jq-quarkus

jq is one of my favorite command line tools for parsing JSON.

Example usage:

echo '{"foo": {"bar": "1"}}' | jq .foo.bar

Imagine if we could use it natively from within Java applications?

JQ.jq(input, ".foo.bar");

This is a POC to show how we could do that! Here is how it works.

1. Build the jq grammar using ANTLR
2. Implement the jq language using GraalVM's Truffle Framework
3. Build a project using Quarkus, and call natively into the language.

Example endpoint:

    @POST
    @Path("jq")
    @Consumes(MediaType.APPLICATION_JSON)
    @Produces(MediaType.TEXT_PLAIN)
    public Object jq(Map input) {
        return JQ.jq(input, ".foo.bar");
    }

One of the interesting aspects of this implementation is that it works on Java objects directly, and doesn't need Jackson to convert input to and from JSON.

Supported language features

This experimental implementation only supports a subset of jq language features, such as .foo.bar for processing JSON. Contributions welcome 😄

Check this test suite for examples of supported jq syntax.

Running the application in dev mode

You can run your application in dev mode that enables live coding using:

./gradlew quarkusDev

NOTE: Quarkus now ships with a Dev UI, which is available in dev mode only at http://localhost:8080/q/dev/.

Packaging and running the application

The application can be packaged using:

./gradlew build

It produces the quarkus-run.jar file in the build/quarkus-app/ directory. Be aware that it’s not an über-jar as the dependencies are copied into the build/quarkus-app/lib/ directory.

If you want to build an über-jar, execute the following command:

./gradlew build -Dquarkus.package.type=uber-jar

The application is now runnable using java -jar build/quarkus-app/quarkus-run.jar.

Creating a native executable

You can create a native executable using:

./gradlew build -Dquarkus.package.type=native

Or, if you don't have GraalVM installed, you can run the native executable build in a container using:

./gradlew build -Dquarkus.package.type=native -Dquarkus.native.container-build=true

You can then execute your native executable with: ./build/jq-quarkus-1.0.0-SNAPSHOT-runner

If you want to learn more about building native executables, please consult https://quarkus.io/guides/gradle-tooling.

Provided examples

RESTEasy JAX-RS example

REST is easy peasy with this Hello World RESTEasy resource.

Related guide section...