Client disconnection guarantee

[mys10gan]

• When setting the Keep-Alive-Interval header to 10s, I receive alive responses every 20s instead of the expected 10s. Is this normal behaviour or a configuration issue?

• Is there a way to check if a client is still connected by channel or connection ID without waiting for a close/disconnected event? I need a method to proactively verify connection status.

• When publishing a message to a channel with no active subscribers (due to client disconnection/websocket disconnected to pushpin), I'd like to receive confirmation that the client is offline and the message wasn't delivered. Currently, there's no feedback mechanism for this scenario. It always says published.

• Sometimes, keep-alive pings continue even after a client (websocket connection) has gone offline. This occurs intermittently. What might be causing this behaviour?

I am using the default config with WebSocket over HTTP.

Client ---[websocket]---> Pushpin ---[http req]---> My Server

[jkarneges]

• Keep-Alive-Interval has a minimum value of 20.
• You can use the command socket for this, using IDs obtained from Connection-Id headers.
• This is true.
• Probably the OS still thinks the connection exists, due to some network issue.

[jkarneges]

The best way to quickly detect if a client is gone is to base it on the absence of activity from the client itself. For example, have the client send a heartbeat every N seconds, or have the server send a PING every N seconds to induce PONG responses from the client, and consider the client gone if the server has not heard anything from it N*2 seconds.

[eduardbareev]

• Keep-Alive-Interval has a minimum value of 20.

The Keep-Alive-Interval is described in a WebSocket section of documentation.

Does a similar feature exist for HTTP connections? Specifically, can Pushpin send a request once per minute regarding every HTTP connection it considers functioning?

[jkarneges]

Not exactly, but you might be able to use unique next links to achieve it:

Grip-Link: </keep-alive/1234>; rel=next; timeout=60

You'd also want the client subscribed to a channel that you never publish to, since at least one channel must be silent for the specified timeout.