/interpreter/tags/at_build150307/src/edu/vub/at/actors/net/cmd/CMDRequireService.java

 1/**
 2 * AmbientTalk/2 Project
 3 * CMDRequireService.java created on 22-feb-2007 at 20:17:06
 4 * (c) Programming Technology Lab, 2006 - 2007
 5 * Authors: Tom Van Cutsem & Stijn Mostinckx
 6 * 
 7 * Permission is hereby granted, free of charge, to any person
 8 * obtaining a copy of this software and associated documentation
 9 * files (the "Software"), to deal in the Software without
10 * restriction, including without limitation the rights to use,
11 * copy, modify, merge, publish, distribute, sublicense, and/or
12 * sell copies of the Software, and to permit persons to whom the
13 * Software is furnished to do so, subject to the following
14 * conditions:
15 *
16 * The above copyright notice and this permission notice shall be
17 * included in all copies or substantial portions of the Software.
18 *
19 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
20 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
21 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
22 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
23 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
24 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
25 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
26 * OTHER DEALINGS IN THE SOFTWARE.
27 */
28package edu.vub.at.actors.net.cmd;
29
30import edu.vub.at.actors.natives.ELVirtualMachine;
31import edu.vub.at.actors.natives.Packet;
32import edu.vub.at.actors.net.Logging;
33
34import org.jgroups.Message;
35import org.jgroups.SuspectedException;
36import org.jgroups.TimeoutException;
37import org.jgroups.blocks.MessageDispatcher;
38
39/**
40 * A CMDRequireService message is sent asynchronously to all connected VMs when an actor
41 * on the sender VM has issued a new subscription. This command is sent to all VMs to ask
42 * them whether they have any publications matching the outstanding subscriptions at the sender VM.
43 * The reply comes asynchronously in the form of a CMDJoinServices command.
44 * 
45 * SENDER: the VM that issued a new subscription on a topic
46 * RECEIVER: all connected VMs
47 * MODE: ASYNCHRONOUS, MULTICAST
48 * PROPERTIES: the new subscription topic of the sender
49 * REPLY: potential CMDJoinServices
50 * 
51 * @author tvcutsem
52 */
53public class CMDRequireService extends VMCommand {
54
55	private final Packet serializedTopic_;
56	
57	public CMDRequireService(Packet topic) {
58		super("requireService");
59		serializedTopic_ = topic;
60	}
61	
62	public void send(MessageDispatcher dispatcher) {
63		try {
64			super.sendAsyncMulticast(dispatcher);
65		} catch (TimeoutException e) {
66			Logging.VirtualMachine_LOG.warn(this + ": timeout while trying to broadcast require query, dropping");
67		} catch (SuspectedException e) {
68			Logging.VirtualMachine_LOG.warn(this + ": remote VM suspected while broadcasting require query");
69		}
70	}
71	
72	/**
73	 * When a connected VM receives a CMDRequireService request, it queries its local publications
74	 * to see if there is a match. If so, all matching local publications are replied.
75	 */
76	public Object uponReceiptBy(ELVirtualMachine remoteHost, Message wrapper) throws Exception {
77		// query local discovery actor for matching topic
78    	remoteHost.discoveryActor_.event_remoteSubscription(serializedTopic_, wrapper.getSrc());
79    	return null;
80	}
81	
82}