| 1 system.api.php | hook_stream_wrappers() | 
Registers PHP stream wrapper implementations associated with a module.
Provide a facility for managing and querying user-defined stream wrappers in PHP. PHP's internal stream_get_wrappers() doesn't return the class registered to handle a stream, which we need to be able to find the handler for class instantiation.
If a module registers a scheme that is already registered with PHP, it will be unregistered and replaced with the specified class.
Return value
A nested array, keyed first by scheme name ("public" for "public://"),: then keyed by the following values:
- 'name' A short string to name the wrapper.
- 'class' A string specifying the PHP class that implements the BackdropStreamWrapperInterface interface.
- 'description' A string with a short description of what the wrapper does.
- 'type' (Optional) A bitmask of flags indicating what type of streams this wrapper will access - local or remote, readable and/or writeable, etc. Many shortcut constants are defined in stream_wrappers.inc. Defaults to STREAM_WRAPPERS_NORMAL which includes all of these bit flags:
See also
Related topics
File
- core/modules/ system/ system.api.php, line 2233 
- Hooks provided by Backdrop core and the System module.
Code
function hook_stream_wrappers() {
  return array(
    'public' => array(
      'name' => t('Public files'),
      'class' => 'BackdropPublicStreamWrapper',
      'description' => t('Public local files served by the webserver'),
      'type' => STREAM_WRAPPERS_LOCAL_NORMAL,
    ),
    'private' => array(
      'name' => t('Private files'),
      'class' => 'BackdropPrivateStreamWrapper',
      'description' => t('Private local files served by Backdrop'),
      'type' => STREAM_WRAPPERS_LOCAL_NORMAL,
    ),
    'temp' => array(
      'name' => t('Temporary files'),
      'class' => 'BackdropTempStreamWrapper',
      'description' => t('Temporary local files for upload and previews'),
      'type' => STREAM_WRAPPERS_LOCAL_HIDDEN,
    ),
    'cdn' => array(
      'name' => t('Content delivery network files'),
      'class' => 'MyModuleCDNStreamWrapper',
      'description' => t('Files served by a content delivery network'),
      // 'type' can be omitted to use the default of STREAM_WRAPPERS_NORMAL
    ),
    'youtube' => array(
      'name' => t('YouTube video'),
      'class' => 'MyModuleYouTubeStreamWrapper',
      'description' => t('Video streamed from YouTube'),
      // A module implementing YouTube integration may decide to support using
      // the YouTube API for uploading video, but here, we assume that this
      // particular module only supports playing YouTube video.
      'type' => STREAM_WRAPPERS_READ_VISIBLE,
    ),
  );
}
