Adds graphQL subscription server

Author: rogelio-o

web-graphql-examples/pom.xml

@@ -6,7 +6,7 @@
 
   <groupId>io.vertx</groupId>
   <artifactId>web-graphql-examples</artifactId>
-  <version>3.8.0</version>
+  <version>4.0.0-SNAPSHOT</version>
 
   <dependencies>
 

web-graphql-examples/src/main/java/io/vertx/example/web/graphql/SubscriptionServer.java

@@ -0,0 +1,90 @@
+package io.vertx.example.web.graphql;
+
+import graphql.GraphQL;
+import graphql.schema.DataFetchingEnvironment;
+import graphql.schema.GraphQLSchema;
+import graphql.schema.idl.RuntimeWiring;
+import graphql.schema.idl.SchemaGenerator;
+import graphql.schema.idl.SchemaParser;
+import graphql.schema.idl.TypeDefinitionRegistry;
+import io.vertx.core.AbstractVerticle;
+import io.vertx.core.Launcher;
+import io.vertx.core.http.HttpServerOptions;
+import io.vertx.ext.web.Router;
+import io.vertx.ext.web.handler.graphql.*;
+import org.reactivestreams.Publisher;
+import org.reactivestreams.Subscriber;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import static graphql.schema.idl.RuntimeWiring.newRuntimeWiring;
+
+public class SubscriptionServer extends AbstractVerticle {
+
+  public static void main(String[] args) {
+    Launcher.executeCommand("run", SubscriptionServer.class.getName());
+  }
+
+  private List<Link> links;
+
+  @Override
+  public void start() {
+    prepareData();
+
+    final Router router = Router.router(vertx);
+    router.route("/graphql").handler(ApolloWSHandler.create(createGraphQL()));
+
+    final HttpServerOptions httpServerOptions = new HttpServerOptions()
+      .setWebsocketSubProtocols("graphql-ws");
+    vertx.createHttpServer(httpServerOptions)
+      .requestHandler(router)
+      .listen(8080);
+  }
+
+  private void prepareData() {
+    User peter = new User("Peter");
+    User paul = new User("Paul");
+    User jack = new User("Jack");
+
+    links = new ArrayList<>();
+    links.add(new Link("https://vertx.io", "Vert.x project", peter));
+    links.add(new Link("https://www.eclipse.org", "Eclipse Foundation", paul));
+    links.add(new Link("http://reactivex.io", "ReactiveX libraries", jack));
+    links.add(new Link("https://www.graphql-java.com", "GraphQL Java implementation", peter));
+  }
+
+  private GraphQL createGraphQL() {
+    String schema = vertx.fileSystem().readFileBlocking("links.graphqls").toString();
+
+    SchemaParser schemaParser = new SchemaParser();
+    TypeDefinitionRegistry typeDefinitionRegistry = schemaParser.parse(schema);
+
+    RuntimeWiring runtimeWiring = newRuntimeWiring()
+      .type("Subscription", builder -> builder.dataFetcher("links", this::linksFetcher))
+      .build();
+
+    SchemaGenerator schemaGenerator = new SchemaGenerator();
+    GraphQLSchema graphQLSchema = schemaGenerator.makeExecutableSchema(typeDefinitionRegistry, runtimeWiring);
+
+    return GraphQL.newGraphQL(graphQLSchema)
+      .build();
+  }
+
+  private Publisher<Link> linksFetcher(DataFetchingEnvironment env) {
+    return subscriber -> {
+      sendData(subscriber, 0);
+    };
+  }
+
+  private void sendData(Subscriber<? super Link> subscriber, int index) {
+    if (index >= links.size()) {
+      subscriber.onComplete();
+    } else {
+      subscriber.onNext(links.get(index));
+
+      vertx.setTimer(1000, t -> sendData(subscriber, index + 1));
+    }
+  }
+
+}

web-graphql-examples/src/main/resources/links.graphqls

@@ -11,3 +11,7 @@ type User {
 type Query {
   allLinks(secureOnly: Boolean = false): [Link]
 }
+
+type Subscription {
+  links: Link
+}