Package org.jgroups.blocks
Class NotificationBus
- java.lang.Object
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- org.jgroups.blocks.NotificationBus
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- All Implemented Interfaces:
MembershipListener
,MessageListener
,Receiver
public class NotificationBus extends java.lang.Object implements Receiver
This class provides notification sending and handling capability. Producers can send notifications to all registered consumers. Provides hooks to implement shared group state, which allows an application programmer to maintain a local cache which is replicated by all instances. NotificationBus sits on top of a channel, however it creates its channel itself, so the application programmers do not have to provide their own channel.- Author:
- Bela Ban
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Nested Class Summary
Nested Classes Modifier and Type Class Description static interface
NotificationBus.Consumer
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Field Summary
Fields Modifier and Type Field Description protected org.apache.commons.logging.Log
log
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Constructor Summary
Constructors Constructor Description NotificationBus()
NotificationBus(java.lang.String bus_name)
NotificationBus(java.lang.String bus_name, java.lang.String properties)
NotificationBus(Channel channel, java.lang.String bus_name)
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
block()
Called (usually by the FLUSH protocol), as an indication that the member should stop sending messages.java.io.Serializable
getCache()
java.io.Serializable
getCacheFromCoordinator(long timeout, int max_tries)
Determines the coordinator and asks it for its cache.java.io.Serializable
getCacheFromMember(Address mbr, long timeout, int max_tries)
Determines the coordinator and asks it for its cache.Channel
getChannel()
Answers the Channel.Address
getLocalAddress()
java.util.Vector
getMembership()
Returns a reference to the real membership: don't modify.byte[]
getState()
Answers the group state; e.g., when joining.boolean
isCoordinator()
void
notifyConsumer(java.io.Serializable n)
Don't multicast this to all members, just apply it to local consumers.void
receive(Message msg)
Called when a message is received.void
sendNotification(java.io.Serializable n)
Pack the argument in a Info, serialize that one into the message buffer and send the messagevoid
sendNotification(Address dest, java.io.Serializable n)
Pack the argument in a Info, serialize that one into the message buffer and send the messagevoid
setConsumer(NotificationBus.Consumer c)
void
setState(byte[] state)
Sets the group state; e.g., when joining.void
start()
void
stop()
void
suspect(Address suspected_mbr)
Called whenever a member is suspected of having crashed, but has not yet been excluded.void
viewAccepted(View new_view)
Called when a change in membership has occurred.
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Constructor Detail
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NotificationBus
public NotificationBus() throws java.lang.Exception
- Throws:
java.lang.Exception
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NotificationBus
public NotificationBus(java.lang.String bus_name) throws java.lang.Exception
- Throws:
java.lang.Exception
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NotificationBus
public NotificationBus(java.lang.String bus_name, java.lang.String properties) throws java.lang.Exception
- Throws:
java.lang.Exception
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NotificationBus
public NotificationBus(Channel channel, java.lang.String bus_name) throws java.lang.Exception
- Throws:
java.lang.Exception
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Method Detail
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setConsumer
public void setConsumer(NotificationBus.Consumer c)
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getLocalAddress
public Address getLocalAddress()
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getMembership
public java.util.Vector getMembership()
Returns a reference to the real membership: don't modify. If you need to modify, make a copy first !- Returns:
- Vector of Address objects
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getChannel
public Channel getChannel()
Answers the Channel. Used to operate on the underlying channel directly, e.g. perform operations that are not provided using only NotificationBus. Should be used sparingly.- Returns:
- underlying Channel
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isCoordinator
public boolean isCoordinator()
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start
public void start() throws java.lang.Exception
- Throws:
java.lang.Exception
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stop
public void stop()
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sendNotification
public void sendNotification(java.io.Serializable n)
Pack the argument in a Info, serialize that one into the message buffer and send the message
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sendNotification
public void sendNotification(Address dest, java.io.Serializable n)
Pack the argument in a Info, serialize that one into the message buffer and send the message
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getCacheFromCoordinator
public java.io.Serializable getCacheFromCoordinator(long timeout, int max_tries)
Determines the coordinator and asks it for its cache. If there is no coordinator (because we are first member), null will be returned. Used only internally by NotificationBus.- Parameters:
timeout
- Max number of msecs until the call returnsmax_tries
- Max number of attempts to fetch the cache from the coordinator
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getCacheFromMember
public java.io.Serializable getCacheFromMember(Address mbr, long timeout, int max_tries)
Determines the coordinator and asks it for its cache. If there is no coordinator (because we are first member), null will be returned. Used only internally by NotificationBus.- Parameters:
mbr
- The address of the member from which to fetch the state. If null, the current coordinator will be asked for the statetimeout
- Max number of msecs until the call returns - if timeout elapses null will be returnedmax_tries
- Max number of attempts to fetch the cache from the coordinator (will be set to 1 if < 1)
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notifyConsumer
public void notifyConsumer(java.io.Serializable n)
Don't multicast this to all members, just apply it to local consumers.
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receive
public void receive(Message msg)
Description copied from interface:MessageListener
Called when a message is received.- Specified by:
receive
in interfaceMessageListener
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getState
public byte[] getState()
Description copied from interface:MessageListener
Answers the group state; e.g., when joining.- Specified by:
getState
in interfaceMessageListener
- Returns:
- byte[]
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setState
public void setState(byte[] state)
Description copied from interface:MessageListener
Sets the group state; e.g., when joining.- Specified by:
setState
in interfaceMessageListener
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viewAccepted
public void viewAccepted(View new_view)
Description copied from interface:MembershipListener
Called when a change in membership has occurred. No long running actions or sending of messages should be done in this callback. If some long running action needs to be performed, it should be done in a separate thread. Note that on reception of the first view (a new member just joined), the channel will not yet be in the connected state. This only happens whenChannel.connect(String)
returns.- Specified by:
viewAccepted
in interfaceMembershipListener
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suspect
public void suspect(Address suspected_mbr)
Description copied from interface:MembershipListener
Called whenever a member is suspected of having crashed, but has not yet been excluded.- Specified by:
suspect
in interfaceMembershipListener
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block
public void block()
Description copied from interface:MembershipListener
Called (usually by the FLUSH protocol), as an indication that the member should stop sending messages. Any messages sent after returning from this callback might get blocked by the FLUSH protocol. When the FLUSH protocol is done, and messages can be sent again, the FLUSH protocol will simply unblock all pending messages. If a callback for unblocking is desired, implementExtendedMembershipListener.unblock()
. Note that block() is the equivalent of reception of a BlockEvent in the pull mode.- Specified by:
block
in interfaceMembershipListener
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getCache
public java.io.Serializable getCache()
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