cgl.narada.protocol
Class Gateway

java.lang.Object
  cgl.narada.protocol.Gateway

All Implemented Interfaces:

ProtocolDebugFlags

public class Gateway
extends Object
implements ProtocolDebugFlags

Gateway.java The individual element in the connectivity graph which we construct to -

Compute the best hop that should be taken from the vertex Node to reach any unit within the system.

To detect partitions - This could either be a system partition or a unit partition within a super unit. The knowledge of such partitions enable us to come up with alternate routing schemes or induce roam within clients connected to the partitioned sub-unit or sub system. The feature tells a node about partitions that concern the node's routing abilities.

Field Summary

Fields inherited from interface cgl.narada.protocol.ProtocolDebugFlags

BrokerLocatorCommunicator_Debug, ClientConnectionHandler_Debug, Connection_Debug, ConnectionPropagation_Debug, Destinations_Debug, DuplicateDetection_Debug, EventBuffer_Debug, EventRoutingProtocol_Debug, Gateway_Debug, GatewayInfo_Debug, GatewayPropagation_Debug, JmsProfilePropagation_Debug, LinkCostMatrix_Debug, NodeAdditionProtocol_Debug, NodeAddress_Debug, Path_Debug, PersistentEventRouting_Debug, ProfilePropagationProtocol_Debug, ProtocolException_Debug, ProtocolHandler_Debug, ProtocolID_Debug, ProtocolIDFactory_Debug, RoutingCache_Debug, RtpEventRoutingProtocol_Debug, RtpProfilePropagation_Debug, SecureMessageRouting_Debug, TagValueEventRoutingProtocol_Debug, TagValueProfilePropagation_Debug, XmlEventRoutingProtocol_Debug, XPathProfilePropagation_Debug

Constructor Summary

Gateway(Gateway vertexNode, NodeAddress node, short level)
This constructor is used to process the information that would be exchanged during the process of unit addition or the addition of a gateway.

Gateway(NodeAddress node, short level, boolean isVertex)
This constructor is used the first time a node is assigned a logical address.

Method Summary

Path	computeShortestPathTo(Gateway gateway, Path path) The recursive call which computes the cost required to reach any given gateway within the system.
Path	computeShortestPathToVertex(Path path) The recursive call which computes the cost required to reach the vertex gateway within the system.
void	connectedToGateway(Gateway gateway) This hooks up two gateway nodes in the connectivity graph.
boolean	containedInRoutingInformation(byte[] routingInformation) Based on the routing information received at a server node, we need to know wether or not we should employ certain hops in the routing information.
boolean	containedInRoutingInformation(Destinations routingInformation) Based on the routing information received at a server node, we need to know wether or not we should employ certain hops in the routing information.
protected void	createDownLink(Gateway gateway)
protected void	createLateralAndUpLink(Gateway gateway)
int	disconnectedFromGateway(Gateway gateway) When a level-l gateway fails, or is added, the shortest paths and next best hop to reach the vertex node needs to be computed for all level-l gateways, and l+1 ...
boolean	equals(Object obj) Compares two objects for equality.
short	getLevel() Returns the level that this node exists in within the connectivity graph
NodeAddress	getNode() Provides the node address of the gateway node in the connectivity graph.
int	hashCode() Generates a hash code for the receiver.
void	invalidateVertexPath() This method forces the invalidation of the vertex path so that a new path is forced to be computed
static void	main(String[] args)
protected void	removeDownLink(Gateway gateway)
protected void	removeLateralAndUpLink(Gateway gateway)
int	reportPartitionStatus() If the lateralAndUpLink sizes are zero, a node is unit partitioned.
String	toString() This method is implemented to enable a System.out.println() on the gateway node.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

Gateway

public Gateway(NodeAddress node,
               short level,
               boolean isVertex)

This constructor is used the first time a node is assigned a logical address.

Parameters:

node - - The node address of the hosting server node

level - - The level of the system that this node is a part of.

isVertex - - Indication that this node is the vertex for the connectivity graph that would be constructed for the node.

Gateway

public Gateway(Gateway vertexNode,
               NodeAddress node,
               short level)

This constructor is used to process the information that would be exchanged during the process of unit addition or the addition of a gateway.

Parameters:

vertexNode - - The node address of the hosting server node

node - - The nodeAddress of the node that is added to the connectivity graph.

level - - The level of the system that this node is a part of.

Method Detail

getNode

public NodeAddress getNode()

Provides the node address of the gateway node in the connectivity graph.

Returns:

The node address of the gateway node.

getLevel

public short getLevel()

Returns the level that this node exists in within the connectivity graph

Returns:

The level of this gateway node

connectedToGateway

public void connectedToGateway(Gateway gateway)

This hooks up two gateway nodes in the connectivity graph. The gateway on which this method is invoked is responsible for creating the edge between the two gateways within the connectivity graph

Parameters:

gateway - - Specifies the gateway node that this node is connected to.

createLateralAndUpLink

protected void createLateralAndUpLink(Gateway gateway)

createDownLink

protected void createDownLink(Gateway gateway)

removeLateralAndUpLink

protected void removeLateralAndUpLink(Gateway gateway)

removeDownLink

protected void removeDownLink(Gateway gateway)

disconnectedFromGateway

public int disconnectedFromGateway(Gateway gateway)

When a level-l gateway fails, or is added, the shortest paths and next best hop to reach the vertex node needs to be computed for all level-l gateways, and l+1 ... till the maximum level of the system. This method, accounts for the link failure case between two nodes. A unit failure corresponds to the failure of all links within that unit

Parameters:

gateway - - The gateway that has been disconnected.

Returns:

partitionStatus

reportPartitionStatus

public int reportPartitionStatus()

If the lateralAndUpLink sizes are zero, a node is unit partitioned. If however there are no links originating from a node, that node is system partitioned

Returns:

partitionStatus

invalidateVertexPath

public void invalidateVertexPath()

This method forces the invalidation of the vertex path so that a new path is forced to be computed

computeShortestPathToVertex

public Path computeShortestPathToVertex(Path path)

The recursive call which computes the cost required to reach the vertex gateway within the system. The rules for traversing the connectivity graph include traversal only along lateral links or to a lower gateway.

Parameters:

path - - The path that is taken by each recursive process. We need this to ensure that each path traverses a gateway node only once and does not get stuck inside a recursive infinite loop.

computeShortestPathTo

public Path computeShortestPathTo(Gateway gateway,
                                  Path path)

The recursive call which computes the cost required to reach any given gateway within the system. The rules for traversing the connectivity graph include traversal only along lateral links or to a lower gateway.

Parameters:

gateway - - The gateway that you seek to reach.

path - - The path that is taken by each recursive process. We need this to ensure that each path traverses a gateway node only once and does not get stuck inside a recursive infinite loop.

containedInRoutingInformation

public boolean containedInRoutingInformation(byte[] routingInformation)

Based on the routing information received at a server node, we need to know wether or not we should employ certain hops in the routing information. This method provides information regarding wether or not the hop (this node) in question can be employed in routing given a certain routing information.

Parameters:

routingInformation - - The routing information associated with the message so far.

Returns:

true - If this hop can be employed in the routing, and false otherwise.

containedInRoutingInformation

public boolean containedInRoutingInformation(Destinations routingInformation)

Based on the routing information received at a server node, we need to know wether or not we should employ certain hops in the routing information. This method provides information regarding wether or not the hop (this node) in question can be employed in routing given a certain routing information.

Parameters:

routingInformation - - The routing information associated with the message so far.

Returns:

true - If this hop can be employed in the routing, and false otherwise.

toString

public String toString()

This method is implemented to enable a System.out.println() on the gateway node. The string returned provides info regarding the node.

Overrides:

toString in class Object

equals

public boolean equals(Object obj)

Compares two objects for equality. Returns a boolean that indicates whether this object is equivalent to the specified object. This method is used when an object is stored in a hashtable.

Overrides:

equals in class Object

Parameters:

obj - the Object to compare with

Returns:

true if these Objects are equal; false otherwise.

See Also:

Hashtable

hashCode

public int hashCode()

Generates a hash code for the receiver. This method is supported primarily for hash tables, such as those provided in java.util. If two objects are equal (equals(Object) returns true) they must have the same hash code

Overrides:

hashCode in class Object

Returns:

an integer hash code for the receiver

main

public static void main(String[] args)