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java.lang.Objectorg.jgroups.stack.Protocol
org.jgroups.protocols.pbcast.STREAMING_STATE_TRANSFER
public class STREAMING_STATE_TRANSFER
STREAMING_STATE_TRANSFER
, as its name implies, allows a
streaming state transfer between two channel instances.
Major advantage of this approach is that transfering application state to a
joining member of a group does not entail loading of the complete application
state into memory. Application state, for example, might be located entirely
on some form of disk based storage. The default STATE_TRANSFER
requires this state to be loaded entirely into memory before being
transferred to a group member while STREAMING_STATE_TRANSFER
does not. Thus STREAMING_STATE_TRANSFER
protocol is able to
transfer application state that is very large (>1Gb) without a likelihood of
such transfer resulting in OutOfMemoryException.
Channel instance can be configured with either
STREAMING_STATE_TRANSFER
or STATE_TRANSFER
but
not both protocols at the same time.
In order to process streaming state transfer an application has to implement
ExtendedMessageListener
if it is using channel in a push style
mode or it has to process StreamingSetStateEvent
and
StreamingGetStateEvent
if it is using channel in a pull style
mode.
ExtendedMessageListener
,
StreamingGetStateEvent
,
StreamingSetStateEvent
,
STATE_TRANSFER
Nested Class Summary | |
---|---|
static class |
STREAMING_STATE_TRANSFER.StateHeader
|
Field Summary |
---|
Fields inherited from class org.jgroups.stack.Protocol |
---|
down_prot, log, props, stack, stats, up_prot |
Constructor Summary | |
---|---|
STREAMING_STATE_TRANSFER()
|
Method Summary | |
---|---|
java.lang.Object |
down(Event evt)
An event is to be sent down the stack. |
double |
getAverageStateSize()
|
java.lang.String |
getName()
|
long |
getNumberOfStateBytesSent()
|
int |
getNumberOfStateRequests()
|
void |
init()
Called after instance has been created (null constructor) and before protocol is started. |
java.util.Vector<java.lang.Integer> |
requiredDownServices()
List of events that are required to be answered by some layer below. |
void |
resetStats()
|
boolean |
setProperties(java.util.Properties props)
Configures the protocol initially. |
void |
start()
This method is called on a Channel.connect(String) . |
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, getDownProtocol, getProperties, getProtocolStack, getThreadFactory, getTransport, getUpProtocol, printStats, providedDownServices, providedUpServices, requiredUpServices, setDownProtocol, setPropertiesInternal, setProtocolStack, setUpProtocol, statsEnabled, upThreadEnabled |
Methods inherited from class java.lang.Object |
---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
---|
public STREAMING_STATE_TRANSFER()
Method Detail |
---|
public final java.lang.String getName()
getName
in class Protocol
public int getNumberOfStateRequests()
public long getNumberOfStateBytesSent()
public double getAverageStateSize()
public java.util.Vector<java.lang.Integer> requiredDownServices()
Protocol
requiredDownServices
in class Protocol
public void resetStats()
resetStats
in class Protocol
public boolean setProperties(java.util.Properties props)
Protocol
"loopback=false;unicast_inport=4444"
setProperties
in class Protocol
public void init() throws java.lang.Exception
Protocol
init
in class Protocol
java.lang.Exception
- Thrown if protocol cannot be initialized successfully. This will cause the
ProtocolStack to fail, so the channel constructor will throw an exceptionpublic void start() throws java.lang.Exception
Protocol
Channel.connect(String)
. Starts work.
Protocols are connected and queues are ready to receive events.
Will be called from bottom to top. This call will replace
the START and START_OK events.
start
in class Protocol
java.lang.Exception
- Thrown if protocol cannot be started successfully. This will cause the ProtocolStack
to fail, so Channel.connect(String)
will throw an exceptionpublic void stop()
Protocol
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)
Protocol
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)
Protocol
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
|
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