nesstar.rdf
Class RDFDB

java.lang.Object
  nesstar.rdf.RDFDB

Direct Known Subclasses:

NetDB

public class RDFDB
extends Object

A repository for RDF objects. Objects can come from an RDF file or be created as Java objects and then loaded in the DB. They have: getType()= the mapped RDFClass getTypeID()=to the original RDF class or = null (if created as an object) Could they be mapped to an RDF class different from the original one? Possibly, if the mapping changes. Mappings: InstanceMapping: All instance of the RDF Class are mapped to instances of the Java Class - Reversible ClassMapping: All RDF classes equal to the RDFClass or subclasses of it are mapped to instances of the given Java Class ex: http://www.nesstar.org/Method -> javaClass=nesstar.rdf.NSMethod java -> RDF. Map them back to RDFS_CLASS DefaultMapping: All RDF entities not mapped otherwise are mapped to instances of the given Java Class. java -> RDF ?? Map back to the original class? The objects pointers (such as to their RDF class) cannot be resolved immediatly as the pointed objects might be declared after the current object. The class object could also not be explicitly declared (is it a problem?). It's probably acceptable that some references might be left dangling.

Created:

26 April 2002

Field Summary

static String	FASTER_NS param
static String	NESSTAR_NS param
static String	NS_BOOLEAN param
static String	NS_COMPLETE a flag to indicate that the object has been returned with all the properties known to the server
static String	NS_DOMAIN param
static String	NS_DOUBLE param
static String	NS_FILE param
static String	NS_FLOAT param
static String	NS_IN param
static String	NS_INTEGER param
static String	NS_LABEL param
static String	NS_METHOD param
static String	NS_METHOD_OBJ param
static String	NS_OBJECT
static String	NS_OPTIONAL param
static String	NS_OUT param
static String	NS_PARAMETER param
static String	NS_PATH param
static String	NS_READONLY param
static String	NS_STRING param
static String	NS_VOID param
static String	NS_ZIPPED_STRING param
static String	RDF_BAG param
static String	RDF_NS param
static String	RDFS_CLASS param
static String	RDFS_DOMAIN param
static String	RDFS_NS param
static String	RDFS_PROPERTY param
static String	RDFS_RANGE param
static String	RDFS_RESOURCE param
static String	RDFS_SUBCLASS param
static String	TRUE param

Constructor Summary

RDFDB()
Constructor for the RDFDB object

Method Summary

void	addClassMapping(String rdfClassName, String javaClassName) Adds a feature to the ClassMapping attribute of the RDFDB object
void	addDefaultMapping(String javaClassName) Adds a feature to the DefaultMapping attribute of the RDFDB object
void	addMapping(String rdfClassName, String javaClassName) Adds a feature to the Mapping attribute of the RDFDB object
void	addRDFSClassMapping(String javaClassName) Adds a feature to the RDFSClassMapping attribute of the RDFDB object
static HashSet	collectObjects(Object rootObject, Filter filter) returns a HashSet of Objects derived from the root object using the Filter object which describes how those objects should be derived
static String	defaultWrap(String s) Method
RDFDB	getContext() Gets the context attribute of the RDFDB object
static String	getLocalObjURL() Gets the localObjURL attribute of the RDFDB class
URL	getUniqueID()
Iterator	iterator() Returns a Vector containing all the known objects of a given class.
Vector	load(File file)
Vector	load(File file, String baseURI) Method
void	load(RDFObject obj) RDFObj can be created: - from an RDF entity - directly , ex: new RDFBag(db) This is called any time an RDFObject is created as part of its initialisation
Vector	load(Reader rdf) Method
Vector	load(String rdf) Method
Vector	load(String rdf, String baseURI) Method
RDFObj	lookup(String id) Resolve RDF URL to an object in this database or in the context DB
RDFObj	lookup(URL url) Both the IDs stored in the database and the ones being looked for can be either in numeric or symbolic form.
void	makeSureTypeIsSet(RDFObject obj) Method
void	markAllAsComplete() Mark all objects in the database as being 'complete'
static void	markAllAsStale() Mark all objects in the all databases as being 'stale'
static void	markAsStale(String serverIP) Mark all objects from the indicated server held in the database as being 'stale'
String	nestedToRDF(RDFObj obj) Method
String	nToRDF(Collection objs) Convert a Vector of objects to their RDF representation
String	nToRDF(Collection objs, RDFProperty prop) Method
String	nToRDF(Iterator objs) Method
String	nToRDF(Iterator objs, RDFProperty prop) Method
static Vector	objsToStringIds(Vector objs) Method
String	printMappings() Method
String	printObjs() Description of the Method
RDFObj	recreate(URL url) Load from the net the object with the given url.
RDFObj	reload(String url) Load from the net the object with the given url.
RDFObject	reload(URL url) Load from the net the object with the given url.
void	remove(RDFObj obj) Remove obj from DB (if present)
void	remove(URL url) Remove obj from DB (if present)
RDFObj	retrieve(String url) If the required object is alread in the DB return it otherwise retrieve it from the network.
RDFObj	retrieve(URL url) If the required object is alread in the DB return it otherwise retrieve it from the network.
RDFObj	retrieveWithClassChain(URL url) If the required object is in the cache returns it otherwise retrieve it from the network.
Vector	search(Class cls)
Vector	search(Iterator objs, RDFProperty property, Object value)
Vector	search(RDFClass cls)
Vector	search(RDFClass cls, RDFProperty property, Object value)
Vector	search(RDFClass cls, RDFProperty property, Object value, RDFProperty select)
Vector	searchAllOfType(String type)
Object	searchOne(Class cls)
RDFObject	searchUniqueOfType(String type) Method
void	setContext(RDFDB context) Sets the context attribute of the RDFDB object
static void	setLocalObjURL(String url) Sets the localObjURL attribute of the RDFDB class
Vector	stringIdsToObjs(String ids) Method
Vector	stringIdsToObjs(Vector ids) Method
String	toRDF() Convert full database to RDF
String	toRDF(RDFObj obj) Convert the object to its rdf representation
String	toRDF(RDFObj obj, RDFProperty prop, Object value) Convert an object and a given property to RDF
String	toRDF(RDFProperty prop, Object value) Method
String	toRDFCasted(RDFObj obj, RDFClass type) Method
String	toRDFNoWrap(RDFObj obj, RDFProperty prop, Object value) Convert an object and a given property to RDF
String	toRDFObj(RDFObj obj, Vector printed, boolean linked) Convert the object (and all its the linked objects if linked==true) to their rdf representation
String	toRDFObj(RDFObj obj, Vector printed, boolean linked, RDFClass rdftype) Method
String	toRDFWrapped(RDFObj obj) Method
RDFObj	unique(Vector r) Method
String	wrap(String s)

Methods inherited from class java.lang.Object

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

Field Detail

TRUE

public static final String TRUE

param

See Also:

Constant Field Values

RDF_NS

public static final String RDF_NS

param

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Constant Field Values

RDF_BAG

public static final String RDF_BAG

param

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Constant Field Values

RDFS_NS

public static final String RDFS_NS

param

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Constant Field Values

RDFS_CLASS

public static final String RDFS_CLASS

param

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Constant Field Values

RDFS_RESOURCE

public static final String RDFS_RESOURCE

param

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Constant Field Values

RDFS_PROPERTY

public static final String RDFS_PROPERTY

param

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Constant Field Values

RDFS_DOMAIN

public static final String RDFS_DOMAIN

param

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Constant Field Values

RDFS_RANGE

public static final String RDFS_RANGE

param

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Constant Field Values

RDFS_SUBCLASS

public static final String RDFS_SUBCLASS

param

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Constant Field Values

NESSTAR_NS

public static final String NESSTAR_NS

param

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Constant Field Values

FASTER_NS

public static final String FASTER_NS

param

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Constant Field Values

NS_OPTIONAL

public static final String NS_OPTIONAL

param

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Constant Field Values

NS_COMPLETE

public static final String NS_COMPLETE

a flag to indicate that the object has been returned with all the properties known to the server

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Constant Field Values

NS_READONLY

public static final String NS_READONLY

param

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Constant Field Values

NS_LABEL

public static final String NS_LABEL

param

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Constant Field Values

NS_PATH

public static final String NS_PATH

param

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Constant Field Values

NS_DOMAIN

public static final String NS_DOMAIN

param

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Constant Field Values

NS_IN

public static final String NS_IN

param

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Constant Field Values

NS_OUT

public static final String NS_OUT

param

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Constant Field Values

NS_METHOD

public static final String NS_METHOD

param

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Constant Field Values

NS_METHOD_OBJ

public static final String NS_METHOD_OBJ

param

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NS_PARAMETER

public static final String NS_PARAMETER

param

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Constant Field Values

NS_VOID

public static final String NS_VOID

param

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NS_OBJECT

public static final String NS_OBJECT

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Constant Field Values

NS_STRING

public static final String NS_STRING

param

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Constant Field Values

NS_INTEGER

public static final String NS_INTEGER

param

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Constant Field Values

NS_FLOAT

public static final String NS_FLOAT

param

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Constant Field Values

NS_DOUBLE

public static final String NS_DOUBLE

param

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Constant Field Values

NS_BOOLEAN

public static final String NS_BOOLEAN

param

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Constant Field Values

NS_ZIPPED_STRING

public static final String NS_ZIPPED_STRING

param

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Constant Field Values

NS_FILE

public static final String NS_FILE

param

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Constant Field Values

Constructor Detail

RDFDB

public RDFDB()
      throws Exception

Constructor for the RDFDB object

Throws:

Exception

Method Detail

setLocalObjURL

public static void setLocalObjURL(String url)

Sets the localObjURL attribute of the RDFDB class

Parameters:

url - The new localObjURL value

setContext

public void setContext(RDFDB context)

Sets the context attribute of the RDFDB object

Parameters:

context - The new context value

getLocalObjURL

public static String getLocalObjURL()

Gets the localObjURL attribute of the RDFDB class

Returns:

The localObjURL value

getUniqueID

public URL getUniqueID()

Returns:

a unique URL

getContext

public RDFDB getContext()

Gets the context attribute of the RDFDB object

Returns:

The context value

wrap

public String wrap(String s)

Parameters:

s -

Returns:

a full RDF document.

defaultWrap

public static String defaultWrap(String s)

Method

Parameters:

s -

Returns:

printObjs

public String printObjs()

Description of the Method

printMappings

public String printMappings()

Method

Returns:

addDefaultMapping

public void addDefaultMapping(String javaClassName)
                       throws ClassNotFoundException

Adds a feature to the DefaultMapping attribute of the RDFDB object

Parameters:

javaClassName - The feature to be added to the DefaultMapping attribute

Throws:

ClassNotFoundException

addMapping

public void addMapping(String rdfClassName,
                       String javaClassName)
                throws Exception

Adds a feature to the Mapping attribute of the RDFDB object

Parameters:

rdfClassName - The feature to be added to the Mapping attribute

javaClassName - The feature to be added to the Mapping attribute

Throws:

Exception

addRDFSClassMapping

public void addRDFSClassMapping(String javaClassName)
                         throws Exception

Adds a feature to the RDFSClassMapping attribute of the RDFDB object

Parameters:

javaClassName - The feature to be added to the RDFSClassMapping attribute

Throws:

Exception

addClassMapping

public void addClassMapping(String rdfClassName,
                            String javaClassName)
                     throws Exception

Adds a feature to the ClassMapping attribute of the RDFDB object

Parameters:

rdfClassName - The feature to be added to the ClassMapping attribute

javaClassName - The feature to be added to the ClassMapping attribute

Throws:

Exception

recreate

public RDFObj recreate(URL url)
                throws Exception

Load from the net the object with the given url. If an object with the same URL already exist in the database it's removed first.

Parameters:

url - the url of the object to recreate

Returns:

the object.

Throws:

Exception

reload

public RDFObject reload(URL url)
                 throws Exception

Load from the net the object with the given url. If the object already exist in the database it won't be recreated.

Parameters:

url - the url of the object to reload

Returns:

the object.

Throws:

Exception

reload

public RDFObj reload(String url)
              throws Exception

Load from the net the object with the given url.

Parameters:

url - the url of the object to reload

Returns:

the object.

Throws:

Exception

retrieve

public RDFObj retrieve(URL url)
                throws Exception

If the required object is alread in the DB return it otherwise retrieve it from the network.

Parameters:

url -

Returns:

Throws:

Exception

retrieve

public RDFObj retrieve(String url)
                throws Exception

If the required object is alread in the DB return it otherwise retrieve it from the network.

Parameters:

url -

Returns:

Throws:

Exception

retrieveWithClassChain

public RDFObj retrieveWithClassChain(URL url)
                              throws Exception

If the required object is in the cache returns it otherwise retrieve it from the network.
Retrieve also all the object that represents the class of the object and its methods and properties.

Parameters:

url - the url of the object to retrieve

Returns:

the retrieved object.

Throws:

Exception

load

public Vector load(Reader rdf)
            throws Exception

Method

Parameters:

rdf -

Returns:

Throws:

Exception

load

public Vector load(String rdf)
            throws Exception

Method

Parameters:

rdf -

Returns:

Throws:

Exception

load

public Vector load(String rdf,
                   String baseURI)
            throws Exception

Method

Parameters:

rdf -

baseURI -

Throws:

Exception

load

public Vector load(File file)
            throws Exception

Parameters:

file -

Throws:

Exception

Bug:

this seems to always use the default character encoding.

load

public Vector load(File file,
                   String baseURI)
            throws Exception

Method

Parameters:

file -

baseURI -

Throws:

Exception

remove

public void remove(RDFObj obj)

Remove obj from DB (if present)

Parameters:

obj - the obj to remove

remove

public void remove(URL url)

Remove obj from DB (if present)

Parameters:

url - the url of the obj to remove

load

public void load(RDFObject obj)
          throws Exception

RDFObj can be created: - from an RDF entity - directly , ex: new RDFBag(db) This is called any time an RDFObject is created as part of its initialisation

Parameters:

obj -

Throws:

Exception

makeSureTypeIsSet

public void makeSureTypeIsSet(RDFObject obj)
                       throws Exception

Method

Parameters:

obj -

Throws:

Exception

toRDFObj

public String toRDFObj(RDFObj obj,
                       Vector printed,
                       boolean linked)
                throws Exception

Convert the object (and all its the linked objects if linked==true) to their rdf representation

Parameters:

obj -

printed -

linked -

Returns:

Throws:

Exception

toRDFObj

public String toRDFObj(RDFObj obj,
                       Vector printed,
                       boolean linked,
                       RDFClass rdftype)
                throws Exception

Method

Parameters:

obj -

printed -

linked -

rdftype -

Returns:

Throws:

Exception

toRDF

public String toRDF(RDFProperty prop,
                    Object value)
             throws Exception

Method

Parameters:

prop -

value -

Returns:

Throws:

Exception

toRDF

public String toRDF(RDFObj obj,
                    RDFProperty prop,
                    Object value)
             throws Exception

Convert an object and a given property to RDF

Parameters:

obj -

prop -

value -

Returns:

Throws:

Exception

toRDF

public String toRDF(RDFObj obj)
             throws Exception

Convert the object to its rdf representation

Parameters:

obj -

Returns:

Throws:

Exception

Bug:

Hard properties are always mapped back to the default namespace

toRDFCasted

public String toRDFCasted(RDFObj obj,
                          RDFClass type)
                   throws Exception

Method

Parameters:

obj -

type -

Returns:

Throws:

Exception

toRDFWrapped

public String toRDFWrapped(RDFObj obj)
                    throws Exception

Method

Parameters:

obj -

Returns:

Throws:

Exception

nestedToRDF

public String nestedToRDF(RDFObj obj)
                   throws Exception

Method

Parameters:

obj -

Returns:

Throws:

Exception

nToRDF

public String nToRDF(Iterator objs)
              throws Exception

Method

Parameters:

objs -

Returns:

Throws:

Exception

toRDF

public String toRDF()
             throws Exception

Convert full database to RDF

Returns:

Throws:

Exception

nToRDF

public String nToRDF(Collection objs)
              throws Exception

Convert a Vector of objects to their RDF representation

Parameters:

objs -

Returns:

Throws:

Exception

nToRDF

public String nToRDF(Collection objs,
                     RDFProperty prop)
              throws Exception

Method

Parameters:

objs -

prop -

Returns:

Throws:

Exception

nToRDF

public String nToRDF(Iterator objs,
                     RDFProperty prop)
              throws Exception

Method

Parameters:

objs -

prop -

Returns:

Throws:

Exception

toRDFNoWrap

public String toRDFNoWrap(RDFObj obj,
                          RDFProperty prop,
                          Object value)
                   throws Exception

Convert an object and a given property to RDF

Parameters:

obj -

prop -

value -

Returns:

Throws:

Exception

lookup

public RDFObj lookup(String id)
              throws Exception

Resolve RDF URL to an object in this database or in the context DB

Parameters:

id -

Returns:

Throws:

Exception

lookup

public RDFObj lookup(URL url)
              throws Exception

Both the IDs stored in the database and the ones being looked for can be either in numeric or symbolic form. Assuming that the URL.equals() take care of equivalences among:

• lower/upper case hosts
• a host nicknames
• 127.0.0.1 and localhost

every host has a single simbolic name (??) and possibly multiple IPs. The set of equivalent names can be derived as getHostName() + all getAllByName

Parameters:

url -

Returns:

Throws:

Exception

searchOne

public Object searchOne(Class cls)
                 throws Exception

Parameters:

cls -

Returns:

an object of class 'cls'

Throws:

Exception

search

public Vector search(Class cls)
              throws Exception

Parameters:

cls -

Returns:

all objects of class cls

Throws:

Exception

search

public Vector search(RDFClass cls)
              throws Exception

Parameters:

cls -

Returns:

all objects of RDFClass cls

Throws:

Exception

searchAllOfType

public Vector searchAllOfType(String type)
                       throws Exception

Parameters:

type -

Returns:

all objects of RDFClass cls

Throws:

Exception

searchUniqueOfType

public RDFObject searchUniqueOfType(String type)
                             throws Exception

Method

Parameters:

type -

Returns:

Throws:

Exception

search

public Vector search(RDFClass cls,
                     RDFProperty property,
                     Object value)
              throws Exception

Parameters:

cls -

property -

value -

Returns:

all objects of RDFClass cls and whose property property is equal to value

Throws:

Exception

search

public Vector search(Iterator objs,
                     RDFProperty property,
                     Object value)
              throws Exception

Parameters:

objs -

property -

value -

Returns:

all objects whose property property is equal to value

Throws:

Exception

unique

public RDFObj unique(Vector r)
              throws Exception

Method

Parameters:

r -

Returns:

Throws:

Exception

search

public Vector search(RDFClass cls,
                     RDFProperty property,
                     Object value,
                     RDFProperty select)
              throws Exception

Parameters:

cls -

property -

value -

select -

Returns:

all objects pointed by the select property of RDFClass cls and whose property property is equal to value

Throws:

Exception

objsToStringIds

public static Vector objsToStringIds(Vector objs)

Method

Parameters:

objs -

Returns:

stringIdsToObjs

public Vector stringIdsToObjs(Vector ids)
                       throws Exception

Method

Parameters:

ids -

Returns:

Throws:

Exception

stringIdsToObjs

public Vector stringIdsToObjs(String ids)
                       throws Exception

Method

Parameters:

ids -

Returns:

Throws:

Exception

iterator

public Iterator iterator()

Returns a Vector containing all the known objects of a given class.

Returns:

a Vector containing all the objects of the reqavailable Servers

markAllAsComplete

public void markAllAsComplete()

Mark all objects in the database as being 'complete'

markAllAsStale

public static void markAllAsStale()

Mark all objects in the all databases as being 'stale'

markAsStale

public static void markAsStale(String serverIP)

Mark all objects from the indicated server held in the database as being 'stale'

Parameters:

serverIP - the IP of the server for whom entries should be marked as stale, e.g. nesport4.essex.ac.uk

Bug:

this might mark as stale more stuff than intended (e.g. objects from other servers on the same machine)

collectObjects

public static HashSet collectObjects(Object rootObject,
                                     Filter filter)
                              throws Exception

returns a HashSet of Objects derived from the root object using the Filter object which describes how those objects should be derived

Parameters:

rootObject - the rootObject from which to derive the Set of objects

filter - the object describing how to derive sub-objects

Throws:

Exception