Good to know! This is also a good example of why I’d like to see new message types.

These ERRORs are due to a “bad msg” with additional information that there’s an unrecognized filter item. In HTTP, this would be a 400 Bad Request—the status code tells you the sort of error you’re experiencing.

A new message type that allows an object payload would give us room to more clearly describe the sort of ERROR that’s occurring.

Some other ways a REQ could fail:

- bad msg for other reasons like empty arrays, wrong types, strings too long, negative numbers, etc.

- too many REQs from same client

- too many filters

- AUTH required (HTTP 401 equivalent)

- forbidden (HTTP 403 equivalent)

- database error (HTTP 502 equivalent)

REQ Non-errors:

- limit field too high

CLOSE errors:

- no such subscription_id (HTTP 404)

- subscription_id missing

- subscription_id wrong type

- extra message entries detected

- subscription_id too long