uk.ac.bbk.dcs.automed.qproc.reformulate
Class AtomicViewMap

java.lang.Object
  uk.ac.bbk.dcs.automed.qproc.reformulate.AtomicViewMap

public class AtomicViewMap
extends java.lang.Object

This class creates atomic views from the Automed Transformations. These views are binary views, i.e., they are created for a pair of source and target schemas. Views are direction sensitive, i.e., direction reflected in the view is from source schema to target schema. No processing is done to the extent query defined in the transformations. For each kind of transformation (ADD/EXTEND/DELETE/CONTRACT/RENAME/IDENTITY) there is a separate view map. Key for the view maps is a special key class called ViewKey which currently wraps a SchemeInfo class. But the key for the view map is the repository object id for each construct, hence the equals() method of ViewKey class has been redefined to compare only the repository object ids. This class also stores a cache of its own instances so that if asked for an existing set of views, it returns a reference to an existing instance of itself rather than recalculating the views again. This is to minimize the repository access which can be expensive.

Author:

Sandeep Mittal, Lucas Zamboulis

Field Summary

protected static java.util.Map	_instanceCache
protected static java.util.logging.Logger	_logger
protected java.lang.String	_name
protected QueryProcessorConfiguration	_qpc
protected Schema	_sourceSchema
protected Schema	_targetSchema
protected java.util.Map	_viewMap

Constructor Summary

protected

AtomicViewMap(Schema source, Schema target, QueryProcessorConfiguration qpc, int action) Constructs a new AtomicViewMap object for the input source and target schemas, then populates it.

Method Summary

static void	addToViewMap(SchemeInfo fromScheme, Cell targetQuery, java.util.Map map, int rangeSemantics)
protected void	buildViews() Traverses the pathway between the source and the target schema and populates the AtomicViewMap with views between a single source schema and a single target schema.
static java.lang.String	computeName(Schema source, Schema target, QueryProcessorConfiguration qpc, int action)
static AtomicViewMap	getInstance(Schema source, Schema target, QueryProcessorConfiguration qpc, int action)
java.lang.String	getName()
protected Cell	getQueryBasedOnRangeSemantics(java.lang.String suppliedQuery)
java.util.Map	getViewMap()
protected void	processTransformation(Schema fromSchema, Schema toSchema)
static void	showInstanceCache()
void	showViewMap()

Methods inherited from class java.lang.Object

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

Field Detail

_logger

protected static java.util.logging.Logger _logger

_instanceCache

protected static java.util.Map _instanceCache

_sourceSchema

protected Schema _sourceSchema

_targetSchema

protected Schema _targetSchema

_name

protected java.lang.String _name

_viewMap

protected java.util.Map _viewMap

_qpc

protected QueryProcessorConfiguration _qpc

Constructor Detail

AtomicViewMap

protected AtomicViewMap(Schema source,
                        Schema target,
                        QueryProcessorConfiguration qpc,
                        int action)
                 throws BuildViewException

Constructs a new AtomicViewMap object for the input source and target schemas, then populates it.

Parameters:

source - the input source schema

target - the input target schema

qpc - QueryProcessorConfiguration

Throws:

BuildViewException - if a problem is encountered during the population of the map

Method Detail

getViewMap

public java.util.Map getViewMap()

getInstance

public static AtomicViewMap getInstance(Schema source,
                                        Schema target,
                                        QueryProcessorConfiguration qpc,
                                        int action)
                                 throws BuildViewException

Parameters:

source - source schema

target - target schema

qpc - QueryProcessorConfiguration

Returns:

the AtomicViewMap specified by the input parameters - if one exists in the internal cache, a reference to it is returned, otherwise a new AtomicViewMap is created based on the input parameters

Throws:

BuildViewException

computeName

public static java.lang.String computeName(Schema source,
                                           Schema target,
                                           QueryProcessorConfiguration qpc,
                                           int action)

getName

public java.lang.String getName()

buildViews

protected void buildViews()
                   throws BuildViewException

Traverses the pathway between the source and the target schema and populates the AtomicViewMap with views between a single source schema and a single target schema.

Throws:

BuildViewException - if a problem is encountered during the population of the map

processTransformation

protected void processTransformation(Schema fromSchema,
                                     Schema toSchema)
                              throws BuildViewException

Throws:

BuildViewException

addToViewMap

public static void addToViewMap(SchemeInfo fromScheme,
                                Cell targetQuery,
                                java.util.Map map,
                                int rangeSemantics)
                         throws BuildViewException

Throws:

BuildViewException

getQueryBasedOnRangeSemantics

protected Cell getQueryBasedOnRangeSemantics(java.lang.String suppliedQuery)
                                      throws BuildViewException

Throws:

BuildViewException

showViewMap

public void showViewMap()

showInstanceCache

public static void showInstanceCache()