Unable to send HTTP Request to localhost #972

nickthiru · 2022-12-05T05:47:51Z

nickthiru
Dec 5, 2022

Hello,

I have a local instance of Node-RED running on localhost:1880. I created a "http in" node in Node-RED, which I have tested with Postman. However, nothing is happening when I try to send a http request, via Moddable, when I run mcrun -d -m -p esp32/nodemcu. I had already successfully installed the host using mcconfig and there is no issue connecting to Wi-Fi (including when I run mcrun). Below is the code:

import { Request } from "http";

let request = new Request({
	host: "http://localhost:1880",
	path: "/mytopic?temp=33&humidity=44",
	response: String
});

request.callback = function (msg, value) {
	if (Request.responseComplete == msg)
		trace(value, "\n");
}

For the host property, I have tried using the following as well:

localhost:1880
127.0.0.1:1880
http://127.0.0.1:1880

Note: I have also tried adding a trailing forward slash to the above, just in case.

Thank you.

Answered by phoddie

Dec 5, 2022

You are close!

the host property is only the host name (e.g. localhost) without the protocol ("http") or port
The port number is passed on the 'port' property

You have find the examples in the documentation for the HTTP request constructor helpful, such as:

let request = new Request({host: "www.example.com", path: "/info.dat", port: 8080, response: ArrayBuffer});

View full answer

phoddie · 2022-12-05T06:00:24Z

phoddie
Dec 5, 2022
Maintainer

You are close!

the host property is only the host name (e.g. localhost) without the protocol ("http") or port
The port number is passed on the 'port' property

You have find the examples in the documentation for the HTTP request constructor helpful, such as:

let request = new Request({host: "www.example.com", path: "/info.dat", port: 8080, response: ArrayBuffer});

12 replies

andycarle Dec 6, 2022

I just tried a more basic test of interacting between the Moddable SDK Simulator and Node-RED via localhost on Windows. That seems to be working as expected, for what it's worth.

My test was:

I ran the Node-RED server on my Windows machine.
I edited the %MODDABLE%\examples\network\http\httpget example to change the Request to: let request = new Request({host: "localhost", path: "/", response: String, port: 1880});
I ran that example in the Windows simulator. In the xsbug console, I got:

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
<meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1, user-scalable=0"/>
<meta name="apple-mobile-web-app-capable" content="yes">
<meta name="mobile-web-app-capable" content="yes">
<!--
  Copyright OpenJS Foundation and other contributors, https://openjsf.org/

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

  http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
-->
<title>Node-RED</title>
<link rel="icon" type="image/png" href="favicon.ico">
<link rel="mask-icon" href="red&#x2F;images&#x2F;node-red-icon-black.svg" color="#8f0000">
<link rel="stylesheet" href="vendor/jquery/css/base/jquery-ui.min.css?v=3.0.2">
<link rel="stylesheet" href="vendor/font-awesome/css/font-awesome.min.css?v=3.0.2">
<link rel="stylesheet" href="red/style.min.css?v=3.0.2">
<link rel="stylesheet" href="vendor/monaco/style.css?v=3.0.2">
</head>
<body spellcheck="false">
<div id="red-ui-editor"></div>
<script src="vendor/vendor.js?v=3.0.2"></script>
<script src="vendor&#x2F;monaco&#x2F;monaco-bootstrap.js?v=3.0.2"></script>
<script src="red&#x2F;red.min.js?v=3.0.2"></script>
<script src="red&#x2F;main.min.js?v=3.0.2"></script>


</body>
</html>

I did have to clear a Windows Defender Firewall pop-up when running Node-RED for the first time. And I'm sure that I would have seen a Firewall pop-up the first time I ran the Moddable Simulator in a network example. You might double-check your firewall settings and make sure the Moddable Simulator is approved. You could also verify that other network examples (that communicate with the outside world) are working correctly.

This was the one triggered by Node-RED (I selected both checkboxes):

I know that Windows Firewall can be touchy about loopback at times. But as far as I know, that is only a major problem with UWP apps, which we're not dealing with here.

Frida854 Dec 6, 2022

You are running the program from an esp32 right?
Then you cannot use localhost or 127.0.0.1,
because it is only on windows or mac direct,
it can be done.
When sending from esp32, it must have the address
on your windows or mac machine to work.

nickthiru Dec 7, 2022
Author

@andycarle Thank you for the effort and detailed feedback. I will look into it further. Regarding what you mentioned about trying out the other network examples, yes I made sure the default examples from "iot-product-dev-book -> ch3-network" were working, which only made me scratch my head more haha.

@Frida854 Yes, I am using an esp32. However, I am a little unclear about what you mean. On my end, I installed node-red on Windows 11 by following the "Quick Start" section here: https://nodered.org/docs/getting-started/windows. I run node-red from the Windows 11 Command Prompt, and the node-red server starts on http://127.0.0.1:1880/. Does this have any bearing on what you mentioned about "only on windows or mac direct it can be done" and "it must have the address on your windows or mac machine to work"? Thanks.

andycarle Dec 7, 2022

@nickthiru I see. We were perhaps confused about what you are trying to accomplish.

If you are running the network application on an ESP32, you will not be able to connect to localhost — that refers to the device itself (in this case, the ESP32). Because your server is running on your Windows machine, you will need to use the IP address of the Windows machine on your local network.

You can find your Windows machine's IP address by running ipconfig /all at the Command Prompt. Look for the network adapter you use to connect to your local network and note the IP address. For instance, I have my laptop connected to the network via it's dock's Ethernet adapter. And I get this from ipconfig /all:

Ethernet adapter Ethernet 2:

   Connection-specific DNS Suffix  . :
   Description . . . . . . . . . . . : Surface Ethernet Adapter
<snipped>
   Link-local IPv6 Address . . . . . : fe80::c661:25af:7e2e:2899%14(Preferred)
   IPv4 Address. . . . . . . . . . . : 192.168.68.73(Preferred)
<snipped>

So, the address I would use to connect my ESP32 to my Windows machine would be 192.168.68.73 and the full request would be:

let request = new Request({
	address: "192.168.68.73",
	path: "/mytopic?temp=33&humidity=44",
	response: String,
        port: 1880
});

You will, of course, need to substitute the IP address that you find from ipconfig /all.

nickthiru Dec 7, 2022
Author

Right, I get it now. Sorry for the confusion and lack of specifics when raising the issue. I completely missed the point that the esp32 is a separate network host, and I have been "pointing" to its localhost all the while.

It's working fine now. But an important thing to note, still, is what @Frida854 mentioned about specifying the port value as a String type. This is also a must.

@phoddie @andycarle @Frida854 Thank you very much for your kind and patient assistance.

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nickthiru Dec 5, 2022

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phoddie Dec 5, 2022 Maintainer

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nickthiru
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phoddie
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