CODEWITHSUNDEEP
wakanda
Greg M
Greg M

Reputation: 125

Wakanda websocket onclose not firing on network disconnect

I have a websocket implementation on Wakanda Server. I am tracking connected browsers server side. When I reload the page, I get the onclose event of the websocket as expected.

I would have expected when I break a network connection that I would also have this event fire. Am I misunderstanding? Is there a way to have a function fire when a network connection is lost to a websocket client?

For reference, I am using Wakanda 10.

Upvotes: 1

Views: 273

Answers (1)

hamzahik
hamzahik

Reputation: 714

To help you understand the problem I will give you some details about websocket connections :

  • It uses TCP
  • If a remote client(browser for instance) closes a TCP connection gracefully the server is notified (FIN)
  • If a remote client crashes, the OS running the client application notifies the server (RST)
  • If a TCP connection is open between a server and a client the connection will be assumed open even if there is absolutely no exchange of data for a while unless keepalive is activated.
  • The WebSocket spec adds a close message so the server/client can handle a graceful close
  • The WebSocket spec adds a ping/pong message exchange but does not impose a timeout. From RFC : Upon receipt of a Ping frame, an endpoint MUST send a Pong frame in response, unless it already received a Close frame. It SHOULD respond with Pong frame as soon as is practical.
  • In Wakanda's implementation of the RFC we respond to received ping messages but don't send our own ping messages

This can be a new feature where we can either :

  • expose a ping method through the message port with a pong timeout
  • add a websocket keepalive option with configurable timeout at the moment of adding the websocket handler.
  • add a TCP keepalive option with configurable timeout at the moment of adding the websocket handler.

For the time being, you can send a message of your choice to the client side every N seconds and wait for a response with a timeout of T. If you don't receive a response you can assume the connexion is lost and close it.

Upvotes: 2

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