Jess (programming language)

الموسوعة الحرة

Jess is a rule engine for the Javacomputing platform, written in the Javaprogramming language. It was developed by Ernest Friedman-Hill of Sandia National Laboratories.[1] It is a superset of the CLIPS language.[1] It was first written in late 1995.[1] The language provides rule-based programming for the automation of an expert system, and is often termed as an expert system shell.[1] In recent years, intelligent agent systems have also developed, which depend on a similar ability.

Rather than a procedural paradigm, where one program has a loop that is activated only one time, the declarative paradigm used by Jess applies a set of rules to a set of facts continuously by a process named pattern matching. Rules can modify the set of facts, or can execute any Java code. It uses the Rete algorithm[1] to execute rules.

License

The licensing for Jess is freeware for education and government use, and is proprietary software, needing a license, for commercial use. In contrast, CLIPS, which is the basis and starting code for Jess, is free and open-source software.

Code examples

Code examples:

; is a comment(bind?x100); x = 100(deffunctionmax(?a?b)(if(>?a?b)then?aelse?b))(deffactsmyroom(furniturechair)(furnituretable)(furniturebed))(deftemplatecar(slotcolor)(slotmileage)(slotvalue))(assert(car(colorred)(mileage10000)(value400)))

Sample code:

(clear)(deftemplateblood-donor(slotname)(slottype))(deffactsblood-bank; put names & their types into [[working memory]](blood-donor(name"Alice")(type"A"))(blood-donor(name"Agatha")(type"A"))(blood-donor(name"Bob")(type"B"))(blood-donor(name"Barbara")(type"B"))(blood-donor(name"Jess")(type"AB"))(blood-donor(name"Karen")(type"AB"))(blood-donor(name"Onan")(type"O"))(blood-donor(name"Osbert")(type"O")))(defrulecan-give-to-same-type-but-not-self; handles A > A, B > B, O > O, AB > AB, but not N1 > N1(blood-donor(name?name)(type?type))(blood-donor(name?name2)(type?type2&:(eq?type?type2)&:(neq?name?name2)))=>(printoutt?name" can give blood to "?name2crlf))(defruleO-gives-to-others-but-not-itself; O to O cover in above rule(blood-donor(name?name)(type?type&:(eq?type"O")))(blood-donor(name?name2)(type?type2&:(neq?type?type2)&:(neq?name?name2)))=>(printoutt?name" can give blood to "?name2crlf))(defruleA-or-B-gives-to-AB; case O gives to AB and AB gives to AB already dealt with(blood-donor(name?name)(type?type&:(or(eq?type"A")(eq?type"B"))))(blood-donor(name?name2)(type?type2&:(eq?type2"AB")&:(neq?name?name2)))=>(printoutt?name" can give blood to "?name2crlf));(watch all)(reset)(run)

See also

References

  1. 12345Hemmer, Markus C. (2008). Expert Systems in Chemistry Research. CRC Press. pp. 47–48. ISBN 9781420053241. Retrieved March 30, 2012.ISBN 978-1-4200-5323-4

Further sources

  • Friedman-Hill, Ernest (2003). Jess in Action: Rule Based Systems in Java. Manning Publications. ISBN 9781930110892. Retrieved March 30, 2012.ISBN 1-930110-89-8
  • "Jess, the Rule Engine for the Java Platform". Archived from the original on 29 December 2011.