rice.scribe
Class Scribe

java.lang.Object
  rice.pastry.client.PastryAppl
      rice.scribe.Scribe

All Implemented Interfaces:

IScribe, MessageReceiver

public class Scribe

extends PastryAppl

implements IScribe

Field Summary

boolean	m_ackOnSubscribeSwitch The AckOnSubscribe switch if true activates the immediate sending of ACK by a node when it receives a SUBSCRIBE message from its child for a topic.
protected static Address	m_address The receiver address for the scribe system.
protected java.util.Set	m_alreadySentHBNodes Optimization on number of HeartBeat Messages sent.
protected java.util.Vector	m_apps The set of IScribeApp's that have registered to this Scribe substrate.
protected static Credentials	m_credentials The Credentials object to be used for all messaging through Pastry.
protected java.util.Hashtable	m_distinctChildrenTable Hashtable having mapping from a child -> list of topics for which this child is in local node's children list for that topic.
protected java.util.Hashtable	m_distinctParentTable Hashtable having mapping from a parent node -> list of topics for which the parent node is local node's parent in the corresponding multicast tree for that topic.
ScribeMaintainer	m_maintainer The ScribeMaintainer object handles all the tree maintenance activities like the sending of heartbeat messages and issuing tree repair events for all the topics residing on the local node.
static int	m_scribeMaintFreq The time period determining Scribe Tree Maintenance Activity frequency
java.util.Set	m_scribeObservers The set of applications which are interested in getting notified whenever the local node becomes an intermediate node for a topic.
protected IScribeSecurityManager	m_securityManager Handles all the security verification.
protected SendOptions	m_sendOptions The SendOptions object to be used for all messaging through Pastry.
java.util.HashMap	m_topics Set of topics on the local scribe node.

Fields inherited from class rice.pastry.client.PastryAppl

address, instance, thePastryNode

Constructor Summary

Scribe(PastryNode pn, Credentials cred)
Constructor.

Method Summary

boolean	addChild(NodeHandle child, NodeId topicId) Add a node as a child in the children table for a topic.
boolean	addChild(NodeHandle child, NodeId topicId, java.io.Serializable data) Add a node as a child in the children table for a topic.
void	addChildForTopic(NodeHandle child, NodeId topicId) Adds a child for a topic into the distinctChildrenTable.
boolean	addChildToAlreadySentHBNodes(NodeId childId) Adds a child to the list of nodes to which this node has already send a implicit HeartBeat message in the form of Publish message in this Heartbeat period.
void	addParentForTopic(NodeHandle parent, NodeId topicId) Adds a parent for a topic into the distinctParentTable.
boolean	anycast(NodeId groupID, MessageAnycast anycastMessage, Credentials cred) An application can create sub-classes of MessageAnycast type of messages and write their own handling functions so as to do some application-specific predicate searching.
boolean	anycast(NodeId groupID, java.io.Serializable obj, Credentials cred) Anycast to a group/topic.
void	childObserver(NodeHandle child, NodeId topicId, boolean wasAdded, ScribeMessage pmsg, java.io.Serializable data) Whenever the children table for a topic is changed, ( a child is added or removed), this method is invoked to do some handling.
void	clearAlreadySentHBNodes() The set is cleared so that the set contains only those nodes to which Publish message was sent in last HeartBeat period.
boolean	create(NodeId topicId, Credentials cred) Creates a group/topic if the credentials are valid.
boolean	enrouteMessage(Message msg, Id target, NodeId nextHop, SendOptions opt) Called by pastry when a message is enroute and is passing through this node.
NodeId	generateTopicId(java.lang.String topicName) Generate a unique id for the topic, which will determine its rendezvous point.
Address	getAddress() Returns the address of this client.
java.util.Vector	getAlreadySentHBNodes() Gets the vector of nodes to which an implicit HeartBeat in form of Publish message was sent in last HeartBeat period.
java.util.Vector	getChildren(NodeId topicId) This returns the most current view of the children in this topic's multicast subtree rooted at the local node.
Credentials	getCredentials() Returns the credentials of this client.
java.util.Vector	getDistinctChildren() Gets the Vector of distinct children of this local node in multicast tree of all topics.
java.util.Vector	getDistinctParents() Gets the Vector of distinct parent of this local node in the multicast trees of all topics.
NodeId	getFingerprintForChildTopics(NodeHandle child)
NodeId	getFingerprintForParentTopics(NodeHandle parent)
NodeHandle	getLocalHandle()
NodeHandle	getNodeHandle() Returns the handle of the local node on which this Scribe application resides.
NodeHandle	getParent(NodeId topicId) Returns the local node's parent in this topic's multicast tree.
PastryNode	getPastryNode() Returns the pastryNode for this application.
IScribeSecurityManager	getSecurityManager() Returns the security manager from the Scribe node.
SendOptions	getSendOptions() Returns the send options in the Scribe system.
Topic	getTopic(NodeId topicId) Returns the topic object associated with topicId.
java.util.Vector	getTopics() Method to access the list of topics this scribe is responsible for.
java.util.Vector	getTopicsForChild(NodeHandle child) Gets the vector of topicIds for which given node is a child.
java.util.Vector	getTopicsForParent(NodeHandle parent) Gets the vector of topicIds for which given node is our parent.
int	getTreeRepairThreshold() Gets the tree repair threshold value.
boolean	isReady() Returns true is the Scribe substrate is ready.
boolean	isRoot(NodeId topicId) Returns true if the local node is currently the root(the node that is closest to the topicId) of the topic.
boolean	join(NodeId topicId, IScribeApp subscriber, Credentials cred) Joins a multicast group/topic.
boolean	join(NodeId topicId, IScribeApp subscriber, Credentials cred, java.io.Serializable obj) Joins a multicast group/topic.
void	leafSetChange(NodeHandle nh, boolean wasAdded) Called by pastry when the leaf set changes.
boolean	leave(NodeId topicId, IScribeApp subscriber, Credentials cred) Leaving a multicast group/topic.
ScribeMessage	makeAckOnSubscribeMessage(NodeId tid, Credentials c) Makes a AckOnSubscribe message using the current Pastry node as the source.
ScribeMessage	makeAckOnSubscribeMessage(NodeId tid, Credentials c, java.io.Serializable data) Makes a AckOnSubscribe message using the current Pastry node as the source.
ScribeMessage	makeAnycastMessage(NodeId tid, Credentials c) Makes a anycast message using the current Pastry node as the source.
ScribeMessage	makeCreateMessage(NodeId tid, Credentials c) Makes a create message using the current Pastry node as the source.
ScribeMessage	makeHeartBeatMessage(Credentials c) Makes a heart-beat message using the current Pastry node as the source.
ScribeMessage	makePublishMessage(NodeId tid, Credentials c) Makes a publish message using the current Pastry node as the source.
ScribeMessage	makeReplyFromParentMessage(Credentials c) Makes a ReplyFromParent message using the current Pastry node as the source.
ScribeMessage	makeRequestToParentMessage(Credentials c) Makes a RequestToParent message using the current Pastry node as the source.
ScribeMessage	makeScribeMaintenanceMessage(Credentials c) Makes a ScribeMaintenance message using the current Pastry node as the source.
ScribeMessage	makeSubscribeMessage(NodeId tid, Credentials c) Makes a subscribe message using the current Pastry node as the source.
ScribeMessage	makeUnsubscribeMessage(NodeId tid, Credentials c) Makes an unsubscribe message using the current Pastry node as the source.
void	messageForAppl(Message msg) Called by pastry when a message arrives for this client.
boolean	multicast(NodeId topicId, java.io.Serializable obj, Credentials cred) Multicast information to a group/topic.
void	notifyReady() This is called when the underlying pastry node is ready.
void	notifyScribeObservers(NodeId topicId) Notifies the applications on top of scribe who are interested in knowing the events of implicit topic creation.
int	numChildren(NodeId topicId) This returns the number of children in this topic's multicast subtree rooted at the local node.
void	registerApp(IScribeApp app) Registers the IScribeApp to the Scribe substrate.
void	registerScribeObserver(IScribeObserver app) Registers the application that implements the IScribeObserver interface.
boolean	removeChild(NodeHandle child, NodeId topicId) Removes a node as a child from the children table for a topic.
void	removeChildForTopic(NodeHandle child, NodeId topicId) Removes a child for a topic from the distinctChildrenTable.
void	removeParentForTopic(NodeHandle parent, NodeId topicId) Removes a parent for a topic fromthe distinctParentTable.
void	scheduleHB() Sends heartbeat messages to this local node's children for all the topics on this local scribe node.
boolean	setParent(NodeHandle parent, NodeId topicId) Sets the parent for the topic specified by topicId.
void	setTreeRepairThreshold(int value) The tree repair event for a particular topic in Scribe is triggered when a node misses a certain threshold number of heartbeat messages from its parent for the topic.

Methods inherited from class rice.pastry.client.PastryAppl

getLeafSet, getNodeId, getRoutingTable, isClosest, receiveMessage, registerReceiver, routeMsg, routeMsgDirect, routeSetChange, sendMessage

Methods inherited from class java.lang.Object

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

Field Detail

m_apps

protected java.util.Vector m_apps

The set of IScribeApp's that have registered to this Scribe substrate.

m_topics

public java.util.HashMap m_topics

Set of topics on the local scribe node.

m_distinctChildrenTable

protected java.util.Hashtable m_distinctChildrenTable

Hashtable having mapping from a child -> list of topics for which this child is in local node's children list for that topic. In this way, this table will have only distinct children and for each child we have the list of topics for which it is a child. Used to identify distinct chidren when sending HeartBeat messages, so that we dont send a node multiple HeartBeat messages when it is child for more than one topic.

m_distinctParentTable

protected java.util.Hashtable m_distinctParentTable

Hashtable having mapping from a parent node -> list of topics for which the parent node is local node's parent in the corresponding multicast tree for that topic. Whenever local node receives a HeartBeat message from a node, it calls the postponeParentHandler method for all topics for which that node is its parent. By having this data structure locally, we avoid sending lists of topics for which a node is parent in the HeartBeat message (this would cause the Heartbeat message to grow very large).

m_alreadySentHBNodes

protected java.util.Set m_alreadySentHBNodes

Optimization on number of HeartBeat Messages sent. Each node keeps track of the distinct children to which it has sent a PUBLISH message in last HeartBeat period. Thus in the scheduleHB() method which denotes the end of the previous HeartBeatPeriod, it need not send an explicit HeartBeat message to these 'marked' children, since a PUBLISH message is an implicit keep-alive message from the parent that it is alive.

m_ackOnSubscribeSwitch

public boolean m_ackOnSubscribeSwitch

The AckOnSubscribe switch if true activates the immediate sending of ACK by a node when it receives a SUBSCRIBE message from its child for a topic. Otherwise, this immediate ACK is not sent. This flag is set to TRUE. Setting it to false will cause several more messages in the form of MessageRequestToParent and MessageReplyFromParent to be exchanged between the child node and the parent node, when the child node receives a HeartBeat message from the parent. NOTE that if the HeartBeat message maintained a list of topics for which the child node(receiver of heartbeat message) was its child, then the AckOnSubscribe switch could have been set to false and these extra messages in the form of MessageRequestToParent and MessageReplyFromParent could have been got rid of. But due to scalability issues of sending the list of topics in the HeartBeat message we have adopted the current approach of setting the AckOnSubscribe switch to TRUE and additionally having the MessageRequestToParent and MessageReplyFromParent type of message.

m_address

protected static Address m_address

The receiver address for the scribe system.

m_sendOptions

protected SendOptions m_sendOptions

The SendOptions object to be used for all messaging through Pastry.

m_credentials

protected static Credentials m_credentials

The Credentials object to be used for all messaging through Pastry.

m_securityManager

protected IScribeSecurityManager m_securityManager

Handles all the security verification.

m_maintainer

public ScribeMaintainer m_maintainer

The ScribeMaintainer object handles all the tree maintenance activities like the sending of heartbeat messages and issuing tree repair events for all the topics residing on the local node.

m_scribeMaintFreq

public static int m_scribeMaintFreq

The time period determining Scribe Tree Maintenance Activity frequency

m_scribeObservers

public java.util.Set m_scribeObservers

The set of applications which are interested in getting notified whenever the local node becomes an intermediate node for a topic.

Constructor Detail

Scribe

public Scribe(PastryNode pn,
              Credentials cred)

Constructor.

Parameters:

pn - the pastry node that client will attach to.

cred - the credentials associated with this scribe object.

Method Detail

setTreeRepairThreshold

public void setTreeRepairThreshold(int value)

The tree repair event for a particular topic in Scribe is triggered when a node misses a certain threshold number of heartbeat messages from its parent for the topic. This threshold value can be set using this method.

Specified by:

setTreeRepairThreshold in interface IScribe

Parameters:

value - The value for the tree repair threshold.

getTreeRepairThreshold

public int getTreeRepairThreshold()

Gets the tree repair threshold value.

Returns:

the tree repair threshold value

isReady

public boolean isReady()

Returns true is the Scribe substrate is ready. The Scribe substrate is ready when underlying PastryNode is ready.

registerApp

public void registerApp(IScribeApp app)

Registers the IScribeApp to the Scribe substrate. This is required for the IScribeApp to get the upcall scribeIsReady() notifying it that the underlying Scribe substrate is ready. The IScribeApp should call create, join, leave, multicast only after they are notified that the underlying Scribe substrate is ready, otherwise these operations fail.

Specified by:

registerApp in interface IScribe

registerScribeObserver

public void registerScribeObserver(IScribeObserver app)

Registers the application that implements the IScribeObserver interface. Whenever a topic is implicitly created, (i.e. a node receives SUBSCRIBE message for a topic it hasnt subscribed to, thereby creating a topic data structure at local node) these registered applications would be notified.

Specified by:

registerScribeObserver in interface IScribe

Parameters:

app - The application interested in getting notified whenever a topic is implicitly created.

notifyReady

public void notifyReady()

This is called when the underlying pastry node is ready. With regard to Scribe, we schedule the periodic tree maintenance activities when the pastry network is a Distributed network instead of a simulate network.

Overrides:

notifyReady in class PastryAppl

scheduleHB

public void scheduleHB()

Sends heartbeat messages to this local node's children for all the topics on this local scribe node. This method should be invoked periodically by the driver with the same frequency in all nodes. In addition to initiating sending of heartbeat messages from this local node, this method also implicitly notifies the local node that it should expect a heartbeat message from its parents for all the topics on this local node. So, if it fails to receive a threshold value of such heartbeat messages from any parent for a particular topic, a tree repair event is triggered for that topic.

Specified by:

scheduleHB in interface IScribe

isRoot

public boolean isRoot(NodeId topicId)

Returns true if the local node is currently the root(the node that is closest to the topicId) of the topic.

Returns:

true if the local node is currently the root for the topic.

create

public boolean create(NodeId topicId,
                      Credentials cred)

Creates a group/topic if the credentials are valid. Nodes must then join this group in order to get information multicast to it.

Specified by:

create in interface IScribe

Parameters:

cred - The credentials of the entity creating the group

topicId - The ID of the group to be created

Returns:

true if the operation was successful, false if the operation failed because the underlying Scribe substrate was not ready.

join

public boolean join(NodeId topicId,
                    IScribeApp subscriber,
                    Credentials cred)

Joins a multicast group/topic. When a node joins a multicast group, it receives all messages multicast to that group.

Specified by:

join in interface IScribe

Parameters:

subscriber - The application joining the group

cred - The credentials of the entity joining the group

topicId - The ID of the group to join to

Returns:

true if the operation was successful, false if the operation failed because the underlying Scribe substrate was not ready.

join

public boolean join(NodeId topicId,
                    IScribeApp subscriber,
                    Credentials cred,
                    java.io.Serializable obj)

Joins a multicast group/topic. When a node joins a multicast group, it receives all messages multicast to that group. An application can specify additional data to be sent with the SUBSCRIBE message.

Specified by:

join in interface IScribe

Parameters:

cred - The credentials of the entity joining the group

subscriber - The application joining the group

obj - Additional data to be passed with the SUBSCRIBE msg, specific to an application. Should be serializable.

topicId - The ID of the group to join to

Returns:

true if the operation was successful, false if the operation failed because the underlying Scribe substrate was not ready.

leave

public boolean leave(NodeId topicId,
                     IScribeApp subscriber,
                     Credentials cred)

Leaving a multicast group/topic. After a node leaves a group, it will no longer receive messages multicast to this group.

Specified by:

leave in interface IScribe

Parameters:

cred - The credentials of the entity leaving the group

subscriber - The application leaving the group. Use null if not directly called by an application.

topicId - The ID of the group to leave

Returns:

true if the operation was successful, false if the operation failed because the underlying Scribe substrate was not ready.

multicast

public boolean multicast(NodeId topicId,
                         java.io.Serializable obj,
                         Credentials cred)

Multicast information to a group/topic. Data will be delivered to All nodes that have joined the group. The message will trickle from the root of the multicast tree for the group DOWN the tree, with each node sending this message to its children for the group.

Specified by:

multicast in interface IScribe

Parameters:

cred - The credentials of the entity multicasting to the group

obj - The information that is to be multicast. This should be serializable.

topicId - The ID of the group to multicast.

Returns:

true if the operation was successful, false if the operation failed because the underlying Scribe substrate was not ready.

anycast

public boolean anycast(NodeId groupID,
                       java.io.Serializable obj,
                       Credentials cred)

Anycast to a group/topic. Data will be delivered to 'ANY' one node which has joined the group. The handling of anycast message is left to the application. Default implementation of anycast message implements DFS of the tree, looking for nodes in the tree which can satisfy the request of the anycast message.

Specified by:

anycast in interface IScribe

Parameters:

groupID - The ID of the group to anycast.

obj - The information that is to be included in anycast message. This should be serializable.

cred - The credentials of the entity anycasting to the group.

Returns:

true if the operation was successful, false if the operation failed because the underlying Scribe substrate was not ready.

anycast

public boolean anycast(NodeId groupID,
                       MessageAnycast anycastMessage,
                       Credentials cred)

An application can create sub-classes of MessageAnycast type of messages and write their own handling functions so as to do some application-specific predicate searching. Also, by this mean they can modify the default DFS satisfying their own conditions and predicates.

Specified by:

anycast in interface IScribe

Parameters:

groupID - The ID of the group to anycast.

anycastMessage - The anycast message created by application specific to its needs, can decide how the message is going to be routed in the anycast tree, how the message is going to be handled and so on.

cred - The credentials of the entity anycasting to the group.

Returns:

true if the operation was successful, false if the operation failed because the underlying Scribe substrate was not ready.

generateTopicId

public NodeId generateTopicId(java.lang.String topicName)

Generate a unique id for the topic, which will determine its rendezvous point. This is a helper method. Applications can use their own methods to generate TopicId.

Specified by:

generateTopicId in interface IScribe

Parameters:

topicName - the name of the topic (unique to the local node)

Returns:

the Topic id.

getAddress

public Address getAddress()

Returns the address of this client.

Overrides:

getAddress in class PastryAppl

Returns:

the address.

getCredentials

public Credentials getCredentials()

Returns the credentials of this client.

Specified by:

getCredentials in class PastryAppl

Returns:

the credentials.

messageForAppl

public void messageForAppl(Message msg)

Called by pastry when a message arrives for this client.

Specified by:

messageForAppl in class PastryAppl

Parameters:

msg - the message that is arriving.

enrouteMessage

public boolean enrouteMessage(Message msg,
                              Id target,
                              NodeId nextHop,
                              SendOptions opt)

Called by pastry when a message is enroute and is passing through this node.

Overrides:

enrouteMessage in class PastryAppl

Parameters:

msg - the message that is passing through.

target - the final destination node id.

nextHop - the next hop for the message.

opt - the send options the message was sent with.

Returns:

true if the message should be routed, false if the message should be cancelled.

leafSetChange

public void leafSetChange(NodeHandle nh,
                          boolean wasAdded)

Called by pastry when the leaf set changes.

Overrides:

leafSetChange in class PastryAppl

Parameters:

nh - the handle of the node that entered or left the leafset.

wasAdded - true if the node was added, false if it was removed.

getNodeHandle

public NodeHandle getNodeHandle()

Returns the handle of the local node on which this Scribe application resides.

Overrides:

getNodeHandle in class PastryAppl

Returns:

the node handle.

getSendOptions

public SendOptions getSendOptions()

Returns the send options in the Scribe system.

Returns:

the send options.

getSecurityManager

public IScribeSecurityManager getSecurityManager()

Returns the security manager from the Scribe node.

Returns:

the security manager.

makeSubscribeMessage

public ScribeMessage makeSubscribeMessage(NodeId tid,
                                          Credentials c)

Makes a subscribe message using the current Pastry node as the source.

Parameters:

tid - the topic id the message refers to.

c - the credentials that will be associated with the message

Returns:

the ScribeMessage.

makeUnsubscribeMessage

public ScribeMessage makeUnsubscribeMessage(NodeId tid,
                                            Credentials c)

Makes an unsubscribe message using the current Pastry node as the source.

Parameters:

tid - the topic id the message reffers to.

c - the credentials that will be associated with the message

Returns:

the ScribeMessage.

makeCreateMessage

public ScribeMessage makeCreateMessage(NodeId tid,
                                       Credentials c)

Makes a create message using the current Pastry node as the source.

Parameters:

tid - the topic id the message reffers to.

c - the credentials that will be associated with the message

Returns:

the ScribeMessage.

makePublishMessage

public ScribeMessage makePublishMessage(NodeId tid,
                                        Credentials c)

Makes a publish message using the current Pastry node as the source.

Parameters:

tid - the topic id the message reffers to.

c - the credentials that will be associated with the message

Returns:

the ScribeMessage.

makeAnycastMessage

public ScribeMessage makeAnycastMessage(NodeId tid,
                                        Credentials c)

Makes a anycast message using the current Pastry node as the source.

Parameters:

tid - the topic id the message reffers to.

c - the credentials that will be associated with the message

Returns:

the ScribeMessage.

makeHeartBeatMessage

public ScribeMessage makeHeartBeatMessage(Credentials c)

Makes a heart-beat message using the current Pastry node as the source.

Parameters:

c - the credentials that will be associated with the message

Returns:

the ScribeMessage.

makeAckOnSubscribeMessage

public ScribeMessage makeAckOnSubscribeMessage(NodeId tid,
                                               Credentials c)

Makes a AckOnSubscribe message using the current Pastry node as the source.

Parameters:

tid - the topic id the message reffers to.

c - the credentials that will be associated with the message

Returns:

the ScribeMessage.

makeAckOnSubscribeMessage

public ScribeMessage makeAckOnSubscribeMessage(NodeId tid,
                                               Credentials c,
                                               java.io.Serializable data)

Makes a AckOnSubscribe message using the current Pastry node as the source. Also takes in a serializable data.

Parameters:

tid - the topic id the message reffers to.

c - the credentials that will be associated with the message

data - the data to be shipped along the message

Returns:

the ScribeMessage.

makeRequestToParentMessage

public ScribeMessage makeRequestToParentMessage(Credentials c)

Makes a RequestToParent message using the current Pastry node as the source.

Parameters:

c - the credentials that will be associated with the message

Returns:

the ScribeMessage.

makeReplyFromParentMessage

public ScribeMessage makeReplyFromParentMessage(Credentials c)

Makes a ReplyFromParent message using the current Pastry node as the source.

Parameters:

c - the credentials that will be associated with the message

Returns:

the ScribeMessage.

makeScribeMaintenanceMessage

public ScribeMessage makeScribeMaintenanceMessage(Credentials c)

Makes a ScribeMaintenance message using the current Pastry node as the source.

Parameters:

c - the credentials that will be associated with the message

Returns:

the ScribeMessage.

getTopic

public Topic getTopic(NodeId topicId)

Returns the topic object associated with topicId.

Parameters:

topicId - the topic id

Returns:

the Topic associated with the topicId

getTopics

public java.util.Vector getTopics()

Method to access the list of topics this scribe is responsible for. Returns a vector of topics residing on this node.

getDistinctChildren

public java.util.Vector getDistinctChildren()

Gets the Vector of distinct children of this local node in multicast tree of all topics.

Returns:

Vector of distinct children

addChildForTopic

public void addChildForTopic(NodeHandle child,
                             NodeId topicId)

Adds a child for a topic into the distinctChildrenTable. If this child already exists, then we add this topic into its corresponding list of topics for which it is our child. Otherwise, we create a new entry into the hashtable.

Parameters:

child - The NodeHandle of Child

topicId - The topicId for the topic for which we are adding this child

removeChildForTopic

public void removeChildForTopic(NodeHandle child,
                                NodeId topicId)

Removes a child for a topic from the distinctChildrenTable. See if we already have it as a child for some other topic , if yes then remove this topicId from the list of topics for which this node is our child. Otherwise, we remove the entry from the hashtable since the list of topics becomes empty.

Parameters:

child - The NodeHandle of Child

topicId - The topicId for the topic for which we are removing this child

getTopicsForChild

public java.util.Vector getTopicsForChild(NodeHandle child)

Gets the vector of topicIds for which given node is a child.

Parameters:

child - The NodeHandle of child node.

Returns:

Vector of topicIds for which this node is a child.

getDistinctParents

public java.util.Vector getDistinctParents()

Gets the Vector of distinct parent of this local node in the multicast trees of all topics.

Returns:

Vector of distinct parents

removeParentForTopic

public void removeParentForTopic(NodeHandle parent,
                                 NodeId topicId)

Removes a parent for a topic fromthe distinctParentTable. See if we already have it as a parent for some other topic , if yes then remove this topicId from the list of topics for which this node is our parent. Otherwise, we remove the entry from the hashtable since the list of topics becomes empty.

Parameters:

parent - The NodeHandle of Parent

topicId - The topicId for the topic for which we are removing this parent

addParentForTopic

public void addParentForTopic(NodeHandle parent,
                              NodeId topicId)

Adds a parent for a topic into the distinctParentTable. If this child already exists, then we add this topic into its corresponding list of topics for which it is our parent. Otherwise, we create a new entry into the hashtable.

Parameters:

topicId - The topicId for the topic for which we are adding this parent

getTopicsForParent

public java.util.Vector getTopicsForParent(NodeHandle parent)

Gets the vector of topicIds for which given node is our parent.

Parameters:

parent - The NodeHandle of parent node.

Returns:

Vector of topicIds for which this node is our parent.

getFingerprintForParentTopics

public NodeId getFingerprintForParentTopics(NodeHandle parent)

getFingerprintForChildTopics

public NodeId getFingerprintForChildTopics(NodeHandle child)

addChildToAlreadySentHBNodes

public boolean addChildToAlreadySentHBNodes(NodeId childId)

Adds a child to the list of nodes to which this node has already send a implicit HeartBeat message in the form of Publish message in this Heartbeat period.

Parameters:

childId - NodeId of child.

Returns:

true if child already exists else false

getAlreadySentHBNodes

public java.util.Vector getAlreadySentHBNodes()

Gets the vector of nodes to which an implicit HeartBeat in form of Publish message was sent in last HeartBeat period.

Returns:

Vector of child nodes to which a publish message was sent in last HeartBeat period.

clearAlreadySentHBNodes

public void clearAlreadySentHBNodes()

The set is cleared so that the set contains only those nodes to which Publish message was sent in last HeartBeat period.

getLocalHandle

public NodeHandle getLocalHandle()

getParent

public NodeHandle getParent(NodeId topicId)

Returns the local node's parent in this topic's multicast tree.

Specified by:

getParent in interface IScribe

Parameters:

topicId - The id of the topic.

Returns:

the parent node.

setParent

public boolean setParent(NodeHandle parent,
                         NodeId topicId)

Sets the parent for the topic specified by topicId.

Specified by:

setParent in interface IScribe

Parameters:

parent - The new parent for the topic

topicId - the topic for which this parent is set

Returns:

true if operation was successful, false otherwise

getChildren

public java.util.Vector getChildren(NodeId topicId)

This returns the most current view of the children in this topic's multicast subtree rooted at the local node.

Specified by:

getChildren in interface IScribe

Parameters:

topicId - The id of the topic.

Returns:

vector of children nodehandles.

childObserver

public void childObserver(NodeHandle child,
                          NodeId topicId,
                          boolean wasAdded,
                          ScribeMessage pmsg,
                          java.io.Serializable data)

Whenever the children table for a topic is changed, ( a child is added or removed), this method is invoked to do some handling. If child was added : if ackOnSubscribe is set, then send AckOnSubscribe mesg to new child If child was dropped: if there are no applications as well as no child for this topic, then local topic object is removed and an unsubscribe message is send.

Parameters:

child - the child which was added/removed

topicId - the topic for which child was added/removed

wasAdded - true if child was added, false if child was removed.

data - the data to be sent with the AckOnSubscribe Message

numChildren

public int numChildren(NodeId topicId)

This returns the number of children in this topic's multicast subtree rooted at the local node.

Specified by:

numChildren in interface IScribe

Parameters:

topicId - The id of the topic.

Returns:

the number of children of local node for this topic if topic exists, else -1

addChild

public boolean addChild(NodeHandle child,
                        NodeId topicId)

Add a node as a child in the children table for a topic.

Specified by:

addChild in interface IScribe

Parameters:

child - the child to be added

topicId - the topic for which this child is added

Returns:

true if operation was successful, false otherwise

addChild

public boolean addChild(NodeHandle child,
                        NodeId topicId,
                        java.io.Serializable data)

Add a node as a child in the children table for a topic. Also, takes in a serializable data object to be propogated along with the ACK to the child.

Parameters:

child - the child to be added

topicId - the topic for which this child is added

data - Serializable data

Returns:

true if operation was successful, false otherwise

removeChild

public boolean removeChild(NodeHandle child,
                           NodeId topicId)

Removes a node as a child from the children table for a topic.

Specified by:

removeChild in interface IScribe

Parameters:

child - the child to be removed

topicId - the topic for which this child is removed

Returns:

true if operation was successful, false otherwise

notifyScribeObservers

public void notifyScribeObservers(NodeId topicId)

Notifies the applications on top of scribe who are interested in knowing the events of implicit topic creation.

Parameters:

topicId - topicId for which Topic data structure is created (implicitly)

getPastryNode

public PastryNode getPastryNode()

Returns the pastryNode for this application.

Returns:

the pastryNode