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Amazon Alexa Uses HTTP/2

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Amazon Alexa Uses HTTP/2

The Amazon Alexa Voice Service API employs HTTP/2 as part of their voice-enablement platform. There's tons of information available in the documentation.

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I track on the different approaches used by API providers so that I know where to find examples of leading approaches to API design and deployment. Then, I write about them so that I have something to reference across my research. I keep an eye out for API providers who employ hypermedia as part of their API design as well as companies who are putting HTTP/2 to work as part of their design and deployment.

The Amazon Alexa Voice Service API employs HTTP/2 as part of their voice-enablement platform. I'm still learning about HTTP/2, so I was pleased to see the amount of education they provide in their documentation, outlining some of the key terms and concepts at play:

  • Frame. Frames are the basic protocol unit in HTTP/2, each frame serves a different purpose. For example, HEADERS and DATA frames form the basis of HTTP requests and responses.
  • Stream: A stream is an independent, bi-directional sequence of frames exchanged between a client and server within an HTTP/2 connection. For detailed information, see Streams and Multiplexing in RFC 7540.
  • Interfaces. AVS exposes interfaces (SpeechRecognizer, AudioPlayer, SynchronizeState, etc.) that provide your product access to Alexa’s built-in skills.
  • Downchannel. Downchannel is a stream you create in your HTTP/2 connection that is used to deliver directives from the cloud to your client. The downchannel remains open in a half-closed state from the device and open from AVS for the life of the connection. The downchannel is primarily used to send cloud-initiated directives and audio attachments to your client
  • Cloud-initiated directives. Directives sent from the cloud to your client. For example, when a user adjusts device volume from the Amazon Alexa App, a directive is sent to your product without a corresponding voice request.

They also provide details on crafting the HTTP/2 message headers, how to construct the HTTP/2 multipart messages, and what to expect with HTTP/2 responses. They have language SDKs in C/C++ (nghttp2), C/C++ (curl and libcurl), Java (OkHttp), Java (Netty), and Java (Jetty). I am particularly interested in learning more about how the cloud-initiated directives work and allow actions to be sent as part of each connection.

I'm tracking on the moving parts so that I can evolve my own understanding of HTTP/2 in action and start building a list of APIs who are taking a step forward when it comes to their HTTP infrastructure. It helps to have several different providers to point at when I'm talking about new approaches. I also like to aggregate the common elements that are present, and hopefully, begin to establish a common set of building blocks present when HTTP/2 is put to use. 

The State of API Integration Report provides data from the Cloud Elements platform and will help all developers navigate the recent explosion of APIs and the implications of API integrations to work more efficiently in 2017 and beyond.

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Published at DZone with permission of Kin Lane, DZone MVB. See the original article here.

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