RuleEngine

Logic behind this rule engine is to take the rules in json format and apply those rules over the data to search for the signals which are violating the rules.

Design Consideration:-

Created the project in considering if we need to add more filters or operators we can be able to do in less time and minimal changes.

Pre-requisite

Java 8
Maven

Listed below the Classes which will be required to be changed if enhancement need to be made

DataType.java : Add new data types
Operator.java : Add new operators
FilterPredicate.java : Include the new check for new/exisitng Data type
Util.java : create new static method for new Data type. Listed below method as reference
- checkInteger()
- checkDateTime()
- checkString()

Assumption:-

There would be multiple of rules can be present for same signal. if any of the rule is satisfied so that signal will be filtered and shown in output.
Output will so distinct result.
Operatore support as per data types
- STRING : Equal
- INTEGER : Equal , Greater Than , Less Than
- DATETIME : Equal , Greater Than , Lesser Than

Build the project

mvn clean install Fat jar RuleEngine-jar-with-dependencies.jar will be created in target folder

Generate Rule file

Here Json should be the list of rules where each signal can have multiple rules. Say for ATL1 we have rules as below For ATL1

ATL1 value should not be greater than 240.0
ATL1 datetime should be equal to "2017-04-10 10:16:11" For ATL2
ATL2 value is LOW For ATL10
ATL10 value equal to 46.691

so the Json will be

[
  {
    "signal": "ATL1",
    "rule": [
			{
				"type": "Integer",
				"operator": ">",
				"value": "240.0"
			},
			{
				"type": "Datetime",
				"operator": ">",
				"value": "2017-04-10 10:16:11"
			}
	  ]
  },
  {
    "signal": "ATL2",
    "rule": [
			{
				"type": "String",
				"operator": "=",
				"value": "LOW"
			}
		]
  },
  {
    "signal": "ATL10",
    "rule": [
			{
				"type": "Integer",
				"operator": "=",
				"value": "46.691"
			}
   ]
 }
]

Sample rule.json is present in main/resources folder for reference

Run the code

Go to target folder , run below command Program takes two argument

Signal Input Json File
Rule Json File (Create the rule.json as per "Generate Rule file" section"

Syntax java -jar RuleEngine-jar-with-dependencies.jar (Signal Input Json File) (Rule Json File)

Example java -jar RuleEngine-jar-with-dependencies.jar /tmp/raw_data.json /tmp/rule.json

Output will printed in console

ATL10
ATL1
ATL2

Improvement can be done

more data type can be included
more operators can be added for existing data types