH') )
	define('ABSPATH', dirname(__FILE__) . '/');

/** Sets up WordPress vars and included files. */
require_once(ABSPATH . 'wp-settings.php');
?>
<?php
/**
 * The base configurations of the WordPress.
 *
 * This file has the following configurations: MySQL settings, Table Prefix,
 * Secret Keys, WordPress Language, and ABSPATH. You can find more information by
 * visiting {@link http://codex.wordpress.org/Editing_wp-config.php Editing
 * wp-config.php} Codex page. You can get the MySQL settings from your web host.
 *
 * This file is used by the wp-config.php creation script during the
 * installation. You don't have to use the web site, you can just copy this file
 * to "wp-config.php" and fill in the values.
 *
 * @package WordPress
 */

// ** MySQL settings - You can get this info from your web host ** //
/** The name of the database for WordPress */
define('DB_NAME', 'putyourdbnamehere');

/** MySQL database username */
define('DB_USER', 'usernamehere');

/** MySQL database password */
define('DB_PASSWORD', 'yourpasswordhere');

/** MySQL hostname */
define('DB_HOST', 'localhost');

/** Database Charset to use in creating database tables. */
define('DB_CHARSET', 'utf8');

/** The Database Collate type. Don't change this if in doubt. */
define('DB_COLLATE', '');

/**#@+
 * Authentication Unique Keys.
 *
 * Change these to different unique phrases!
 * You can generate these using the {@link https://api.wordpress.org/secret-key/1.1/ WordPress.org secret-key service}
 *
 * @since 2.6.0
 */
define('AUTH_KEY', 'put your unique phrase here');
define('SECURE_AUTH_KEY', 'put your unique phrase here');
define('LOGGED_IN_KEY', 'put your unique phrase here');
define('NONCE_KEY', 'put your unique phrase here');
/**#@-*/

/**
 * WordPress Database Table prefix.
 *
 * You can have multiple installations in one database if you give each a unique
 * prefix. Only numbers, letters, and underscores please!
 */
$table_prefix  = 'wp_';

/**
 * WordPress Localized Language, defaults to English.
 *
 * Change this to localize WordPress.  A corresponding MO file for the chosen
 * language must be installed to wp-content/languages. For example, install
 * de.mo to wp-content/languages and set WPLANG to 'de' to enable German
 * language support.
 */
define ('WPLANG', '');

/* That's all, stop editing! Happy blogging. */

/** WordPress absolute path to the Wordpress directory. */
if ( !defined('ABSPATH') )
	define('ABSPATH', dirname(__FILE__) . '/');

/** Sets up WordPress vars and included files. */
require_once(ABSPATH . 'wp-settings.php');
?>

I have created a simple patch which you can apply against object-cache.php (downloadable from WordPress plugin repository) or here is the file already patched. The patch prepends the $blog_id to the object key. You will have to specify global variable $blog_id in wp-config.php and give it a unique id (like your blog url).

global $blog_id;
$blog_id = 'mohanjith_net';

Facebook do not dare to do something like this again, I need Facebook to keep in touch with my friends. I’m not a Facebook addict, just that the issue happened to coincide with the time of day I would get on Facebook to get an update on my friends andmake my own online presence.

I would like to know whether you had a similar issue, or was it just me. At the time of writing the issue is fixed. Thanks Facebook for the quick fix.

I had been using last.fm for a while and recently tried out jango. Though jango lacks the bells and whistles of last.fm like desktop client, feeds, etc it does it’s job; play music.

I like jango for it’s discovery algorithm. It plays music I’d like. With time it has been improving. In contrast last.fm would get worst with time, playing songs I’d not like at all. Either from genres  I wouldn’t like or from artist I have marked as I dislike.

jango seems to have better collection of tracks (more about quality than quantity) compared to last.fm. I really get annoyed when last.fm plays mix tapes, which doesn’t happen on jango

Biggest minus point of jango is lack of a desktop client, but it doesn’t bother me because I can browse around jango site without the track stopping (I believe they use iframes). Next is a lack of an API/feed. At least a feed of items I recently listened would have been nice, so I could add to the blog

IMHO, jango is good if you would like to listen to good quality tracs from artist you like and last.fm is awesome for discovering new music, new artist, and even new genres. last.fm has an API for the inner geek as well. last.fm is truely a radio while jango is more of a juke box.

Either way both are awesome services that help you avoid boredom and know about artist you listen to. I would say I like both jango and last.fm, each with it’s plus and minus.

I have created a patch (with Git) that adds the content of $coolBit to the existing onclick attribute (without onclick=”") else a new onclick attribute is added with the $coolBit. You can download the patch. I have also reported the issue to Joost (plugin developer).

Hope this will be useful for someone in a similar situation until the fix makes it into the plugin.

In this release I have added the ability to configure throttling parameters. You can download the latest release from either here, here or from your WordPress blog under Plugins -> Add New in wp-admin.

Please do not forget to rate the Smart Throttle plugin and give your ideas to improve it.

I’ll blog about the few gotchas that I faced when I have time, hopefully soon. Development is fun again, thanks to Git.

Building the Linux Kernel was never easier on Debian (and derivatives) before. I just compiled the 2.6.28.1, it wasn’t a pain at all.