Comment by notheguyouthink

7 years ago

> Idempotence is not the problem here, by the way. That just means calling the method twice has the same effect. But GET should have no side-effect, in an ideal world. Of course, in the case of unsubscribe links, it needs to have a side-effect to comply with the law.

Thank you! I felt like I was taking crazy pills with my understanding of idempotence.

Calling GET /door/open is idempotent too, but it's still gross in my opinion. The author makes it sound like that would be fine.

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notheguyouthink

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chaosmonkey  7 years ago

I think he only had GET /door/toggle, which cannot be idempotent.

  • notheguyouthink  7 years ago

    Yea, but his point was that GET requests should be idempotent.. when that's not the important part of GET. That's why I used the example of GET /door/open, because that is idempotent, but it's still gross - it's causing a state change from a GET request while still being idempotent.

    GET being idempotent is not the issue the author was dealing with. State change from a GET is the real issue.

  • luma  7 years ago

    He mentions later in the thread that he doesn't have a sensor to indicate door position, which is going to kill this project and absolutely prevents an idempotent approach. There are a bunch of ways to approach this, most of which are patented by Chamberlain, which is the specific reason you don't find many garage automation solutions sold as a bundle in the US.

    Typical bolt-on solutions would be a range finder pointing down from the ceiling near the door which can tell if the door is obstructing it, a tilt sensor mounted to the top door panel, or limit switches on the carriage way/tracks. With a door position sensor in place a simple momentary-contact dry relay can be used to trigger door motion.

    Once that is in place, you can add another WeMos D1 mini to your car to open and close the door with no interaction: https://github.com/aderusha/MQTTCarPresence

    • wpearse  7 years ago

      I wasn't looking forward to running cable for sensors (I need two reed switches per door, as the doors can stop half-open). The D1s are at the back of the garage, so maybe 8m of cable per switch and two doors = 30-ish metres of cable? (90 feet?)

      Range finder seems like the best idea. I was thinking of mounting it on the door motor and pointing horizontally down the track at a reflector attached to the chain/handle.

      I love the idea of putting a D1 in the car. Thanks for the link!

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