Bootstraping GraphQL clients

In general, it is recommended to use SmallRye GraphQL client through the Quarkus extension, or the WildFly feature pack, each of them having their own documentation about how to set up dependencies and bootstrap a client. It is however also possible to use SmallRye GraphQL Client in a standalone application outside any container. The single dependency that you need is io.smallrye:smallrye-graphql-client-implementation-vertx, as the Vert.x based implementation is currently the only supported one.

If you're using the client as a script and notice that the JVM doesn't exit even after you close the client instance, it's probably because the client is maintaining a Vertx instance that it created automatically. To solve this issue, you might need to create a Vertx instance on your own, pass it to the client builder, and then close it after closing the client. See the following JBang snippet for an example.

Using with JBang

This is a full script runnable directly with JBang that uses a dynamic client for connecting to countries.trevorblades.com to obtain a list of countries from its database.

///usr/bin/env jbang "$0" "$@" ; exit $?
//DEPS io.smallrye:smallrye-graphql-client-implementation-vertx:1.5.0

import io.smallrye.graphql.client.dynamic.api.DynamicGraphQLClientBuilder;
import io.smallrye.graphql.client.dynamic.api.DynamicGraphQLClient;
import io.smallrye.graphql.client.Response;
import io.smallrye.graphql.client.vertx.dynamic.VertxDynamicGraphQLClientBuilder;

import io.vertx.core.Vertx;

// Has a multiline string literal, requires Java 15+!
class Client {
    public static void main(String... args) throws Exception {
        Vertx vertx = Vertx.vertx();
        DynamicGraphQLClient client = new VertxDynamicGraphQLClientBuilder()
            .url("https://countries.trevorblades.com")
            .vertx(vertx)
            .build();
        try {
            Response response = client.executeSync("""
                query {
                  countries {
                    name
                  }
                }
                """);
            System.out.println(response);
        } finally {
            client.close();
            vertx.close();
        }
    }
}

Save this file as client.java and execute with jbang client.java.