Is there a chance of overlooking messages when utilizing long polling with nginx and the pushstream module?

After extensive research through documentation, forums, and examples, I have not been able to locate a clear description of how the pushstream module functions in the following scenario:

I am utilizing nginx+pushstream to provide status updates for users waiting on server-side actions. The long polling technique is used where the client reconnects after each message delivery or connection timeout.

In cases where multiple messages are sent to the subscribed queue simultaneously, is there a possibility that the client might miss a message while in the process of reconnecting? Does the pushstream module handle this situation?

Appreciate any insights provided on this matter! :-)

javascriptnginxpushmessage-queue

Answer №1

After an unexpected search on a different topic, I stumbled upon a discussion in Google Groups that provided the perfect answer to my question.

The developer of the pushstream module shared the following insight:

To achieve your goal, you can set the If-Modified-Since header when connecting, using the current time as the reference for new user connections. This way, the user will only receive messages sent after this specific time.

I have concerns about potential message loss when using long polling without storing messages or with a limited setting for push_stream_max_messages_stored_per_channel.

Source: https://groups.google.com/forum/#!topic/nginxpushstream/4VutBQwx3zM

Therefore, ensuring that messages are stored (with push_stream_store_messages enabled) eliminates the risk of losing messages. The HTTP-Headers If-None-Match and If-Modified-Since play a crucial role in guaranteeing this.

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