Playing with Shindig/OpenSocial Adding a New Feature and a Service

I have been talking recently with folks at the Open University (UK), Open University of Catelonia, Ian Boston from Sakai 3, and a few other organizations about the emergence of an “OpenSocial Learning Gadget”. We had a nice Gadget BOF at the Sakai Conference in Denver where Ian Boston (also a Shindig committer) gave a little tutorial on Shindig Architecture and how to add a Shindig feature and plug Shindig into something like Sakai.

It seemed really clear and obvious and it felt to me that there was a nice way forward to build a Shindig feature (i.e. extension) to define a learning gadget and perhaps line up all of these disparate efforts across vendors and projects and make it so a “learning gadget” could run in any LMS that had Shindig with the learning extension.

So two weeks ago with some help from Ian, I downloaded the source to Shindig and started banging around with Shindig. Ian helped me a lot and the Apache Shindig developer list also gave me some wise advice at key moments where I would get lost and confused.

I had three goals in mind as I went through the Shindig code:

(1) Add a “feature” – an extension loaded into the browser that makes an API available to the Javascript code running in the widget.

(2) Add a run-time server-side service to support the feature – the code of the client-side feature would call this server-server API/service to retrieve things like course name, role of current user, set outcomes, etc. I need do find out how to write a service and register it both in the server Java code and in the client JavaScript code.

(3) Bang around until I understood the security model and the provisioning and launching of gadgets from the container (i.e. the LMS)

I also wanted to explore how the SPI (Server Program Interface) pattern worked in Shindig. Pluto 1.1 used the SPI pattern and it was really well done and made it really straightforward to add JSR-168 support to Sakai 2 back in the 2.4/2.5 days.

Part of my investigation was to take notes as I went along and possibly propose a general capability for Shindig list to add these features without touching any core Shindig code. It may be tricky because even though there is Javascript, there is compile and run-time bits needed.

Along the way, I banged away at Apache Shiro – the generic Authentication and Authorization project. I found Shiro kind of interesting and I particularly liked its feature where Session can exist even if a web browser is not involved in the interaction. In one of my early explorations, I tried to hack Basic LTI Provider code in to Shiro and came up with some ways to improve the plug-ability of Shiro – but then I realized it had little to do with what I was investigating with Shindig – so I dropped my Shiro investigation and went back to Shindig.

I am happy to report that Shindig is pretty cool and well structured internally. It was pretty easy to find all of the necessary places to plug my code in. It is not all too well documented and it is not set up to add features or services without modifying source code.

I promised to write someShindig documentation regarding how this all worked which I will do in a couple of blog posts over the next week after I clean up the code a bit to make it more presentable.

Next post in the series.

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