prajna.structure.accessor

Class RecordAccessor

java.lang.Object

prajna.structure.AbstractDataAccessor<DataRecord,DataRecord>

prajna.structure.accessor.RecordAccessor

All Implemented Interfaces:

DataAccessor<DataRecord,DataRecord>

Direct Known Subclasses:

CommonMLAccessor, DataCoordinator, DbpediaAccessor, DelimitedAccessor, FusionAccessor, JdbcAccessor, RecordAccessorClient, SolrAccessor, StreamSemanticAccessor, StructureReader, XmlDataAccessor

public abstract class RecordAccessor
extends AbstractDataAccessor<DataRecord,DataRecord>

Simple utility class which extends the AbstractDataAccessor which specifies that the node and edge classes for the accessor are DataRecord objects.

Author:

Edward Swing

Constructor Summary

Constructors

Constructor and Description
RecordAccessor()

Method Summary

Methods

Modifier and Type	Method and Description
void	addFieldHandler(java.lang.String fieldName, FieldHandler handler) Add a field handler for a particular field.
protected void	addToGraph(Graph<DataRecord,DataRecord> graph, GraphSpec spec) Add a set of records to the graph provided.
protected Tree<DataRecord>	addToTree(Tree<DataRecord> tree, TreeSpec spec) Add a set of records to the tree provided.
protected DataRecord	createReferenceNode(DataRecord referrer, java.lang.String name, FieldDesc<?> desc) Derive a data record for inclusion in a graph, tree, or other structure based upon a referring node.
boolean	extendGraph(java.lang.String graphName, Graph<DataRecord,DataRecord> graph, DataRecord node) Extend the given graph around the specified node.
boolean	extendTree(java.lang.String treeName, Tree<DataRecord> tree, DataRecord node) Extend the given tree around the specified node.
java.util.Set<DataRecord>	getDataset(java.lang.String datasetName) Retrieve the dataset from the underlying data source.
FieldHandler	getFieldHandler(java.lang.String fieldName) Get the field handler associated with the specified field
Graph<DataRecord,DataRecord>	getGraph(java.lang.String graphName) Retrieve the graph from the underlying data source.
Grid<DataRecord>	getGrid(java.lang.String gridName) Retrieve the grid from the underlying data source.
int	getMaxRecords() Get the maximum number of records returned by this accessor on any particular query.
RecordReasoner	getReasoner(DataTemplate template) Get the reasoner for the specified template for this accessor
java.util.Set<RecordReasoner>	getStructureReasoners(java.lang.String dataName) Get any reasoners which apply to the named data structure.
Tree<DataRecord>	getTree(java.lang.String treeName) Retrieve the tree from the underlying data source.
protected abstract java.util.Set<DataRecord>	retrieveRecords(DataTemplate template) Retrieve a set of data records for a particular DataTemplate.
void	setMaxRecords(int recCnt) Set the maximum number of records returned by this accessor on any particular query.
void	setReasoner(DataTemplate template, RecordReasoner reasoner) Set the reasoner for the template.
void	setReasoner(java.lang.String templateName, RecordReasoner reasoner) Set the reasoner for the template.

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

setInitParameters

Constructor Detail

RecordAccessor

public RecordAccessor()

Method Detail

addFieldHandler

public void addFieldHandler(java.lang.String fieldName,
                   FieldHandler handler)

Add a field handler for a particular field. The field handler can be used to perform more complex handling of a data field. The FieldHandler.handleField() method is invoked when a new value is added to the named data field.

Parameters:

fieldName - the data field within the DataRecord

handler - the field handler

addToGraph

protected final void addToGraph(Graph<DataRecord,DataRecord> graph,
              GraphSpec spec)

Add a set of records to the graph provided. This method iterates over the set of templates in the given graph specification, and creates new nodes and edges as needed. It retrieves records based upon the template, relying on the current state of the SemanticAccessor to provide the correct records.

Parameters:

graph - the current graph

spec - the current Graph specification

addToTree

protected final Tree<DataRecord> addToTree(Tree<DataRecord> tree,
                         TreeSpec spec)

Add a set of records to the tree provided. This method iterates over the set of templates in the given tree specification, and creates new child nodes as needed. It retrieves records based upon the template, relying on the current state of the SemanticAccessor to provide the correct records.

Parameters:

tree - the current tree

spec - the current tree specification

Returns:

the new root of the tree.

createReferenceNode

protected DataRecord createReferenceNode(DataRecord referrer,
                             java.lang.String name,
                             FieldDesc<?> desc)

Derive a data record for inclusion in a graph, tree, or other structure based upon a referring node. This method is used when a data structure contains a reference to a record which is not available. For instance, this method is called when a graph contains an edge which refers to a node which is not in the current set of graph nodes, and cannot be retrieved from the underlying data source.

The default implementation simply creates an empty DataRecord with the provided name.

Parameters:

referrer - the data record containing the reference to the node

name - The name for the new Data Record.

desc - The field descriptor for the field containing the reference.

Returns:

A data record with the given name and a navigation link.

extendGraph

public boolean extendGraph(java.lang.String graphName,
                  Graph<DataRecord,DataRecord> graph,
                  DataRecord node)

Extend the given graph around the specified node. The default implementation simply returns false. SemanticAccessors which can extend the graph should override this method.

Parameters:

graphName - The name of the graph

graph - The graph to extend

node - The node to use as an extension point.

Returns:

true if more data was added to the graph, false otherwise.

extendTree

public boolean extendTree(java.lang.String treeName,
                 Tree<DataRecord> tree,
                 DataRecord node)

Extend the given tree around the specified node. This method adds any children which are not already part of the tree. The default implementation simply returns false. SemanticAccessors which can extend the graph should override this method.

Parameters:

treeName - The name of the graph

tree - The graph to extend

node - The node to use as an extension point.

Returns:

true if more data was added to the tree, false otherwise.

getDataset

public java.util.Set<DataRecord> getDataset(java.lang.String datasetName)

Retrieve the dataset from the underlying data source. If the datasetName is empty or null, and there is only one dataset defined, that dataset will be used by default.

Parameters:

datasetName - the name of the dataset

Returns:

the dataset

getFieldHandler

public FieldHandler getFieldHandler(java.lang.String fieldName)

Get the field handler associated with the specified field

Parameters:

fieldName - the name of the field

Returns:

the field handler for the field, or null if there is no handler defined

getGraph

public Graph<DataRecord,DataRecord> getGraph(java.lang.String graphName)

Retrieve the graph from the underlying data source. If the graphName is empty or null, and there is only one graph defined, that graph will be used by default.

Parameters:

graphName - the name of the graph

Returns:

the graph

getGrid

public Grid<DataRecord> getGrid(java.lang.String gridName)

Retrieve the grid from the underlying data source. If the gridName is empty or null, and there is only one grid defined, that grid will be used by default.

Parameters:

gridName - the name of the grid

Returns:

the grid

getMaxRecords

public int getMaxRecords()

Get the maximum number of records returned by this accessor on any particular query.

Returns:

the number of records returned

getReasoner

public RecordReasoner getReasoner(DataTemplate template)

Get the reasoner for the specified template for this accessor

Parameters:

template - the data template

Returns:

the reasoner for the template

getStructureReasoners

public java.util.Set<RecordReasoner> getStructureReasoners(java.lang.String dataName)

Get any reasoners which apply to the named data structure. This method never returns null, but will return an empty set if no reasoners match

Parameters:

dataName - the name of the data structure

Returns:

the set of reasoners that apply to the structure.

getTree

public Tree<DataRecord> getTree(java.lang.String treeName)

Retrieve the tree from the underlying data source. If the treeName is empty or null, and there is only one tree defined, that tree will be used by default.

Parameters:

treeName - the name of the tree

Returns:

the tree

retrieveRecords

protected abstract 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.

Parameters:

template - The data template specifying field mappings and descriptions

Returns:

the set of DataRecords for the template

setMaxRecords

public void setMaxRecords(int recCnt)

Set the maximum number of records returned by this accessor on any particular query. Implementations may ignore this parameter when creating the various data structures.

Parameters:

recCnt - the number of records returned

setReasoner

public void setReasoner(DataTemplate template,
               RecordReasoner reasoner)

Set the reasoner for the template. If set, the reasoner is applied to all data records after they are created by the retrieveRecords method for the specified template.

Parameters:

template - the data template

reasoner - the reasoner to set

setReasoner

public void setReasoner(java.lang.String templateName,
               RecordReasoner reasoner)

Set the reasoner for the template. If set, the reasoner is applied to all data records after they are created by the retrieveRecords method for the specified template.

Parameters:

templateName - the data template name

reasoner - the reasoner to set