Response streamer: This stage streams out posting instruction batch requests to the relevant Kafka topic (each integration has its own response topic). To route a response to a caller, the Postings API retrieves the Postings API client associated with the posting instruction batch’s specified client_id. All posting instruction batches will be streamed out by the response streamer, whether accepted, rejected or errored.

Event streamer: This stage streams out a PostingInstructionBatchCreatedEvent for every accepted or rejected posting instruction batch. Unlike the response streamer, this is a stream that merges posting instruction batches from all Postings API clients into a single, unified Kafka stream.