public function head()
{
if (method_exists($this, 'get')) {
call_user_func_array(array($this, 'get'), func_get_args());
} else {
Http::setHttpResponseCode(405);
}
return '';
}
public function get($resourceId = null)
{
// call the method that populate resultGraph
$this->linkData();
$hasNextPage = $this->detectIfHasNextPage();
// add metadata and weblinks to single-page resource
if ($this->context->isSinglePageResource()) {
// provide web links as required by LDP specifications
$this->weblinks[] = WebLink::factory('http://www.w3.org/ns/ldp-paging#Page')->rel('type');
// LDP servers may provide a first page link when responding to requests with any single-page
// resource as the Request-URI.
$this->weblinks[] = WebLink::factory($this->context->firstPageUri())->rel('first');
// LDP servers may provide a last page link in responses to GET requests with any single-page
// resource as the Request-URI.
// LDP servers must provide a next page link in responses to GET requests with any single-page
// resource other than the final page as the Request-URI. This is the mechanism by which clients c
// an discover the URL of the next page.
// LDP servers must not provide a next page link in responses to GET requests with the final
// single-page resource as the Request-URI. This is the mechanism by which clients can discover
// the end of the page sequence as currently known by the server.
if ($hasNextPage) {
$this->weblinks[] = WebLink::factory($this->context->nextPageUri())->rel('next');
}
// LDP servers may provide a previous page link in responses to GET requests with any
// single-page resource other than the first page as the Request-URI.
// This is one mechanism by which clients can discover the URL of the previous page.
// LDP servers must not provide a previous page link in responses to GET requests with the
// First single-page resource as the Request-URI. This is one mechanism by which clients
// can discover the beginning of the page sequence as currently known by the server.
if ($this->context->getPageNum() > 0) {
$this->weblinks[] = WebLink::factory($this->context->prevPageUri())->rel('prev');
}
// add metadata about linked Data Single page resource
$metadata = $this->templateEngine->setTemplate('
@base <{requestedUri}> .
@prefix ldp-paging: <http://www.w3.org/ns/ldp-paging#> .
<> a ldp-paging:Page; ldp-paging:pageOf <{pagedResourceUri}>.
')->render();
$this->resultGraph->parse($metadata, 'turtle');
} elseif ($hasNextPage) {
// Server side initiated page management:
// WARNING THI IMPLEMENTATION USES A LDP SPECIFICATIO FEATURE AT RISK:
// LDP servers should respond with HTTP status code 333 (Returning Related) to successful
// GET requests with any paged resource as the Request-URI, although any appropriate code may be used.
Http::setHttpResponseCode(333);
header('Location: ' . $this->context->firstPageUri());
// N.B. 333 code is not yet standarized..it is threathed as 302 by many agents
// In that case you coud return withoud any other payload setup.
// but if 333 will be standarized the payload is ready to serve first page
}
// add to result graph the metadata about Linked Data paged resource in first page
// Note that this apply both for Single-Page resource and for Paged Resource
if ($this->context->getPageNum() == 0) {
$this->linkMetadata();
}
return $this->stateTransfer($this->resultGraph, $this->weblinks);
}
/**
* This routine drive http caching process
* Not sure to have well understand caching :-(
*
* Note that this routine is called by stateTransfer and may be called also from
* End-Point routine after the controller exit.
*
* @link http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html
*/
public static function processor($data, $sec = 0)
{
// ensure not negative caching age!
if ($sec < 0) {
$sec = 0;
}
$etag = Http::setETagHeader($data);
$lastModifiedOn = Http::setLastModifiedHeader($data, new \DateTime());
// this is the caching algorithm: only return data if necessary..
if (self::isNotModified($etag, $lastModifiedOn)) {
// Return http status 304 Not Modified and stop data flow processing
Http::setHttpResponseCode(304);
return '';
// return empty data
}
// advertise caching policy
self::setCacheControl($sec);
return $data;
}
public function render(Exception $e)
{
// build error model from Exception
if ($e instanceof HttpErrorException) {
$problem = $e->getHttpProblem();
} else {
// guess http status code
$errorCode = $e->getCode();
$isHttpErrorCode = $errorCode >= 400 && array_key_exists($errorCode, Http::$STATUS_CODES);
$statusCode = $isHttpErrorCode ? $errorCode : 500;
$phpErrorURI = 'http://php.net/manual/errorfunc.constants';
$problem = new HttpProblem($statusCode, null, (string) $e, $isHttpErrorCode ? null : $phpErrorURI . '#' . $errorCode, $isHttpErrorCode ? null : $phpErrorURI);
}
// Set header and rendering payload
Http::setHttpResponseCode($problem->httpStatus);
return $this->serializeHttpProblem($problem);
}
