[Beowulf] Lambda and Alexa [EXT]

[Tim Cutts]

Indeed, my main personal experience with Lambda so far has been in writing an Alexa skill in my spare time.  It’s been quite fun, and very instructive in the benefits and pitfalls of lambda.

My main takehomes so far:

1.  I love the fact that there’s basically no code at all other than that required to deliver the actual skill. Just handler functions for the incoming requests (Intents, as Amazon call them)

2.  Debugging is awkward.  There is no interactive debugging, as far as I can tell.   Log inspection is about all you have, and some errors are obtuse (for example, some valid Node.js constructs produce syntax errors on Lambda, and it’s very hard to track down when it happens - unit tests all pass locally but then you get a syntax error in the LogWatch logs, with a useless stack trace that doesn’t tell you where the syntax error is).  Debugging and unit testing on your laptop is hard to do; many Alexa APIs rely on real hardware functions and the simulators don’t handle them.

3.  Persistence of data is fairly straightforward using S3 buckets or DynamoDB, and I haven’t noticed latency issues with those (of course the interactions are on a human timescale, so latency isn’t really much of an issue)

4.  Interaction with external services can be problematic; Alexa lambda functions must return within 8 seconds, which can be fun if your skill needs to fetch data from some other source (in my case a rather sluggish data service in Azure run by my local council), and there’s no clean way to handle the event if you hit the 8 second limit, the function just gets terminated and Alexa returns a rather meaningless error to the user.

Tim

On 25 Nov 2020, at 09:45, John Hearns <hearnsj at gmail.com<mailto:hearnsj at gmail.com>> wrote:

BTW, I am sure everyone knows this but if you have a home assistant such as Alexa everytime you ask Alexa it is a lambda which is spun up





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