Rule Engine

The rule engine executes custom business rules dependent on the device data. The rules may be deployed from our OpenGate IOT Platform and are loaded at runtime.

The rules are based in a when -> then paradigm:

when: Predicates defining when the rule should be executed
then: Actions to execute when the predicates evaluates to true.

The scope available inside this functions includes the state of the device (all the values of the datastreams in the current moment) and the new value that has triggered the rules evaluation.

The interface of a rule is defined as:

public interface Rule {
   boolean when(State state, DatastreamValue newValue);
   State then(State state, DatastreamValue newValue);
}

Implementation

Nashorn Rule Engine

The main implementation of the Rule Engine has been developed using Nashorn engine, allowing to easily define the business rules using JavaScript.

The rules are written in JavaScript and deployed in the device to be registered.

Every time an event is triggered inside the device with a datastream value update, all the registered rules are triggered to take the necessary actions.

A catalogue of actions is provided to ease the rule definitions.

Alternative implementations

New implementations may be added in the future implementing the RuleEngine interface:

public interface RuleEngine { 
 State engine(State state, DatastreamValue value);
 void createDatastreamDirectory(String nameRule);
 void deleteDatastreamDirectory(String nameRule);
 void createRule(String nameRule);
 void deleteRule(String nameRule);
 void reloadAllRules();
 void stop();
}