The sse service is responsible for sending sse (Server-Sent Events) to a user. See What is Server-Sent Events for a simple introduction and examples of server sent events.

The Log Service Ecosystem

Log services like the userlog, clientlog and sse are responsible for composing notifications for a certain audience.

The userlog service translates and adjusts messages to be human readable.
The clientlog service composes machine readable messages, so clients can act without the need to query the server.
The sse service is only responsible for sending these messages. It does not care about their form or language.

Subscribing

Clients can subscribe to the /sse endpoint to be informed by the server when an event happens. The sse endpoint will respect language changes of the user without needing to reconnect. Note that SSE has a limitation of six open connections per browser which can be reached if one has opened various tabs of the Web UI pointing to the same Infinite Scale instance.

Keep SSE Connections Alive

Some intermediate proxies drop connections after an idle time with no activity. If this is the case, configure the SSE_KEEPALIVE_INTERVAL envvar. This will send periodic SSE comments to keep connections open.