org.javagroups.protocols
Class MERGE2

java.lang.Object
  |
  +--org.javagroups.stack.Protocol
        |
        +--org.javagroups.protocols.MERGE2

public class MERGE2
extends Protocol

Protocol to discover subgroups, e.g. existing due to a network partition (that healed). Example: group {p,q,r,s,t,u,v,w} is split into 3 subgroups {p,q}, {r,s,t,u} and {v,w}. This protocol will eventually send a MERGE event with the coordinators of each subgroup up the stack: {p,r,v}. Note that - depending on the time of subgroup discovery - there could also be 2 MERGE events, which first join 2 of the subgroups, and then the resulting group to the last subgroup. The real work of merging the subgroups into one larger group is done somewhere above this protocol (typically in the GMS protocol).

This protocol works as follows:

Requires: FIND_INITIAL_MBRS event from below
Provides: sends MERGE event with list of coordinators up the stack

Author:
Bela Ban, Oct 16 2001

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
 
Constructor Summary
MERGE2()
           
 
Method Summary
 void down(Event evt)
          An event is to be sent down the stack.
 java.lang.String getName()
           
 java.util.Vector requiredDownServices()
          List of events that are required to be answered by some layer below.
 boolean setProperties(java.util.Properties props)
          Configures the protocol initially.
 void startDownHandler()
          DON'T REMOVE ! This prevents the down-handler thread to be created, which is not needed in the protocol.
 void startUpHandler()
          DON'T REMOVE ! This prevents the up-handler thread to be created, which is not needed in the protocol.
 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, init, passDown, passUp, providedDownServices, providedUpServices, receiveDownEvent, receiveUpEvent, requiredUpServices, setDownProtocol, setObserver, setPropertiesInternal, setProtocolStack, setUpProtocol, stopInternal
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

MERGE2

public MERGE2()
Method Detail

getName

public java.lang.String getName()
Overrides:
getName 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

requiredDownServices

public java.util.Vector requiredDownServices()
Description copied from class: Protocol
List of events that are required to be answered by some layer below.
Overrides:
requiredDownServices in class Protocol
Following copied from class: org.javagroups.stack.Protocol
Returns:
Vector (of Integers)

startUpHandler

public void startUpHandler()
DON'T REMOVE ! This prevents the up-handler thread to be created, which is not needed in the protocol.
Overrides:
startUpHandler in class Protocol

startDownHandler

public void startDownHandler()
DON'T REMOVE ! This prevents the down-handler thread to be created, which is not needed in the protocol.
Overrides:
startDownHandler in class Protocol

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


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