Class PING

java.lang.Object
org.jgroups.stack.Protocol
org.jgroups.protocols.Discovery
org.jgroups.protocols.PING
Direct Known Subclasses:
MPING
public class PING extends Discovery
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 GossipRouter). 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. The following properties are available property: gossip_host - if you are using GOSSIP then this defines the host of the GossipRouter, default is null property: gossip_port - if you are using GOSSIP then this defines the port of the GossipRouter, default is null

Version:
$Id: PING.java,v 1.36.2.5 2008/12/08 13:18:49 belaban Exp $
Author:
Bela Ban

  • Field Details

  • Constructor Details

    • PING

      public PING()

  • Method Details

    • getName

      public String getName()
      Specified by:
      getName in class Protocol

    • setProperties

      public boolean setProperties(Properties props)
      sets the properties of the PING protocol. The following properties are available property: timeout - the timeout (ms) to wait for the initial members, default is 3000=3 secs property: num_initial_members - the minimum number of initial members for a FIND_INITAL_MBRS, default is 2 property: gossip_host - if you are using GOSSIP then this defines the host of the GossipRouter, default is null property: gossip_port - if you are using GOSSIP then this defines the port of the GossipRouter, default is null
      Overrides:
      setProperties in class Discovery
      Parameters:
      props - - a property set containing only PING properties
      Returns:
      returns true if all properties were parsed properly returns false if there are unrecnogized properties in the property set

    • getGossipPort

      public int getGossipPort()

    • setGossipPort

      public void setGossipPort(int gossip_port)

    • getGossipRefresh

      public long getGossipRefresh()

    • setGossipRefresh

      public void setGossipRefresh(long gossip_refresh)

    • init

      public void init() throws 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 Discovery
      Throws:
      Exception - Thrown if protocol cannot be initialized successfully. This will cause the ProtocolStack to fail, so the channel constructor 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 Discovery

    • localAddressSet

      public void localAddressSet(Address addr)
      Description copied from class: Discovery
      Called after local_addr was set
      Overrides:
      localAddressSet in class Discovery

    • handleConnect

      public void handleConnect()
      Overrides:
      handleConnect in class Discovery

    • handleDisconnect

      public void handleDisconnect()
      Overrides:
      handleDisconnect in class Discovery

    • sendGetMembersRequest

      public void sendGetMembersRequest()
      Specified by:
      sendGetMembersRequest in class Discovery

    • up

      public Object up(Event evt)
      Description copied from class: Discovery
      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.

      For the PING protocol, the Up operation does the following things. 1. If the event is a Event.MSG then PING will inspect the message header. If the header is null, PING simply passes up the event If the header is PingHeader.GET_MBRS_REQ then the PING protocol will PassDown a PingRequest message If the header is PingHeader.GET_MBRS_RSP we will add the message to the initial members vector and wake up any waiting threads. 2. If the event is Event.SET_LOCAL_ADDR we will simple set the local address of this protocol 3. For all other messages we simple pass it up to the protocol above

      Overrides:
      up in class Discovery
      Parameters:
      evt - - the event that has been sent from the layer below

    • waitForDiscoveryRequestReception

      protected void waitForDiscoveryRequestReception()