In my recent quest to integrate Alexa with my HAI OmniPro system, I had looked at both direct Amazon integration and at the Samsung SmartThings device. Because of the complexity involved with the Amazon setup, I had decided I would take the easier route and write an interface to SmartThings. SmartThings has an open API, allows you to create "virtual" devices and has built in support for Alexa without using the "trigger" word kludge.
Fast forward two weeks from when I made that decision and now Amazon has released (4/5/2016) an easier framework for integrating Smart Home devices/systems to the Alexa service. Since I'm still waiting for the SmartThings device to arrive, I started playing with the new Alexa Smart Home API. You need to create an Amazon developer account to do it, but individual usage should be low enough that there shouldn't be any monthly billing. The one requirement of using the Amazon interface is that you need a web based/cloud service that Amazon can talk to. That part I already have with a program I built a few years back that I call HAI Data Service. It currently logs all HAI activity and lets me control items via web links. I'll need to extend it and tweak it to work with Amazon, but that shouldn't be too difficult. Right now, my first learning hurdle is implementing oAuth 2.0 authentication with Amazon, but once that's ironed out, the rest should be pretty easy.
I see this new offering from Amazon as really opening up the options for people to integrate with Alexa. Right now they only support lighting and thermostats with the API, but it's not hard to map macros or scenes into the lighting on/off capability.
Blog post from Amazon:
https://developer.amazon.com/public/community/post/Tx1KIRDSNFDHEA4/Amazon-Enables-Developers-to-Extend-Alexa-s-Smart-Home-Capabilities-a-New-Additi
Developer Home Page:
https://developer.amazon.com/public/solutions/alexa/alexa-skills-kit/content/smart-home