org.qbroker.cluster

Class PacketNode

java.lang.Object

org.qbroker.cluster.PacketNode

All Implemented Interfaces:

java.lang.Runnable, ClusterNode

public class PacketNode
extends java.lang.Object
implements ClusterNode, java.lang.Runnable

PacketNode is a cluster node of a MulticastGroup. The cluster contains a number of PacketNodes communicating with each other via DatagramPackets. One of the nodes is the manager that supervises the entire group or cluster. The rest of nodes are workers reporting to the manager and monitoring its behavior closely. In case that the manager quits or any node misses certain number of heartbeats from the manager, the rest of the workers will elect a new manager and resume to work. Any new node can join the group anytime as long as there is a room available in the group. Any worker can leave the group anytime. If the last node leaves the group, the cluster goes down.

PacketNode also supports the extra path for communications between nodes if ExtraReceiver is defined. With ExtraReceiver, each outgoing packet will be duplicated on its content. Then it will be sent out via the extra communication path. Currently, ExtraReceiver only supports two of the schemes, comm or udp. In case of comm, an RS232 connection is required. It means the cluster size will be limited to 2. In case of udp, it requires a separate subnet as the secondary communication path. Also the URI of ExtraReceiver must be different from the primary one. Due to the limit on the udp IP bindings, each machine can only host one node at most. Either way, it increases the reliability and the redundancy of the cluster.

PacketNode is supposed to run at backgroud. It is designed to be a black automaton box. It will automatically maitain the state of the cluster. But if the escalation outLink is specified at startup, it will also send the state information and relay the data. The application on the node can intercept the events from the node and send data to any other nodes via the API of relay().

A PacketNode may be in one of the following states:
NODE_NEW: just starting up, not joining the cluster yet
NODE_RUNNING: joined in the cluster and running OK
NODE_STANDBY: joined in the cluster but still in transient state
NODE_TIMEOUT: missed a fixed number of heartbeats from the node
NODE_DOWN: no longer active

Author:

yannanlu@yahoo.com

Field Summary

Fields inherited from interface org.qbroker.cluster.ClusterNode

ACTION_ADD, ACTION_CHK, ACTION_DEL, ACTION_IGR, ACTION_MOD, ACTION_OVR, ACTION_VOTE, DEBUG_ALL, DEBUG_CHECK, DEBUG_CLOSE, DEBUG_EXAM, DEBUG_HBEAT, DEBUG_INIT, DEBUG_NONE, DEBUG_RELAY, HB_ECOUNT, HB_ETIME, HB_PCOUNT, HB_PTIME, HB_SIZE, HB_TYPE, NODE_DOWN, NODE_NEW, NODE_RUNNING, NODE_STANDBY, NODE_TIMEOUT, RCVR_COMM, RCVR_JMS, RCVR_NONE, RCVR_TCP, RCVR_UDP

Constructor Summary

Constructors

Constructor and Description
PacketNode(java.util.Map props)

Method Summary

Modifier and Type	Method and Description
void	close() closes the node and all resources
int	getDebug() returns the debug mode of the node
int	getRole() returns the role of the node
int	getSize() returns the size of the cluster
int	getStatus() returns the status of the node
int	getTimeout() returns the sessionTimeout of the node
java.lang.String	getURI() returns the URI of the node
boolean	isMaster()
static void	main(java.lang.String[] args)
int	relay(Event data, int waitTime) It is the API for application to send data to the node or group asynchronously.
void	run()
void	setDebug(int debug) sets the debug mode of the node
void	start() It starts the cluster node and supervises its state.
void	start(XQueue out, int begin, int len) It starts the cluster node and supervises its state.

Methods inherited from class java.lang.Object

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

Constructor Detail

PacketNode

public PacketNode(java.util.Map props)

Method Detail

run

public void run()

Specified by:

run in interface java.lang.Runnable

close

public void close()

Description copied from interface: ClusterNode

closes the node and all resources

Specified by:

close in interface ClusterNode

relay

public int relay(Event data,
                 int waitTime)

It is the API for application to send data to the node or group asynchronously. It returns a non-negative number for success, or -1 otherwise.

Specified by:

relay in interface ClusterNode

isMaster

public boolean isMaster()

Specified by:

isMaster in interface ClusterNode

getRole

public int getRole()

Description copied from interface: ClusterNode

returns the role of the node

Specified by:

getRole in interface ClusterNode

getStatus

public int getStatus()

Description copied from interface: ClusterNode

returns the status of the node

Specified by:

getStatus in interface ClusterNode

getTimeout

public int getTimeout()

Description copied from interface: ClusterNode

returns the sessionTimeout of the node

Specified by:

getTimeout in interface ClusterNode

getURI

public java.lang.String getURI()

Description copied from interface: ClusterNode

returns the URI of the node

Specified by:

getURI in interface ClusterNode

getSize

public int getSize()

Description copied from interface: ClusterNode

returns the size of the cluster

Specified by:

getSize in interface ClusterNode

getDebug

public int getDebug()

Description copied from interface: ClusterNode

returns the debug mode of the node

Specified by:

getDebug in interface ClusterNode

setDebug

public void setDebug(int debug)

Description copied from interface: ClusterNode

sets the debug mode of the node

Specified by:

setDebug in interface ClusterNode

start

public void start()

It starts the cluster node and supervises its state.

start

public void start(XQueue out,
                  int begin,
                  int len)

It starts the cluster node and supervises its state. With the communication XQueue defined, the cluster node will escalate or relay events to/from external caller via the XQueue. The cluster node will keep running until its shutdown.

Specified by:

start in interface ClusterNode

main

public static void main(java.lang.String[] args)