GraphQL-IO-Server-Java

GraphQL Network Communication Framework (Server) for Java

About

This is a GraphQL network communication framework for Java based on the JavaScript Graphql-IO-Server reference implementation. For more detailed information , we recommend you visit the website of GraphQL-IO Java. If you're looking for a suitable client implementation, you can use the GraphQL-IO-Client written in JavaScript.

Important note: This is a newly founded project that is in active development, so we strongly recommend to use this software for testing purposes only until it is declared stable.

Dependencies

GraphQL-IO Server Java is a GraphQL that primarily depends on the following projects:

Installation

Our releases are hosted on on Maven central. To integrate GraphQL-IO Server Java into your application just add the following dependency to your project and set the appropriate version (checkout available versions on Maven central):

Maven

<dependency>
	<groupId>com.graphqlio</groupId>
	<artifactId>graphql-io-server-java</artifactId>
	<version>${version}</version>
</dependency>

Gradle

dependencies {
  compile 'com.graphqlio:graphql-io-server-java:${version}'
}

Usage

To get a better understanding on how to use this Framework we defined a minimal example.

Minimal example: Counter

In this example we show how a client can receive real-time updates on a server-side counter object via a GraphQL-IO query, without consuming a separate Subscription, as we know from common GraphQL.

Following steps are necessary to archive this:

Setup a GraphQL scheme containing a Counter object having a field value we're interested in and a corresponding field on the Query object to resolve an instance of this type:
```
schema {
    query: Query
    mutation: Mutation
}
type Query {
    counter: Counter!
}
type Mutation {
    increase: Counter!
}
type Counter {
    value: Int!
}
```

Implement a GraphQLQueryResolver containing a suitable resolver method for the field counter defined in the Query object:

@Component
public class RootQueryResolver implements GraphQLQueryResolver {

   public Counter counter(DataFetchingEnvironment env) {
       Counter counter = counterRepository.getCounter();

       GtsContext context = env.getContext();
       GtsScope scope = context.getScope();
       scope.addRecord(
           GtsRecord.builder()
               .op(GtsOperationType.READ)
               .arity(GtsArityType.ALL)
               .dstType(Counter.class.getName())
               .dstIds(new String[] { "0" })
               .dstAttrs(new String[] { "*" })
               .build()
           );

       return counter;
   }
}

Define a GraphQL-IO query, subscribing to changes for the field value using the GraphQL-IO extension _Subscription { subscribe }. To better understand the magic that's happening here, take a look at our documentation.
```
query { _Subscription { subscribe } counter { value }}
```

Implement a WebSocket client sending the query in text format defined by WebSocket-Framed or just use the JavaScript GraphQL-IO-Client implementation. In this example we used a Websocket client provided by Spring Boot. Of course you can also use any other Websocket client that you like the best.

    final String Query = "[1,0,\"GRAPHQL-REQUEST\",query { _Subscription { subscribe } counter { value } } ]";

    final WebSocketClient webSocketClient = new StandardWebSocketClient();
    final WebSocketHandler webSocketHandler = new CounterClientSubscriptionHandler();
    final WebSocketHttpHeaders webSocketHttpHeaders = new WebSocketHttpHeaders();
    final URI uri = URI.create("ws://127.0.0.1:8080/api/data/graph");

    final WebSocketSession webSocketSession = webSocketClient
            .doHandshake(webSocketHandler, webSocketHttpHeaders, uri).get();

    final AbstractWebSocketMessage message = new TextMessage(Query);
    webSocketSession.sendMessage(message);

    System.out.println("Subscription::waiting 60 seconds...");
    Thread.sleep(60000);
    webSocketSession.close();

Create an application class instantiating the GraphQL-IO Server and setting a few properties, e.g. to define the location of the schema file. In this example we created a small Spring Boot application:

@SpringBootApplication
@EnableGraphQLIOServer
public class CounterServerApplication implements ApplicationRunner {

    public static void main(String[] args) {
        Properties properties = new Properties();
        properties.put("graphqlio.server.schemaLocationPattern", "**/*.counter.graphql");
        properties.put("graphqlio.server.endpoint", "/api/data/graph");
        properties.put("graphqlio.toolssubscribe.useEmbeddedRedis", "true");

        SpringApplication application = new SpringApplication(CounterServerApplication.class);
        application.setDefaultProperties(properties);
        application.run(args);
    }

    @Autowired
    private GsServer graphqlioServer;

    @Override
    public void run(ApplicationArguments args) throws Exception {
        this.graphqlioServer.start();
    }

    @PreDestroy
    public void destroy() throws Exception {
        this.graphqlioServer.stop();
    }
}

For more information, e.g. on how to modify the counter (via Mutations) take a look at our example code.

Roadmap

tbd

Documentation

The documentation can be found here.

Contributing

We welcome anyone to contribute to this project. Detailed information about contribution can be found here.

msg-systems/graphql-io-server-java