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com.hp.hpl.jena.ontology.event
Class OntEventManager  

java.lang.Object
  com.hp.hpl.jena.rdf.listeners.StatementListener
      com.hp.hpl.jena.ontology.event.OntEventManager

All Implemented Interfaces:

com.hp.hpl.jena.rdf.model.ModelChangedListener

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public class OntEventManager

extends com.hp.hpl.jena.rdf.listeners.StatementListener

An adapter that translates RDF model-level changes into higher level changes that are appropriate to ontology users. The large number of specific events that the ontology model can produce makes the traditional Java style of listener interface impractical. Instead, this event manager allows the user to register handlers, based on command pattern, against specific event types.

For example, to register a handler for the declaration of an ontology class:

 OntModel m = ...
 OntEventManager em = m.getEventManager();
 em.addHandler( OntEvents.CLASS_DECLARATION,
                new OntEventHandler() {
                    public void action( Resource ev, boolean added,
                                        RDFNode arg0, RDFNode arg1 ) {
                        OntClass c = (OntClass) arg0;
                        if (added) {
                            // class c added to model
                        }
                        else {
                            // class c removed from model
                        }
                    }
                }
              );
 

This listener acts as an adapter for graph events (i.e. adding and removing triples), converting them to higher-level ontology events. This is non-trivial, because Jena currently doesn't have a means of batching changes so that only consistent graph states are seen. For efficiency in non event-using models, this listener is only attached as a statement listener to the underlying graph when the first ontology event listener is added.

Version:

CVS $Id: OntEventManager.java,v 1.6 2005/02/21 12:06:02 andy_seaborne Exp $

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Nested Class Summary
private static interface	OntEventManager.ProfileAccessor           Simple wrapper to allow us to dynamically extract elements from the profile

 

Field Summary
private  OntEventHandler	m_defaultHandler           Default event handler
private  java.util.Map	m_handlers           Map from event types to handlers
private  java.util.Map	m_predicateToEventType           Map from predicate to event type
private  java.util.Map	m_rdfTypeToEventType           Map from rdf:type to event type
private static java.lang.Object[][]	s_predicateInit           Initialisation data for the predicate to event type table
private static java.lang.Object[][]	s_rdfTypeInit           Initialisation data for the rdf:type to event type table

 

Constructor Summary

OntEventManager(com.hp.hpl.jena.ontology.OntModel m)           Construct an ontology event manager for the given ontology model.

 

Method Summary
void	addDefaultHandler(OntEventHandler handler)           Add the given handler as the default event handler, which will be invoked if no other handler is applicable to a given event.
void	addedStatement(com.hp.hpl.jena.rdf.model.Statement s)           Handle the addition of a statement to the model.
void	addHandler(com.hp.hpl.jena.rdf.model.Resource event, OntEventHandler handler)           Add the given handler as the handler for the given event type, replacing any existing handler.
void	addHandlers(java.lang.Object[][] handlers)           Add the given handlers as the handler for the given event types, replacing any existing handlers.
OntEventHandler	getDefaultHandler()           Answer the default event handler, or null if not defined
OntEventHandler	getHandler(com.hp.hpl.jena.rdf.model.Resource event)           Answer the event handler for the given event, or null if not defined
boolean	hasHandler(com.hp.hpl.jena.rdf.model.Resource event)           Answer true if there is a defined handler for the given event type.
private  void	initialiseTable(java.util.Map map, com.hp.hpl.jena.ontology.Profile p, java.lang.Object[][] source)           Initialise the given map from static initialisation data.
java.util.Iterator	listRegisteredEvents()           Answer an iterator over the events that are registered in this event manager.
private  void	processStatement(com.hp.hpl.jena.rdf.model.Statement s, boolean added)           Process an incoming added or removed statement to raise the appropriate ontology event.
void	raise(com.hp.hpl.jena.rdf.model.Resource event, boolean added, com.hp.hpl.jena.rdf.model.Model source, com.hp.hpl.jena.rdf.model.RDFNode arg0, com.hp.hpl.jena.rdf.model.RDFNode arg1, com.hp.hpl.jena.rdf.model.RDFNode arg2)           Raise an event to be handled by the attached event handlers.
void	removedStatement(com.hp.hpl.jena.rdf.model.Statement s)           Handle the removal of a statement to the model
void	removeHandler(com.hp.hpl.jena.rdf.model.Resource event)           Remove any existing handler for the given event type.

 

Methods inherited from class com.hp.hpl.jena.rdf.listeners.StatementListener

addedStatements, addedStatements, addedStatements, addedStatements, notifyEvent, removedStatements, removedStatements, removedStatements, removedStatements

 

Methods inherited from class java.lang.Object

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

 

Field Detail

s_rdfTypeInit

private static java.lang.Object[][] s_rdfTypeInit

Initialisation data for the rdf:type to event type table

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s_predicateInit

private static java.lang.Object[][] s_predicateInit

Initialisation data for the predicate to event type table

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m_handlers

private java.util.Map m_handlers

Map from event types to handlers

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m_rdfTypeToEventType

private java.util.Map m_rdfTypeToEventType

Map from rdf:type to event type

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m_predicateToEventType

private java.util.Map m_predicateToEventType

Map from predicate to event type

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m_defaultHandler

private OntEventHandler m_defaultHandler

Default event handler

Constructor Detail

OntEventManager

public OntEventManager(com.hp.hpl.jena.ontology.OntModel m)

Construct an ontology event manager for the given ontology model. This involves registering adapters for the ontology events corresponding to the language profile of the given model.

Method Detail

addedStatement

public void addedStatement(com.hp.hpl.jena.rdf.model.Statement s)

Handle the addition of a statement to the model.

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removedStatement

public void removedStatement(com.hp.hpl.jena.rdf.model.Statement s)

Handle the removal of a statement to the model

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raise

public void raise(com.hp.hpl.jena.rdf.model.Resource event,
                  boolean added,
                  com.hp.hpl.jena.rdf.model.Model source,
                  com.hp.hpl.jena.rdf.model.RDFNode arg0,
                  com.hp.hpl.jena.rdf.model.RDFNode arg1,
                  com.hp.hpl.jena.rdf.model.RDFNode arg2)

Raise an event to be handled by the attached event handlers.

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addDefaultHandler

public void addDefaultHandler(OntEventHandler handler)

Add the given handler as the default event handler, which will be invoked if no other handler is applicable to a given event.

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addHandler

public void addHandler(com.hp.hpl.jena.rdf.model.Resource event,
                       OntEventHandler handler)

Add the given handler as the handler for the given event type, replacing any existing handler.

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addHandlers

public void addHandlers(java.lang.Object[][] handlers)

Add the given handlers as the handler for the given event types, replacing any existing handlers.

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getHandler

public OntEventHandler getHandler(com.hp.hpl.jena.rdf.model.Resource event)

Answer the event handler for the given event, or null if not defined

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getDefaultHandler

public OntEventHandler getDefaultHandler()

Answer the default event handler, or null if not defined

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removeHandler

public void removeHandler(com.hp.hpl.jena.rdf.model.Resource event)

Remove any existing handler for the given event type.

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hasHandler

public boolean hasHandler(com.hp.hpl.jena.rdf.model.Resource event)

Answer true if there is a defined handler for the given event type.

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listRegisteredEvents

public java.util.Iterator listRegisteredEvents()

Answer an iterator over the events that are registered in this event manager.

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initialiseTable

private void initialiseTable(java.util.Map map,
                             com.hp.hpl.jena.ontology.Profile p,
                             java.lang.Object[][] source)

Initialise the given map from static initialisation data. This will be a mapping that allows us to determine the correct ontology event type for a given triple.

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processStatement

private void processStatement(com.hp.hpl.jena.rdf.model.Statement s,
                              boolean added)

Process an incoming added or removed statement to raise the appropriate ontology event.

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