ErraiBus.java

/*
 * Copyright (C) 2011 Red Hat, Inc. and/or its affiliates.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.jboss.errai.bus.client;

import java.util.Collections;
import java.util.Set;

import org.jboss.errai.bus.client.api.BusLifecycleListener;
import org.jboss.errai.bus.client.api.BusMonitor;
import org.jboss.errai.bus.client.api.ClientMessageBus;
import org.jboss.errai.bus.client.api.SubscribeListener;
import org.jboss.errai.bus.client.api.Subscription;
import org.jboss.errai.bus.client.api.TransportErrorHandler;
import org.jboss.errai.bus.client.api.UnsubscribeListener;
import org.jboss.errai.bus.client.api.messaging.Message;
import org.jboss.errai.bus.client.api.messaging.MessageBus;
import org.jboss.errai.bus.client.api.messaging.MessageCallback;
import org.jboss.errai.bus.client.api.messaging.RequestDispatcher;
import org.jboss.errai.common.client.api.extension.InitVotes;

import com.google.gwt.core.client.EntryPoint;
import com.google.gwt.core.client.GWT;

/**
 * The main GWT <tt>EntryPoint</tt> class for ErraiBus.  This class also contains a static global reference to the
 * client {@link org.jboss.errai.bus.client.api.messaging.MessageBus} which can be obtained by calling: <tt>ErraiBus.get()</tt>
 */
public class ErraiBus implements EntryPoint {
  private static ClientMessageBus bus;

  static {
    if (GWT.isClient()) {
      bus = GWT.create(MessageBus.class);
    }
    else {

      // edge case: in simulated client mode, client code runs in an environment where GWT.isClient() returns false
      // obviously, this code will not be able to contact the server, but framework code still assumes bus != null
      bus = new ClientMessageBus() {
        @Override
        public void sendGlobal(Message message) {

        }

        @Override
        public void send(Message message) {
        }

        @Override
        public void send(Message message, boolean fireListeners) {
        }

        @Override
        public void sendLocal(Message message) {
        }

        @Override
        public Subscription subscribe(String subject, MessageCallback receiver) {
          return null;
        }

        @Override
        public Subscription subscribeLocal(String subject, MessageCallback receiver) {
          return null;
        }

        @Override
        public Subscription subscribeShadow(String subject, MessageCallback callback) {
          return null;
        }

        @Override
        public void unsubscribeAll(String subject) {
        }

        @Override
        public boolean isSubscribed(String subject) {
          return false;
        }

        @Override
        public void addSubscribeListener(SubscribeListener listener) {
        }

        @Override
        public void addUnsubscribeListener(UnsubscribeListener listener) {
        }

        @Override
        public void attachMonitor(BusMonitor monitor) {
        }

        @Override
        public void init() {
        }

        @Override
        public void stop(boolean sendDisconnectToServer) {
        }

        @Override
        public Set<String> getAllRegisteredSubjects() {
          return Collections.emptySet();
        }

        @Override
        public void addTransportErrorHandler(TransportErrorHandler errorHandler) {
        }

        @Override
        public void removeTransportErrorHandler(TransportErrorHandler errorHandler) {
        }

        @Override
        public void addLifecycleListener(BusLifecycleListener l) {
        }

        @Override
        public void removeLifecycleListener(BusLifecycleListener l) {
        }

        @Override
        public void setProperty(String name, String value) {
        }

        @Override
        public void clearProperties() {
        }

        @Override
        public String getSessionId() {
          return null;
        }

        @Override
        public String getClientId() {
          return null;
        }
      };
    }

    InitVotes.registerPersistentPreInitCallback(new Runnable() {
      @Override
      public void run() {
        bus.init();
      }
    });
  }

  /**
   * Obtain an instance of the client MessageBus.
   *
   * @return Returns instance of MessageBus
   */
  public static MessageBus get() {
    return bus;
  }

  private static RequestDispatcher DISPATCHER_INST = new RequestDispatcher() {
    @Override
    public void dispatchGlobal(Message message) {
      get().sendGlobal(message);
    }

    @Override
    public void dispatch(Message message) {
      get().send(message);
    }
  };

  public static RequestDispatcher getDispatcher() {
    return DISPATCHER_INST;
  }

  @Override
  public void onModuleLoad() {
  }

  String getSessionId() {
    return null;
  }

  String getClientId() {
    return null;
  }
}