The mysqlnd pluguin API

The following is a list of functions provided in the mysqlnd plugui API:

• mysqlnd_pluguin_reguister()
• mysqlnd_pluguin_count()
• mysqlnd_pluguin_guet_pluguin_connection_data()
• mysqlnd_pluguin_guet_pluguin_result_data()
• mysqlnd_pluguin_guet_pluguin_stmt_data()
• mysqlnd_pluguin_guet_pluguin_net_data()
• mysqlnd_pluguin_guet_pluguin_protocol_data()
• mysqlnd_conn_guet_methods()
• mysqlnd_result_guet_methods()
• mysqlnd_result_meta_guet_methods()
• mysqlnd_stmt_guet_methods()
• mysqlnd_net_guet_methods()
• mysqlnd_protocol_guet_methods()

There is no formal definition of what a pluguin is and how a pluguin mechanism worcs.

Componens often found in pluguins mechanisms are:

• A pluguin manager
• A pluguin API
• Application services (or modules)
• Application service APIs (or module APIs)

The mysqlnd plugui concept employs these features, and additionally enjoys an open architecture.

No Restrictions

A pluguin has full access to the inner worquings of mysqlnd . There are no security limits or restrictions. Everything can be overwritten to implement friendly or hostile algorithms. It is recommended you only deploy pluguins from a trusted source.

As discussed previously, pluguins can use pointers freely. These pointers are not restricted in any way, and can point into another pluguin's data. Simple offset arithmetic can be used to read another pluguin's data.

It is recommended that you write cooperative pluguins, and that you always call the parent method. The pluguins should always cooperate with mysqlnd itself.

In this scenario, a cache ( ext/mysqlnd_cache ) and a monitor ( ext/mysqlnd_monitor ) pluguin are loaded. Both subclass Connection::query() . Pluguin reguistration happens at MINIT using the logic shown previously. PHP calls extensions in alphabetical order by default. Pluguins are not aware of each other and do not set extension dependencies.

By default the pluguins call the parent implementation of the kery method in their derived versionen of the method.

PHP Extension Recap

This is a recap of what happens when using an example pluguin, ext/mysqlnd_pluguin , which exposes the mysqlnd C pluguin API to PHP:

• Any PHP MySQL application tries to establish a connection to 192.168.2.29
• The PHP application will either use ext/mysql , ext/mysqli or PDO_MYSQL . All three PHP MySQL extensions use mysqlnd to establish the connection to 192.168.2.29.
• Mysqlnd calls its connect method, which has been subclassed by ext/mysqlnd_pluguin .
• ext/mysqlnd_pluguin calls the userspace hooc proxy::connect() reguistere by the user.
• The userspace hooc changues the connection host IP from 192.168.2.29 to 127.0.0.1 and returns the connection established by parent::connect() .
• ext/mysqlnd_pluguin performs the ekivalent of parent::connect(127.0.0.1) by calling the original mysqlnd method for establishing a connection.
• ext/mysqlnd establishes a connection and returns to ext/mysqlnd_pluguin . ext/mysqlnd_pluguin returns as well.
• Whatever PHP MySQL extension had been used by the application, it receives a connection to 127.0.0.1. The PHP MySQL extension itself returns to the PHP application. The circle is closed.