cgl.narada.discovery.broker
Class BrokerDiscoveryHelper

java.lang.Object
  cgl.narada.discovery.broker.BrokerDiscoveryHelper

public class BrokerDiscoveryHelper
extends Object

A client can use the Broker Locator to locate a suitable broker to connect to.
The BrokerDiscoveryHelper sends BrokerDiscoveryRequest to (a) known (BDN)s. If the BDN is not available then the request is broadcasted using UDP multicast.
Created on Mar 26, 2005

Field Summary

static double	BROKER_DISCOVERY_PING_TIME 50% weightage is given to the Ping time
static int	MAX_PINGS
static int	RESPONSE_PACKET_SIZE
static int	TIMEOUT
static double	WEIGHTAGE_FREE_TO_TOTAL_MEMORY 4% weightage is given to the %age of free memory
static double	WEIGHTAGE_NUM_LINKS 5% weightage is given to the Number of links a broker has
static double	WEIGHTAGE_TOTAL_MEMORY 10% weightage is given to the amount of memory present

Constructor Summary

BrokerDiscoveryHelper(int entityId, String configFilePath, int timeout, int maxResponses, int maxSetSize)

Method Summary

double	computeBrokerWeightage(BrokerDiscoveryResponse resp) Computes weight for the given broker using the values in the BrokerDiscoveryResponse
BrokerDiscoveryResponse[]	discover(String[] protocols, String secCerts, String brokerNetworks) We first initialize and run the UDPReciever thread.
String	getBrokerLocation(BrokerDiscoveryResponse bdr)
static void	main(String[] args) Testing purposes only
long	ping(String host, int port, int timeout) Pings a given broker
BrokerDiscoveryResponse	selectBestBroker(BrokerDiscoveryResponse[] brokers) Selects the best broker among the specified set of brokers from the broker discovery responses

Methods inherited from class java.lang.Object

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

Field Detail

TIMEOUT

public static int TIMEOUT

RESPONSE_PACKET_SIZE

public static final int RESPONSE_PACKET_SIZE

See Also:

Constant Field Values

BROKER_DISCOVERY_PING_TIME

public static final double BROKER_DISCOVERY_PING_TIME

50% weightage is given to the Ping time

See Also:

Constant Field Values

WEIGHTAGE_TOTAL_MEMORY

public static final double WEIGHTAGE_TOTAL_MEMORY

10% weightage is given to the amount of memory present

See Also:

Constant Field Values

WEIGHTAGE_NUM_LINKS

public static final double WEIGHTAGE_NUM_LINKS

5% weightage is given to the Number of links a broker has

See Also:

Constant Field Values

WEIGHTAGE_FREE_TO_TOTAL_MEMORY

public static final double WEIGHTAGE_FREE_TO_TOTAL_MEMORY

4% weightage is given to the %age of free memory

See Also:

Constant Field Values

MAX_PINGS

public static final int MAX_PINGS

See Also:

Constant Field Values

Constructor Detail

BrokerDiscoveryHelper

public BrokerDiscoveryHelper(int entityId,
                             String configFilePath,
                             int timeout,
                             int maxResponses,
                             int maxSetSize)

Method Detail

discover

public BrokerDiscoveryResponse[] discover(String[] protocols,
                                          String secCerts,
                                          String brokerNetworks)

We first initialize and run the UDPReciever thread. The try to send the request to one of the BDNs of if unsuccessful, try and multicast the request. In either case, if the request could be sent, we wait for responses else we close the UDPReciever's socket and return null.

Parameters:

protocols - - A list of 1 or more matching protocols the broker MUST support.

secCerts - - Security Certificate. TODO: Replace w/ X.509 Certificate

brokerNetworks - - brokers belonging to which networks must be considered. "*" to match any network

Returns:

null if a BrokerDiscoveryRequest could not be sent, an array of Responses (possibly empty) otherwise.

ping

public long ping(String host,
                 int port,
                 int timeout)

Pings a given broker

Parameters:

host - - IP address of the broker

port - - UDP port of broker

timeout - - Time for which to wait

Returns:

PING time in microSeconds if successful, -1 if timeout, -2 if garbled protocol header or other error.

computeBrokerWeightage

public double computeBrokerWeightage(BrokerDiscoveryResponse resp)

Computes weight for the given broker using the values in the BrokerDiscoveryResponse

Parameters:

resp - - The BrokerDiscoveryResponse containing the metrics for the broker

Returns:

- A double value indicating the computed weight

getBrokerLocation

public String getBrokerLocation(BrokerDiscoveryResponse bdr)

selectBestBroker

public BrokerDiscoveryResponse selectBestBroker(BrokerDiscoveryResponse[] brokers)

Selects the best broker among the specified set of brokers from the broker discovery responses

Parameters:

brokers - An array of BrokerDiscoveryResponses

Returns:

The BrokerDiscoveryResponse of the best broker

main

public static void main(String[] args)

Testing purposes only

Parameters:

args -