regorus/bindings/java/README.md

Regorus Java

Regorus is

• Rego-Rus(t) - A fast, light-weight Rego interpreter written in Rust.
• Rigorous - A rigorous enforcer of well-defined Rego semantics.

See main Regorus page for more details about the project.

Building

Due to operational overhead we don't publish Java bindings to Maven Central currently (see https://github.com/microsoft/regorus/issues/237) and you need to build from source to use it.

In order to build Regorus Java for a target platform, you need to install Rust target for that platform first:

$ rustup target add aarch64-apple-darwin

Afterwards, you can build native library for that target using:

$ cargo build --release --target aarch64-apple-darwin

You will then have a native library at target/aarch64-apple-darwin/release/libregorus_java.dylib depending on your target.

You then need to build Java bindings using:

$ mvn package

And you will have a JAR at ./target/regorus-java-0.1.5.jar.

Usage

You can use Regorus Java bindings as:

import com.microsoft.regorus.Engine;

public class Test {
    public static void main(String[] args) {
        try (Engine engine = new Engine()) {
            engine.addPolicy(
                "hello.rego",
                "package test\nmessage = concat(\", \", [input.message, data.message])"
            );
            engine.addDataJson("{\"message\":\"World!\"}");
            engine.setInputJson("{\"message\":\"Hello\"}");
            String resJson = engine.evalQuery("data.test.message");

            System.out.println(resJson);
        }
    }
}

You need to ensure artifacts built in previous section are in Java's classpath.

For example with java CLI:

$ java -Djava.library.path=../../target/aarch64-apple-darwin/release/ -cp target/regorus-java-0.1.5.jar Test.java

should gave you the output:

{"result":[{"expressions":[{"value":"Hello, World!","text":"data.test.message","location":{"row":1,"col":1}}]}]}