Moodle 2.0

Please use talk page for comments and proposals, thanks.

Current problems

Some general problems:

plain text and html resource types separate
embedded images and files in general are stored in course files without appropriate access control
local course files and Internet links are mixed
HarvestRoad Hive repository type is not maintained.
can't move a "whole" web page properly from one course to another (eg course import).

The idea of resource types implemented as subtypes has always been a little awkward and not that helpful, incomplete list of problems follows:

sub-plugin APIs are not as well-defined as module APIs
refactoring inside the module is made harder
subplugins can't uninstall
subplugins need to bump the module version to upgrade
universal data fields get reused for different things
capability in subplugins not supported
subplugin upgrade is not integrated into main module upgrade - subplugin upgrade is executed after the main module upgrade (critical)
subplugins can not have own lang packs
subplugins do not have own log actions
instead of reducing code duplication advanced plugins may duplicate a lot more core
it is not easy to move unmaintained subplugins into contrib
unofficial subplugins not reported during upgrade
no support for subplugins in file api

Migration of resource types in Moodle 2.0

Splitting resource into multiple modules

After some discussion, we've decided to split resource into normal modules, simplifying the structure at the same time. The benefits are cleaner, more maintainable code and a simpler Moodle.

mod/resource will still remain and will be used for two purposes - to serve uploaded resource materials and also to redirect old URLs to the new modules. We will add a new table with backup of current resource table with all other information needed for upgrades and URL redirections.

In order to still be able to group the new modules together in the user interface as "resource" plugins, we can mark these as "resource" plugins in the modules table in core, in a field called "archetypes" (later there might be "assignment" in here too).

Resource types

Resource type	Moodle 1.9	New module	Moodle 2.0
directory	an arbitrary directory of files in course files	mod/folder	a collection of files in separate file area
html	A html page, containing absolute links to media from course files or external	mod/page	a general text page - html markup, format FORMAT_HTML and files stored in separate file area
text	A plain text page in some format	mod/page	a general text page - no markup, format FORMAT_PLAIN and no files
file	link to file from course files of the same course, files may contain relative links to other files	mod/resource	one file or collection of files, one file is always selected as main file
file	link to other course or general external URL	mod/url	general URL
ims	Files extracted into moddata from an IMS resource package obtained from course files or web repository	mod/ims	Files in separate file area extracted from an IMS resource package obtained from repository
repository	Links to external files in repositories (ie Hive)	mod/url?	(na)

Contrib resource types

There are other third party plugins in contrib that need to be migrated:

mod/resource/type/digitalnz - browser and add items listed in http://www.digitalnz.org/
mod/resource/type/globe - browser and add items in Ariadne repositories
mod/resource/type/jmol - display chemistry structures from a jmol format file
mod/resource/type/rss - display one RSS feed on a page
mod/resource/type/slideshow - display a directory of images as a slideshow

Resource-like contrib modules

Separate modules will use similar migration techniques:

mod/book - displays multiple pages of HTML, print support, table of contents, etc.
mod/lightboxgallery - http://moodle.greenhead.ac.uk/external/lightbox_gallery/

New resource modules

The new modules will be:

mod/page - formatted text pages (combines text and html subtypes)
mod/resource - a folder of files, with one file selected as main file
mod/folder - a folder of files, listed for selection (view/download)
mod/url - a URL to an external page or file
mod/ims - an IMS package

mod/page

TODO: add mockups and descriptions of functionality

mod/resource

TODO: add mockups and descriptions of functionality

mod/folder

TODO: add mockups and descriptions of functionality

mod/url

TODO: add mockups and descriptions of functionality

mod/ims

TODO: add mockups and descriptions of functionality

Automatic upgrade

Each resource type requires different upgrade code because the files are stored in different places that require special handling. They also have different settings and options with different text encoding in the table fields: reference, alltext and options.

Resources that can not be completely migrated during upgrade time will be flagged using a new field called legacyfiles:

0 = new resource created in Moodle 2
1 = upgraded resource that has completed migration
2 = upgraded resource that has not started migration yet
timestamp = last date of a migrated file within this resource

File

Files in the course directory

Copy the linked file (image, sound, pdf, HTML, etc.) from course area to resource file area
If the file is HTML or SWF then flag this resource for post-upgrade processing with legacyfiles = 2 (see next section), otherwise flag with legacyfiles = 1

Files referenced by URL

(This includes links to other courses and site files)

This does not require any upgrade. The url is stored in reference field and will continue working.

Page (Web and Text)

Convert to one plug-in called 'page' (editable via the new editor forms element)
Flag this resource for post-upgrade processing with legacyfiles = 2 (see next section).

IMS

Copy files from moddata to new resource file area
Copy original backup of package file to another new resource area

No other special upgrade steps required.

Repository

Work out the URL of the resource and convert it to a simple URL.

Others

(TODO: Add some docs here for each type)

Post-upgrade processing

After the Moodle 2.0 upgrade has completed we take the admin to a special page that:

explains the issue of resources that contain links to other files
explains how it can be fixed by on-demand migration (see below)
presents an option for "automatic parsing" which tries to automatically migrate simpler resources such as HTML files with links to HTML files, images, CSS
presents a list of remaining flagged resources as links that need to be visited manually in the browser to be fixed

I imagine this interface might have a small frame on the left with the main pages being loaded in the larger frame on the right. The left frame has controls and info like:

total number of pages to process
next and previous buttons
some button to say "I have completely viewed this resource"

So the admin will have to sit there and go through all these resources and check them off to complete the upgrade. Until this process is finished none of these operations can be guaranteed to work so we might even think about disabling those operations:

Backup
Restore
Import of a course

Normal viewing of resources WILL work fine for teachers and students, because it will just trigger the normal on-demand migration of files.

On-demand migration of files

After the upgraded process we will have resources flagged with legacyfiles = 2 that need migrating, including:

html files possibly containing images, applets and javascript
flash applets containing relative links to media (eg sounds or images)
java applets containing relative links to media
javascript that loads media via relative links (eg imagine an auto-generated slideshow)

We still want to move all these legacy files into the correct resource filearea, so we do it like this:

When a browser requests to view one of these "legacyfile" HTML files, it will load all the JS and Java and Flash it contains.
These programs run, and make relative requests to media if they want to.
These requests to Moodle will hit the pluginfile.php script
The pluginfile.php script checks that the file doesn't exist yet in the resource file area, and if so:
1. pluginfile.php uses the relative path to copy the original file from the courses area to the resource file area
2. pluginfile.php updates legacyfile field for the resource to be the current timestamp, indicating that some processing has happened.

Problem: we don't really know when the resource is completely "finished" (ie every single associated file has been checked), so we can't automatically reset legacyfiles = 1 after this process. That's why the manual post-upgrade script described above is necessary.

Since we have a timestamp in there we COULD consider a cron job to reset the value to 1 once the timestamp has reached some old age (and it's unlikely that any more files need to be migrated for that resource) to prevent too much parsing. Alternatively we could contact the admin or teacher and ask them to confirm migration using the postupgrade script.

Candidates for removal

List of obsoleted or unmaintained features proposed for discontinuation.

hive repositories
hive SSO
special mod/resource/type/file/localfile.php (win32 only tweak), intended for large files stored on local networks or CDs
weblinkauth hook from login/index.php

TODO: add sections with more explanation and alternative solutions for sites that are still using these features

Other ideas

Dealing with caching issues

To have more control over the caching of files, we could use the same mechanism already implemented in the SCORM module, by changing the URL:

Internally store all files as itemid=0
Add new revision db field into resource table
When serving files always construct links with itemid==revision
Ignore itemid for resource files in pluginfile.php

Documentation

Resource module file API migration

Contents