3.1.5.4.25 PROGRESS_RECORD Message
The syntax of this message is specified in section 2.2.2.25.
The server sends this message to notify a client about a pipeline's Progress data.
The client's pipeline MUST be in a Running state while processing this message.
It is up to the client to process this message and transmit the data to higher-layers.
For more details about how a client executes a pipeline on a server, see section 3.1.4.3.