The most common way to start developing for Alexa is with custom skills while not too many of us except for device manufacturers get in touch with Smart Home skills on Alexa. This session introduces and demonstrates the power of Smart Home skills and it takes a look behind the technical scene of what happens in between an “Alexa, turn on the lights” and Alexa´s final “Ok” confirmation. Once you are familiar with the concept of Smart Home skills you will find out that it’s not just for implementing large-scale Smart Home solutions as the Smart Home API is also a great playground for your next Do it Yourself project. At the end of this session you’ve learned about the probably simplest way to build a Smart Home project with Raspberry Pi and AWS IoT – and you will be equipped with essential knowledge on how to build your own voice-controlled “thing”.

1. © 2018, Amazon Alexa, All rights reserved.
Kay Lerch, EU Head of Solutions Architecture, Alexa Smart Home, Amazon, @kaylerch
October 19th, 2018
Building Smart Home Skills for Alexa
Alexa Smart Home

2. Agenda
Alexa Skills Kit
Alexa Smart Home Skills
Alexa Smart Home API
Demonstration

3. Alexa Skills Kit

4. Alexa Skills
Skills represent the interaction capabilities of Alexa
Answering questions
Providing news and weather information
Playing music
Playing puzzles or games
Control lights and other devices in the home
Viewing smart home camera feeds
Checking the status of orders
... Plus many others …
Visit alexa.amazon.com and review the skills available

5. Types of Alexa Skills
Custom Skills
Smart Home Skills
Flash Briefing Skills
Video Skills
List Skills
For crafting unique game or app experiences
For providing flash briefing content
For providing video playback of content
For using and maintaining lists
For controlling a smart home and devices

6. Alexa Skills Kit
The Alexa Skills Kit (ASK) lets you teach Alexa new skills
It contains the documentation, tools, and sample code
needed to build Alexa skills
Documentation
https://developer.amazon.com/docs/ask-overviews/build-skills-with-the-alexa-skills-kit.html
Tools
ASK CLI
https://developer.amazon.com/docs/smapi/quick-start-alexa-skills-kit-command-line-interface.html
Sample Code
https://github.com/alexa
https://github.com/alexa/alexa-smarthome

7. Alexa Frameworks

8. Alexa Skills Kit

9. Alexa Skills Kit: Signal Processing

10. Alexa Skills Kit: Utterances into Intents
Text to Speech
SSML, streaming audio

11. Alexa Smart Home Skills

12. What can an Alexa Smart Home Skill do?
Turn lights on and off
Turn a switch on or off
Change the brightness of dimmable lights
Change the color or color temperature of a tunable light
Change the temperature on a thermostat
Lock a lock
Query a lock to see if it is currently locked
Ask for a smart home camera feed
Change the volume on a speaker
Change the channel of a TV
… and many more
https://developer.amazon.com/docs/device-apis/list-of-interfaces.html

13. Alexa Smart Home Skills
Alexa Smart Home Skills are a type of skill designed to control home
automation devices
Smart Home Skills have common invocation commands to control lights, switches, locks,
TVs, cameras, fans, thermostats and other devices
Smart Home Skills have a section in the Alexa application for configuration, control, and
status of devices
Customers link their account through the Alexa application with a device cloud and the
devices associated with that account
Usually have their own device cloud for tracking external user/device mappings
https://developer.amazon.com/docs/smarthome/understand-the-smart-home-skill-api.html

14. Alexa Skills Kit: Smart Home Skills
Text to Speech
SSML, streaming audio
Golden Utterances Directives,
Controllers
Capabilities,
Device State
Your Lambda

15. Alexa Smart Home API

16. Messages
Information exchanged between Alexa and a Skill is done
through Messages
Directive
A type of message from Alexa to a Skill
Alexa sends directive messages to a skill on behalf of the customer
Event
A type of message from a Skill to Alexa
A skill responds to directives with event messages

17. Message Structure
A Message is JSON formatted content consisting of a
Header, Endpoint, Payload and optional Context sections
Header
Provides identifying information about the message
Endpoint
Identifies a directive target and event origin
Payload
Message content that varies by the type of capability
Context
Allows state reporting from any event message

18. Directive
{
"directive": {
"header": {},
"endpoint": {},
"payload": {}
}
}
Message Structure Example
Event
{
"context":{
"properties":[]
},
"event":{
"header":{},
"endpoint":{},
"payload":{}
}
}
https://github.com/alexa/alexa-smarthome/tree/master/sample_messages

19. Alexa Smart Home Skill API
Account Linking

20. Account Linking
Account linking "links" a User Smart Home Skill to a device cloud
User credentials are provided and authenticated when a smart home skill is enabled
Alexa sends the User credentials as a bearer token in the directive scope
That token is used to validate the User with your system
Device Cloud provider is responsible for securely storing the Access and Refresh Tokens
Account linking is required for a smart home skill
Account Linking Flow
1. User enables a Smart Home Skill in the Alexa application
2. User authenticates and links their account with a device cloud
3. User then discovers devices associated with that account and device cloud
4. The linked credentials can be used for sending asynchronous messages to Alexa

21. Smart Home API - Authorization

22. Smart Home Skill Account Linking Flow
1. User
Enable and Account Link my Partner Skill
2. Alexa
Redirect the User to the Partner authorization
3. Authorizer
Validate the User credentials and return an Access Token to Alexa
4. User
Commands: Alexa, turn on Light
5. Alexa
Asks Partner to use the provided Access Token to turn on the Light
6. Authorizer
Validates the Access Token and turns on the Light

23. Alexa Smart Home Skill API
Device Discovery

24. Capabilities
Capability interfaces describe the functional capabilities of an endpoint
The interfaces are composed of functional primitives that allow generic
commands to be used for different types of endpoints
For a full reference, see the Smart Home Skill API Message Reference
https://developer.amazon.com/docs/smarthome/smart-home-skill-api-message-reference.html

25. Smart Home API - Discovery
“discover my smart devices”
Capabilities
Controllers
Directive

26. Capability Interface Examples
Interface Capability
Alexa.PowerController Turning on or off
Alexa.ChannelController Change, increment, and report the channel
Alexa.PercentageController Sets a percentage
(Percentage, Intensity, Speed, etc.)
Alexa.ColorController Change and report the color
(Hue, Saturation, Brightness)
Alexa.PlaybackController Control playback
(Play, Pause, Rewind, etc.)
Alexa.ThermostatController Set a temperature or point or range

27. Capability Interface Examples
Thermostats
Home Audio
Small Appliances
Large Appliances
Home Security
TV / Video
Alexa.InputController
Alexa.StepSpeaker
Alexa.Speaker
Alexa.ChannelController
Alexa.PowerController
Alexa.ThermostatController
Alexa.TemperatureController
Alexa.LockController
Alexa.PowerController
Alexa.TemperatureController
Alexa.PowerLevelController
Alexa.TemperatureController

28. Capability Interface Examples: What is Next?
Possible Capability Interfaces
Alexa.BrightnessController
Alexa.CameraStreamController
Alexa.ChannelController
Alexa.InputController
Alexa.PlaybackController
Alexa.PowerController
Alexa.Speaker
Alexa.StepSpeaker
Alexa.ThermostatController
Super Console 3000
Imagine a prototype device that
is packed with all sorts of
functionality
Display
Speakers
Camera
Thermostat

29. Alexa Smart Home Skill API
Device controls

30. Smart Home API – Control action
“turn on my living room light”
Directive
Controller
Device State

31. Synchronous/Asynchronous Messaging
A directive response event can be either synchronous or
asynchronous
A synchronous response must be handled in 8 seconds or less
An asynchronous response is used for some slower interface operations
For example, a DeferredResponse is supported by the LockController interface

32. Smart Home API – Control action
“set living room light to green”
Directive
Controller
Device State

33. Alexa Smart Home Skill API
Device state management

34. Smart Home API – State updates matter …

35. Smart Home API – But what if …

36. Smart Home API – Proactively reporting state
Alexa Event
Gateway

37. Smart Home API – Reactively reporting state
Alexa Cloud

38. Smart Home API – Configure state updates
Device
proactively
reports state
updates
Device
responds to
state report
requests

39. Reporting State
Device State Change Notifications
Event messages are used to provide proactive state updates to Alexa
Changes in state can be reported during normal responses via the context in a Response
Endpoints can be asked by Alexa to report state directly from a ReportState directive
State changes can also be reported asynchronously through the Alexa Event Gateway via a
ChangeReport
For example, if a switch is manually turned off by a user, the device cloud controlling the switch can send a
message to Alexa that will update the representation of the device to the user

40. Smart Home API – End to End

41. Smart Home Skills vs Custom Skills
Smart Home API Common Directives
Users have easier, common invocation commands:
"Alexa, lock the front door." vs "Alexa, tell {skill} to lock the front door."
"Alexa, show me the backyard camera." vs "Alexa, ask {skill} to show me the
backyard"
Users don't have to remember custom skill invocation names
Developers have less control over the user experience but also do not have to craft
the interaction model
Endpoint directives map to the capability interface defined in the
namespace
Alexa.PowerController: "Alexa, turn on office light"
Alexa.ThermostatController: "Alexa, set thermostat to 20"
Alexa.ColorController: "Alexa, set the kitchen light to orange"
…
https://www.amazon.com/gp/help/customer/display.html/ref=hp_left_v4_sib?ie=UTF8&nodeId=201749260

42. Demonstration

43. Resources
Smart Home Portal
https://alexa.design/smarthome
Smart Home Code
https://github.com/alexa/alexa-smarthome
https://github.com/alexa/alexa-smarthome/wiki
Developer Slack Channel
https://alexasmarthome.slack.com
Invite Link: https://alexa.design/smarthome-invite-slack
Legacy Smart Home API V2 Reference
https://developer.amazon.com/public/solutions/alexa/alexa-skills-kit/docs/archive/shv2-
understanding-the-smart-home-skill-api