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=== What is Common Cartridge? ===
=== What is Common Cartridge? ===

Revision as of 15:14, 18 May 2009

Note: This page is a work-in-progress. Feedback and suggested improvements are welcome. Please join the discussion on moodle.org or use the page comments.

Moodle1.9 Moodle 2.0

What is Common Cartridge?

Common Cartridge is a specification that describes format for creating and sharing primarily educational digital content. The specification is developed by IMS Global Learning Consortium and describes in details the packaging format and infrastructure needed to support format for presenting it to the end-user. (See FAQ for more info especially What is Common Cartridge?)

Why Common Cartridge?

Common Cartridge solves two problems. The first is to provide a standard way to represent digital course materials for use in on-line learning systems so that such content can be developed in one format and used across a wide variety of learning systems (often referred to as course management systems, learning management systems, virtual learning environments, or instructional management systems). The second is to enable new publishing models for on-line course materials and digital books that are modular, web-distributed, interactive, and customizable. (cited from CC FAQ - http://www.imsglobal.org/cc/ccfaqs.html#2) We feel that it is important to support all efforts in on-line educational community and try to standardize content exchange format(s). That way we support openness of Moodle and increase possibility of interoperability with other LMS systems.


Since Moodle 2.0 is still not ready for integration of any third-party format we will start development on experimental import extension for Moodle 1.9. In Moodle 1.9 the only supported third-party format (other than native moodle) is Blackboard 5.5&6. Blackboard package support is implemented through use of XSL transformation. That means that if we try to upload directly blacboard package moodle will detect that and transform package manifest using XSL transformation, reorder it's resources thus creating a moodle package and import that transformed package. This is a prefferd way of implementing support for importing any third-party format. The main reason for this is that there is no currently any API for managing restore of course content and that would mean that any third-party format developer would have to develop all that code again from scratch.

As we can see in restorelib.php blackboard conversion is initiated in function restore_precheck. That would be appropriate place for adding precheck for any other third-party format.

function restore_precheck($id,$file,&$errorstr,$noredirect=false) {
        //Check for IMS Common Cartridge backups and convert
        //Note that CC check goes before blackboard which is
        //important based on how current detection of blackboard package is
        if ($status){
            if (!defined('RESTORE_SILENTLY')) {
                echo "<li>".get_string("checkingforccexport").'</li>';
            $status = ims_cc_convert($CFG->dataroot."/temp/backup/".$backup_unique_code);
        //Check for Blackboard backups and convert
        if ($status){
            if (!defined('RESTORE_SILENTLY')) {
                echo "<li>".get_string("checkingforbbexport").'</li>';
            $status = blackboard_convert($CFG->dataroot."/temp/backup/".$backup_unique_code);

Additional notes regarding package type detection

Current third-party format checking in Moodle 1.9 is far from being adequate. In case of blackboard type detection system only checks for existence of imsmanifest.xml. Almost all IMS based content packages use this file name for their manifest (blackboard, SCORM, Common Cartridge etc.). Therefore a better file type detection is needed, not only for the presence of the manifest file but also regarding it's content.

Every manifest has a specific xml namespaces that define organization of the file. By checking for specific item described in particular standard for a content type in question we can detect what type of package we are working with.

For example Common Cartridge manifest looks like this:

<?xml version="1.0" encoding="UTF-8" ?> 
<manifest identifier="M102815" xmlns="http://www.imsglobal.org/xsd/imscc/imscp_v1p1"

By checking for existence and value of xmlns attribute we can reliably detect the type in question. As additional check a validation can be performed using XSD files from common cartridge definition.

This would be basic example of format detection function:

function detect_backup_format(DOMDocument $xml_dom) {
	$format = FORMAT_UNKNOWN;
	$rootNode = $xml_dom->documentElement;
    //Is it IMS manifest at all?
    if (   is_object($rootNode) 
        && ($rootNode->tagName == 'manifest')
        ) {
        //Is it common cartridge
        if ( $rootNode->hasAttribute('xmlns') ) {
            $xmlns = $rootNode->getAttribute('xmlns');
            if ($xmlns == <common cartridge namespace uri>) {
                $format = FORMAT_COMMON_CARTRIDGE;
        //Is it Blackboard
        if ( ($format == FORMAT_UNKNOWN) && $rootNode->hasAttribute('xmlns:bb') ) {
            $xmlns = $rootNode->getAttribute('xmlns:bb');
            if ($xmlns == <blackboard 5.5 & 6 namespace uri>) {
                $format = FORMAT_BLACK_BOARD;
    return $format;

Mapping specific content type inside common cartridge into appropriate Moodle type

Based on the common cartridge profile document supported content types in common cartridge are these:

  • folder
  • web content
  • web link
  • discussion topic
  • assesment (QTI assesment - quiz)
  • associated content
  • intra-package reference
  • metadata
  • question bank (in qti 1.2 format)

Investigation is required to determine exactly what maps to what, how long will it take to implement appropriate transformation etc.

For now we can say that following mappings apply:

Moodle Common Cartridge
Forum Discussion topic
Quiz QTI assesment
Link to static web page Web link or web content
Text page Web content
Web page Web content

CC Discussion topic transformation to Moodle Forum

An example of forum discussion topic:

<?xml version="1.0" encoding="UTF-8"?>
<dt:topic xmlns:dt="http://www.imsglobal.org/xsd/imsdt_v1p0" 
  <title>Discussion Topic</title>
  <text texttype="text/html"><h3>Hello World!</h3></text>
    <attachment href="media/info.jpg"/>

Common Cartridge supports storing only forum topics. Forum topic contains only topic title, message text and optional attachments.

CC QTI assesment transformation to Moodle Quiz

{Description to be added...}

CC web link/web content - web content transformation to Moodle web link/text page/web page

Example of web link xml:

<?xml version="1.0" encoding="UTF-8"?>
<wl:webLink xmlns:wl="http://www.imsglobal.org/xsd/imswl_v1p0" 
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" >
  <title>WebLink Example</title>
  <url href="http://www.uvcms.com" target="_parent" windowFeatures=""/>

Additional Information