Zeebe carries a JSON document from task to task. This is called the workflow instance payload. For every task, we can define input and output mappings in order to transform the workflow instance payload JSON to a JSON document that the job worker can work with.

name: order-process

tasks:
    - id: collect-money
      type: payment-service
      inputs:
          - source: $.totalPrice
            target: $.price
      outputs:
          - source: $.success
            target: $.paymentSuccess

    - id: fetch-items
      type: inventory-service

    - id: ship-parcel
      type: shipment-service

Every mapping element has a source and a target element which must be a JSON Path expression. source defines which data is extracted from the source payload and target defines how the value is inserted into the target payload.

Related resources:

• More detailed introduction on data flow in the BPMN reference
• JSON Path Reference
• Payload Mapping Reference