gulpfile.js

// grab our gulp packages
var gulp  = require('gulp'),
    gutil = require('gulp-util'),
    exec = require('gulp-exec')

gulp.task('server', function (cb) {
  exec('node app.js', function (err, stdout, stderr) {
    console.log(stdout);
    console.log(stderr);
    cb(err);
  });
})

gulp.task('default', ['server']);