whomping-willow

whomping-willow is a platform that allows you to create, edit and maintain complex conditional based actions and business rules in the form of decision trees.

Features

• Create decision nodes supported by predicates that are evaluated at runtime.
• Create value nodes as final results of the tree evaluation.
• Link nodes to create powerful decision trees.
• You can provide input parameters used to evaluate the decision tree at runtime.
• Also, rust gang gang.

whomping-willow as a platform

• User can CRUD on DTs.
• Each DT also has context, that can be updated or fetched externally from another service.
• This will allow for use cases, where we don't have context data stored but it is managed in another system.
• For a DT, a predicate should be constructed with an lhs and an rhs.
• lhs will be data received during evaulation via input parameters supplied.
• rhs will be constructed using context for the DT.
• lhs and rhs can be constructed using a serde_json's pointer notation.

Example:

input params:

{ "monthly_income": 30000 }

context:

{
    "account_details": {
  	  "min_monthly_income": 20000
    }
}

You would create your predicate with paths as following.

lhs: /monthly_income

rhs: /account_details/min_monthly_income

Predicates

• LTNumber: Checks if lhs < rhs (both are numbers)
• GTNumber: Checks if lhs > rhs (both are numbers)
• EQNumber: Checks if lhs = rhs (both are numbers)
• EQString: Checks if lhs = rhs (both are strings)
• InListOfString: Checks if lhs is in rhs (lhs is a string, rhs is a list of strings)

An example decision tree for a bank application

TODO

• Make it non domain specific, use json path
• Make it a platform? Allow creation of mutliple DTs, with context
• Add a nice JSON editor