Evrete
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.
Project home
The official project description, documentation, and usage examples can be found at https://www.evrete.org
Prerequisites
Evrete is Java 8+ compatible and ships with zero dependencies.
Installation
Maven Central Repository, core module:
<dependency>
<groupId>org.evrete</groupId>
<artifactId>evrete-core</artifactId>
<version>2.2.00</version>
</dependency>Support for annotated rules (optional):
<dependency>
<groupId>org.evrete</groupId>
<artifactId>evrete-dsl-java</artifactId>
<version>2.2.00</version>
</dependency>Quick start
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()
.newRule("prime numbers")
.forEach(
"$i1", Integer.class,
"$i2", Integer.class,
"$i3", Integer.class
)
.where("$i1 * $i2 == $i3")
.execute(ctx -> ctx.deleteFact("$i3"));
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) throws IOException {
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
License
This project uses the following license: MIT