The Data API provides two options for working with stream layers via REST APIs: Ingest API for publishing abd Stream API for consumption, as well as direct Kafka access using binary Kafka protocol.
To have full control and achieve the best possible performance, HERE recommends using direct Kafka access and fallback to REST APIs only when direct Kafka access is not available, such as when using proxy settings or firewalls.
The maximum throughput and parallelization for stream layers is set during stream layer creation. You can specify the maximum throughput for data going into the layer and, separately, the maximum throughput for data going out of the layer.
The service begins throttling inbound messages when the inbound rate exceeds the inbound throughput. The service begins throttling outbound messages when the total outbound rate to all consumers exceeds the outbound throughput. When throttling occurs, the service response is delayed, but no messages are dropped.
The maximum message size for a stream layer is 1 MB. For messages larger than 1 MB, HERE recommends you upload the data to Blob API first and pass a message in stream by reference (data handle). If you are using the HERE Data SDK for Java & Scala, this is done automatically for you.