gistfile1.js

var express = require('express');  
var _ = require('highland');  
var fs = require('fs');  
var app = express();

function chain(s, f) {
  return s.flatMap(_.wrapCallback(f))
}

app.post('/process-file', function(req, res) {  
  var inputFile = 'input.txt';
  var outputFile = 'output.txt';

  var data = _([inputFile]);
  
  _([
    fs.readFile,
    process1,
    process2,
    process3,
    writeToFileName(outputFile)
  ]).reduce(data, chain).flatten()
    .stopOnError(function (err) {
      return res.status(500).send(err);
    }).apply(function (data) {
      return res.status(200).send('processed');
    });
});