org.jgroups.protocols

## Class MPING

- java.lang.Object
- - org.jgroups.stack.Protocol
  - - org.jgroups.protocols.Discovery
    - - org.jgroups.protocols.PING
      - - org.jgroups.protocols.MPING

All Implemented Interfaces:
  java.lang.Runnable

    public class MPING
    extends PING
    implements java.lang.Runnable

Uses its own IP multicast socket to send and receive discovery requests/responses. Can be used in conjuntion with a non-UDP transport, e.g. TCP.

The discovery is assymetric: discovery requests are broadcast via the multicast socket, and received via the multicast socket by everyone in the group. However, the discovery responses are sent back via the regular transport (e.g. TCP) to the sender (discovery request contained sender's regular address, e.g. 192.168.0.2:7800).

Author:
  Bela Ban

### Nested Class Summary

### Nested classes/interfaces inherited from class org.jgroups.protocols.Discovery

`Discovery.Responses`

### Field Summary

Fields
`protected java.lang.String` `bind_interface_str`

### Fields inherited from class org.jgroups.protocols.PING

`discovery_reception`

### Fields inherited from class org.jgroups.protocols.Discovery

`group_addr, local_addr, members, ping_responses, rank, timer, view`

### Fields inherited from class org.jgroups.stack.Protocol

`down_prot, ergonomics, id, log, name, stack, stats, up_prot`

### Constructor Summary

Constructors
Constructor and Description
`MPING()`

### Method Summary

Methods
`java.net.InetAddress` `getBindAddr()`
`java.net.InetAddress` `getMcastAddr()`
`int` `getMcastPort()`
`java.util.List<java.net.NetworkInterface>` `getReceiveInterfaces()`
`java.util.List<java.net.NetworkInterface>` `getSendInterfaces()`
`int` `getTTL()`
`void` `init()` Called after instance has been created (null constructor) and before protocol is started.
`boolean` `isReceiveOnAllInterfaces()`
`boolean` `isSendOnAllInterfaces()`
`void` `run()`
`void` `setBindAddr(java.net.InetAddress bind_addr)`
`void` `setMcastAddr(java.net.InetAddress mcast_addr)`
`void` `setMcastPort(int mcast_port)`
`void` `setMulticastAddress(java.lang.String addr)`
`void` `setTTL(int ip_ttl)`
`void` `start()` This method is called on a `Channel.connect(String)`.
`void` `stop()` This method is called on a `Channel.disconnect()`.
`java.lang.Object` `up(Event evt)` An event was received from the layer below.

### Methods inherited from class org.jgroups.protocols.PING

`sendGetMembersRequest, waitForDiscoveryRequestReception`

### Methods inherited from class org.jgroups.protocols.Discovery

`discoveryRequestReceived, down, findAllMembers, findAllViews, findAllViewsAsString, findInitialMembers, findInitialMembers, findInitialMembersAsString, getNumberOfDiscoveryRequestsSent, getNumInitialMembers, getNumPingRequests, getTimeout, getView, handleConnect, handleDisconnect, makeView, providedUpServices, resetStats, setNumInitialMembers, setNumPingRequests, setTimeout`

### Methods inherited from class org.jgroups.stack.Protocol

`destroy, downThreadEnabled, dumpStats, enableStats, getConfigurableObjects, getDownProtocol, getId, getLevel, getName, getProperties, getProtocolStack, getSocketFactory, getThreadFactory, getTransport, getUpProtocol, getValue, isErgonomics, printStats, providedDownServices, requiredDownServices, requiredUpServices, setDownProtocol, setErgonomics, setId, setLevel, setProperties, setPropertiesInternal, setProperty, setProtocolStack, setSocketFactory, setUpProtocol, setValue, setValues, statsEnabled, upThreadEnabled`

### Methods inherited from class java.lang.Object

`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

### Field Detail

#### bind_interface_str

    protected java.lang.String bind_interface_str

### Constructor Detail

#### MPING

    public MPING()

### Method Detail

#### getBindAddr

    public java.net.InetAddress getBindAddr()

#### setBindAddr

    public void setBindAddr(java.net.InetAddress bind_addr)

#### getReceiveInterfaces

    public java.util.List<java.net.NetworkInterface> getReceiveInterfaces()

#### getSendInterfaces

    public java.util.List<java.net.NetworkInterface> getSendInterfaces()

#### isReceiveOnAllInterfaces

    public boolean isReceiveOnAllInterfaces()

#### isSendOnAllInterfaces

    public boolean isSendOnAllInterfaces()

#### getTTL

    public int getTTL()

#### setTTL

    public void setTTL(int ip_ttl)

#### getMcastAddr

    public java.net.InetAddress getMcastAddr()

#### setMcastAddr

    public void setMcastAddr(java.net.InetAddress mcast_addr)

#### setMulticastAddress

    public void setMulticastAddress(java.lang.String addr)
                             throws java.net.UnknownHostException

Throws:
  `java.net.UnknownHostException`

#### getMcastPort

    public int getMcastPort()

#### setMcastPort

    public void setMcastPort(int mcast_port)

#### up

    public java.lang.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 `PING`
Parameters:
  `evt` - - the event that has been sent from the layer below

#### 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. Properties are already set. Other protocols are not yet connected and events cannot yet be sent.

Overrides:
  `init` in class `Discovery`
Throws:
  `java.lang.Exception` - Thrown if protocol cannot be initialized successfully. This will cause the ProtocolStack to fail, so the channel constructor will throw an exception

#### start

    public void start()
               throws java.lang.Exception

Description copied from class: `Protocol`
This method is called on a `Channel.connect(String)`. Starts work. Protocols are connected and queues are ready to receive events. Will be called from bottom to top. This call will replace the START and START_OK events.

Overrides:
  `start` in class `Discovery`
Throws:
  `java.lang.Exception` - Thrown if protocol cannot be started successfully. This will cause the ProtocolStack to fail, so `Channel.connect(String)` 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 `PING`

#### run

    public void run()

Specified by:
  `run` in interface `java.lang.Runnable`