Question about long polling and duplicate poll requests

[MSE99]

In test-suite.js there's a test that checks if the server closes the session and sends a 1 close packet when the client makes duplicate poll requests at the same time here, I have two questions about that:

1. Why is it a problem that the client can make duplicate poll requests?
2. What is the best way for a server to detect that the client made a duplicate poll request i was thinking of doing something with a timestamp we can attach a timestamp to the session and check it when the client makes a poll request.

I'm making my own engine.io implementation and I never done something like this before so i apologize for my ignorance, thanks :).

[darrachequesne]

Hi!

1. Why is it a problem that the client can make duplicate poll requests?

That's a great question. I think that this is to ensure the ordering of the packets. Also, what would be the benefit of multiple long-polling requests?

2. What is the best way for a server to detect that the client made a duplicate poll request

You need to make sure the HTTP request effectively acquires a read lock. In the Node.js implementation, the ongoing HTTP request is stored in the socket.transport object: https://github.com/socketio/engine.io/blob/917d1d29e13f2e8f523c3738f6413f67b587aebe/lib/transports/polling.ts#L18

I'm making my own engine.io implementation

That's awesome! Do not hesitate if something is not clear enough 👍