Package org.jgroups.blocks
Class NotificationBus
java.lang.Object
org.jgroups.blocks.NotificationBus
- All Implemented Interfaces:
MembershipListener
,MessageListener
,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 -
Field Summary
Fields -
Constructor Summary
ConstructorsConstructorDescriptionNotificationBus
(String bus_name) NotificationBus
(String bus_name, String properties) NotificationBus
(Channel channel, String bus_name) -
Method Summary
Modifier and TypeMethodDescriptionvoid
block()
Called (usually by the FLUSH protocol), as an indication that the member should stop sending messages.getCache()
getCacheFromCoordinator
(long timeout, int max_tries) Determines the coordinator and asks it for its cache.getCacheFromMember
(Address mbr, long timeout, int max_tries) Determines the coordinator and asks it for its cache.Answers the Channel.Returns a reference to the real membership: don't modify.byte[]
getState()
Answers the group state; e.g., when joining.boolean
void
Don't multicast this to all members, just apply it to local consumers.void
Called when a message is received.void
Pack the argument in a Info, serialize that one into the message buffer and send the messagevoid
sendNotification
(Address dest, Serializable n) Pack the argument in a Info, serialize that one into the message buffer and send the messagevoid
void
setState
(byte[] state) Sets the group state; e.g., when joining.void
start()
void
stop()
void
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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Field Details
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log
protected final org.apache.commons.logging.Log log
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Constructor Details
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Method Details
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setConsumer
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getLocalAddress
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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
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() -
start
- Throws:
Exception
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stop
public void stop() -
sendNotification
Pack the argument in a Info, serialize that one into the message buffer and send the message -
sendNotification
Pack the argument in a Info, serialize that one into the message buffer and send the message -
getCacheFromCoordinator
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
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 invalid input: '<' 1)
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notifyConsumer
Don't multicast this to all members, just apply it to local consumers. -
receive
Description copied from interface:MessageListener
Called when a message is received.- Specified by:
receive
in interfaceMessageListener
- Parameters:
msg
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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
- Parameters:
state
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viewAccepted
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
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
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