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Class com.sun.jaw.impl.agent.services.jawdiscovery.DiscoveryClient

java.lang.Object
   |
   +----com.sun.jaw.impl.agent.services.jawdiscovery.DiscoveryClient

public class DiscoveryClient

extends Object

implements Serializable, ActivatableIf

• a DiscoveryClient broadcasts a discovery request on a MulticastSocket
• DiscoveryResponder objects listening on the multicast group catch the request. Each DiscoveryResponder sends a discovery response to the DiscoveryClient

A DiscoveryClient can only reach the DiscoveryResponder objects that listen on the same multicast group and port. The default group is 224.224.224.224 and the default port is 9000. Other values can be used by configuring the multicastGroup and multicastPort properties on the DiscoveryClient and DiscoveryResponder objects.

The scope of the discovery depends on the time-to-live used by the MulticastSocket. By default, the time-to-live is 1. It can be changed by setting the property timeToLive on the DiscoveryClient.

After it has sent its discovery request, a DiscoveryClient waits a finite time for responses. The default is 1 second. This can be customized by setting the timeOut property on the DiscoveryClient.

An application triggers a discovery operation by invoking either the performFindHosts method or the performFindAdaptors method on a DiscoveryClient object. These methods represent the discovery result by a Vector of DiscoveryResponse. A DiscoveryResponse is included for each discovered agent, it provides the host of the agent and optionally the list of adaptors available in the agent.

A DiscoveryResponder can send back responses using two modes:

• Unicast mode. A datagram socket is sent from the DiscoveryResponder to the DiscoveryClient. The response is NOT multicasted to the group. The default datagram socket port is 9001. The port number can be changed using the setPointToPointResponsePort method. Invoking this method with a negative value unsets unicast response mode and multicast response mode is used. The datagram socket inet address is defined by the local host name. It cannot be customized.
• Multicast mode. A multicast socket is used between the DiscoveryResponder and the DiscoveryClient. The response is multicasted to the group. This behavior allows DiscoveryMonitor objects to be aware of changes. To enable multicast mode, either invoke setPointToPointResponsePort with a negative value or invoke the unsetPointToPointResponsePort.

It is possible to instantiate multiple DiscoveryClient objects with different groups and ports for multicast responses and datagram sockets for unicast responses.

OFFLINE

ONLINE

STOPPING

DiscoveryClient()

Class constructor.

deleteCmf()

For Java DMK internal use only.

getClassVersion()

Returns the version of this class.

getMulticastGroup()

Returns the multicast group.

getMulticastPort()

Returns the multicast port.

getPointToPointResponse()

Get the unicast datagram socket port for the Java DMK agent response.

getState()

Returns the state of this DiscoveryResponder.

getStateString()

Returns the state of this DiscoveryResponder in string form.

getTimeOut()

Returns the time to wait for discovery responses in milliseconds.

getTimeToLiveByte()

Returns the time-to-live as a byte value.

getTimeToLiveInt()

Returns the time-to-live as a int value.

initCmf(Framework, ObjectName, boolean, ModificationList)

For Java DMK internal use only.

isActive()

Tests if the AdaptorServer is active.

performFindAdaptors()

Discovers all agents and associated adaptors.

performFindAdaptors(String)

Discovers all agents and associated adaptors present on an host.

performFindHosts()

Discovers all agents.

performFindHosts(String)

Discovers whether a Java DMK agent with a DiscoveryResponder registered in its framework is on a host.

performStart()

Connects this DiscoveryClient, the socket joins its multicast group.

performStop()

Disconnects this DiscoveryClient, the socket leaves its multicast group.

setMulticastGroup(String)

Sets the multicast group name.

setMulticastPort(int)

Sets the multicast port.

setPointToPointResponse(boolean)

Set unicast datagram socket mode for the Java DMK agent response.

setTimeOut(int)

Sets the time during which the DiscoveryClient waits for discovery responses.

setTimeToLiveByte(byte)

Sets the default time-to-live expressed as a byte value.

setTimeToLiveInt(int)

Sets the default time-to-live for this DiscoveryClient.

 public static final int ONLINE

 public static final int OFFLINE

 public static final int STOPPING

 public DiscoveryClient() throws IOException

Class constructor. This constructor creates a multicast socket that is used to broadcast the discovery request using the default group (224.224.224.224) and port (9000).

Throws: IOException

The creation of the socket failed.

 public void initCmf(Framework cmf,
                     ObjectName name,
                     boolean db,
                     ModificationList list) throws IllegalAccessException, ServiceNotFoundException, InstanceAlreadyExistException

For Java DMK internal use only.

 public void deleteCmf() throws InstanceNotFoundException, IllegalAccessException, ServiceNotFoundException

For Java DMK internal use only.

 public void performStart()

Connects this DiscoveryClient, the socket joins its multicast group.

 public void performStop()

Disconnects this DiscoveryClient, the socket leaves its multicast group.

 public boolean isActive()

Tests if the AdaptorServer is active.

 public Vector performFindHosts() throws CommunicationException

Discovers all agents. Each DiscoveryResponse contains the host names of all agents that were discovered.

Returns:

A vector of DiscoveryResponse.

Throws: CommunicationException

An error occurred during the discovery.

See Also:

DiscoveryResponse

 public Vector performFindHosts(String SelectedHost) throws CommunicationException

Discovers whether a Java DMK agent with a DiscoveryResponder registered in its framework is on a host. The DiscoveryResponse only contains the host name.

Parameters:

SelectedHost - The host on which the discovery is to be performed.

Returns:

A vector of DiscoveryResponse.

Throws: CommunicationException

An error occurred during the discovery.

See Also:

DiscoveryResponse

 public Vector performFindAdaptors() throws CommunicationException

Discovers all agents and associated adaptors.

Returns:

A vector of DiscoveryResponse.

Throws: CommunicationException

An error occurred during the discovery.

See Also:

DiscoveryResponse

 public Vector performFindAdaptors(String SelectedHost) throws CommunicationException

Discovers all agents and associated adaptors present on an host.

Parameters:

SelectedHost - The host on which the discovery is to be performed.

Returns:

A vector of DiscoveryResponse.

Throws: CommunicationException

An error occurred during the discovery.

 public String getClassVersion()

Returns the version of this class.

 public String getMulticastGroup()

Returns the multicast group.

 public void setMulticastGroup(String multicastGroup)

Sets the multicast group name. Only available if state in OFFLINE

Parameters:

multicastGroup - The multicast group name.

 public int getMulticastPort()

Returns the multicast port.

 public void setMulticastPort(int multicastPort)

Sets the multicast port. Only available if state in OFFLINE

Parameters:

multicastPort - The multicast port.

 public void setTimeOut(int timeOut)

Sets the time during which the DiscoveryClient waits for discovery responses. This time is expressed in milliseconds. The default value is 1000. If the specified argument is negative or zero, the timeOut is reset to 1000.

The methods performFindHosts and performFindAdaptors block until this time elapsed.

Parameters:

timeOut - The timeOut in milliseconds.

See Also:

getTimeOut

 public int getTimeOut()

Returns the time to wait for discovery responses in milliseconds.

Returns:

The timeOut in milliseconds.

See Also:

 public void setTimeToLiveInt(int ttl) throws IOException

Sets the default time-to-live for this DiscoveryClient. The time-to-live is the number of 'hops' that the multicast packet is forwarded on the network.

Parameters:

ttl - A number between 1 and 255.

Throws: IOException

If the socket rejected the specified value.

 public void setTimeToLiveByte(byte ttl) throws IOException

Sets the default time-to-live expressed as a byte value.

Parameters:

ttl - A byte value.

Throws: IOException

If the socket rejected the specified value.

 public byte getTimeToLiveByte()

Returns the time-to-live as a byte value.

Returns:

The time-to-live as a byte value.

 public int getTimeToLiveInt()

Returns the time-to-live as a int value.

Returns:

The time-to-live as a int value.

 public boolean getPointToPointResponse()

Get the unicast datagram socket port for the Java DMK agent response.

Returns:

True indicates that unicast datagram socket is being used. false indicates that the multicast response mode is being used.

 public void setPointToPointResponse(boolean pointToPointResponse)

Set unicast datagram socket mode for the Java DMK agent response. The client sends a request for a unicast response in each discovery request. The multicast group Inet address is used for the unicast response.

Parameters:

pointToPointResponse - The datagram socket mode. false value unsets the use of unicast socket for the response, multicast is used instead.

 public Integer getState()

Returns the state of this DiscoveryResponder.

Returns:

ONLINE, OFFLINE or STOPPING.

 public String getStateString()

Returns the state of this DiscoveryResponder in string form.

Returns:

One of the strings "ONLINE", "OFFLINE" or "STOPPING".

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