JavaGroups.JavaStack.Protocols
Class PING

java.lang.Object
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  +--JavaGroups.JavaStack.Protocol
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        +--JavaGroups.JavaStack.Protocols.PING

public class PING

extends Protocol

The PING protocol layer retrieves the initial membership (used by the GMS when started by sending event FIND_INITIAL_MBRS down the stack). We do this by mcasting PING requests to an IP MCAST address (or, if gossiping is enabled, by contacting the router). The responses should allow us to determine the coordinator whom we have to contact, e.g. in case we want to join the group. When we are a server (after having received the BECOME_SERVER event), we'll respond to PING requests with a PING response.

The FIND_INITIAL_MBRS event will eventually be answered with a FIND_INITIAL_MBRS_OK event up the stack.

Constructor Summary

PING()

Method Summary

void	Down(Event evt) An event is to be sent down the stack.
java.lang.String	GetName()
java.util.Vector	ProvidedUpServices() List of events that are provided to layers above (they will be handled when sent down from 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 JavaGroups.JavaStack.Protocol

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

Methods inherited from class java.lang.Object

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

Constructor Detail

PING

public PING()

Method Detail

GetName

public java.lang.String GetName()

Overrides:

GetName in class Protocol

ProvidedUpServices

public java.util.Vector ProvidedUpServices()

Description copied from class: Protocol

List of events that are provided to layers above (they will be handled when sent down from above).

Overrides:

ProvidedUpServices in class Protocol

Tags copied from class: Protocol

Returns:

Vector (of Integers)

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

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