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/*******************************************************************************
* Copyright (c) 2007 Wind River Systems, Inc. and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Wind River Systems - initial API and implementation
*******************************************************************************/
package com.windriver.tcf.api.protocol;
import com.windriver.tcf.api.internal.core.LocalPeer;
import com.windriver.tcf.api.internal.core.Transport;
import com.windriver.tcf.api.internal.services.local.LocatorService;
import com.windriver.tcf.api.services.ILocator;
/**
*
* Class Protocol provides static methods to access Target Communication Framework root objects:
* 1. the framework event queue and dispatch thread;
* 2. local instance of Locator service, which maintains a list of available targets;
* 3. list of open communication channels.
*/
public class Protocol {
private static IEventQueue event_queue;
/**
* Before TCF can be used it should be given an object implementing IEventQueue interface.
* The implementation maintains a queue of objects implementing Runnable interface and
* executes <code>run</code> methods of that objects in a sequence by a single thread.
* The thread in referred as TCF event dispatch thread. Objects in the queue are called TCF events.
* Executing <code>run</code> method of an event is also called dispatching of event.
*
* Only few methods in TCF APIs are thread safe - can be invoked from any thread.
* If a method description does not say "can be invoked from any thread" explicitly -
* the method must be invoked from TCF event dispatch thread. All TCF listeners are
* invoked from the dispatch thread.
*
* @param event_queue - IEventQueue implementation.
*/
public static void setEventQueue(IEventQueue event_queue) {
assert Protocol.event_queue == null;
Protocol.event_queue = event_queue;
event_queue.invokeLater(new Runnable() {
public void run() {
new LocatorService();
new LocalPeer();
}
});
}
/**
* @return instance of IEventQueue that is used for TCF events.
*/
public static IEventQueue getEventQueue() {
return event_queue;
}
/**
* Returns true if the calling thread is TCF event dispatch thread.
* Use this call the ensure that a given task is being executed (or not being)
* on dispatch thread.
*
* @return true if running on the dispatch thread.
*/
public static boolean isDispatchThread() {
return event_queue != null && event_queue.isDispatchThread();
}
/**
* Causes <code>runnable</code> to have its <code>run</code>
* method called in the dispatch thread of the framework.
* Events are dispatched in same order as queued.
* If invokeLater is called from the dispatching thread
* the <i>runnable.run()</i> will still be deferred until
* all pending events have been processed.
*
* This method can be invoked from any thread.
*
* @param runnable the <code>Runnable</code> whose <code>run</code>
* method should be executed asynchronously.
*/
public static void invokeLater(Runnable runnable) {
event_queue.invokeLater(runnable);
}
/**
* Causes <code>runnable</code> to have its <code>run</code>
* method called in the dispatch thread of the framework.
* Calling thread is suspended until the method is executed.
*
* This method can be invoked from any thread.
*
* @param runnable the <code>Runnable</code> whose <code>run</code>
* method should be executed on dispatch thread.
*/
public static void invokeAndWait(final Runnable runnable) {
if (event_queue.isDispatchThread()) {
runnable.run();
}
else {
Runnable r = new Runnable() {
public void run() {
try {
runnable.run();
}
finally {
synchronized (this) {
notify();
}
}
}
};
synchronized (r) {
event_queue.invokeLater(r);
try {
r.wait();
}
catch (InterruptedException x) {
throw new Error(x);
}
}
}
}
/**
* Get instance of the framework locator service.
* The service can be used to discover available remote peers.
*
* @return instance of ILocator.
*/
public static ILocator getLocator() {
return LocatorService.getLocator();
}
/**
* Return an array of all open channels.
* @return an array of IChannel
*/
public static IChannel[] getOpenChannels() {
return Transport.getOpenChannels();
}
/**
* Interface to be implemented by clients willing to be notified when
* new TCF communication channel is opened.
*/
public interface ChannelOpenListener {
public void onChannelOpen(IChannel channel);
}
/**
* Add a listener that will be notified when new channel is opened.
* @param listener
*/
public static void addChannelOpenListener(ChannelOpenListener listener) {
Transport.addChanalOpenListener(listener);
}
/**
* Remove channel opening listener.
* @param listener
*/
public static void removeChannelOpenListener(ChannelOpenListener listener) {
Transport.removeChanalOpenListener(listener);
}
/**
* Transmit TCF event message.
* The message is sent to all open communication channels – broadcasted.
*/
public static void sendEvent(String service_name, String event_name, byte[] data) {
Transport.sendEvent(service_name, event_name, data);
}
/**
* Call back after TCF messages sent by this host up to this moment are delivered
* to their intended target. This method is intended for synchronization of messages
* across multiple channels.
*
* Note: Cross channel synchronization can reduce performance and throughput.
* Most clients don't need cross channel synchronization and should not call this method.
*
* @param done will be executed by dispatch thread after communication
* messages are delivered to corresponding targets.
*/
public static void sync(Runnable done) {
Transport.sync(done);
}
}
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