extended by org.jgroups.stack.Protocol
      extended by org.jgroups.protocols.SMACK
All Implemented Interfaces:

public class SMACK
extends Protocol
implements AckMcastSenderWindow.RetransmitCommand

Simple Multicast ACK protocol. A positive acknowledgment-based protocol for reliable delivery of multicast messages, which does not need any group membership service. Basically works as follows:

Advantage of this protocol: no group membership necessary, fast.

Bela Ban Aug 2002
Fix membershop bug: start a, b, kill b, restart b: b will be suspected by a.

Nested Class Summary
static class SMACK.SmackHeader
Field Summary
Fields inherited from class org.jgroups.stack.Protocol
down_prot, ergonomics, id, log, name, stack, stats, up_prot
Constructor Summary
Method Summary
 java.lang.Object down(Event evt)
          An event is to be sent down the stack.
 void retransmit(long seqno, Message msg, Address dest)
          Retranmit the given msg
 void stop()
          This method is called on a Channel.disconnect().
 java.lang.Object up(Event evt)
          An event was received from the layer below.
Methods inherited from class org.jgroups.stack.Protocol
destroy, downThreadEnabled, dumpStats, enableStats, getConfigurableObjects, getDownProtocol, getId, getLevel, getName, getProperties, getProtocolStack, getSocketFactory, getThreadFactory, getTransport, getUpProtocol, getValue, init, isErgonomics, printStats, providedDownServices, providedUpServices, requiredDownServices, requiredUpServices, resetStats, setDownProtocol, setErgonomics, setId, setLevel, setProperties, setPropertiesInternal, setProperty, setProtocolStack, setSocketFactory, setUpProtocol, setValue, setValues, start, statsEnabled, upThreadEnabled
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail


public SMACK()
Method Detail


public void stop()
Description copied from class: Protocol
This method is called on a Channel.disconnect(). Stops work (e.g. by closing multicast socket). Will be called from top to bottom. This means that at the time of the method invocation the neighbor protocol below is still working. This method will replace the STOP, STOP_OK, CLEANUP and CLEANUP_OK events. The ProtocolStack guarantees that when this method is called all messages in the down queue will have been flushed

stop in class Protocol


public java.lang.Object up(Event evt)
Description copied from class: Protocol
An event was received from the layer below. Usually the current layer will want to examine the event type and - depending on its type - perform some computation (e.g. removing headers from a MSG event type, or updating the internal membership list when receiving a VIEW_CHANGE event). Finally the event is either a) discarded, or b) an event is sent down the stack using down_prot.down() or c) the event (or another event) is sent up the stack using up_prot.up().

up in class Protocol


public java.lang.Object down(Event evt)
Description copied from class: Protocol
An event is to be sent down the stack. The layer may want to examine its type and perform some action on it, depending on the event's type. If the event is a message MSG, then the layer may need to add a header to it (or do nothing at all) before sending it down the stack using down_prot.down(). In case of a GET_ADDRESS event (which tries to retrieve the stack's address from one of the bottom layers), the layer may need to send a new response event back up the stack using up_prot.up().

down in class Protocol


public void retransmit(long seqno,
                       Message msg,
                       Address dest)
Description copied from interface: AckMcastSenderWindow.RetransmitCommand
Retranmit the given msg

Specified by:
retransmit in interface AckMcastSenderWindow.RetransmitCommand
seqno - the sequence number associated with the message
msg - the msg to retransmit (it should be a copy!)
dest - the msg destination

Copyright © 1998-2009 Bela Ban / Red Hat. All Rights Reserved.