prajna.structure.stream

Class StreamSemanticAccessor<D>

java.lang.Object

prajna.structure.AbstractDataAccessor<DataRecord,DataRecord>

prajna.structure.accessor.RecordAccessor

prajna.structure.stream.StreamSemanticAccessor<D>

Type Parameters:

D - the data element which is handled by this stream accessor.

All Implemented Interfaces:

DataAccessor<DataRecord,DataRecord>, StreamingAccessor<DataRecord,DataRecord>

public abstract class StreamSemanticAccessor<D>
extends RecordAccessor
implements StreamingAccessor<DataRecord,DataRecord>

Abstract implementation of a SemanticAccessor for streaming data. This class provides a mechanism for storing and aging the data elements which stream into the accessor. The data element handled by this accessor should coincide with individual records and nodes in the various data structures.

Author:

Edward Swing

Constructor Summary

Constructors

Constructor and Description
StreamSemanticAccessor() Create a new StreamSemanticAccessor.

Method Summary

Methods

Modifier and Type	Method and Description
void	addDataStructureListener(DataStructureListener listener) Add a data structure listener to listen for events when a particular data structure changes.
protected abstract DataRecord	convertData(D data, DataTemplate template) Convert data from the data objects streaming into the accessor into a DataRecord matching the particular template.
protected void	fireChangeEvent(DataStructureEvent event) Fire a data structure event for any listeners which match the event.
int	getAgingTime() Get the length of time that a particular data element will be retained.
protected java.util.Set<java.lang.String>	matchStructures(prajna.structure.stream.StreamSemanticAccessor.ConvertRecord rec) Determine which structures a particular ConvertRecord matches.
void	receiveData(D data) Receive a data element.
protected java.util.Set<DataRecord>	retrieveRecords(DataTemplate template) Retrieve a set of data records for a particular DataTemplate.
void	setAgingTime(int time) Set the length of time that a particular data element will be retained.

Methods inherited from class prajna.structure.accessor.RecordAccessor

addFieldHandler, addToGraph, addToTree, createReferenceNode, extendGraph, extendTree, getDataset, getFieldHandler, getGraph, getGrid, getMaxRecords, getReasoner, getStructureReasoners, getTree, setMaxRecords, setReasoner, setReasoner

Methods inherited from class prajna.structure.AbstractDataAccessor

addStructure, addTemplate, getDatasetNames, getGraphNames, getGridNames, getSpec, getStructureType, getTemplate, getTemplateNames, getTreeNames, setConfig, setConfigFile, setConfigFile, setQuery

Methods inherited from class java.lang.Object

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

Methods inherited from interface prajna.structure.DataAccessor

extendGraph, extendTree, getDataset, getDatasetNames, getGraph, getGraphNames, getGrid, getGridNames, getStructureType, getTree, getTreeNames, setConfig, setInitParameters

Constructor Detail

StreamSemanticAccessor

public StreamSemanticAccessor()

Create a new StreamSemanticAccessor. This constructor starts the aging thread

Method Detail

addDataStructureListener

public void addDataStructureListener(DataStructureListener listener)

Add a data structure listener to listen for events when a particular data structure changes.

Specified by:

addDataStructureListener in interface StreamingAccessor<DataRecord,DataRecord>

Parameters:

listener - the DataStructureListener

convertData

protected abstract DataRecord convertData(D data,
                     DataTemplate template)

Convert data from the data objects streaming into the accessor into a DataRecord matching the particular template. This abstract method is used to transform the data objects when needed.

Parameters:

data - the source data element.

template - The data template specifying field mappings and descriptions

Returns:

The converted DataRecord

fireChangeEvent

protected void fireChangeEvent(DataStructureEvent event)

Fire a data structure event for any listeners which match the event.

Parameters:

event - the DataStructureEvent

getAgingTime

public int getAgingTime()

Get the length of time that a particular data element will be retained. If the value is less than 0, the data elements are not aged. The aging time is specified in seconds.

Specified by:

getAgingTime in interface StreamingAccessor<DataRecord,DataRecord>

Returns:

the aging time

matchStructures

protected java.util.Set<java.lang.String> matchStructures(prajna.structure.stream.StreamSemanticAccessor.ConvertRecord rec)

Determine which structures a particular ConvertRecord matches. This method can determine which data structures change as a result of adding, removing or changing a particular data element.

Parameters:

rec - the ConvertRecord for a changed data element

Returns:

the names of the structures which may change as a result of a change to the data element.

receiveData

public void receiveData(D data)

Receive a data element. This method checks whether a particular data element should be included in one of the observed data structures. If so, this method triggers DataStructureEvents for the appropriate data structure. It also stores the data element and indexes it according to time. This method should be called by the implementing class whenever a data element is received.

Parameters:

data - the data element received.

retrieveRecords

protected java.util.Set<DataRecord> retrieveRecords(DataTemplate template)

Retrieve a set of data records for a particular DataTemplate. This method is used by the default implementation of the various getStructure methods. The method should create the individual DataRecord objects.

Specified by:

retrieveRecords in class RecordAccessor

Parameters:

template - The data template specifying field mappings and descriptions

Returns:

the set of DataRecords for the template

setAgingTime

public void setAgingTime(int time)

Set the length of time that a particular data element will be retained. If the value is less than 0, the data elements are not aged. The aging time is specified in seconds. The default value is -1.

Specified by:

setAgingTime in interface StreamingAccessor<DataRecord,DataRecord>

Parameters:

time - the aging time