/**
* Return a singleton instance of this class.
*
* @return Services_Yadis_Xri
*/
public static function getInstance()
{
if (self::$instance === null) {
self::$instance = new self();
}
return self::$instance;
}
/**
* Performs Service Discovery, i.e. the requesting and parsing of a valid
* Yadis (XRD) document into a list of Services and Service Data. The
* return value will be an instance of Services_Yadis_Xrds which will
* implement SeekableIterator. Returns FALSE on failure.
*
* @return Services_Yadis_Xrds|boolean
* @throws Services_Yadis_Exception
*/
public function discover()
{
$currentUri = $this->getYadisUrl();
$xrdsDocument = null;
$request = null;
$xrdStatus = false;
// Check XRI first
if (in_array($this->yadisId[0], $this->xriIdentifiers)) {
$xri = Services_Yadis_Xri::getInstance();
$xrds = $xri->toCanonicalID($xri->getXri());
$this->httpResponse = $xri->getHTTPResponse();
return new Services_Yadis_Xrds_Service($xrds, $this->namespace);
}
while ($xrdsDocument === null) {
$this->httpResponse = $this->get($currentUri);
$responseType = $this->getResponseType($this->httpResponse);
/**
* If prior response type was a location header, or a http-equiv
* content value, then it should have contained a valid URI to
* an XRD document. Each of these when detected would set the
* xrdStatus flag to true.
*/
if (!$responseType == self::XRDS_CONTENT_TYPE && $xrdStatus == true) {
throw new Services_Yadis_Exception('Yadis protocol could not locate a valid XRD document');
}
/**
* The Yadis Spec 1.0 specifies that we must use a valid response
* header in preference to other responses. So even if we receive
* an XRDS Content-Type, if it also includes an X-XRDS-Location
* header we must request the Location URI and ignore the response
* body.
*/
switch ($responseType) {
case self::XRDS_LOCATION_HEADER:
$xrdStatus = true;
$currentUri = $this->xrdsLocationHeaderUrl;
break;
case self::XRDS_META_HTTP_EQUIV:
$xrdStatus = true;
$currentUri = $this->metaHttpEquivUrl;
break;
case self::XRDS_CONTENT_TYPE:
$xrdsDocument = $this->httpResponse->getBody();
break;
default:
throw new Services_Yadis_Exception('Yadis protocol could not locate a valid XRD document');
}
}
try {
$serviceList = $this->parseXrds($xrdsDocument);
} catch (PEAR_Exception $e) {
throw new Services_Yadis_Exception('XRD Document could not be parsed with the following message: ' . $e->getMessage(), $e->getCode());
}
return $serviceList;
}
