ksml/examples/07-example-convert.yaml at main · Axual/ksml · GitHub

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# $schema: https://axual.github.io/ksml/latest/ksml-language-spec.json

# This example shows how to read from a simple AVRO stream, then perform a series of conversions:
#
# source topic --> AVRO --> JSON --> String --> JSON --> XML --> String --> XML --> target topic
# output to a target topic.
#
# Note that AVRO, XML and JSON all have the same INTERNAL representation, so printing one or the other won't give any
# other output on stdout. The difference only shows when converting to a String or writing to a target topic.

streams:
  sensor_source:
    topic: ksml_sensordata_avro
    keyType: string
    valueType: avro:SensorData
    offsetResetPolicy: latest
  sensor_target:
    topic: ksml_sensordata_xml
    keyType: string
    valueType: xml:SensorData

pipelines:
  # The main pipeline reads messages, converts to json, outputs them, and saves to a target topic
  main_to_xml:
    from: sensor_source
    via:
      # Change notation from AVRO to JSON
      - type: convertValue
        into: json
        name: avro_to_json
      - type: peek
        forEach:
          code: log.info("AVRO TO JSON - key={}, value={}", key, value)
      # Convert from JSON to String
      - type: convertValue
        into: string
        name: json_to_string
      - type: peek
        forEach:
          code: log.info("JSON TO STRING - key={}, value={}", key, value)
      # Convert back from String to JSON
      - type: convertValue
        into: json
        name: string_to_json
      - type: peek
        forEach:
          code: log.info("STRING TO JSON - key={}, value={}", key, value)
      # Change notation from JSON to XML
      - type: convertValue
        into: xml:SensorData
        name: json_to_xml
      - type: peek
        forEach:
          code: log.info("JSON TO XML - key={}, value={}", key, value)
      # Convert from XML to String
      - type: convertValue
        into: string
        name: xml_to_string
      - type: peek
        forEach:
          code: log.info("XML TO STRING - key={}, value={}", key, value)
      # Convert back from String to XML
      - type: convertValue
        into: xml:SensorData
        name: string_to_xml
      - type: peek
        forEach:
          code: log.info("STRING TO XML - key={}, value={}", key, value)
    to:
      topic: ksml_sensordata_xml

  # The alternative pipeline achieves the same, but by inlining the target topic definition and its
  # data types (conversion is done implicitly on writing to the target topic)
  alternate_to_xml:
    from: sensor_source
    to: sensor_target