/interpreter/tags/at2-build060407/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.comm.Address;
33import edu.vub.at.actors.net.comm.CommunicationBus;
34
35/**
36 * A CMDRequireService message is sent asynchronously to all connected VMs when an actor
37 * on the sender VM has issued a new subscription. This command is sent to all VMs to ask
38 * them whether they have any publications matching the outstanding subscriptions at the sender VM.
39 * The reply comes asynchronously in the form of a CMDJoinServices command.
40 * 
41 * SENDER: the VM that issued a new subscription on a topic
42 * RECEIVER: all connected VMs
43 * MODE: ASYNCHRONOUS, MULTICAST
44 * PROPERTIES: the new subscription topic of the sender
45 * REPLY: potential CMDJoinServices
46 * 
47 * @author tvcutsem
48 */
49public class CMDRequireService extends VMCommand {
50
51	private final Packet serializedTopic_;
52	
53	public CMDRequireService(Packet topic) {
54		super("requireService");
55		serializedTopic_ = topic;
56	}
57	
58	public void send(CommunicationBus dispatcher) {
59		dispatcher.sendAsyncMulticast(this);
60	}
61	
62	/**
63	 * When a connected VM receives a CMDRequireService request, it queries its local publications
64	 * to see if there is a match. If so, all matching local publications are replied.
65	 */
66	public void uponReceiptBy(ELVirtualMachine remoteHost, Address senderAddress) {
67		// query local discovery actor for matching topic
68    	remoteHost.discoveryActor_.event_remoteSubscription(serializedTopic_, senderAddress);
69	}
70	
71}