node.js - NodeJS/Express - live stream stdout of child_process.spawn to client -


i have small node application using express displays form, gets values , files, , feeds elf executable. i've been able capture stdout using child_process.spawn, can't send live client.

the stdout shows on client, when res.end() called. there way show output on client produced algorithm?

here's server code (the form basic form, , stdout should render blank webpage):

// builtin libraries var spawn = require('child_process').spawn; var exec = require('child_process').exec;  // external libraries var express = require('express'); var multer = require('multer'); var bodyparser = require('body-parser'); var s = require('string');  // create upload directory if doesn't exist var dir_upload = "/tmp/algorithm/files/" exec("mkdir -p " + dir_upload, {}, function (err, stdout, stderr) {  if (err) throw err; });  app.use(express.static('public'));  // parse text fields app.use(bodyparser.urlencoded({ extended: false }));  // parse files app.use(multer({ dest : dir_upload }).fields([{name: 'out'}, {name: 'label'}, {name: 'minor'}]));  // display form app.get('/', function (req, res) {   res.sendfile(__dirname + '/form.html'); })  app.post('/', function (req, res) {    res.writehead(200, {'content-type': 'text/plain', 'transfer-encoding': 'chunked'});    // add parameters array   var args = [];   var vopt = false;   var vstr = "";   var keys = object.keys(req.body), len = keys.length, = 0;   while (i < len) {       // basic argument parsing - not shown here   }    // input file paths   args.push(req.files.out[0].path);   args.push(req.files.label[0].path);   if (req.files.minor) args.push(req.files.minor[0].path);    // run algorithm   var command = __dirname + "/../algorithm_dir/src/algorithm";    // provide env aws centos environments old gcc versions   var algorithm = spawn(command, args, { shell: true, env: { 'ld_library_path': '/usr/local/lib:/usr/lib:/usr/local/lib64:/usr/lib64' }});   var output = "";    algorithm.stdout.on('data', function (data) {     res.write(data.tostring());   });    algorithm.on('close', function () {     res.end("\n----------done----------");      // remove input files     exec("rm -rf " + req.files.out[0].path + " " + req.files.label[0].path + " " + req.files.minor[0].path,          {}, function (err, stdout, stderr) {       if (err) throw err;     });   }); })  // listen on port 8080 var server = app.listen(8080, function () {   var host = server.address().address   var port = server.address().port })

just try set header not write then, as:

res.setheader("content-type", "some/type");

then write data & close did


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