This demo service is a vanilla implementation of a Rails application using Crichton. It exposes several resources representing Diagnostic Repair Drones (DRDs).

The Crichton resource_descriptor describes a simple state machine with conditions on the various transitions. These conditions would typically be determined in the context of a request and passed in as options in the response. In order to see Crichton's runtime generation of available transitions based on both the state of resources and the satisfied conditions, a query parameter ?conditions=can_do_something can be added in the browser to mimic this on the fly.

It further describes the semantics of the resources and the protocol-specific implementations used to generate the responses.

$ bundle install
$ rake setup
$ bundle exec rackup -p 3000

Take a look at the controllers and models to see the basic implementation for both single entities and resources that embed other resources with meta-data.

So, enter the API by browsing to localhost:3000/drds in browser and and follow your nose. You can add the following conditions, either as a single value, or comma-separated list at any time to see what changes:

• can_do_anything
• can_create
• can_update
• can_delete
• can_activate
• can_deactivate
• airlock_open

E.g. localhost:3000/drds?conditions=can_delete,can_activate

Crichton also supports out of the box a lighter xHTML response. You can play with this, as a machine client would, using curl:

$ curl --header "Content-Type: application/xhtml+xml" GET localhost:3000/drds

You can add the conditions query parameter here as well.

$ curl --header "Content-Type: application/xhtml+xml" GET localhost:3000/drds?conditions=airlock_open

Don't miss the profile link when you view source in the head tag for responses. This ALPS profile is generated from the resource descriptor and represents all the semantics and affordances that you will find in a response: localhost:3000/alps/DRDs

If you are wondering what happens if I include an HTML view, change the name of the index.html.orb file to index.html.erb and then reload the URL localhost:3000/drds.

Hint: it works like it should.