Whether the message was sent by Mockttp, or received from a Mockttp client.
A high-precision floating-point monotonically increasing timestamp. Comparable and precise, but not related to specific current time.
To link this to the current time, compare it to timingEvents.startTime.
Whether this is a string message or a raw binary data message.
The id of this websocket stream. This will match the id of the request, the initial connection response, and any other WebSocket events for the same connection stream.
The contents of the message as a raw buffer. This is already decompressed, if the WebSocket uses compression.