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Lifting the lid on the registry

In a previous blog entry on IP.Board 3.0's new framework, I mentioned that at the core of the new framework is something called 'ipsRegistry'. This blog post will go into more detail and will be of interest to modification authors.

IP.Board, like most complex applications, has a need for 'core' data, like settings, session and input data ($_GET, $_POST, etc). There is also a need for a database connection and access to global objects like cached data. It would be incredibly wasteful to make each file and class set up a database connection, load any cached data, authorize the browser session and build up any settings. This could happen many time in any IP.Board view.

Clearly there is a need for a way to initialize this data once and then pass it throughout the application. This is exactly what the ipsRegistry is for. Previous versions of IP.Board relied on the 'ipsclass' object as a registry; but this quickly became tarnished without clear boundries as more and more data was attached to it. It was more of a global variable than anything else. The new registry is composed of clearly defined objects. Also in previous versions initialization of the settings, caches, input data, sessions, etc was handled over a scattering of classes and files. The new registry is a single point for this initialization. This initialization occurs when init() is called. This makes it much easier to use IPS registry data in your own scripts and modifications. Previously you would have needed to copy out half of the default index.php. Now your scripts can be as simple as:

  require_once( 'classes/base/ipsRegistry.php' );    /* Call init which loads up input, caches, settings, creates the DB handle, authorizes and loads the member  $registry = ipsRegistry::instance()->init();    print $registry->request()->getField('foo');  $registry->DB()->do_update( 'table', array( 'foo' => 'bar' ); );  print ( $registry->member()->getProperty('member_id') ) ? 'Hello ' . $registry->member()->getProperty('members_display_name') : 'You are a guest';

require_once( 'conf_data.php' );

Gathering Input from URLs and Forms
One key part of IP.Board's initialization was the sanitization of $_GET and $_POST into a clean array. This was vital to the overall security of the board. IP.Board 3.0 as a 'request' registry object for this and all functions relating to this initialization (parse_key, parse_value, etc). This is available via either $this->request->getField('foo') or $this->request['foo']. This effectively replaces $this->ipsclass->input['foo'];

Cached Data
There are many improvements to the caching backend which we'll go into more detail in a later blog entry. The cache registry object simply returns the cache when requested via $this->registry->cache()->getCache('forums'); The cache is loaded and unpacked during initialization so you do not need to manually call it.

The Database
So much of the database code has been refactored that it's almost a separate blog on its own. Here, I'll concentrate on the registry object. The main function is getDB() which is interfaced via $this->DB (or ipsRegistry: :D B() when outside of class scope). This is a simple function to return the DB object which is set up during initialization via setDB(). This happens transparently when the file is included and init() called (which is done so by ipsController.php). You may set up more connections by specifying a key, for example:

  return $this->registry->DB( 'newConnection' )->build_and_exec_query( array( 'select' => '*', 'from' => 'table' ) );

$this->DB->setDB( 'mysql', 'newConnection', 'user@localhost.com', 'password', 'localhost' );

The setting cache is loaded and unpacked during initialization. This registry object merely returns the setting when requested via $this->settings->getSetting('foo') or $this->settings['foo'].

Member Information
Previously member information was scattered through 'ipsclass'. IP.Board's member registry centralizes this information. This object sets up the incoming IP address, browser and operating system and attaches it to the member class. It also authorizes the current browser session (via cookies or an inline URL) and loads up the session member and builds up the permission arrays. All this is done during initialization meaning there is less to do on the front end.

I hope this post has given you some insight into the IPS registry and the improvements it brings not only to IP.Board itself, but also to modification authors who will find their workload greatly reduced by automatic set up of all the required information. If you find that you do not need all of this information set up, then you can write a child class of ipsRegistry and alter the 'protected' functions to prevent them from initializing.

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