如果其他服务器无法访问，则Node.js应用程序退出。 如何防止我的应用程序停止？

Question

I am writing an application that regularly checks in with a remote server to check in for new versions of software. It's my first attempt in node.js so please bear with me. When the server is up and running, the program runs totally fine.
However, when the server is not running, the program quits with the error:

events.js:72
throw er; // Unhandled 'error' event
      ^
Error: connect ECONNREFUSED
at errnoException (net.js:904:11)
at Object.afterConnect [as oncomplete] (net.js:895:19)

From what I've read, I believe I have set up my code to handle errors correctly, by including a response.on('error', ...) part of my callback. However, as you can see from the error, it's not giving me the error console.logs that I tried to set up. Here's the part of my code that is not working, I can include other parts if need be, it's just a pretty big application at this point:

var index = require ("./index");
var http = require ('http');
var fs = require ("fs");

var apps = [{
  "name":"IDSocket",
  "localVersion": "",
  "hostVersion": "",
  "downloadURL": ""
},
{
  "name": "X-Wing vs. Tie Fighter",
  "localVersion": "4.2.1",
  "hostVersion": "",
  "downloadURL": ""
}]

//checks host server for host version, stores as json object
function checkHost(hostinfo){
  callback1 = function(response) {
    var str = '';
    var hostObject;

    response.on('data', function (chunk) {
      str += chunk;
    });

    response.on('error', function(err) {
      console.log('problem with request: ' + err.message);
      hostObject = "why, error? " + err.message
    });

    response.on('end', function () {
      hostObject = str;
      hostObject = JSON.parse(hostObject);
      apps[0]["hostVersion"] = hostObject[0]["version"];
      apps[0]["downloadURL"] = hostObject[0]["downloadURL"];
      apps[1]["hostVersion"] = hostObject[1]["version"]
      apps[1]["downloadURL"] = hostObject[1]["downloadURL"]
      console.log(apps[0]["hostVersion"] + ": recieved IDSocket host version");
      index.everyFourHours();
    });
  }

  http.request(hostinfo, callback1).end();

};

Thanks in advance for any helping me understand what's going on here!

EDIT: things I have tried so far:

try block on both the http.request line as well as the whole callback function with catch blocks that just console.log the error

process.on('uncaughtException'

domain.create & domain.run

Answer 1

You should be adding an error handler to instance of your http.request .

For example, you could change your http.request call to:

var req = http.request(hostinfo, callback1);
req.on('error', function(err) { console.log("ERROR: " + err.message); });
req.end();

Read here for more info.