net.sf.ehcache.distribution

Class MulticastRMICacheManagerPeerProvider

public final class MulticastRMICacheManagerPeerProvider extends RMICacheManagerPeerProvider implements CacheManagerPeerProvider

A peer provider which discovers peers using Multicast.

Hosts can be in three different levels of conformance with the Multicast specification (RFC1112), according to the requirements they meet.

  1. Level 0 is the "no support for IP Multicasting" level. Lots of hosts and routers in the Internet are in this state, as multicast support is not mandatory in IPv4 (it is, however, in IPv6). Not too much explanation is needed here: hosts in this level can neither send nor receive multicast packets. They must ignore the ones sent by other multicast capable hosts.
  2. Level 1 is the "support for sending but not receiving multicast IP datagrams" level. Thus, note that it is not necessary to join a multicast group to be able to send datagrams to it. Very few additions are needed in the IP module to make a "Level 0" host "Level 1-compliant".
  3. Level 2 is the "full support for IP multicasting" level. Level 2 hosts must be able to both send and receive multicast traffic. They must know the way to join and leave multicast groups and to propagate this information to multicast routers. Thus, they must include an Internet Group Management Protocol (IGMP) implementation in their TCP/IP stack.

The list of CachePeers is maintained via heartbeats. rmiUrls are looked up using RMI and converted to CachePeers on registration. On lookup any stale references are removed.

Version: $Id: MulticastRMICacheManagerPeerProvider.java 108 2006-06-04 12:44:06Z gregluck $

Author: Greg Luck

Nested Class Summary
protected static classMulticastRMICacheManagerPeerProvider.CachePeerEntry
Entry containing a looked up CachePeer and date
Field Summary
protected static intSHORT_DELAY
One second, in ms
Constructor Summary
MulticastRMICacheManagerPeerProvider(CacheManager cacheManager, InetAddress groupMulticastAddress, Integer groupMulticastPort)
Creates and starts a multicast peer provider
Method Summary
voiddispose()
Shutdown the heartbeat
protected longgetStaleTime()
The time after which an unrefreshed peer provider entry is considered stale.
longgetTimeForClusterToForm()
Time for a cluster to form.
voidinit()
ListlistRemoteCachePeers(Ehcache cache)
voidregisterPeer(String rmiUrl)
Register a new peer.
protected booleanstale(Date date)
Whether the entry should be considered stale.

Field Detail

SHORT_DELAY

protected static final int SHORT_DELAY
One second, in ms

Constructor Detail

MulticastRMICacheManagerPeerProvider

public MulticastRMICacheManagerPeerProvider(CacheManager cacheManager, InetAddress groupMulticastAddress, Integer groupMulticastPort)
Creates and starts a multicast peer provider

Parameters: groupMulticastAddress 224.0.0.1 to 239.255.255.255 e.g. 230.0.0.1 groupMulticastPort 1025 to 65536 e.g. 4446

Method Detail

dispose

public final void dispose()
Shutdown the heartbeat

getStaleTime

protected long getStaleTime()
The time after which an unrefreshed peer provider entry is considered stale.

getTimeForClusterToForm

public long getTimeForClusterToForm()
Time for a cluster to form. This varies considerably, depending on the implementation.

Returns: the time in ms, for a cluster to form

init

public final void init()
{@inheritDoc }

listRemoteCachePeers

public final List listRemoteCachePeers(Ehcache cache)

Returns: a list of CachePeer peers, excluding the local peer.

registerPeer

public final void registerPeer(String rmiUrl)
Register a new peer.

Parameters: rmiUrl

stale

protected final boolean stale(Date date)
Whether the entry should be considered stale. This will depend on the type of RMICacheManagerPeerProvider. This method should be overridden for implementations that go stale based on date

Parameters: date the date the entry was created

Returns: true if stale