Package com.luciad.ogc.csw.server

Class ALcdCSWFilterQueryHandler

java.lang.Object

com.luciad.ogc.csw.server.ALcdCSWFilterQueryHandler

All Implemented Interfaces:

ILcdCSWQueryHandler

public abstract class ALcdCSWFilterQueryHandler
extends Object
implements ILcdCSWQueryHandler

Abstract handler for OGC Filter based catalog record queries. It takes care of all data-independent functionality. The data-dependent functionality is to execute an OGC Filter query. The method should retrieve metadata from a data storage, such as a database or in-memory collection.

The simplest implementation of a filter query handler is backed by an in-memory collection of Dublin Core records. It can use TLcdOGCFilter.asPredicate(com.luciad.ogc.filter.evaluator.TLcdOGCFilterContext) and TLcdOGCSortBy.asComparator(com.luciad.ogc.filter.evaluator.TLcdOGCFilterContext) to filter and sort, and TLcdCSWRecordTransformationFactory to perform the needed record transformations.

Database backed implementations should translate the filter, pagination, and sorting constraints into equivalent database query statements, such as SQL or QueryDSL.

Since:

2017.0

Constructor Summary

Constructors

Constructor	Description
ALcdCSWFilterQueryHandler()

Method Summary

Modifier and Type	Method	Description
protected abstract Object	executeFilter(TLcdOGCFilter filter, TLcdCSWQuery aQuery, TLcdCSWRecordType aOutputFormat, long aMaxRecords, long aStartPosition, ILcdRequest aRequest)	Returns the result of applying the given OGC filter expression to the underlying data set(s) corresponding to the types referred to in the query.
final Object	executeQuery(TLcdCSWQuery aQuery, long aMaxRecords, long aStartPosition, TLcdCSWRecordType aOutputFormat, ILcdRequest aRequest)	Executes the given query and returns its result.
boolean	validateQuery(TLcdCSWQuery aQuery, ILcdRequest aRequest)	Returns true if the given query is a valid query, meaning that is is syntactically correct and uses the right property and type names.

Methods inherited from class java.lang.Object

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

Constructor Details

ALcdCSWFilterQueryHandler

public ALcdCSWFilterQueryHandler()

Method Details

validateQuery

public boolean validateQuery(TLcdCSWQuery aQuery,
 ILcdRequest aRequest)
                      throws TLcdCSWServiceException

Description copied from interface: ILcdCSWQueryHandler

Returns true if the given query is a valid query, meaning that is is syntactically correct and uses the right property and type names.

Specified by:

validateQuery in interface ILcdCSWQueryHandler

Parameters:

aQuery - the query to validate

aRequest - the request triggering the query

Returns:

true if the given query is a valid query, false otherwise.

Throws:

TLcdCSWServiceException - can be thrown to provide more meaningful error messages

executeQuery

public final Object executeQuery(TLcdCSWQuery aQuery,
 long aMaxRecords,
 long aStartPosition,
 TLcdCSWRecordType aOutputFormat,
 ILcdRequest aRequest)
                          throws TLcdCSWServiceException

Description copied from interface: ILcdCSWQueryHandler

Executes the given query and returns its result.

Specified by:

executeQuery in interface ILcdCSWQueryHandler

Parameters:

aQuery - A query to execute

aMaxRecords - the maximum number of records to return

aStartPosition - The start position to return queries for

aOutputFormat - the output format for the record

aRequest - the request triggering the query

Returns:

a result set corresponding to the output format and output schema (for example, TLcdCSWSearchResults with Dublin Core or ISO metadata, or an atom feed

Throws:

TLcdCSWServiceException - if the query could not be executed

executeFilter

protected abstract Object executeFilter(TLcdOGCFilter filter,
 TLcdCSWQuery aQuery,
 TLcdCSWRecordType aOutputFormat,
 long aMaxRecords,
 long aStartPosition,
 ILcdRequest aRequest)
                                 throws TLcdCSWServiceException

Returns the result of applying the given OGC filter expression to the underlying data set(s) corresponding to the types referred to in the query. The implementation is responsible for pagination, sorting, and transforming the results into the request output type.

Parameters:

filter - An OGC Filter. Can be null, in which case no filter should be applied.

aQuery - additional query properties of the corresponding GetRecords or GetRecordByID request

aOutputFormat - the requested record output format

aMaxRecords - The maximum amount of records to return

aStartPosition - a start position: a positive non-zero value included in the query.

aRequest - the request triggering the query

Returns:

a result set corresponding to the output format and output schema (usually a TLcdCSWSearchResults object with Dubline Core or ISO metadata, or an atom feed)

Throws:

TLcdCSWServiceException - if the query could not be executed