nchan_longpoll_multipart_response
The `nchan_longpoll_multipart_response` directive specifies whether to use multipart responses for long-polling subscribers in Nchan.
Description
The nchan_longpoll_multipart_response directive is a configuration option in Nchan that enables multipart responses when handling long-polling requests. When this directive is set, the server constructs responses in a multipart format, allowing for multiple messages to be sent in a single HTTP response to a subscriber. This can enhance efficiency and reduce latency by decreasing the number of HTTP connections required to send multiple messages, making it an effective choice for applications with high message throughput.
When enabled, Nchan will send long-polling responses using the multipart/x-mixed-replace content type, which allows multipart responses to be streamed over a single HTTP connection. This behavior can be particularly useful in scenarios where messages are expected to arrive frequently and need to be pushed to the client immediately, as the subscriber can receive each message as it is published instead of waiting for a new connection to be established for each one. The directive accepts a single argument: either on to enable or off to disable this feature.
It’s important to note that the server must be configured properly to handle these multipart responses, and client-side code should also be capable of parsing this format. Additionally, using multipart responses may require specific handling depending on the chosen subscriber technology such as EventSource or custom JavaScript clients interacting with WebSockets or long-polling endpoints, to ensure that messages are processed correctly.
Config Example
location /subscribe {
nchan_longpoll_multipart_response on;
nchan_subscriber_channel_id $arg_channel;
nchan_pubsub;
}Ensure that the client can handle multipart responses correctly; not all clients do this natively.
Using multipart responses may require more careful handling on the server side to ensure messages are formatted correctly before being sent.