Important!
Starting with version 3.2.00, the default build (release) version targets Java 11. Java 8 artifacts are now published with the '-8' suffix.
Evrete is a forward-chaining Java rule engine that implements the RETE algorithm and is fully compliant with the Java Rule Engine specification (JSR 94).
Historically designed as a fast and lightweight alternative to full-scale rule management systems, the engine also brings its own mix of features:
Rule authoring
- Rules can be authored both externally and inline as a plain Java 8 code.
- The engine allows rules to be authored as annotated Java sources, classes, or archives.
- The library itself is a flexible tool for creating custom domain-specific rule languages (DSL).
Intuitive and developer-friendly
- Library's type system allows it to seamlessly process any kinds of objects, including JSON and XML.
- Fluent builders, Java functional interfaces, and other best practices keep developers' code concise and clear.
- Key components are exposed as Service Provider Interfaces and can be customized.
Performance and security
- The engine's algorithm and memory are optimized for large-scale and labeled data.
- Built-in support of Java Security Manager protects against unwanted or potentially malicious code in the rules.
The official project description, documentation, and usage examples can be found at https://www.evrete.org
Evrete is Java 8+ compatible and ships with zero dependencies.
Maven:
<dependency>
<groupId>org.evrete</groupId>
<artifactId>evrete-core</artifactId>
<version>3.2.02</version>
</dependency>Gradle:
implementation 'org.evrete:evrete-core:3.2.02'Maven:
<dependency>
<groupId>org.evrete</groupId>
<artifactId>evrete-dsl-java</artifactId>
<version>3.2.02</version>
</dependency>Gradle:
implementation 'org.evrete:evrete-dsl-java:3.2.02'Below is a simple example of rule that removes from session memory every integer except prime numbers.
As inline Java code:
public class PrimeNumbersInline {
public static void main(String[] args) {
KnowledgeService service = new KnowledgeService();
Knowledge knowledge = service
.newKnowledge()
.builder()
.newRule("prime numbers")
.forEach(
"$i1", Integer.class,
"$i2", Integer.class,
"$i3", Integer.class
)
.where("$i1 * $i2 == $i3")
.execute(ctx -> ctx.deleteFact("$i3"))
.build();
try (StatefulSession session = knowledge.newStatefulSession()) {
// Inject candidates
for (int i = 2; i <= 100; i++) {
session.insert(i);
}
// Execute rules
session.fire();
// Print current memory state
session.forEachFact((handle, o) -> System.out.println(o));
}
service.shutdown();
}
}As annotated Java source file:
public class PrimeNumbersDSLUrl {
public static void main(String[] args) {
KnowledgeService service = new KnowledgeService();
Knowledge knowledge = service
.newKnowledge(
"JAVA-SOURCE",
new URL("https://www.evrete.org/examples/PrimeNumbersSource.java")
);
try (StatefulSession session = knowledge.newStatefulSession()) {
// Inject candidates
for (int i = 2; i <= 100; i++) {
session.insert(i);
}
// Execute rules
session.fire();
// Printout current memory state
session.forEachFact((handle, o) -> System.out.println(o));
}
}
}where the rule itself is stored externally as PrimeNumbersSource.java
For further details see the official documentation
This project uses the following license: MIT
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