functions component: execute custom processing functions. Used for lightweight custom node implementation, allowing your Golang custom functions to become components in seconds. Supports getting the function name value from metadata dynamically using ${metadataKey}.

Before using this component, you must register custom processing functions using the following method, and the default framework does not provide any processing functions.

action.Functions.Register(functionName string, f func(ctx types.RuleContext, msg types.RuleMsg))

If the function processing is successful, you must use the following method to notify the rule engine that it has been successfully processed:

//TellSuccess notifies the rule engine that the current message processing is successful and sends the message to the next node through the `Success` relationship
ctx.TellSuccess(msg RuleMsg)
//TellNext sends the message to the next node using the specified relationTypes
ctx.TellNext(msg RuleMsg, relationTypes ...string)

If the function processing fails, the implementation must call the tellFailure method:

//TellFailure notifies the rule engine that the current message processing failed and sends the message to the next node through the `Failure` relationship
ctx.TellFailure(msg RuleMsg, err error)

• ctx: context
• msg: the message passed in by the previous node

Configuration

Field	Type	Description	Default value
functionName	string	The name of the function to call, can using Component Configuration Variables	None

Relation Type

Function custom

Execution result

Function custom

Configuration example

{
  "id": "s1",
  "type": "functions",
  "name": "Call function 1",
  "configuration": {
    "functionName": "handleMsg"
  }
}

Application example

Example reference: Example (opens new window)

Difference between config.Udf and functions custom functions

• config.Udf : custom functions called by js script at runtime, functions have no fixed parameters and return values.
• functions : custom functions called by the functions node through the configuration function name, functions must be of this type: func(ctx types.RuleContext, msg types.RuleMsg).