/**
* Copyright (c) 2013, Institute of Information Systems (Sven Groppe and contributors of LUPOSDATE), University of Luebeck
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
* following conditions are met:
*
* - Redistributions of source code must retain the above copyright notice, this list of conditions and the following
* disclaimer.
* - Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the
* following disclaimer in the documentation and/or other materials provided with the distribution.
* - Neither the name of the University of Luebeck nor the names of its contributors may be used to endorse or promote
* products derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
* GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package lupos.event.consumer;
import java.io.IOException;
import java.io.Serializable;
import java.util.*;
import lupos.datastructures.bindings.Bindings;
import lupos.datastructures.bindings.BindingsMap;
import lupos.datastructures.queryresult.QueryResult;
import lupos.event.action.Action;
import lupos.event.communication.*;
import lupos.event.pubsub.IQueryResultReceivedHandler;
import lupos.event.pubsub.PubSubClient;
import lupos.event.pubsub.Subscription;
import lupos.event.util.TimedWrapper;
/**
* The consumer component which is used to connect to a broker and submit subscription.
*/
public class Consumer extends Observable implements IMessageReceivedHandler<Serializable>, IQueryResultReceivedHandler, IDisconnectedHandler {
/**
* define which transport type should be used for communication
*/
private final Class<? extends IMessageTransport> transportClass = TcpMessageTransport.class;
/**
* the message service that is used for communication
*/
private SerializingMessageService msgService = null;
private PubSubClient pubSubClient;
private TcpConnectInfo connectingSubBroker;
private Map<Subscription, Action> subscriptionActionMap = new HashMap<Subscription, Action>();
//final List<IResultReceivedHandler> resultReceivedHandlers = new ArrayList<IResultReceivedHandler>();
public Consumer() throws Exception {
Bindings.instanceClass = BindingsMap.class;
this.msgService = new SerializingMessageService(this.transportClass);
}
/**
* Connects to the master broker and sends
* a connection request to get notified about
* a possible subbroker connection (this will
* be handled in messageRecieved())
* @param host the host of the master
* @param port the port of the master
* @throws Exception if the connection has
* not been built properly
*/
public void connect(String host, int port) throws Exception {
this.msgService.connect(new TcpConnectInfo(host, port));
ConnectionRequest conReq = new ConnectionRequest(ConnectionRequest.REQUESTTYPE_CONSUMER);
this.msgService.sendMessage(conReq);
this.msgService.addHandler2(this);
this.msgService.addDisconnectHandler(this);
this.pubSubClient = new PubSubClient(this.msgService);
this.pubSubClient.addHandler(this);
this.setChanged();
this.notifyObservers();
}
/**
* Closes the connection.
*/
public void disconnect() {
this.connectingSubBroker = null;
this.msgService.disconnect();
this.setChanged();
this.notifyObservers();
}
/**
* Submits a subscription to the broker.
* @param s
* @throws IOException
*/
public void subscribe(Subscription s, Action a) throws IOException {
this.pubSubClient.subscribe(s);
this.subscriptionActionMap.put(s, a);
}
@Override
public void messageReceived(Object src, Serializable msg) {
if(msg instanceof TcpConnectInfo){
this.connectingSubBroker = (TcpConnectInfo)msg;
this.msgService.disconnect();
}
}
/**
* Checks if the consumer is currently connected.
* @return true, if connected
*/
public boolean isConnected() {
return this.msgService.isConnected();
}
/**
* Get the query results for a particular subscription.
* @param The subscription whose query results should be returned.
* @return A list of query results.
*/
public List<TimedWrapper<QueryResult>> getQueryResults(Subscription s) {
return this.pubSubClient.getQueryResults(s);
}
@Override
public void queryResultReceived(QueryResult qr, Subscription sub) {
System.out.println("QUERY RESULT RECEIVED");
if(this.subscriptionActionMap.containsKey(sub)) {
Action action = this.subscriptionActionMap.get(sub);
action.execute(qr);
}
}
/**
* After a disconnect, this could be a sign for
* reconnecting to a new broker. this is done in
* this handler method
*/
@Override
public void disconnected() {
if (this.connectingSubBroker == null)
return;
// Connect to the sub broker when disconnected
try {
this.msgService.connect(this.connectingSubBroker);
ConnectionRequest conReq = new ConnectionRequest(ConnectionRequest.REQUESTTYPE_CONSUMER);
conReq.setPort(TcpMessageTransport.SERVER_PORT);
this.msgService.sendMessage(conReq);
this.pubSubClient.changeMessageService(this.msgService);
// resend all former subscriptions
this.pubSubClient.resendSubscriptions();
} catch (Exception e) {
e.printStackTrace();
}
}
}