de.fhg.igd.semoa.net.farsight
Class ExplorerStrategy

java.lang.Object
  de.fhg.igd.semoa.net.farsight.DiscoveryStrategy
      de.fhg.igd.semoa.net.farsight.ExplorerStrategy

All Implemented Interfaces:

ArrivalListener

public class ExplorerStrategy

extends DiscoveryStrategy

implements ArrivalListener

This discovery strategy uses mobile agents to detect SeMoA hosts. The used agent type is ExplorerAgent.

On creation of this class the AgentArrivalFilter is installed in the filter pipeline of SeMoA. Every incoming agent is tested for certain properties. If the agent is accepted, an ExplorerAgent will be created that will examine the SeMoA host the incoming agent did come from. The following must not be true for the incoming agent:

• It's an ExplorerAgent
• No reverse ticket was set
• It's from the LAN and known to Vicinity
• It's last host is already known to Farsight

Version:

"$id: $"

Author:

Jan Haevecker

See Also:

ExplorerAgent

Field Summary

private static Logger	log_ The Logger instance for this class
private static String	VALID_PREFIX_CHARS Sorted list of valid filter prefix characters (see installAgentArrivalFilter().

Fields inherited from class de.fhg.igd.semoa.net.farsight.DiscoveryStrategy

Constructor Summary

ExplorerStrategy(String config)
Sole constructor.

Method Summary

void	agentArrived(AgentContext context) Called by the AgentArrivalFilter when a new agent arrives at this SeMoA server.
private void	explore(Map contacts) Sends an ExplorerAgent to every value from the contacts map.
private static URL	getRawURL(URL shipURL) Replaces the protocol of shipURL with "raw".
private void	installAgentArrivalFilter() Installs the AgentArrivalFilter into this SeMoA server's filter pipeline.
protected boolean	isExplorer(AgentContext context) Returns whether a given agent context is a ExplorerAgent.
protected boolean	isKnownHost(URL url) Checks whether FarSight does already know the host at url.
private void	loadDefaultGateways() Reads the default gateways from the properties file and sends an ExplorerAgent.
static void	sendExplorer(URL target) Sends an ExplorerAgent to a given target.

Methods inherited from class de.fhg.igd.semoa.net.farsight.DiscoveryStrategy

getConfig

Methods inherited from class java.lang.Object

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

Field Detail

VALID_PREFIX_CHARS

private static final String VALID_PREFIX_CHARS

Sorted list of valid filter prefix characters (see installAgentArrivalFilter().

See Also:

Constant Field Values

log_

private static Logger log_

The Logger instance for this class

Constructor Detail

ExplorerStrategy

public ExplorerStrategy(String config)
                 throws ObjectExistsException

Sole constructor.

Method Detail

agentArrived

public void agentArrived(AgentContext context)

Called by the AgentArrivalFilter when a new agent arrives at this SeMoA server.

Specified by:

agentArrived in interface ArrivalListener

Parameters:

context - The agent context of the arriving agent.

explore

private void explore(Map contacts)

Sends an ExplorerAgent to every value from the contacts map.

sendExplorer

public static void sendExplorer(URL target)

Sends an ExplorerAgent to a given target. The protocol of the target URL will be set to "raw".

getRawURL

private static URL getRawURL(URL shipURL)
                      throws ShipException,
                             MalformedURLException

Replaces the protocol of shipURL with "raw".

Throws:

ShipException

MalformedURLException

isExplorer

protected boolean isExplorer(AgentContext context)

Returns whether a given agent context is a ExplorerAgent.

isKnownHost

protected boolean isKnownHost(URL url)

Checks whether FarSight does already know the host at url.

installAgentArrivalFilter

private void installAgentArrivalFilter()
                                throws ObjectExistsException

Installs the AgentArrivalFilter into this SeMoA server's filter pipeline.

Throws:

ObjectExistsException

loadDefaultGateways

private void loadDefaultGateways()

Reads the default gateways from the properties file and sends an ExplorerAgent.