Error: Not connected to the internet when invoking http.createServer

[espruino-discuss]

Posted at 2016-11-02 by pthieu

Want to invoke http.createServer outside of connecting to a network or creating access point. But I get this error:

Error: Not connected to the internet

My code follows this logic in event loop:

1. Start AP
2. Try to connect to network
3. Start web server
4. Stop AP when successfully connected to a network

i.e.

E.on('init', function() {
    APCheck = enableWifiScan();
    startAP();
  // If we try to connect to wifi at the same time we scan, there will be
  // conflicts and scan will return nothing
  setTimeout(function() {
    connectToWifi(); // If successful, stops AP
  }, 2000);

  // Create server anyway as we'll allow for control of the MCU through AP
  // if it has not connected to a network
  http.createServer(getPage).listen(80);
});

The reason for this is I want to be able to have the MCU serve a configuration page which will allow user to configure the network to connect to, making the device portable without hardcoding a network.

I could probably start the server after access point has been created, add a check to see if a server has been instantiated after connecting to a network, but wondering if there's an easier way.

[espruino-discuss]

Posted at 2016-11-02 by @gfwilliams

I'm pretty sure the problem is that JavaScript executes asynchronously. Obviously I don't know what is in your startAP/enableWifiScan functions, but usually when you execute a command startAP, it returns immediately and calls a callback when the AP is connected.

For instance for Espruino Wifi you need:

wifi.startAP(ssid, options, function() { 
  // this is executed when connected and should start the server
});
// this code is executed before it is connected

Also, which device are you using the Wifi on?

---

Posted at 2016-11-02 by pthieu

@gfwilliams:

ESP8266 NodeMCU 1.0 (ESP-12E)

Yes, the issue is the event-driven nature of JS. I was looking for a way to write simpler code since there isn't a reliable async or Promise flow control library to use; I'll have to work with flags then. Some questions:

1. Do you know if http.createServer() returns a new instance with a listener every time it's invoked like node.js? Or is there code beneath the hood that will check for an existence of a http.Server object? I did a quick test to invoke http.createServer() twice in succession and there was no namespace conflicts or EADDRINUSE errors, nor did the callback trigger twice upon a POST to my ESP8266.

2. Does the Wifi class trigger an event when it has connected to a network? Something like Wifi.on('connected', function(){...}) -- Nevermind, found the docs: http://www.espruino.com/Reference#t_l_Wifi_connected

3. Is there a way to save a key/value pair to flash? (or just any variable)

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Posted at 2016-11-02 by @gfwilliams

There is a promise library, at least in later versions of Espruino. createServer will create a second server in JS which will confuse matters, but presumably the ESP8266 doesn't check for overlapping sockets, or you're not calling .listen twice.

Moving this to the ESP8266 forum though - folks there might know what happens with connected.

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Posted at 2016-11-07 by julian

Gordon, pthieu,

I seem to have a related problem. I am trying to get a web server running on boot up, I've used samples from the forums to test with. Here's the code I'm using:

>dump()

E.on("init", function () {
  var http = require("http");
                   http.createServer(function (req, res) {
                   res.writeHead(200);
                   res.end("Hello World");
                   }).listen(8080);
});

As you can see, the code was saved(). I've also saved the wifi settings (which do work btw)! However, when booting I get:

Loading 1836 bytes from flash...
ERROR: Not connected to the internet

And, when I try to browse to port 8080 on the IP address of my ESP8266, the web browser can't load the page, however, if I type:

>load()
=undefined
Loading 1836 bytes from flash...

Voila, it starts working! I am assuming that the http server is starting before the wifi interface, thus producing the Not connected to the internet error and when I load the code manually after the ESP8266 has finished booting, it works. This isn't very handy!

Any ideas chaps? Oh and pthieu, I think I have the same ESP8266 as you...

Julian

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Posted at 2016-11-07 by pthieu

@Julian: Yes, it will take some time for the network interface to establish a connection with the access point; the E.init will trigger immediately after a power cycle (or save() invocation).

Change your code to this:

var Wifi = require('Wifi');
E.on("init", function () {
  Wifi.on('connected', function(){
    var http = require("http");
    http.createServer(function (req, res) {
    res.writeHead(200);
    res.end("Hello World");
    }).listen(8080);
  });
});

The doc for the Wifi class has a number of events that are emitted on specific situations that you can utilize to your advantage.

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Posted at 2016-11-07 by julian

Hi pthieu,

Wowzers, yes that works! The error has gone and the http server is running after a hard reboot. That link makes sense to me now, good find!