Returns a QTI xml representation of the question. 
Returns a QTI xml representation of the question and sets the internal domxml variable with the DOM XML representation of the QTI xml representation
        {
                global $ilias;
                
                include_once("./Services/Xml/classes/class.ilXmlWriter.php");
                
                $a_xml_writer->xmlStartTag("questestinterop");
                $attrs = array(
                        "ident" => "il_".IL_INST_ID."_qst_".$this->object->getId(),
                        "title" => $this->object->getTitle(),
                        "maxattempts" => $this->object->getNrOfTries()
                );
                $a_xml_writer->xmlStartTag("item", $attrs);
                
                $a_xml_writer->xmlElement("qticomment", NULL, $this->object->getComment());
                
                $workingtime = $this->object->getEstimatedWorkingTime();
                $duration = sprintf("P0Y0M0DT%dH%dM%dS", $workingtime["h"], $workingtime["m"], $workingtime["s"]);
                $a_xml_writer->xmlElement("duration", NULL, $duration);
                
                $a_xml_writer->xmlStartTag("itemmetadata");
                $a_xml_writer->xmlStartTag("qtimetadata");
                $a_xml_writer->xmlStartTag("qtimetadatafield");
                $a_xml_writer->xmlElement("fieldlabel", NULL, "ILIAS_VERSION");
                $a_xml_writer->xmlElement("fieldentry", NULL, $ilias->getSetting("ilias_version"));
                $a_xml_writer->xmlEndTag("qtimetadatafield");
                $a_xml_writer->xmlStartTag("qtimetadatafield");
                $a_xml_writer->xmlElement("fieldlabel", NULL, "QUESTIONTYPE");
                $a_xml_writer->xmlEndTag("qtimetadatafield");
                $a_xml_writer->xmlStartTag("qtimetadatafield");
                $a_xml_writer->xmlElement("fieldlabel", NULL, "AUTHOR");
                $a_xml_writer->xmlElement("fieldentry", NULL, $this->object->getAuthor());
                $a_xml_writer->xmlEndTag("qtimetadatafield");
                $a_xml_writer->xmlStartTag("qtimetadatafield");
                $a_xml_writer->xmlElement("fieldlabel", NULL, "shuffle");
                $a_xml_writer->xmlElement("fieldentry", NULL, $this->object->getShuffle());
                $a_xml_writer->xmlEndTag("qtimetadatafield");
                $a_xml_writer->xmlStartTag("qtimetadatafield");
                $a_xml_writer->xmlElement("fieldlabel", NULL, "thumb_geometry");
                $a_xml_writer->xmlElement("fieldentry", NULL, $this->object->getThumbGeometry());
                $a_xml_writer->xmlEndTag("qtimetadatafield");
                $a_xml_writer->xmlStartTag("qtimetadatafield");
                $a_xml_writer->xmlElement("fieldlabel", NULL, "element_height");
                $a_xml_writer->xmlElement("fieldentry", NULL, $this->object->getElementHeight());
                $a_xml_writer->xmlEndTag("qtimetadatafield");
                $a_xml_writer->xmlEndTag("qtimetadata");
                $a_xml_writer->xmlEndTag("itemmetadata");
                
                $attrs = array(
                        "label" => $this->object->getTitle()
                );
                $a_xml_writer->xmlStartTag("presentation", $attrs);
                
                $a_xml_writer->xmlStartTag("flow");
                
                $this->object->addQTIMaterial($a_xml_writer, $this->object->getQuestion());
                
                $attrs = array(
                        "ident" => "MQ",
                        "rcardinality" => "Multiple"
                );
                $a_xml_writer->xmlStartTag("response_grp", $attrs);
                $solution = $this->object->getSuggestedSolution(0);
                if (count($solution))
                {
                        if (preg_match("/il_(\d*?)_(\w+)_(\d+)/", $solution["internal_link"], $matches))
                        {
                                $a_xml_writer->xmlStartTag("material");
                                $intlink = "il_" . IL_INST_ID . "_" . $matches[2] . "_" . $matches[3];
                                if (strcmp($matches[1], "") != 0)
                                {
                                        $intlink = $solution["internal_link"];
                                }
                                $attrs = array(
                                        "label" => "suggested_solution"
                                );
                                $a_xml_writer->xmlElement("mattext", $attrs, $intlink);
                                $a_xml_writer->xmlEndTag("material");
                        }
                }
                
                $attrs = array();
                if ($this->object->getShuffle())
                {
                        $attrs = array(
                                "shuffle" => "Yes"
                        );
                }
                else
                {
                        $attrs = array(
                                "shuffle" => "No"
                        );
                }
                $a_xml_writer->xmlStartTag("render_choice", $attrs);
                
                $matchingtext_orders = array();
                foreach ($this->object->getMatchingPairs() as $index => $matchingpair)
                {
                        array_push($matchingtext_orders, $matchingpair->term->identifier);
                }
                $termids = array();
                foreach ($this->object->getTerms() as $term)
                {
                        array_push($termids, $term->identifier);
                }
                
                foreach ($this->object->getDefinitions() as $definition)
                {
                        $attrs = array(
                                "ident" => $definition->identifier,
                                "match_max" => "1",
                                "match_group" => join($termids, ",")
                        );
                        $a_xml_writer->xmlStartTag("response_label", $attrs);
                        $a_xml_writer->xmlStartTag("material");
                        if (strlen($definition->picture))
                        {
                                if ($force_image_references)
                                {
                                        $attrs = array(
                                                "imagtype" => "image/jpeg",
                                                "label" => $definition->picture,
                                                "uri" => $this->object->getImagePathWeb() . $definition->picture
                                        );
                                        $a_xml_writer->xmlElement("matimage", $attrs);
                                }
                                else
                                {
                                        $imagepath = $this->object->getImagePath() . $definition->picture;
                                        $fh = @fopen($imagepath, "rb");
                                        if ($fh != false)
                                        {
                                                $imagefile = fread($fh, filesize($imagepath));
                                                fclose($fh);
                                                $base64 = base64_encode($imagefile);
                                                $attrs = array(
                                                        "imagtype" => "image/jpeg",
                                                        "label" => $definition->picture,
                                                        "embedded" => "base64"
                                                );
                                                $a_xml_writer->xmlElement("matimage", $attrs, $base64, FALSE, FALSE);
                                        }
                                }
                        }
                        if (strlen($definition->text))
                        {
                                $attrs = array(
                                        "texttype" => "text/plain"
                                );
                                if ($this->object->isHTML($definition->text))
                                {
                                        $attrs["texttype"] = "text/xhtml";
                                }
                                $a_xml_writer->xmlElement("mattext", $attrs, $definition->text);
                        }
                        $a_xml_writer->xmlEndTag("material");
                        $a_xml_writer->xmlEndTag("response_label");
                }
                
                foreach ($this->object->getTerms() as $term)
                {
                        $attrs = array(
                                "ident" => $term->identifier
                        );
                        $a_xml_writer->xmlStartTag("response_label", $attrs);
                        $a_xml_writer->xmlStartTag("material");
                        if (strlen($term->picture))
                        {
                                if ($force_image_references)
                                {
                                        $attrs = array(
                                                "imagtype" => "image/jpeg",
                                                "label" => $term->picture,
                                                "uri" => $this->object->getImagePathWeb() . $term->picture
                                        );
                                        $a_xml_writer->xmlElement("matimage", $attrs);
                                }
                                else
                                {
                                        $imagepath = $this->object->getImagePath() . $term->picture;
                                        $fh = @fopen($imagepath, "rb");
                                        if ($fh != false)
                                        {
                                                $imagefile = fread($fh, filesize($imagepath));
                                                fclose($fh);
                                                $base64 = base64_encode($imagefile);
                                                $attrs = array(
                                                        "imagtype" => "image/jpeg",
                                                        "label" => $term->picture,
                                                        "embedded" => "base64"
                                                );
                                                $a_xml_writer->xmlElement("matimage", $attrs, $base64, FALSE, FALSE);
                                        }
                                }
                        }
                        if (strlen($term->text))
                        {
                                $attrs = array(
                                        "texttype" => "text/plain"
                                );
                                if ($this->object->isHTML($term->text))
                                {
                                        $attrs["texttype"] = "text/xhtml";
                                }
                                $a_xml_writer->xmlElement("mattext", $attrs, $term->text);
                        }
                        $a_xml_writer->xmlEndTag("material");
                        $a_xml_writer->xmlEndTag("response_label");
                }
                $a_xml_writer->xmlEndTag("render_choice");
                $a_xml_writer->xmlEndTag("response_grp");
                $a_xml_writer->xmlEndTag("flow");
                $a_xml_writer->xmlEndTag("presentation");
                
                $a_xml_writer->xmlStartTag("resprocessing");
                $a_xml_writer->xmlStartTag("outcomes");
                $a_xml_writer->xmlStartTag("decvar");
                $a_xml_writer->xmlEndTag("decvar");
                $a_xml_writer->xmlEndTag("outcomes");
                
                foreach ($this->object->getMatchingPairs() as $matchingpair)
                {
                        $attrs = array(
                                "continue" => "Yes"
                        );
                        $a_xml_writer->xmlStartTag("respcondition", $attrs);
                        
                        $a_xml_writer->xmlStartTag("conditionvar");
                        $attrs = array(
                                "respident" => "MQ"
                        );
                        $a_xml_writer->xmlElement("varsubset", $attrs, $matchingpair->term->identifier . "," . $matchingpair->definition->identifier);
                        $a_xml_writer->xmlEndTag("conditionvar");
                        
                        $attrs = array(
                                "action" => "Add"
                        );
                        $a_xml_writer->xmlElement("setvar", $attrs, $matchingpair->points);
                        
                        $attrs = array(
                                "feedbacktype" => "Response",
                                "linkrefid" => "correct_" . $matchingpair->term->identifier . "_" . $matchingpair->definition_identifier
                        );
                        $a_xml_writer->xmlElement("displayfeedback", $attrs);
                        $a_xml_writer->xmlEndTag("respcondition");
                }
                $feedback_allcorrect = $this->object->getFeedbackGeneric(1);
                if (strlen($feedback_allcorrect))
                {
                        $attrs = array(
                                "continue" => "Yes"
                        );
                        $a_xml_writer->xmlStartTag("respcondition", $attrs);
                        
                        $a_xml_writer->xmlStartTag("conditionvar");
                        foreach ($this->object->getMatchingPairs() as $matchingpair)
                        {
                                $attrs = array(
                                        "respident" => "MQ"
                                );
                                $a_xml_writer->xmlElement("varsubset", $attrs, $matchingpair->term->identifier . "," . $matchingpair->definition->identifier);
                        }
                        $a_xml_writer->xmlEndTag("conditionvar");
                        
                        $attrs = array(
                                "feedbacktype" => "Response",
                                "linkrefid" => "response_allcorrect"
                        );
                        $a_xml_writer->xmlElement("displayfeedback", $attrs);
                        $a_xml_writer->xmlEndTag("respcondition");
                }
                $feedback_onenotcorrect = $this->object->getFeedbackGeneric(0);
                if (strlen($feedback_onenotcorrect))
                {
                        $attrs = array(
                                "continue" => "Yes"
                        );
                        $a_xml_writer->xmlStartTag("respcondition", $attrs);
                        
                        $a_xml_writer->xmlStartTag("conditionvar");
                        $a_xml_writer->xmlStartTag("not");
                        foreach ($this->object->getMatchingPairs() as $matchingpair)
                        {
                                $attrs = array(
                                        "respident" => "MQ"
                                );
                                $a_xml_writer->xmlElement("varsubset", $attrs, $matchingpair->term->identifier . "," . $matchingpair->definition->identifier);
                        }
                        $a_xml_writer->xmlEndTag("not");
                        $a_xml_writer->xmlEndTag("conditionvar");
                        
                        $attrs = array(
                                "feedbacktype" => "Response",
                                "linkrefid" => "response_onenotcorrect"
                        );
                        $a_xml_writer->xmlElement("displayfeedback", $attrs);
                        $a_xml_writer->xmlEndTag("respcondition");
                }
                $a_xml_writer->xmlEndTag("resprocessing");
                
                foreach ($this->object->getMatchingPairs() as $matchingpair)
                {
                        $attrs = array(
                                "ident" => "correct_" . $matchingpair->term->identifier . "_" . $matchingpair->definition->identifier,
                                "view" => "All"
                        );
                        $a_xml_writer->xmlStartTag("itemfeedback", $attrs);
                        
                        $a_xml_writer->xmlStartTag("flow_mat");
                        $a_xml_writer->xmlStartTag("material");
                        $a_xml_writer->xmlElement("mattext");
                        $a_xml_writer->xmlEndTag("material");
                        $a_xml_writer->xmlEndTag("flow_mat");
                        $a_xml_writer->xmlEndTag("itemfeedback");
                }
                if (strlen($feedback_allcorrect))
                {
                        $attrs = array(
                                "ident" => "response_allcorrect",
                                "view" => "All"
                        );
                        $a_xml_writer->xmlStartTag("itemfeedback", $attrs);
                        
                        $a_xml_writer->xmlStartTag("flow_mat");
                        $this->object->addQTIMaterial($a_xml_writer, $feedback_allcorrect);
                        $a_xml_writer->xmlEndTag("flow_mat");
                        $a_xml_writer->xmlEndTag("itemfeedback");
                }
                if (strlen($feedback_onenotcorrect))
                {
                        $attrs = array(
                                "ident" => "response_onenotcorrect",
                                "view" => "All"
                        );
                        $a_xml_writer->xmlStartTag("itemfeedback", $attrs);
                        
                        $a_xml_writer->xmlStartTag("flow_mat");
                        $this->object->addQTIMaterial($a_xml_writer, $feedback_onenotcorrect);
                        $a_xml_writer->xmlEndTag("flow_mat");
                        $a_xml_writer->xmlEndTag("itemfeedback");
                }
                $a_xml_writer->xmlEndTag("item");
                $a_xml_writer->xmlEndTag("questestinterop");
                $xml = $a_xml_writer->xmlDumpMem(FALSE);
                if (!$a_include_header)
                {
                        $pos = strpos($xml, "?>");
                        $xml = substr($xml, $pos + 2);
                }
                return $xml;
        }