ClearOS Documentation

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Libraries

Libraries (Models) are the meat and potatoes of a ClearOS App.

Getting Started

Header Documentation

The documentation must be the first block of code to appear in your ClearOS App library. Among other pieces of information, the author and copyright are documented.

License

Please make sure you have a license notice just after the header documentation. It is important that you heed the requirements of a license.

Namespace

ClearOS libraries use the namespace feature that was released with PHP 5.3.x. By using namespaces, you avoid any class name conflicts with other ClearOS App developers. The name space format for Apps is clearos\apps\app_name (see example below).

///////////////////////////////////////////////////////////////////////////////
// N A M E S P A C E
///////////////////////////////////////////////////////////////////////////////
 
namespace clearos\apps\openvpn;

Bootstrap Code

The ClearOS engine needs to pull in core functions (e.g. clearos_load_library) and the framework configuration. The location of the bootstrap file can be changed by using an environment variable – very handy for developers working outside the default /usr/clearos directory.

///////////////////////////////////////////////////////////////////////////////
// B O O T S T R A P
///////////////////////////////////////////////////////////////////////////////
 
$bootstrap = isset($_ENV['CLEAROS_BOOTSTRAP']) ? $_ENV['CLEAROS_BOOTSTRAP'] : '/usr/clearos/framework/shared';
require_once $bootstrap . '/bootstrap.php';

Translations

Translations for your application are stored in the languages directory in your application. In order to keep the ClearOS framework lightweight, you need to explicitly pull in any translations that you need. The clearos_load_language() function is used for this purpose. This function is analogous to the $this→lang→load() call in the “View” and “Controller”.

You can use translations from other base applications. In fact, most libraries can take advantage of the base translations - it contains a large list of commonly used words in ClearOS, for example:

  • day, week, month, year
  • username, password
  • low, medium, high
  • etc.
///////////////////////////////////////////////////////////////////////////////
// T R A N S L A T I O N S
///////////////////////////////////////////////////////////////////////////////
 
clearos_load_language('base');
clearos_load_language('date');

Dependencies

Your ClearOS library can use other libraries installed on the system. The ClearOS base application (app-base-core) contains a number of useful libraries, including:

  • File: for manipulating files on the system
  • Folder: for manipulating folders on the system
  • Daemon: a generic base class for daemons

… and others. Use the clearos_load_library() function to load a library. This function is analogous to CodeIgniter's $this->load->library() call in the “View” and “Controller”.

///////////////////////////////////////////////////////////////////////////////
// D E P E N D E N C I E S
///////////////////////////////////////////////////////////////////////////////
 
clearos_load_library('base/Folder');
clearos_load_library('base/File');

Exceptions

If you need to create custom exceptions for your library, you can create this class exception in the same source code file. As a rule of thumb, avoid creating a new exception unless you think a developer using your library will really need it.

All custom exceptions must extend the EngineException. The only two parameters available in the EngineException are:

  • message a short error message
  • code one of the following status codes
    • ClearOsError::CODE_ERROR
    • ClearOsError::CODE_WARNING
    • ClearOsError::CODE_INFO
///////////////////////////////////////////////////////////////////////////////
// E X C E P T I O N  C L A S S
///////////////////////////////////////////////////////////////////////////////
 
/**
 * Timezone not set exception.
 *
 * @package ClearOS
 * @subpackage Exception
 * @author {@link http://www.clearfoundation.com/ ClearFoundation}
 * @license http://www.gnu.org/copyleft/lgpl.html GNU Lesser General Public License version 3 or later
 * @copyright Copyright 2003-2010 ClearFoundation
 */
 
class TimezoneNotSetException extends EngineException
{
    /**
     * TimezoneNotSetException constructor.
     *
     * @param string $message error message
     */
 
    public function __construct($message)
    {
        parent::__construct($message, ClearOsError::CODE_ERROR);
    }
}

Class

Class Declaration

All classes must extend the Engine class or other ClearOS classes. You will also need to have the required documentation block that describes the class.

///////////////////////////////////////////////////////////////////////////////
// C L A S S
///////////////////////////////////////////////////////////////////////////////
 
/** 
 * System time manager.
 *  
 * @package ClearOS
 * @subpackage API
 * @author {@link http://www.clearfoundation.com/ ClearFoundation}
 * @license http://www.gnu.org/copyleft/lgpl.html GNU Lesser General Public License version 3 or later
 * @copyright Copyright 2003-2010 ClearFoundation
 */
 
class Time extends Engine
{
...

Constants

Like all good programmers, you should avoid hard coding constant values in your library. Class constants are commonly used for:

  • Paths to files and directories
  • Default configuration values
  • Configuration options
///////////////////////////////////////////////////////////////////////////////
// C O N S T A N T S
///////////////////////////////////////////////////////////////////////////////
 
const FILE_CONFIG = '/etc/sysconfig/clock';
const COMMAND_HWCLOCK = '/sbin/hwclock';
const DEFAULT_TIME_ZONE = 'US/Eastern';

Variables

Among other things, class variables are useful for improving the speed and efficiency of a series of method calls. However, one of the design principles of ClearOS is keep libraries stateless. This principle makes it possible to support remote calls to the library (via REST or SOAP for example). For this reason, please use class variables with caution! You can find more about stateless libraries here.

///////////////////////////////////////////////////////////////////////////////
// V A R I A B L E S
///////////////////////////////////////////////////////////////////////////////
 
/**
 * @var configuration array
 */
 
protected $config = array();
 
/**
 * @var configuration loaded flag
 */
 
protected $is_loaded = FALSE;

Constructor

Methods

For the most part, a ClearOS library should always have fine grained method calls. In other words, the preferred approach is to use distinct Get/Set methods for each distinct entity in your library. Consider a generic user library. A fine grained solution looks like:

  • GetLastName()
  • GetFirstName()
  • GetEmailAddress()
  • GetXyz()

While a coarse grained solution would return all the user information in one method call:

  • GetUserInfo()

This coarse grained approach is sometimes necessary when it comes to building out efficient remote procedure calls. If you think your library might need this type of coarse grained access, then feel free to add such methods to complement your fine grained implementation.

///////////////////////////////////////////////////////////////////////////////
// M E T H O D S
///////////////////////////////////////////////////////////////////////////////
 
/**
 * Returns DNS server pushed out to clients.
 *
 * @return string DNS server IP address
 * @throws EngineException
 */
 
public function GetDnsServer()
{
    ClearOsLogger::Profile(__METHOD__, __LINE__);
 
    if (! $this->is_loaded)
        $this->_LoadConfig();
 
    return $this->config['push']['dhcp-option']['DNS'];
}

Validation

Profiling

All method calls should start with the following line:

ClearOsLogger::Profile(__METHOD__, __LINE__);

You can also add profiling inside your method. This can be handy when you are dealing with a block of code that can take a significant amount of time. Large parts of ClearOS depend on external calls to the operating system and these can sometimes take a significant amount of time. When adding extra profiling, use the optional third parameter for custom messaging:

ClearOsLogger::Profile(__METHOD__, __LINE__, 'starting Windows network probe');
// ... scan that may take a long time....
ClearOsLogger::Profile(__METHOD__, __LINE__, 'finished Windows network probe');
content/en_us/dev_framework_reference_guide_libraries.txt · Last modified: 2015/03/01 19:14 (external edit)

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