java - I need a simple rules engine, I think? -

i need advice on best approach solving problem.

i've researched drools, java rule engine , few others. of these powerful, , have things them. don't know (if any) best choice me.

i have 1 business object. (simplified demo)

person      firstname:string      lastname:string      department:string      hiredate:date 

i need write editor in web application allow complex rules built around these fields. need support complex nested and/or logic. need basic operators, , rule should evaluate true or false. if rule evaluates true or false, 1 action occur respectively.

for example,

firstname contains "value" , (lastname equals "input" or department contains "input")

i had thought, maybe should write own parser , evaluate logic in own code. don't know do, advice or links read appreciated. there specific design pattern research?

how solve problem? 1 reservations rules engines maybe complex simple problem?

this not yes/no question, can share experiences, , hope helps. have used drools quite in few projects. apart cases (another team had issues drools under heavy load,) drools quite useful library.

i built application which:
1. read input source
2. chose next action based on input set of available operations

as trivial looks, needed flexible:
1. input variable set of name-value pairs, names not predetermined.
2. values, presence/absence of name/values (based on occurrence/absence of events), trigger different actions.
3. business rules can change while application running.

maybe there better solutions, better or worse, ended using drools. developed bpel in decisions made drools component. drools component internally reads decision making rules microsoft excel spreadsheet. rebuilds rules if there change in file. domain experts change spreadsheet when required, , not go through painful deployments!

if want sophisticated ui, drools guvnor readily available web-application (with rich ui,) domain/subject-matter experts build rules , store them in database.