Publish a Message

The server supports publishing SSE messages via HTTP POST to the URL path configured by the --pub-path=<path> option (defaults to /sse).

It accepts data encoded as both application/x-www-form-urlencoded and application/json. The specific content type must always be indicated in the request or it will be rejected.

curl \
  --include \
  --request POST \
  --header "content-type: application/json" \
  --data-raw '{"data": "Hello World"}' \
  127.0.0.1:1983/sse

A successful publish will respond with a 202 Accepted status code and an application/json body with the current number of subscribers and the number of messages in the queue that have not been delivered to all subscribers (yet).

HTTP/1.1 202 Accepted
content-type: application/json
content-length: 31

{"queued": 1, "subscribers": 1}

The size of the internal message queue can be configured with the --capacity=<size> option. It defaults to 256.

SSE message fields

All fields are optional but at least one must be provided or the message will be rejected with a 400 Bad Request error.

{
  "id": "some-id",
  "event": "custom-event",
  "data": "Some data",
  "comment": ["First comment", "Second comment"]
}

Equivalent message as application/x-www-form-urlencoded:

id=some-id
&event=custom-event
&data=Some%20data
&comment=First%20comment
&comment=Second%20comment

data containing newlines is automatically split across multiple data: lines in the SSE message.