beehive.util

Class NodeData

java.lang.Object

beehive.util.NodeData

All Implemented Interfaces:

Externalizable, Serializable

public class NodeData
extends Object
implements Externalizable

The NodeData class provides the capability to query and update specific properties of a node without having to fetch the entire node from the StorageSystem. This serves as a means to reduce communication costs when subclasses of Node are complex and "heavy." This is achieved by having each NodeData maintaining the following information:

• node id -- The id of the node that this NodeData is associated with
• timestamp -- The timestamp at which this NodeData was constructed for validation purposes
• nodeClassId -- TODO describe this...
• properties -- A mapping from node property to a value. This mapping is used in one of two ways:
  1. Mapping the desired node properties to null to fetch the desired properties. The desired values are returned back as a NodeData object where the mapping (properties) is now a mapping from the desired properties to their actual values.
  2. Mapping the node properties you want to update to the desired value.

The NodeData class only supports primitive types and the String type.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
byte	nodeClassId
String	nodeId
Map<String,Object>	properties
long	TS

Constructor Summary

Constructors

Constructor and Description
NodeData()
NodeData(NodeData_thrift n, HashMap<Byte,Class> nodeClassMap) Constructs a Java NodeData representation of the Thrift NodeData representation
NodeData(NodeData n) Constructs a shallow copy of the NodeData that is passed in
NodeData(String nodeID, byte nodeClassId)
NodeData(String nodeId, long ts, byte nodeClassId)

Method Summary

Modifier and Type	Method and Description
void	addProperty(String property, Object value)
Vector<String>	getProperties()
Object	getProperty(String property)
void	readExternal(ObjectInput in)
String	toString()
void	writeExternal(ObjectOutput out)

Methods inherited from class java.lang.Object

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

Field Detail

nodeId

public String nodeId

TS

public long TS

nodeClassId

public byte nodeClassId

properties

public Map<String,Object> properties

Constructor Detail

NodeData

public NodeData()

NodeData

public NodeData(String nodeID,
                byte nodeClassId)

Parameters:

nodeID - The id of the node that this NodeData was constructed from.

nodeClassId - The id of the class of the node this NodeData was constructed from.

NodeData

public NodeData(String nodeId,
                long ts,
                byte nodeClassId)

Parameters:

nodeId - The id of the node that this NodeData was constructed from.

ts - The timestamp of this NodeData's creation

nodeClassId - The id of the class of the node this NodeData was constructed from.

NodeData

public NodeData(NodeData n)

Constructs a shallow copy of the NodeData that is passed in

Parameters:

n - The NodeData that is to be shallowly copied

NodeData

public NodeData(NodeData_thrift n,
                HashMap<Byte,Class> nodeClassMap)

Constructs a Java NodeData representation of the Thrift NodeData representation

Parameters:

n - The Thrift representation of a NodeData

nodeClassMap -

Method Detail

readExternal

public void readExternal(ObjectInput in)
                  throws IOException,
                         ClassNotFoundException

Specified by:

readExternal in interface Externalizable

Throws:

IOException

ClassNotFoundException

writeExternal

public void writeExternal(ObjectOutput out)
                   throws IOException

Specified by:

writeExternal in interface Externalizable

Throws:

IOException

addProperty

public void addProperty(String property,
                        Object value)

getProperty

public Object getProperty(String property)

getProperties

public Vector<String> getProperties()

toString

public String toString()

Overrides:

toString in class Object