IMS common cartridge Implementation specifics

Jump to: navigation, search

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


Package import implementation

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.

<?php
 
...
 
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
        //implemented
        if ($status){
            require_once("$CFG->dirroot/backup/cc/restore_cc.php");
            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 ($status){
            require_once("$CFG->dirroot/backup/bb/restore_bb.php");
            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"
                               xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
 
...
 
</manifest>

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 assessment
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" 
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <title>Discussion Topic</title>
  <text texttype="text/html"><h3>Hello World!</h3></text>
  <attachments>
    <attachment href="media/info.jpg"/>
  </attachments>
</dt:topic>

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=""/>
</wl:webLink>

This link will be transformed during import from common cartridge into moodle link pointing to the specified url.

In case we are importing item that points to static html file that will be also imported as moodle link pointing to that static file.

Since common cartridge does not support pages with embedded HTML/txt no such pages can be imported.

Package export implementation

As stated before export in common cartridge format will be supported only in Moodle 2.0. Before we dwell into details of how is something like this to be accomplished let us start with some data regarding moodle.

Types of data available for export

Resource name Type of resource Equivalent in Common Cartridge
Forum Activity Discussion topic
Quiz Activity QTI assessment
Link to static web page Static Web link or web content
Text page Static Web content
Web page Static Web content
Label Static
Display a directory Static
Advanced uploading of files Activity
Online Text Activity
Upload a single file Activity
Offline activity Activity
Chat Activity
Choice Activity
Database Activity
Flashcard-Trainer Activity
Glosarry Activity
Lesson Activity