JavaScript Interop #9
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This allows me to extend the opts:
requestPort: 'requestPort',
responsePort: 'responsePort',
bindPorts: bindPorts,
});
and provide an intercept:
const bindPorts = function(app) {
| , parseRoute = UrlParser.parseString Route.route | ||
| , update = update | ||
| , subscriptions = subscriptions | ||
| , interop = Serverless.Interop interopEncode interopDecoder |
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Replacing general purpose subscriptions with interop parameter. This is because we need to associate calls to JavaScript with specific connections. Serverless.Interop provides a way to do that
| -} | ||
| type Interop | ||
| = GetRandom Int | ||
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This is an enumeration of the kinds of interop functions we can call, with signatures
| interopEncode interop = | ||
| case interop of | ||
| GetRandom upper -> | ||
| Encode.int upper |
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Note that signatures are not restricted to the usual values that can pass through a port, because we JSON encode the arguments before passing them through the port. This is to avoid a type explosion. The user provides a function to JSON encode arguments to Interop functions
demo/src/API.elm
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| ( GET, Number ) -> | ||
| ( Conn.interop (GetRandom 10) conn | ||
| , Cmd.none | ||
| ) |
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Here the interop function is being called. Not super happy about the side-effect being put into the conn, but it was the cleanest syntax. It also opens up interop to middleware (i.e. Conn -> Conn functions), which could either be seen as a good thing, or a bad thing.
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| interop: { | ||
| getRandom: upper => Promise.resolve(Math.floor(Math.random() * upper)), | ||
| }, |
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On the JavaScript side, the user writes an interop function handler. The interop call was GetRandom 10, so the function is named getRandom
| interopDecoder interopName = | ||
| case interopName of | ||
| "getRandom" -> | ||
| Just <| Decode.map RandomNumber Decode.int |
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The value that gets returned from JavaScript needs to be decoded, and wrapped in an app msg
demo/src/API.elm
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| RandomNumber val -> | ||
| ( Conn.respond ( 200, text <| (++) "Random value: " <| toString val ) conn | ||
| , Cmd.none | ||
| ) |
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Now the interop value can be handled in the usual update function
Also Converted endpoint from message into a function.
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Fixes #2 |
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