JavaGroups.JavaStack.Protocols
Class UNIFORM

java.lang.Object
  |
  +--JavaGroups.JavaStack.Protocol
        |
        +--JavaGroups.JavaStack.Protocols.UNIFORM

public class UNIFORM

extends Protocol

implements RequestHandler, Transport

The algorithms implements dynamically-uniform failure-atomic group multicast, that is, a message is delivered by all members if it is delivered by at least 1 non-faulty member even if the sender crashes after sending. If the sender crashes, it will eventually be removed from the group membership: the FLUSH protocol preceding the view change causes all pending multicasts to be flushed out of the system, thereby re-sending pending multicasts to members that haven't received them yet.

The protocol makes use of GroupRequest (which itself uses RequestCorrelator) to send a request to all members and receive responses from all non-faulty members.

Constructor Summary

UNIFORM()

Method Summary

void	Down(Event evt) An event is to be sent down the stack.
java.lang.String	GetName()
java.lang.Object	Handle(Message msg) 1.
java.lang.Object	Receive(long timeout)
void	Reset() Just remove if you don't need to reset any state
void	Send(Message msg)
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 JavaGroups.JavaStack.Protocol

GetDownProtocol, GetProperties, GetUpProtocol, PassDown, PassUp, ProvidedDownServices, ProvidedUpServices, RequiredDownServices, RequiredUpServices, SetDownProtocol, SetProtocolStack, SetUpProtocol, StartDownHandler, StartUpHandler, StopInternal

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

UNIFORM

public UNIFORM()

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

Reset

public void Reset()

Just remove if you don't need to reset any state

Overrides:

Reset 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

Handle

public java.lang.Object Handle(Message msg)

1. Remove UniformHeader from message and get ID and type
2. If type == SAVE: add message to save-table (key=sender + ID) and send response (SAVE_OK)
If type == OK:   add message to ok-table, remove from save-table. Deliver message (pass up
the stack) and send response (OK_OK).
If type == SEEN: find message in ok-table. If found, send SEEN_OK response, else NOT_SEEN.
If type == GC: delete message from ok-table.

Specified by:

Handle in interface RequestHandler

Send

public void Send(Message msg)
          throws java.lang.Exception

Specified by:

Send in interface Transport

Receive

public java.lang.Object Receive(long timeout)
                         throws java.lang.Exception

Specified by:

Receive in interface Transport