switch

Executes a user-defined function that returns a connection label or a list of connection labels. The message is routed via the specified connection(s). If the script returns a single string, it is treated as a one-element list. If the script execution fails, the message is routed via the Failure connection. Supports TBEL and JavaScript.

Configuration

Field descriptions

• Script language — defines which scripting language is used. Can be either TBEL or JavaScript.
• Script body — the body of the function used to evaluate the incoming message. This script must return either a single string or an array of strings (each string is a connection label). The script can access the following arguments:
  • msg — the message data, typically an object or array.
  • metadata — the message metadata. In JavaScript, this is an object where all values are strings. In TBEL, it is a java.util.Map<String, String>.
  • msgType — the type of the message as a string.

JSON Schema

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{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "title": "TbJsSwitchNodeConfiguration",
  "type": "object",
  "required": [
    "scriptLang"
  ],
  "properties": {
    "scriptLang": {
      "type": "string",
      "description": "Scripting language used to execute the function.",
      "enum": [
        "TBEL",
        "JS"
      ]
    },
    "jsScript": {
      "type": "string",
      "description": "JavaScript function body that must return a string or array of strings. Used when 'scriptLang' is 'JS'."
    },
    "tbelScript": {
      "type": "string",
      "description": "TBEL function body that must return a string or array of strings. Used when 'scriptLang' is 'TBEL'."
    }
  },
  "additionalProperties": false
}

Message processing algorithm

1. Determine which script to execute based on the configured Script language:
   • If TBEL, use the configured TBEL script.
   • If JS, use the configured JavaScript script.
2. Execute the script as a function.
3. The script must return:
   • A string — treated as a one-element array with that connection label.
   • An array of strings — used as the list of connections to route the message through.
4. If the result is not a string or string array, or if the script throws an exception, route via the Failure connection.

Output connections

• Any connection name returned by the script:
  • If the returned value is a string or array of strings, the message is routed via the corresponding connection(s).
• Failure:
  • If the script returns an invalid type (e.g., number, object).
  • If the script throws an error.

Examples

Example 1 — Return a single string → A

Node configuration

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{
  "scriptLang": "TBEL",
  "jsScript": "return 'A';"
}

Output connections: A.

Explanation: the script returns a string. It is treated as a one-element array, and the message is routed via A.

Example 2 — Return a one-element array → A

Node configuration

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{
  "scriptLang": "TBEL",
  "jsScript": "return ['A'];"
}

Output connections: A.

Explanation: the script returns a one-element array. The message is routed via A.

Example 3 — Return multiple connections → A, B, C

Node configuration

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{
  "scriptLang": "TBEL",
  "jsScript": "return ['A', 'B', 'C'];"
}

Output connections: A, B, and C.

Explanation: the script returns an array of connection labels. The message is routed via each of them.

Example 4 — Dynamic routing based on temperature → High, Normal, or Low

Incoming message

Data:

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{
  "temperature": 85
}

Node configuration

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{
  "scriptLang": "TBEL",
  "jsScript": "var t = msg.temperature;\nif (t > 80) return 'High';\nif (t > 60) return 'Normal';\nreturn 'Low';"
}

Output connections: High.

Explanation: temperature is greater than 80, so the script returns "High" and the message is routed accordingly.