org.jgroups.protocols.pbcast
Class STREAMING_STATE_TRANSFER
java.lang.Object
org.jgroups.stack.Protocol
org.jgroups.protocols.pbcast.STREAMING_STATE_TRANSFER
public class STREAMING_STATE_TRANSFER
- extends Protocol
STREAMING_STATE_TRANSFER
, as its name implies, allows a
streaming state transfer between two channel instances.
Major advantage of this approach is that transferring 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.
STREAMING_STATE_TRANSFER
allows use of either default channel
transport or separate tcp sockets for state transfer. If firewalls are not a
concern then separate tcp sockets should be used as they offer faster state
transfer. Transport for state transfer is selected using
use_default_transport boolean property.
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.
- Since:
- 2.4
- Author:
- Vladimir Blagojevic
- See Also:
ExtendedMessageListener
,
StreamingGetStateEvent
,
StreamingSetStateEvent
,
STATE_TRANSFER
Methods inherited from class org.jgroups.stack.Protocol |
destroy, downThreadEnabled, dumpStats, enableStats, getConfigurableObjects, getDownProtocol, getId, getLevel, getName, getProperties, getProtocolStack, getSocketFactory, getThreadFactory, getTransport, getUpProtocol, getValue, isErgonomics, printStats, providedDownServices, providedUpServices, requiredUpServices, setDownProtocol, setErgonomics, setId, setLevel, setProperties, setPropertiesInternal, setProperty, setProtocolStack, setSocketFactory, setUpProtocol, setValue, setValues, statsEnabled, upThreadEnabled |
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
bind_interface_str
protected java.lang.String bind_interface_str
STREAMING_STATE_TRANSFER
public STREAMING_STATE_TRANSFER()
getNumberOfStateRequests
public int getNumberOfStateRequests()
getNumberOfStateBytesSent
public long getNumberOfStateBytesSent()
getAverageStateSize
public double getAverageStateSize()
requiredDownServices
public java.util.Vector<java.lang.Integer> requiredDownServices()
- Description copied from class:
Protocol
- List of events that are required to be answered by some layer below.
- Overrides:
requiredDownServices
in class Protocol
- Returns:
- Vector (of Integers)
resetStats
public void resetStats()
- Overrides:
resetStats
in class Protocol
init
public void init()
throws java.lang.Exception
- Description copied from class:
Protocol
- Called after instance has been created (null constructor) and before protocol is started.
Properties are already set. Other protocols are not yet connected and events cannot yet be sent.
- Overrides:
init
in class Protocol
- Throws:
java.lang.Exception
- Thrown if protocol cannot be initialized successfully. This will cause the
ProtocolStack to fail, so the channel constructor will throw an exception
start
public void start()
throws java.lang.Exception
- Description copied from class:
Protocol
- This method is called on a
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.
- Overrides:
start
in class Protocol
- Throws:
java.lang.Exception
- Thrown if protocol cannot be started successfully. This will cause the ProtocolStack
to fail, so Channel.connect(String)
will throw an exception
stop
public void stop()
- Description copied from class:
Protocol
- This method is called on a
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
- Overrides:
stop
in class Protocol
up
public java.lang.Object up(Event evt)
- Description copied from class:
Protocol
- An event was received from the layer below. Usually the current layer will want to examine
the event type and - depending on its type - perform some computation
(e.g. removing headers from a MSG event type, or updating the internal membership list
when receiving a VIEW_CHANGE event).
Finally the event is either a) discarded, or b) an event is sent down
the stack using
down_prot.down()
or c) the event (or another event) is sent up
the stack using up_prot.up()
.
- Overrides:
up
in class Protocol
down
public java.lang.Object down(Event evt)
- Description copied from class:
Protocol
- An event is to be sent down the stack. The layer may want to examine its type and perform
some action on it, depending on the event's type. If the event is a message MSG, then
the layer may need to add a header to it (or do nothing at all) before sending it down
the stack using
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()
.
- Overrides:
down
in class Protocol
Copyright © 1998-2009 Bela Ban / Red Hat. All Rights Reserved.