org.javagroups.protocols
Class STATE_TRANSFER
java.lang.Object
|
+--org.javagroups.stack.Protocol
|
+--org.javagroups.protocols.STATE_TRANSFER
- All Implemented Interfaces:
- RequestHandler
- public class STATE_TRANSFER
- extends Protocol
- implements RequestHandler
State transfer layer. Upon receiving a GET_STATE event from JChannel, a MAKE_COPY message is
sent to all members. When the originator receives MAKE_COPY, it queues all messages to the
channel.
When another member receives the message, it asks the JChannel to provide it with a copy of
the current state (GetStateEvent is received by application, returnState() sends state down the
stack). Then the current layer sends a unicast RETURN_STATE message to the coordinator, which
returns the cached copy.
When the state is received by the originator, the GET_STATE sender is unblocked with a
GET_STATE_OK event up the stack (unless it already timed out).
Requires QUEUE layer on top.
- Author:
- Bela Ban
Fields inherited from class org.javagroups.stack.Protocol |
down_handler, down_prot, down_queue, down_thread, observer, props, stack, up_handler, up_prot, up_queue, up_thread |
Method Summary |
void |
down(Event evt)
An event is to be sent down the stack. |
java.lang.String |
getName()
All protocol names have to be unique ! |
java.lang.Object |
handle(Message msg)
|
void |
init()
Called after instance has been created (null constructor) and before protocol is started |
java.util.Vector |
requiredUpServices()
List of events that are required to be answered by some layer above. |
boolean |
setProperties(java.util.Properties props)
Configures the protocol initially. |
void |
up(Event evt)
An event was received from the layer below. |
Methods inherited from class org.javagroups.stack.Protocol |
getDownProtocol, getDownQueue, getProperties, getUpProtocol, getUpQueue, passDown, passUp, providedDownServices, providedUpServices, receiveDownEvent, receiveUpEvent, requiredDownServices, setDownProtocol, setObserver, setPropertiesInternal, setProtocolStack, setUpProtocol, startDownHandler, startUpHandler, stopInternal |
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
STATE_TRANSFER
public STATE_TRANSFER()
getName
public java.lang.String getName()
- All protocol names have to be unique !
- Overrides:
getName
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
- Overrides:
init
in class Protocol
setProperties
public boolean setProperties(java.util.Properties props)
- Description copied from class:
Protocol
- Configures the protocol initially. A configuration string consists of name=value
items, separated by a ';' (semicolon), e.g.:
"loopback=false;unicast_inport=4444"
- Overrides:
setProperties
in class Protocol
requiredUpServices
public java.util.Vector requiredUpServices()
- Description copied from class:
Protocol
- List of events that are required to be answered by some layer above.
- Overrides:
requiredUpServices
in class Protocol
- Following copied from class:
org.javagroups.stack.Protocol
- Returns:
- Vector (of Integers)
up
public void 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
passDown()
or c) the event (or another event) is sent up
the stack using passUp()
.
- Overrides:
up
in class Protocol
down
public void 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
passDown()
. 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 passUp()
.
- Overrides:
down
in class Protocol
handle
public java.lang.Object handle(Message msg)
- Specified by:
handle
in interface RequestHandler
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