/**
* Removes a local object.
*
* <p>This method also sends "UNSUBSCRIBE own-object-ID-as-channel" to pubsub server to stop
* receiving PUBLISH destined to the remote object.
*
* @param localObject a remote object
*/
public void removeLocalObject(RemoteObject localObject) {
String objectId = localObject.getObjectId();
if (localObjectsMap.remove(objectId) != null) {
// Unsubscribes objectId as a channel to stop receiving Request
// from remote objects via PubSub.
driverImpl.unsubscribeChannel(objectId);
}
}
/**
* Adds a local object as a listener of messages.
*
* <p>The user (i.e., RemoteObject) of this class calls this method to register the RemoteObject
* as "local RemoteObject" with this class.
*
* <pre>
* [RemoteObject] [RemoteObject] [RemoteObject]
* dispatchEvent() dispatchRequest() dispatchRequest()
* ^ ^ ^
* | | |
* +---------------+ + +---------------+
* | | |
* [MessageDispatcher]<>-----[SubscribersMap]
* |
* message
* |
* [pubsub server]
* </pre>
*
* <p>This method also sends "SUBSCRIBE own-object-ID-as-channel" to pubsub server to receive
* PUBLISH destined to the remote object, since requestSync() method sends PUBLISH as "request" to
* the remote object.
*
* @param localObject a remote object
* @see org.o3project.odenos.remoteobject.RemoteObject#dispatchEvent
* @see org.o3project.odenos.remoteobject.RemoteObject#dispatchRequest
*/
public void addLocalObject(RemoteObject localObject) {
String objectId = localObject.getObjectId();
if (localObjectsMap.putIfAbsent(objectId, localObject) == null) {
driverImpl.subscribeChannel(objectId);
}
if (objectId.equals(systemManagerId)) {
driverImpl.systemManagerAttached();
}
}
/**
* Synchronous request/response service (remote transactions)
*
* <p>This method operates in two modes:
*
* <ul>
* <li>if the request is to "local RemoteObject", then this method works like a local loopback
* interface to dispatch the request to "local RemoteObject".
* <li>else if the request is to "remote RemoteObject", then this method uses RemoteTransactions
* class to send the request to "remote RemoteObject" via pubsub server.
* </ul>
*
* <pre>
* (local)
* [RemoteObject] [RemoteObject]
* requestSync() ^
* | |
* | |
* +---------------+
* loopback
*
* (remote)
* [RemoteObject] [RemoteObject]
* requsetSync() ^
* | |
* | |
* +-------[pubsub server]-------+
* </pre>
*
* @param request Request to be sent
* @return Response response to the request
* @throws Exception exception
*/
public Response requestSync(Request request) throws Exception {
String objectId = request.objectId;
Response response;
RemoteObject localObject = localObjectsMap.get(objectId);
if (localObject != null && !localRequestsToPubSubServer) {
// synchronized with Actor#read()
synchronized (localObject) {
Request requested = deepCopy(request);
Response responsed = localObject.dispatchRequest(requested);
response = deepCopy(responsed);
}
// TODO: remoteObjectsMap is not unused.
} else if (remoteObjectsMap.containsKey(objectId)) {
response = remoteTransactions.sendRequest(request);
} else {
// request to an unregistered remote object
remoteObjectsMap.put(objectId, Boolean.valueOf(false));
response = remoteTransactions.sendRequest(request);
}
return response;
}
// When closed, componentManager will be deleted. (Expect when
// componentManager is finalized, the components created by it automatically
// deleted.)
@Override
public void onFinalize() {
deleteAllComponentConnection();
deleteAllComponentManagers();
super.onFinalize();
}
/**
* onMessage implementation.
*
* <p>This method has two roles:
*
* <ul>
* <li>Works like a mail transfer agent to transfer a received request or event to {@link
* org.o3project.odenos.remoteobject.RemoteObject}.
* <li>Supports both synchronous and asynchronous messaging.
* </ul>
*/
@Override
public void onMessage(final String channel, byte[] message) {
serial++; // Serial number for incoming messages.
try {
BufferUnpacker upk = msgpack.createBufferUnpacker(message);
// read delivery header.
byte type = upk.readByte();
final int sno = upk.readInt(); // Sequence number for outgoing request messages.
final String sourceObjectId = upk.readString(); // i.e., channel
RemoteObject localObject = null;
Queue<Mail> mailbox = null;
Mail mail = null;
switch (type) {
case TYPE_REQUEST: // Transaction(request): synchronous operation
/*
* --- request --> dispatchRequest() -------> [RemoteObject]
* |
* <-- response --- publishResponseAsync() <-------+
*/
final Request request = upk.read(Request.class);
if (log.isDebugEnabled()) {
log.debug(
"Request received:\n"
+ " MessageDispatcher: {}\n"
+ " sno: {}\n"
+ " channel: {}\n"
+ " method: {}\n"
+ " objectId: {}\n"
+ " sourceObjectId: {}\n"
+ " path: /{}/\n"
+ " body: {}",
sourceDispatcherId,
sno,
channel,
request.method,
request.objectId,
sourceObjectId,
request.path,
request.getBodyValue());
}
// Wraps the request with Mail and deliver it to a mailbox.
String to = request.objectId;
mail = new Mail(serial, sno, to, sourceObjectId, this, request, null);
localObject = localObjectsMap.get(to);
if (localObject != null) {
mailbox = localObject.getMailbox();
synchronized (mailbox) {
mailbox.add(mail);
if (!localObject.isRunning()) {
localObject.setRunning(true);
// Assigns a thread to read a mail in the mailbox.
actor.read(localObject);
}
}
}
break;
case TYPE_RESPONSE: // Transaction(response): synchronous operation
/*
* publishRequestAsync()
* requestSync() -> [RemoteTransaction] ---- request -----> [RemoteObject]
* <-- ^ |
* | publishResponseAsync()
* | |
* +- signalResponse() <-- response --+
*/
Response response = upk.read(Response.class);
if (log.isDebugEnabled()) {
log.debug(
"Response received:\n"
+ " MessageDispatcher: {}\n"
+ " channel: {}\n"
+ " statusCode: {}\n"
+ " body: {}",
sourceDispatcherId,
channel,
response.statusCode,
response.getBodyValue());
}
remoteTransactions.signalResponse(sno, response);
break;
case TYPE_EVENT: // Asynchronous
/*
* publishEventAsync() -- event --> dispatchEvent() --> [RemoteObject]
* :
* [EventSubscriptionMap]
*/
final Event event = upk.read(Event.class);
if (log.isDebugEnabled()) {
log.debug(
"Event received:\n"
+ " MessageDispatcher: {}\n"
+ " channel: {}\n"
+ " body: {}",
sourceDispatcherId,
channel,
event.getBodyValue());
}
// All the subscribers of the channel
final Collection<String> subscribers = subscribersMap.getSubscribers(channel);
if (subscribers == null) { // No subscribers found on the channel
if (log.isDebugEnabled()) {
log.debug("no subscribers subscribing the channel: {}", channel);
}
return; // Silently discards the event
}
// Wraps the event with Mail and deliver it to a mailbox.
for (String subscriber : subscribers) {
localObject = localObjectsMap.get(subscriber);
if (localObject != null) {
mail = new Mail(serial, sno, subscriber, channel, this, null, event);
mailbox = localObject.getMailbox();
synchronized (mailbox) {
mailbox.add(mail);
if (!localObject.isRunning()) {
localObject.setRunning(true);
// Assigns a thread to read a mail in the mailbox.
actor.read(localObject);
}
}
}
}
break;
default:
break;
}
} catch (Exception e) {
log.error("onMessage failed", e);
}
}