Expression Language / Expression Engine / Rule Engine

[oldratlee]

Expression Language

The Java Unified Expression Language is a special purpose programming language mostly used in Java web applications for embedding expressions into web pages. The Java specification writers and expert groups of the Java web-tier technologies have worked on a unified expression language which was first included in the JSP 2.1 specification (JSR-245), and later specified by itself in JSR-341, part of Java EE 7.
https://en.wikipedia.org/wiki/Unified_Expression_Language

• Spring Expression Language (SpEL)
  • a powerful expression language that supports querying and manipulating an object graph at runtime. The language syntax is similar to Unified EL but offers additional features, most notably method invocation and basic string templating functionality.
  • https://docs.spring.io/spring/docs/5.1.x/spring-framework-reference/core.html#expressions
  • https://github.com/spring-projects/spring-framework
• Aviator
  • a lightweight,high performance expression evaluator for java. Aviator compiles expression to byte code and evaluate it on the fly.
  • https://github.com/killme2008/aviator/wiki
  • https://github.com/killme2008/aviator
• QLExpress
  • a powerful, lightweight, dynamic language for the Java platform aimed at improving developers’ productivity in different business scenes.
  • https://github.com/alibaba/QLExpress
• MVEL (MVFLEX Expression Language)
  • MVEL has largely been inspired by Java syntax, but has some fundamental differences aimed at making it more efficient as an expression language, such as operators that directly support collection, array and string matching, as well as regular expressions. MVEL is used to evaluate expressions written using Java syntax.
  • http://mvel.documentnode.com/
  • https://github.com/mvel/mvel
• Object-Graph Navigation Language - OGNL
  • an expression language for getting and setting properties of Java objects. You use the same expression for both getting and setting the value of a property.
  • https://github.com/jkuhnert/ognl
• Java Expression Language (JEXL) - commons-jexl
  • a library intended to facilitate the implementation of dynamic and scripting features in applications and frameworks
  • http://commons.apache.org/proper/commons-jexl/
  • https://github.com/apache/commons-jexl
• JUEL - Java Unified Expression Language
  • an implementation of the Unified Expression Language (EL), specified as part of the JSP 2.1 standard (JSR-245), which has been introduced in JEE5. Additionally, JUEL 2.2 implements the JSP 2.2 maintenance release specification for full JEE6 compliance.
  • http://juel.sf.net/
  • https://github.com/beckchr/juel

Rule Engine

• Drools
  • Drools Expert is the rule engine and Drools Fusion does complex event processing (CEP).
  • http://www.drools.org/
  • https://github.com/kiegroup/drools
• easy-rules
  • provides the Rule abstraction to create rules with conditions and actions, and the RulesEngine API that runs through a set of rules to evaluate conditions and execute actions.
  • https://github.com/j-easy/easy-rules/wiki
  • https://github.com/j-easy/easy-rules

Articles

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