react-native websocket ERR_NAME_NOT_RESOLVED stopping network requests - sockets

Every now and then our react-native app has a problem connecting to our websocket (we're using sockjs). When this happens it blocks all network requests and essentially stops our app from functioning.
When it occurs the console doesn't stop logging:
GET http://192.168.0.11.xip.io:8080/sock/194/noeli4ep/eventsource
net::ERR_NAME_NOT_RESOLVED
This is our connect script, which runs when the app starts, it also runs when socket closes (this is so we can re-connect to the socket).
connectToServer() {
if (!this.flagConnect) {
this.webSocket = new SockJS(`${config.endpoint}sock`);
this.webSocket.onopen = this.onOpen; // Just sets this.opened to true
this.webSocket.onmessage = this.onMesssage; // Just reads the msgs
this.webSocket.onclose = this.onClose; // Re-calls connectToServer()
this.webSocket.onerror = this.onError; // Console.logs the error
}
}
We're using React-native 0.41 & using sockJS on the app & backend (nodejs).

I found that removing xip.io fixed this issue.
So using http://<ip>:><port> was fine.

Related

PWA not working correctly offline. Uncaught (in promise) TypeError: Failed to fetch

I am trying to convert a simple webpage I have into a PWA in case the site it uses goes down.
I think I have done the majority of the work. The page is installable on my phone and passes all the Chrome lighthouse tests. But I get the following warning,
Web app manifest meets the installability requirements
Warnings: Page does not work offline. The page will not be regarded as installable after Chrome 93, stable release August 2021.
I also get the following warning and error in console,
The FetchEvent for "https://dannyj1984.github.io/index.html" resulted in a network error response: the promise was rejected.
Promise.then (async)
(anonymous) # serviceWorker.js:30
serviceWorker.js:1 Uncaught (in promise) TypeError: Failed to fetch
There is then a warning saying the site cannot be installed as does not work offline. I have read the chrome dev article which says from the chrome release in Aug21 apps that dont work offline wont be installable. But I am stuck on which part of my fetch is causing an issue. The code in my service worker is,
const TGAbxApp = "TG-ABX-App-v1"
const assets = [
//paths to files to add
]
self.addEventListener("install", installEvent => {
installEvent.waitUntil(
caches.open(TGAbxApp).then(cache => {
cache.addAll(assets)
})
)
})
self.addEventListener('fetch', function(event) {
event.respondWith(
caches.match(event.request)
.then(function(response) {
// Cache hit - return response
if (response) {
return response;
}
return fetch(event.request);
}
)
);
});
The above code for the fetch part of the service worker I took from Google and as I understand it, it first checks if there is data in the cache stored on install, if not it will request it from the network.
https://developer.chrome.com/blog/improved-pwa-offline-detection/
From Chrome 89 March 2021, it gives a warning if this check does not pass:
The installed service worker fetch event returns an HTTP 200 status code (indicating a successful fetch) in simulated offline mode.
So, in your case, the service worker should return a cached 'index.html' when fetch(event.request) is failed.
I've had the same problem. I re enabled the cache through the developer console->network. fixed

Flutter - Socket.Connect() - SocketException: OS Error: Connection timed out

When I was working on debug mode (with "flutter run") by using my device (real), Socket.Connect() method doesn't work.
Also I would like to say that this Connect method is in "dart:io" library.
In shortly;
I opened a server (TCP) with Python.
I wrote the Flutter client like below to be able to connecting to the server in Python.
Future den() async {
print("Started");
Socket sock = await Socket.connect("192.168.0.159", 5431);
print("Done +++++++++++++++++++++++++"); }
However, I took a SocketError as Connection time out.
The error message I took:
E/flutter (17655): [ERROR:flutter/lib/ui/ui_dart_state.cc(177)] Unhandled Exception: SocketException: OS Error: Connection timed out, errno = 110, address = 192.168.0.159, port = 43836
NOTE:
I tried to change the manifest file by adding INTERNET permission, but it is not working.
It was a strange problem, because there is no problem the code I shared. Windows Defender performed a rule to block to open a port as server. Hence, I started the server on my machine, however, I couldn't connect it from my Android device.
Maybe, the error code that is shown by Flutter isn't clear. If you took a error about socket programming for connection or binding, looking to Defender (or firewall) can be affective method. Unfortunately, as I was just starting to learn Flutter, I thought of checking out Defender afterwards.

Issue starting ROS launch-File using RQT Plugin push button

I implemented a RQT Plugin with several push buttons. The push button is supposed to start a ROS launch file. For some reason every time I start it I get the error message: Shutdown request received. Reason given for shutdown: [new node registered with same name]
Even though the launch file has only been started once. The launch file also works fine when it's started without the plugin.
This is my code sample for the implementation of the slot:
`
void PluginStartButtons::buttonPressedKameraStart(bool checked)
{
QProcess* k_process = new QProcess;
k_process->setProcessChannelMode(QProcess::MergedChannels);
QString command = "roslaunch neo_watch_launch thermal_rgb_camera.launch";
k_process->start(command);
system(qPrintable(command));
}
`
Do you have any idea why this error might occur?

Debugging a crashing language server

I apologize if I'm a bit low on details here, but the main issue is actually trying to find the problem with my code. I'm updating an older extension of my own that was based on the Language Server example (https://code.visualstudio.com/docs/extensions/example-language-server). I've run into an issue where when I run the client part of my code using F5, and the debug window fires, I get:
The CSSLint Language Client server crashed 5 times in the last 3 minutes. The server will not be restarted.
Ok... so... here's the thing. The problems view in my extension client code shows nothing. DevTools for that Code window shows nothing.
The problems view for my server code shows nothing. DevTools, ditto.
For the Extension Developer Host instance, DevTools does show this:
messageService.ts:126 The CSSLint Language Client server crashed 5 times in the last 3 minutes. The server will not be restarted.e.doShow # messageService.ts:126
But I can't dig into the details to find a bug. So the question is - assuming that my server code is failing, where exactly would the errors be available?
Here is what I usually do to track server crashes down (I assume your server is written in JavaScript / TypeScript).
Use the following server options:
let serverModule = "path to your server"
let debugOptions = { execArgv: ["--nolazy", "--debug=6009"] };
let serverOptions = {
run: { module: serverModule, transport: TransportKind.ipc },
debug: { module: serverModule, transport: TransportKind.ipc, options: debugOptions}
};
Key here is to use the TransportKind.ipc. Errors that happen in the server and printed to stdio will then show in the output channel associated to your server (the name of the output channel is the name passed to the LanguageClient)
If you want to debug the server startup / initialize sequence you can change the debugOptions to:
let debugOptions = { execArgv: ["--nolazy", "--debug-brk=6009"] };
If the extension is started in debug mode (e.g. for example launched from VS Code using F5) then the LanguageClient automatically starts the server in debug mode. If the extension is started normally (for example as a real extension in VS Code) then the server is started normally as well.
To make this all work you need a latest version of the LSP node npm module both for server can client (e.g. 2.6.x)

FTP timing out on Heroku

Using Apache Commons FTPClient in a Scala application works as expected on my local machine, but always times out when running on Heroku. Relevant code:
val ftp = new FTPClient
ftp.connect(hostname)
val success = ftp.login(username, pw)
if (success) {
ftp.changeWorkingDirectory(path)
//a logging statement here WILL print
val engine = ftp.initiateListParsing(ftp.printWorkingDirectory)
//a logging statement here will NOT print
while (engine.hasNext) {
val files = engine.getNext(5)
//do stuff with files
}
}
By adding some loggings I've confirmed the client is successfully connecting, logging in, and changing the directory. But stops when trying to begin retrieving files (either via the above paged access or unpaged with ftp.listFiles) and throws a connection time out exception (after about 15 minutes).
Any reason the above code works fine locally but not on Heroku?
Turns out FTP has two modes, active and passive, and Apache-Commons' FTPClient defaults to active. Heroku's firewall presumably doesn't allow active FTP (which is why this was functioning properly locally but not once deployed) - changing to passive mode by adding ftp.enterLocalPassiveMode() resolved the issue.