For December’s [Project a Month Project]–ject.html) I decided to tackle an idea I’ve been meaning to work on for a few years now. Back in 2008 I built a contextual help system into a Rails 2-point-something application. The idea was a simple one–I created an external knowledge base of tutorials for the application. My application assigned a URL for a specific tutorial to a Rails controller-action combination. Finally, the Help link present in the application’s layout file intelligently linked to a context-specific tutorial based on where the user was within the application. It worked well, and since then I’ve had other uses for such a technique. I just never got around to doing anything with it until now.

Rather than just embedding such an approach in future applications, I can now use Docent. To build Docent I took advantage of mountable engines in Rails, meaning that it technically runs as a small, separate application within a main Rails app. I hadn’t yet done much with mountable engines, so this was a good opportunity to learn more about them.

As it turns out, mountable engines are easy to get started with. I’m going to write some more technical information in an upcoming Everyday Rails post. I also took the opportunity to publish my first gem–which means it’s easy for anyone to install Docent into their own Rails 3.2 applications. Not suggesting that anyone should–I’ve still got more real-world testing to do, but hopefully making it accessible will help others make improvements on the concept.

My big takeaways:

• Engines–mountable or otherwise–are an excellent way to extract functionality from medium-to-larger Rails applications and make for more manageable codebases.
• Engines are also great opportunities to contribute your work to open source.

I do have a couple of things I’d like to keep messing around with in Docent:

• I’d like to figure out how to replace the HTTP basic authentication I’m using with the host application’s authentication. Still looking around for different approaches to this–the challenge is the separation inherent between the mounted and host applications.
• Big ticket: I’d someday like to be able to post directly from the likes of ScreenSteps into a knowledge base contained within Docent itself. I figure this involves fun stuff like XMLRPC (as ScreenSteps supports it), handling file uploads in the process.