This is the core of the PHP Yadis library. This is the only class a user needs to use to perform Yadis discovery. This class performs the discovery AND stores the result of the discovery.

First, require this library into your program source:

  require_once "Services/Yadis/Yadis.php";

To perform Yadis discovery, first call the "discover" method statically with a URI parameter:

  $http_response = array();
  $fetcher = Services_Yadis_Yadis::getHTTPFetcher();
  $yadis_object = Services_Yadis_Yadis::discover($uri,
                                    $http_response, $fetcher);

If the discovery succeeds, $yadis_object will be an instance of Services_Yadis_Yadis. If not, it will be null. The XRDS document found during discovery should have service descriptions, which can be accessed by calling

  $service_list = $yadis_object->services();

which returns an array of objects which describe each service. These objects are instances of Services_Yadis_Service. Each object describes exactly one whole Service element, complete with all of its Types and URIs (no expansion is performed). The common use case for using the service objects returned by services() is to write one or more filter functions and pass those to services():

  $service_list = $yadis_object->services(
                               array("filterByURI",
                                     "filterByExtension"));

The filter functions (whose names appear in the array passed to services()) take the following form:

  function myFilter(&$service) {
       // Query $service object here.  Return true if the service
       // matches your query; false if not.
  }

This is an example of a filter which uses a regular expression to match the content of URI tags (note that the Services_Yadis_Service class provides a getURIs() method which you should use instead of this contrived example):

  function URIMatcher(&$service) {
      foreach ($service->getElements('xrd:URI') as $uri) {
          if (preg_match("/some_pattern/",
                         $service->parser->content($uri))) {
              return true;
          }
      }
      return false;
  }

The filter functions you pass will be called for each service object to determine which ones match the criteria your filters specify. The default behavior is that if a given service object matches ANY of the filters specified in the services() call, it will be returned. You can specify that a given service object will be returned ONLY if it matches ALL specified filters by changing the match mode of services():

  $yadis_object->services(array("filter1", "filter2"),
                          SERVICES_YADIS_MATCH_ALL);

See SERVICES_YADIS_MATCH_ALL and SERVICES_YADIS_MATCH_ANY.

Services described in an XRDS should have a library which you'll probably be using. Those libraries are responsible for defining filters that can be used with the "services()" call. If you need to write your own filter, see the documentation for Services_Yadis_Service.

Located in /openid/Services/Yadis/Yadis.php (line 114)

 Services_Yadis_Yadis