I would only reach for service-oriented architecture after the application is very mature and it is apparent which parts will benefit by moving to their own services.
I find rails in particular to be very easy to just "api all the things" right off the bat. Add in some nice authentication / authorization with something like devise and CanCan and you will be saved from the headache of bolting an api onto your app as an afterthought.
I'd like to hear more on how you setup your service architecture afex (if time permits). Sounds like exactly what I'm trying to accomplish. Thanks in advance!
