join component: Join node. Gather and merge the results of multiple asynchronous node executions. Example: Retrieve data from different databases or call APIs, then merge.

Configuration

Field	Type	Required	Description	Default
timeout	int	No	Execution timeout in seconds, 0: no timeout	0
mergeToMap	bool	No	Whether to merge the results into a map. false: result is []WrapperMsg list; true: result merged into Map (JSON merges fields, others use nodeId as key)	false

Relation Type

• Success: Send the message to the Success chain.
• Failure: If execution times out or node execution fails, send to the Failure chain.

Execution Result

• metadata: Merge the metadata after each node is processed, and override if the same key exists.
• data: Determine merge strategy based on mergeToMap configuration:
  • mergeToMap=false (default): Encapsulate messages processed by all nodes into a WrapperMsg array.
  • mergeToMap=true: Merge data from all nodes into a single Map.
    • If the node output is in JSON format, merge its fields into the result Map.
    • If the node output is not in JSON format, merge it into the result Map using the node ID as the key and the message content as the value.

Example of merged result when mergeToMap=true:

Assuming there are three nodes:

• Node A (id=nodeA) output: {"temperature": 25}
• Node B (id=nodeB) output: {"humidity": 60}
• Node C (id=nodeC) output: running (Non-JSON)

Merged data result:

{
  "temperature": 25,
  "humidity": 60,
  "nodeC": "running"
}

WrapperMsg Structure (Valid only when mergeToMap=false):

Field	Type	Description	Default
msg	types.RuleMsg without merging metadata	Message conforms	None
err	string		""
nodeId	string	The last processing node	""

Configuration Example

{
  "ruleChain": {
    "id": "frcYgBtVbDaV",
    "name": "Test Merge Node",
    "debugMode": true,
    "root": true,
    "additionalInfo": {
      "createTime": "2024/09/24 16:56:52",
      "description": "",
      "layoutX": "280",
      "layoutY": "280",
      "updateTime": "2024/09/24 21:50:38",
      "username": "admin"
    }
  },
  "metadata": {
    "endpoints": [],
    "nodes": [
      {
        "id": "node_a",
        "additionalInfo": {
          "description": "",
          "layoutX": 490,
          "layoutY": 280
        },
        "type": "jsTransform",
        "name": "A",
        "debugMode": false,
        "configuration": {
          "jsScript": "msg.a=\"aa\"\nreturn {'msg':msg,'metadata':metadata,'msgType':msgType};"
        }
      },
      {
        "id": "node_b",
        "additionalInfo": {
          "description": "",
          "layoutX": 730,
          "layoutY": 210
        },
        "type": "jsTransform",
        "name": "B",
        "debugMode": false,
        "configuration": {
          "jsScript": "msg.b=\"bb\"\nreturn {'msg':msg,'metadata':metadata,'msgType':msgType};"
        }
      },
      {
        "id": "node_c",
        "additionalInfo": {
          "description": "",
          "layoutX": 730,
          "layoutY": 340
        },
        "type": "jsTransform",
        "name": "C",
        "debugMode": false,
        "configuration": {
          "jsScript": "msg.c=\"cc\"\nreturn {'msg':msg,'metadata':metadata,'msgType':msgType};"
        }
      },
      {
        "id": "node_d",
        "additionalInfo": {
          "description": "",
          "layoutX": 1010,
          "layoutY": 260
        },
        "type": "join",
        "name": "D",
        "debugMode": false,
        "configuration": {
          "timeout": 1
        }
      }
    ],
    "connections": [
      {
        "fromId": "node_a",
        "toId": "node_b",
        "type": "Success"
      },
      {
        "fromId": "node_a",
        "toId": "node_c",
        "type": "Success"
      },
      {
        "fromId": "node_b",
        "toId": "node_d",
        "type": "Success"
      },
      {
        "fromId": "node_c",
        "toId": "node_d",
        "type": "Success"
      }
    ]
  }
}