GraphQL subscription does not receive messages after successful handshake - node.js

I have created a simple GraphQL Subscription using Nest.js/Apollo GraphQL over Node.js. My client application which is a react.js/apollo client works find with the server. The client subscibes to the server via GraphQL similar to:
subscription
{
studentAdded
{
id
}
}
My problem is that it works only locally. When I deploy my server back-end to a hosted docker over internet, client won't receive data anymore.
I have traced the client, it sends GET request on ws://api.example.com:8010/graphql and receives the successful HTTP/1.1 101 Switching Protocols response. However, nothing is received from server like when the server was on my local machine. Checking the remote server log showed me that the client successfully connects to server. There, I can see onConnect log messages.
Now I need any guidance to solve the problem.
I check several things myself. Firstly, I thought WebSocket address is prohibited in the network but then realized that it is on same port as normal HTTP. Secondly, supposed that WebSocket messages/frames are transmitted over UDP but I was not correct, it is over TCP and no need to worry about network settings.
Additionally I have read several github threads and StackOverflow questions. But did not find any clue. I am not directly using Node.js/WebSocket, instead, I am using Nest.js/GraphqQL subscription. It has made my search tougher.
Your help is highly appreciated.

Related

beginner webrtc/nodejs issue connecting remote clients

I'm trying to develop a web application in nodejs. I'm using an npm package called "simple-peer" but i don't think this issue is related to that. I was able to use this package and get it working when integrating it with a laravel application using an apache server as the back end. I could access the host machine through it's IP:PORT on the network and connect a separate client to the host successfully with a peer-to-peer connection. However, I'm now trying to develop this specifically in node without an apache back end. I have my express server up and running on port 3000, I can access the index page from a remote client on the same network through IP:3000. But when I try to connect through webrtc, I get a "Connection failed" error. If I connect two different browser instances on the same localhost device, the connection succeeds.
For reference: i'm just using the copy/pasted code from this usage demo. I have the "simplepeer.min.js" included and referenced in the correct directory.
So my main questions are: is there a setting or some webRTC protocol that could be blocking the remote clients from connecting? What would I need to change to meet this requirement? Why would it work in a laravel/webpack app with apache and not with express?
If your remote clients can not get icecandidates, you need TURN server.
When WebRTC Peer behind NAT, firewall or using Cellular Network(like smartphone), P2P Connection will fail.
At that time, for fallback, TURN server will work as a relay server.
I recommend coTURN.
Here is an simple implementation of simple-peer with nodejs backend for multi-user video/audio chat. You can find the client code in /public/js/main.js. Github Project and the Demo.
And just like #JinhoJang said. You do need a turn server to pass the information. Here is a list of public stun/turn servers.

Multiple Socket.io app processes cause each client socket connects and disconnects repeatedly

I am working on a nodejs app with Socket.io and I did a test in a single process using PM 2 and it was no errors. Then I move to our production environment(We use Google Cloud Compute Instance).
I run 3 app processes and a iOS client connects to the server.
By the way the iOS client doesn't keep the socket connection. It doesn't send disconnect to the server. But it's disconnected and reconnect to the server. It happens continuously.
I am not sure why the server disconnects the client.
If you have any hint or answer for this, I would appreciate you.
That's probably because requests end up on a different machine rather than the one they originated from.
Straight from Socket.io Docs: Using Multiple Nodes:
If you plan to distribute the load of connections among different processes or machines, you have to make sure that requests associated with a particular session id connect to the process that originated them.
What you need to do:
Enable session affinity, a.k.a sticky sessions.
If you want to work with rooms/namespaces you also need to use a centralised memory store to keep track of namespace information, such as the Redis/Redis Adapter.
But I'd advise you to read the documentation piece I posted, things might have changed a bit since the last time I've implemented something like this.
By default, the socket.io client "tests" out the connection to its server with a couple http requests. If you have multiple server requests and those initial http requests don't go to the exact same server each time, then the socket.io connect will never get established properly and will not switch over to webSocket and it will keep attempting to use http polling.
There are two ways to fix this.
You can configure your clients to just assume the webSocket protocol will work. This will initiate the connection with one and only one http connection which will then be immediately upgraded to the webSocket protocol (with socket.io running on top of that). In socket.io, this is a transport option specified with the initial connection.
You can configure your server infrastructure to be sticky so that a request from a given client always goes back to the exact same server. There are lots of ways to do this depending upon your server architecture and how the load balancing is done between your servers.
If your servers are keeping any client state local to the server (and not in a shared database that all servers access), then you will need even a dropped connection and reconnect to go back to the same server and you will need sticky connections as your only solution. You can read more about sticky sessions on the socket.io website here.
Thanks for your replies.
I finally figured out the issue. The issue was caused by TTL of backend service in Google Cloud Load Balancer. The default TTL was 30 seconds and it made each socket connection tried to disconnect and reconnect.
So I updated the value to 3600s and then I could keep the connection.

Websockets with Socket.io Node apps on Microsoft Azure

We have a Nodejs server that communicates with the websocket protocol (WebRTC, socket.io).
During our development on Heroku, we did not encounter any particular problem.
However, we encountered problems during the deployment of our application on Azure:
The client / server communication is unstable, after analysis we noticed that there is a failure to communicate in websocket and that the transport protocol used is 'polling':
websocket.js:112 WebSocket connection to
'wss://hote.fr/socket.io/?EIO=3&transport=websocket&sid=EgjKLAtp89wrBKMzAAAG'
failed: Error during WebSocket handshake: Unexpected response code:
503
When you activate the "Websocket" function on the administration, the site becomes even more unstable and very long and communication is impossible. The problem of websocket communication is not solved with this function. Example
After having informed us we did disable the websockets in the web.config but without change.
Note that with the same code, everything works well under heroku and the protocol used is websocket.
Has anyone ever encountered this problem, and has a solution?
I'm sorry about my English.
Thank you in advance for your time.
You need do the following to make it work on Azure App Service.
Enable Web sockets via the Azure portal.
Disable the IIS WebSocket module to allow Node.js to provide its own
WebSocket implementation by add this to your web.config file:
<webSocket enabled="false" />
Tell Socket.IO to use WebSocket only instead of a few XHR requests by adding this to the Node.js server:
io.set('transports', ['websocket']);
And on the client add this:
var socket = io({transports: ['websocket']});
Try the suggestions outlined by Aaron to narrow the issue, I would like to highlight a few restrictions on the Azure Sandbox to help isolate the issue further:
1.In App Service, limits are enforced for the maximum number of outbound connections that can be made for each VM instance.
As mentioned in the document Cross-VM numerical limits:
“These limits apply only for customers of Basic or higher plans; in other words, customers running on their own dedicated VMs. These limits are there to protect the entire VM even though one particular site may be with its limits described above. The limits are different depending on the size of VM configured.”
This error also might occur if you try to access a local address from your application.
As mentioned in the document Local address requests:
“Connection attempts to local addresses (e.g. localhost, 127.0.0.1) and the machine's own IP will fail, except if another process in the same sandbox has created a listening socket on the destination port.
Rejected connection attempts, such as the following example which attempts to connect to 127.0.0.1:80, from .NET will result in the following exception:
Exception Details: System.Net.Sockets.SocketException: An attempt was made to access a socket in a way forbidden by its access permissions 127.0.0.1:80.”
3.For more information about outbound connections in your web app, see the blog post about outgoing connections to Azure websites.

How to scrape socket.io updates to a third-party site?

I basically want to know if its possible to use Socket.io using the server-side only with no client side? BUT I want to know if my server-side can instead connect with a different site that I cannot use Socket.io to connect to.
Use PhantomJS to load the third-party site and then inject your own javascript into the page to catch events and send those events back to your own server.
socket.io is a two-way connection. Client <--> Server. You must have a socket.io endpoint at both ends to even establish a connection in the first place. And, then once you establish the connection, you must have agreed upon messages that can be exchanged between the two ends for it to do anything useful.
It is not useful to have a server-side socket.io that doesn't actually connect to anything and nothing connects to it. It wouldn't be doing anything, just sitting there waiting for someone to connect to it.
It is possible to have two cooperating servers connect to one another with socket.io (one server just acts like a client in that case by initiating the connection to the other server). But, again both endpoints must participate in the connection for the connection to even be established and certainly for it to do anything useful.
If you just want to download the contents of a site for scraping purposes, then you would not use socket.io for that. You would just use the nodejs http module (or any of several other modules built on top of it). Your server would essentially pretend to be a browser. It would request a web page from any random web server using HTTP (not socket.io). That web server would return the web page via the normal HTTP request. Your receiving server can then do whatever it wants with that web page (scrape it, whatever).

Setting up a websocket capable application on an azure ubuntu vm

Okay, so I have created an ubuntu vm in the azure cloud, I have successfully launched nodejs, redis, socket.io, Express and all the components for a game I am writing.
I have setup azure endpoints on internal and external port 8080, and use app.listen(8080) in my js code.
When I browser to http://< app-name >.cloudapp.net:8080/ I can view the result of my nodejs application fine, it displays the html, css etc.
However when it attempts to start a socket connection (using socket.io) I get only this (on my chrome dev console under websockets):
HeadersPreviewResponseWebSocket Frames
Request URL:ws://<app-name>.cloudapp.net:8080/socket.io/1/websocket/13510496541533398587
Request Method:GET
Status Code:101 Switching Protocols
Request Headersview source
Connection:Upgrade
Host:<app-name>.cloudapp.net:8080
Origin:http://<app-name>.cloudapp.net:8080
Sec-WebSocket-Extensions:x-webkit-deflate-frame
Sec-WebSocket-Key:y5vueHE66phl70gle7KCtw==
Sec-WebSocket-Version:13
Upgrade:websocket
(Key3):00:00:00:00:00:00:00:00
Response Headersview source
Connection:Upgrade
Sec-WebSocket-Accept:dn+2lA6sMIXHLEmDS/Q4j/IIwxI=
Upgrade:websocket
(Challenge Response):00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00
It will also crash the nodejs app on azure when i try send anything using socket.emit() on the client (browser); in my azure ssh, it just says 'DEBUG: Program node app.js exited with code null' which isn't particularly helpful.
So it obviously isn't connecting properly? I have also tried in my nodejs listening on port 80, but then I don't even get the standard webpage (html,css,etc).
From what I have read online, it is very possible to get sockets working providing your not using the web role (which I assume the vm is not).
Any idea how I can get this to work? (and preferably on port 80)?
Edit: starting to wonder if this has nothing todo with sockets, realized I get the same switching protocol message, on my home vm (where it is working). Spin off question: How can I view crash details for a nodejs program on a ubunu azure vm?
There is a time out of around 60s on the Windows Azure loadbalancer.
Does it work if you send a message back to the client just after the websocket connection is established?
If it is the case you will have to implement some keep a live message send every minutes.

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