Class DiscoveryManager
- java.lang.Object
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- org.eclipse.persistence.sessions.coordination.DiscoveryManager
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- All Implemented Interfaces:
java.lang.Runnable
public class DiscoveryManager extends java.lang.Object implements java.lang.RunnablePurpose: Detects new members of a logical EclipseLink cluster.
Description: Each RemoteCommandManager has its own DiscoveryManager, which handles the detection of other remote command services as they become available. The DiscoveryManager is an active object (in that it extends Thread) and becomes a separate thread when it is started using startDiscovery().
Discovery is done through the use of a multicast. Each discovery manager joins the multicast group and announces itself to the group. As it receives service announcements from other discovery managers it notifies the RCM to establish connections to and from the new service.
- See Also:
RemoteCommandManager,MulticastSocket- Author:
- Steven Vo
- Since:
- OracleAS TopLink 10g (9.0.4)
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Field Summary
Fields Modifier and Type Field Description protected intannouncementDelayDelay time in millis between initialization and when the announcement is sentprotected java.net.MulticastSocketcommunicationSocketThe multicast socket used for discoverystatic intDEFAULT_ANNOUNCEMENT_DELAYstatic java.lang.StringDEFAULT_MULTICAST_GROUPDefault value constantsstatic intDEFAULT_MULTICAST_PORTstatic intDEFAULT_PACKET_TIME_TO_LIVEprotected java.lang.StringmulticastGroupAddressDefines the IP address of the multicast groupprotected intmulticastPortDefines the port the multicast socket will be usingprotected intpacketTimeToLiveNumber of hops in the life of the datapacket Default is 2, a hub and an interface card to prevent the data packets from leaving the localnetwork.protected RemoteCommandManagerrcmThe remote command manager responsible for this serviceprotected booleanstopListeningIndicates to the listening thread that it should stop
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Constructor Summary
Constructors Constructor Description DiscoveryManager(java.lang.String address, int port, int delay, RemoteCommandManager mgr)DiscoveryManager(java.lang.String address, int port, RemoteCommandManager mgr)DiscoveryManager(RemoteCommandManager mgr)Constructors to create a discovery manager.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description voidannounceSession()INTERNAL: Send out an announcement that we are here.voidcreateCommunicationSocket()INTERNAL: Create the multicast socket and join the multicast group.intgetAnnouncementDelay()PUBLIC: Return the amount of time in millis that the service should wait between the time that this Remote Service is available and a session announcement is sent out to other discovery managers.java.net.MulticastSocketgetCommunicationSocket()INTERNAL: Return the socket that will be used for the multicast.java.lang.StringgetMulticastGroupAddress()PUBLIC: Return the host address of the multicast group.intgetMulticastPort()PUBLIC: Return the multicast port used for discovery.intgetPacketTimeToLive()PUBLIC: Returns the number of hops the data packets of the session announcement will take before expiring.booleanisDiscoveryStopped()ADVANCED: Return true if discovery has been stopped at the time this method is called.voidreceivedAnnouncement(ServiceId serviceId)INTERNAL: Process the announcement that indicates that a new service is onlinevoidrun()INTERNAL: This is the main execution method of discovery.voidsetAnnouncementDelay(int millisecondsToDelay)PUBLIC: Set the amount of time in millis that the service should wait between the time that this Remote Service is available and a session announcement is sent out to other discovery managers.voidsetMulticastGroupAddress(java.lang.String address)PUBLIC: Set the host address of the multicast group.voidsetMulticastPort(int port)PUBLIC: Set the multicast port used for discovery.voidsetPacketTimeToLive(int newPacketTimeToLive)PUBLIC: Set the number of hops the data packets of the session announcement will take before expiring.protected voidshallowCopy(DiscoveryManager dmgr)INTERNAL: invoke when the RCM shutdown.voidstartDiscovery()ADVANCED: Announce the local service and join the clustervoidstartListening()INTERNAL: This method puts us into the listening mode loop.voidstopDiscovery()ADVANCED: Stop accepting announcements from other services becoming available.voidstopListening()INTERNAL: Signal this instance to stop listening.
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Field Detail
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DEFAULT_MULTICAST_GROUP
public static final java.lang.String DEFAULT_MULTICAST_GROUP
Default value constants- See Also:
- Constant Field Values
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DEFAULT_MULTICAST_PORT
public static final int DEFAULT_MULTICAST_PORT
- See Also:
- Constant Field Values
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DEFAULT_PACKET_TIME_TO_LIVE
public static final int DEFAULT_PACKET_TIME_TO_LIVE
- See Also:
- Constant Field Values
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DEFAULT_ANNOUNCEMENT_DELAY
public static final int DEFAULT_ANNOUNCEMENT_DELAY
- See Also:
- Constant Field Values
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multicastGroupAddress
protected java.lang.String multicastGroupAddress
Defines the IP address of the multicast group
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multicastPort
protected int multicastPort
Defines the port the multicast socket will be using
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communicationSocket
protected java.net.MulticastSocket communicationSocket
The multicast socket used for discovery
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packetTimeToLive
protected int packetTimeToLive
Number of hops in the life of the datapacket Default is 2, a hub and an interface card to prevent the data packets from leaving the localnetwork.
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stopListening
protected boolean stopListening
Indicates to the listening thread that it should stop
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announcementDelay
protected int announcementDelay
Delay time in millis between initialization and when the announcement is sent
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rcm
protected RemoteCommandManager rcm
The remote command manager responsible for this service
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Constructor Detail
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DiscoveryManager
public DiscoveryManager(RemoteCommandManager mgr)
Constructors to create a discovery manager.
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DiscoveryManager
public DiscoveryManager(java.lang.String address, int port, RemoteCommandManager mgr)
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DiscoveryManager
public DiscoveryManager(java.lang.String address, int port, int delay, RemoteCommandManager mgr)
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Method Detail
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announceSession
public void announceSession()
INTERNAL: Send out an announcement that we are here.
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startDiscovery
public void startDiscovery()
ADVANCED: Announce the local service and join the cluster
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stopDiscovery
public void stopDiscovery()
ADVANCED: Stop accepting announcements from other services becoming available. Note that this does not remove the local service from the cluster.
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isDiscoveryStopped
public boolean isDiscoveryStopped()
ADVANCED: Return true if discovery has been stopped at the time this method is called. If false is returned then it is undefined whether discovery is started or stopped. It may be started, or it may be in the process of starting or stopping.
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createCommunicationSocket
public void createCommunicationSocket()
INTERNAL: Create the multicast socket and join the multicast group.
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getCommunicationSocket
public java.net.MulticastSocket getCommunicationSocket()
INTERNAL: Return the socket that will be used for the multicast.
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run
public void run()
INTERNAL: This is the main execution method of discovery. It will create a socket to listen on, create a local connection for this service and announce that we are open for business.- Specified by:
runin interfacejava.lang.Runnable
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startListening
public void startListening()
INTERNAL: This method puts us into the listening mode loop. This thread blocks, waiting on announcements that we receive from other discovery managers.
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stopListening
public void stopListening()
INTERNAL: Signal this instance to stop listening.
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receivedAnnouncement
public void receivedAnnouncement(ServiceId serviceId)
INTERNAL: Process the announcement that indicates that a new service is online
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setAnnouncementDelay
public void setAnnouncementDelay(int millisecondsToDelay)
PUBLIC: Set the amount of time in millis that the service should wait between the time that this Remote Service is available and a session announcement is sent out to other discovery managers. This may be needed to give some systems more time to post their connections into the naming service. Takes effect the next time listening is started.
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getAnnouncementDelay
public int getAnnouncementDelay()
PUBLIC: Return the amount of time in millis that the service should wait between the time that this Remote Service is available and a session announcement is sent out to other discovery managers.
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getMulticastGroupAddress
public java.lang.String getMulticastGroupAddress()
PUBLIC: Return the host address of the multicast group.
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setMulticastGroupAddress
public void setMulticastGroupAddress(java.lang.String address)
PUBLIC: Set the host address of the multicast group. Takes effect the next time listening is started.
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setMulticastPort
public void setMulticastPort(int port)
PUBLIC: Set the multicast port used for discovery. Takes effect the next time listening is started.
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getMulticastPort
public int getMulticastPort()
PUBLIC: Return the multicast port used for discovery.
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shallowCopy
protected void shallowCopy(DiscoveryManager dmgr)
INTERNAL: invoke when the RCM shutdown. Subclass overrides this method if necessary.
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getPacketTimeToLive
public int getPacketTimeToLive()
PUBLIC: Returns the number of hops the data packets of the session announcement will take before expiring. The default is 2, a hub and an interface card to prevent the data packets from leaving the local network.
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setPacketTimeToLive
public void setPacketTimeToLive(int newPacketTimeToLive)
PUBLIC: Set the number of hops the data packets of the session announcement will take before expiring. The default is 2, a hub and an interface card to prevent the data packets from leaving the local network. Note that if sessions are hosted on different LANs that are part of WAN, the announcement sending by one session may not reach other sessions. In this case, consult your network administrator for the right time-to-live value or test your network by increase the value until sessions receive announcement sent by others.
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