ndjson-process-stream

Duplex stream which takes objects, pushes them into process stdin as ndjson, takes ndjson from the process, and returns objects. It's like a through stream for processes. Meant as a convenience module for when you want to compute on JSONs from an external process. Comes with hello world examples from several languages (TODO). Exposes the underlying child process from this.cp.

const ndjsonProcess = require('ndjson-process-stream')
const intoStream = require('into-stream')

const data = [
  { foo: 1 },
  { foo: 2 },
  { foo: 3 },
  { foo: 4 },
  { foo: 5 }
]

intoStream(data)
    .pipe(ndjsonProcess('./foo_doubler.py'))
    .on('data', function (data) {
      console.log('Result: ', data.foo)

      // Python process has while True loop, need to manually kill
      if (data.foo === 10) this.cp.kill()
    })

Script Examples

TODO Node, R, Go, ...

Python

TODO a way without while True that doesn't have to wait for EOF from stdin?

#!/usr/bin/env python

import sys
import json

def compute(obj):
    obj['foo'] *= 2
    return obj

try:
    buff = ''
    while True:
        buff += sys.stdin.read(1)
        if buff.endswith('\n'):
            results = compute(json.loads(buff))
            print(json.dumps(results))
            sys.stdout.flush()
            buff = ''
except KeyboardInterrupt:
    sys.stdout.flush()
    pass

License

MIT http://jmazz.mit-license.org/