reactphp NDJSON client decoder

processJSON.php

<?php
// NDJSON Ping/Pong communication:
//    1. Client send ONE JSON object
//    2. Server respond with ONE JSON obect
//    3. Client MIGHT send another JSON object
//    4. Server WOULD respond with OND JSON object 
//    5. ....
// Questions:
// [1] I use first() in combination with once(), because a data chunk MIGHT contain multiple NDJSON objects
//     2nd, 3rd object should be ignored... Is this a good practice?
// [2] Is it good practice to use once() rather than on() to "ignore" future data?
//     I reuse function in case of 2nd, 3rd,.. ping->pong call
function(Socket\ConnectionInterface $connection) : Promise\PromiseInterface {
    // new empty (temp) stream for processing
    $stream = new Stream\ThroughStream();
    // ... new JSON decoded stream
    $streamDecoded = new Clue\React\NDJson\Decoder($stream);

    // promise get resolved on first emit('data') [1]
    $promise = Promise\Stream\first($streamDecoded);

    // register on('data') for main input stream [2]
    $connection->once('data', function ($chunk) use ($stream) {
        // send current data chunk to processing stream -> resolves promise
        $stream->emit('data', [$chunk]);
    });

    return $promise;
};