express-end

Express middleware to emit end event on res.end()

res object has following events:

• header - when HTTP Header is written,
• close - when connection is closed from client side
• finish - when request processing finished (*)

(*) Unfortunately, if client has closed its connection, there is no event signalling that the server side finished the processing of the request as finish event does not fires in this case. It may be correct from abstract framework perspective as the request to be terminated without response to the client (and network connection is closed) and looks like it's does not matter whether the server finished the processing or not. However, there are several negative outcomes of this approach. One of them is that middleware has no information when the server has really finished the processing of the request.

This module overrides res.end() function to emit end when res.end() is called, i.e. when processing by server is finished independently of whether the connection was closed by client or not.

Usage example:

'use strict';

var express = require('express');
var http    = require('http');
var endMw = require('express-end');
//var endMw = require('../');
var app = express();

app.use(endMw);

var count = 0;

app.use(function(req, res, next) {
  var current = ++count;
  console.log('[%d] app.use()', current);

  res.once('close',  function() {
    console.log('[%d] app.use(): res.once(close)', current);
  });

  res.once('end',    function() {
    console.log('[%d] app.use(): res.once(end)', current);
  });

  res.once('finish', function() {
    console.log('[%d] app.use(): res.once(finish)', current);
  });

  next();
});


var httpPort = 8080;
var RESPONSE_DELAY = 1000; // Milliseconds

app.get('/test1', function (req, res) {
  var result = { test: 'test' };
  setTimeout(function() {
    res
      .status(200)
      .send(result);
  }, RESPONSE_DELAY);
});


var server = http.createServer(app);

server.listen(httpPort, function () {
  console.log('* Server listening at %s:%d', server.address().address, server.address().port);
});

Log (first request completed by server, second request cancelled by client):

$ node app.js 
* Server listening at :::8080
[1] app.use()
[1] app.use(): res.once(end)
[1] app.use(): res.once(finish)
[2] app.use()
[2] app.use(): res.once(close)
[2] app.use(): res.once(end)

The source code for this example is located in demo/ subdirectory of package

You may also have a look on the discussion on the topic at stackexchange: http://codereview.stackexchange.com/questions/20069/monkey-patching-extra-events-in-node-js-http-express

If you have different needs regarding the functionality, please add a feature request.

Installation

npm install --save express-end

Usage

Credits

Alexander

Links to package pages:

github.com   npmjs.com   travis-ci.org   coveralls.io   inch-ci.org

License

MIT