Migrating Kafka C Applications to HPE Ezmeral Data Fabric Streams

With some modification, you can use existing Kafka C applications to consume and produce topics in HPE Ezmeral Data Fabric Streams. The HPE Ezmeral Data Fabric Streams C Client is a distribution of librdkafka that is compatible with HPE Ezmeral Data Fabric Streams.

  1. Install and configure the MapR Streams C Client.
  2. When you refer to a topic in the application code, include the path and name of the stream in which the topic is located: 
    /<path and name of stream>:<name of topic>

    For example, you might have a stream in a HPE Ezmeral Data Fabric cluster that is named stream_A, and the stream might be in a volume named IoT and in a directory named automobile_sensors. You want to redirect a producer application to a topic in that stream. The syntax of the path to the topic might look like this: /mapr/IoT/automobile_sensors/stream_A:<name of topic>.

    NOTE
    Optionally, use the streams.consumer.default.stream and streams.producer.default.stream configuration parameters. When you configure these parameters, applications can specify just the topic name to write or read from the default stream. To use these HPE Ezmeral Data Fabric-specific parameters in your application, compile your application with the rdkafka.h file (/opt/mapr/include/librdkafka/rdkafka.h) that was installed with the HPE Ezmeral Data Fabric Streams C Client. See the Compile the Apps section of Developing a HPE Ezmeral Data Fabric Streams C Application.
  3. See Configuration Properties for HPE Ezmeral Data Fabric Streams C Client for the list of supported configuration parameters, including a few parameters that are HPE Ezmeral Data Fabric-specific. Make changes to your application, as needed.
    NOTE
    SSL-related configuration parameters are ignored. When you set these parameters, the HPE Ezmeral Data Fabric Streams Client issues a warning indicating that the parameters are not supported.
  4. Review the list of librdkafka APIs that are not supported by the HPE Ezmeral Data Fabric Streams C Client and make changes to your application, as needed.
    Simple/low level consumer APIs that are not supported
    • rd_kafka_queue_new
    • rd_kafka_queue_destroy
    • rd_kafka_consume_start
    • rd_kafka_consume_start_queue
    • rd_kafka_consume_stop
    • rd_kafka_consume
    • rd_kafka_consume_batch
    • rd_kafka_consume_callback
    • rd_kafka_consume_queue
    • rd_kafka_consume_batch_queue
    • rd_kafka_consume_callback_queue
    • rd_kafka_offset_store
    • rd_kafka_pause_partitions
    • rd_kafka_resume_partitions
    Producer/Consumer common APIs that are not supported
    • rd_kafka_conf_set_dr_cb
    • rd_kafka_conf_set_throttle_cb
    • rd_kafka_conf_set_stats_cb
    • rd_kafka_conf_set_socket_cb
    • rd_kafka_conf_set_open_cb
    • rd_kafka_conf_dump
    • rd_kafka_conf_dump_free
    • rd_kafka_name
    • rd_kafka_set_log_level
    • rd_kafka_mem_free
    • rd_kafka_set_log_level
    • rd_kafka_mem_free
    Topic APIs that are not supported
    • rd_kafka_query_watermark_offsets
      NOTE
      As of HPE Ezmeral Data Fabric 6.0.1, this API is supported.
    • rd_kafka_get_watermark_offsets
      NOTE
      As of HPE Ezmeral Data Fabric 6.0.1, this API is supported.
    Cluster APIs that are not supported
    • rd_kafka_memberid
    • rd_kafka_metadata
    • rd_kafka_metadata_destroy
    Miscellaneous APIs that are not supported
    • rd_kafka_version
    • rd_kafka_version_str
    • rd_kafka_get_debug_contexts
    • rd_kafka_dump
    • rd_kafka_thread_cnt
    • rd_kafka_message_timestamp