Question

I need to create a PHP script that receives XML input via an HTTP POST request, processes it, and then returns an XML response. I have spent quite a while attempting this on my own, and here is what I have so far.

I first quickly threw together an HTML form that allows a user to submit XML data as a string, an XML URI as a string, or an XML URI to my PHP script. This form is for testing only, as I am only tasked with creating this script.

In my PHP script I do some input handling…

// Checks that some XML input has been given
if (!(isset($_POST['xmlinput']))) {
    handleErrors("No XML Input Given");
}

// Creates a new DOM Document
$domdoc = new DomDocument;

// Sets the URL of the XML Schema
$xmlschema = "xmlschema.xsd";

// If XML input is a file, tries to load it
if (file_exists($_POST['xmlinput'])) {
    if (!$domdoc->load($_POST['xmlinput'])) {
        handleErrors("Error in XML File");
    }
}
// If XML input is not a file, tries to load it as a string
else {
    if (!$domdoc->loadXML($_POST['xmlinput'])) {
        handleErrors("Error in XML Document");
    }
}

// Validates the XML against the schema
if (!($domdoc->schemaValidate($xmlschema))) {
    handleErrors("XML Does Not Conform To Schema");
}

I then do some stuff based on what the XML data is, and then I want to generate an XML response. I am fairly certain I can create XML in DOM or SimpleXML, but I simply do not understand how to return it to the original page. Also, is this the best method to handle XML input in PHP? I have seen a ton of posts about php://input or $HTTP_RAW_POST_DATA but these don’t seem to be any better than the method I use. Any information you can give me would be a big help. If I can clarify any more, just let me know.

Answer 1

Very simply, you create your xml document using SimpleXml,

then just

echo $xml->asXML();

If you need to post xml data to a webservice,

You can use the following code to acheive that.

function do_post_request($url, $data, $optional_headers = null)
{
  $params = array('http' => array(
              'method' => 'POST',
              'content' => $data
            ));
  if ($optional_headers !== null) {
    $params['http']['header'] = $optional_headers;
  }
  $ctx = stream_context_create($params);
  $fp = @fopen($url, 'rb', false, $ctx);
  if (!$fp) {
    throw new Exception("Problem with $url, $php_errormsg");
  }
  $response = @stream_get_contents($fp);
  if ($response === false) {
    throw new Exception("Problem reading data from $url, $php_errormsg");
  }
  return $response;
}