workflow_dsl

{
    "main": {
      "steps": [
        {
          "call_subworkflow": {
            "call": "name_message",
            "args": {
              "first_name": "Sherlock",
              "last_name": "Holmes"
            },
            "result": "output"
          }
        },
        {
          "call_subworkflow2": {
            "call": "name_message",
            "args": {
              "first_name": "Ada",
              "last_name": "Lovelace"
            },
            "result": "output2"
          }
        },
        {
          "return_message": {
            "return": "${output + \" \" + output2}"
          }
        }
      ]
    },
    "name_message": {
      "params": [
        "first_name",
        "last_name",
        "country: \"England\""
      ],
      "steps": [
        {
          "prepareMessage": {
            "return": "${\"Hello \" + first_name + \" \" + last_name + \" from \" + country + \".\"}"
          }
        }
      ]
    }
}