science

Jess (programming language)

Jess (programming language) is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Jess (programming language) rather than just read about it. In short: Jess is a rule engine for the Java computing platform, written in the Java programming language. It was developed by Ernest Friedman-Hill of Sandia National Laboratories.

Key takeaways

Jess (programming language) belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Jess (programming language) to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Jess (programming language) from memory before moving on to harder problems.

Reference excerpt

Jess is a rule engine for the Java computing platform, written in the Java programming language. It was developed by Ernest Friedman-Hill of Sandia National Laboratories. It is a superset of the CLIPS language. It was first written in late 1995. The language provides rule-based programming for the automation of an expert system, and is often termed as an expert system shell. 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 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:

Sample code:

See also Semantic reasoner Decision Model and Notation

Related systems CLIPS: public-domain software tool to build expert systems ILOG rules: business rule management system JBoss Drools: business rule management system (BRMS) Prolog: general purpose logic programming language OpenL Tablets: business centric rules and BRMS DTRules: decision table based, open-source rule engine for Java

References

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

External links "Jess, the Rule Engine for the Java Platform". Archived from the original on 29 December 2011.

Worked examples

Example 1 — a first encounter with Jess (programming language)

Start with the simplest possible case. Write down what Jess (programming language) claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Jess (programming language) before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Jess (programming language) ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Jess (programming language)

In research: Jess (programming language) appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Jess (programming language) in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Jess (programming language) is common in secondary-school and first-year university syllabi. It links to neighbouring topics Expert systems, Java APIs, Knowledge representation languages, so understanding it makes those chapters shorter.
In everyday life: Look for Jess (programming language) outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Jess (programming language) in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Jess (programming language) means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Jess (programming language) out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Jess (programming language) in simple terms?

Jess is a rule engine for the Java computing platform, written in the Java programming language. It was developed by Ernest Friedman-Hill of Sandia National Laboratories.

Why does Jess (programming language) matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Jess (programming language)?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Jess (programming language).