General plugins

Offline Moodle: OLPC and GG-based offline-moodle

Martin Langhoff - Sailing
Offline Moodle: OLPC and GG-based offline-moodle
Hi all! I have been away for a while working on other olpc stuff, but now my attention is returning to Moodle, and offline moodle is definitely in my roadmap.

In the AU and NZ moot I had good chances to talk with Dan and MartinD about a cunning plan to get a Gears-based offline moodle going.

When we disscussed architecture for the current moodle-on-a-stick (MoaS) based we also talked quite a bit about a Gears-based approach. At the time, it looked huge and risky. Google had just released GG, and was talking about upgrading Reader to use it.

So there many things stacked against it: Noone had seen Reader doing the offline thing yet, Gears had a somewhat restrictive license, and it seemed that we'd have to implement a significant chunk of Moodle as an AJAX application.

Things have changed between then and now. Google has made things much simpler now with a BSD license and Reader shows it can make the offline thing work very well.

Reimplementing Moodle as an AJAX app was still a big monster in my head until recently. But a volunteer approached me recently saying he could take a stab at it, and I thought "what would be the simplest thing that could possibly work?"

The answer was suprisingly simple: store the damn HTML, CSS and JS in the sqlite DB that Gears provides.

So from the course page, we can "go offline" by

- Storing the html+css in sqlite -
- Requesting a special 'manifest of resources that are ok to use offline' - published by the course-format page...
- Retrieving those offline resources. Initially, just mod/resource contents. Later we can extend this support to work with other modules.
- When we use the course homepage later while offline, we'll walk the DOM to show CSS blocks 'disabled' (by graying them out) and we will disable links to resources we cannot support offline.
- As the user browses the content we do have offline, the JS code keeps track of resources visited. Upon reconnection to the moodle site, we push back the collected logs to mdl_log(*)
- Other modules (mod/forum for example) can be supported with ob magic and/or more explicit/AJAXy use of JS.

* - we'll need to review the log handling code. So far we've never had "out-of-sequence" log entries, and this will introduce them for the first time. I'm sure there'll be a few gotchas there.

Hearing this, MartinD suggested that - as long as we go the "store html" way (supported with output buffering tricks if needed) then we can add the ability to produce a plain old zipfile with a course homepage + static resources. I think it's a good secondary goal to have -- though I'm not sure what limits we'll have with this.

Tony Anderson - the volunteer who sparked this - has been working on a proof-of-concept implementation. It currently uses Gears and GreaseMonkey, and requires a few manual tweaks. Unfortunately, I don't think that code can be merged directly - we will want to refine the approach to avoid GreaseMonkey and other inconveniences. My take is that we can either adapt it, or use it as a reference for a more moodlish implentation -- Tony is not a moodle dev, so he's not necessarily familiar with our odd style smile ).

Tony's code is here together with some discussion around it.

I also hear noises from Barcelona -- Ludo and Ruben may be able to get involved. This could start getting interesting.

Getting this from a PoC to something shippable will take a bit of work. Right now I still have a ton of work to do on other aspects of Moodle that are more urgent for OLPC, but I will find the time to work on this working with Tony, Ludo and Ruben. Sleeping is optional, right? wink

Once the urgent infrastructure stuff for olpc is sorted, I'll be keen on bringing this to completion -- at least of an initial stage.

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Picture of Ludo (Marc Alier)
Re: Offline Moodle: OLPC and GG-based offline-moodle
Gears sounded like a exciting way to go right when Martin L told me on Skype two weeks ago. That's why I've committed a talented guy like Ruben to dig on this task. We are starting to work on it, and it might even work wink

BUT, in I've been working on a WS architecture for Moodle that can allow SOME features of Moodle to be taken out to offline clients (I'm thinking about Java Phones, iPhones and other no Gears powered machines.

As Martin L. says some things move so fast we will not keep up to, BUT maybe we can choose a part of moodle that makes sense to have in a limited device like a phone or an ipod or nintendo ds, and bring it there. This way will never aspire to take out all the features (due to the development rithms that wise ML tells me ) like the gears approach... but hey! is worth a try. So I will put people on both bets. And we are working on WS for other purposes as important as this one

Sleeping is optional, sure :p
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Dan at desk in Moodle HQ, Perth
Re: Offline Moodle: OLPC and GG-based offline-moodle
Core developersMoodle Course Creator Certificate holdersMoodle HQPlugin developersTesters
Interesting idea - though I do wonder how many moodle courses would survive this transition without some sort of proxying magic for external sites.
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Martin Langhoff - Sailing
Re: Offline Moodle: OLPC and GG-based offline-moodle
True, if you are using external content a lot, this won't help mixed

This depends on your course content prep style. If you are going to be supportive of offline users, then you want to pull more stuff "into" the course -- still providing suitable links.
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Picture of Tony Anderson
Re: Offline Moodle: OLPC and GG-based offline-moodle
This feature is being reimplemented. The basic framework is in place. The roadmap is (1) add resources (.swf, .pdf) to the Gears manifest, (2) collect information from offline student activity to update the Moodle database when the student goes back online, and (3) complete the process for appropriate interactive elements (lesson, quiz, forum, ...).

The context is that the Moodle site will be the local schoolserver. There will be intermittent access to the internet with low bandwidth. This means that courses will have to bring all essential resources local to the schoolserver. The XO has limited local storage (1 GB) so that the student will take sections (topic/week) offline, not the entire course.

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