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

The examples below show only the relevant parts of the incoming message, rule node configuration, and system state. Any information not explicitly shown has no effect on the processing.

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.