org.gcube.common.core.informationsystem.client.impl
Class AbstractClient

java.lang.Object
  org.gcube.common.core.informationsystem.client.impl.AbstractClient

All Implemented Interfaces:

ISClient

public abstract class AbstractClient
extends Object
implements ISClient

Partial implementation of the ISClient. Subclasses implement specific methods to load implementations of standard {link ISQuery ISQueries}, and to execute those queries against the associated Information System.

Author:

Andrea Manzi (CNR), Fabio Simeoni (University of Strathclyde)

Nested Class Summary

Nested classes/interfaces inherited from interface org.gcube.common.core.informationsystem.client.ISClient

ISClient.ISMalformedQueryException, ISClient.ISMalformedResultException, ISClient.ISUnsupportedQueryException

Field Summary

protected static Map<String,String>	genericQueries Query implementations indexed by their implementation-defined name.
protected static Map<Class<? extends ISQuery<?>>,Class<? extends ISQuery<?>>>	implementationMap Query implementations indexed by their standard interface.
protected GCUBELog	logger Object logger.

Constructor Summary

AbstractClient()
Creates a new instance and loads query implementations if not previously done.

Method Summary

protected void	checkQuery(ISQuery<?> query) Invoked internally by execute(ISQuery, GCUBEScope) to check that a can be handled by the implementation and is in fact well-formed.
abstract <RESULT> List<RESULT>	execute(ISQuery<RESULT> query, GCUBEScope scope) Evaluates a query in a given scope and returns its results a local list.
abstract <RESULT> ISInputStream<RESULT>	executeByRef(ISQuery<RESULT> query, GCUBEScope scope) Implement to execute the query against the associated Information System in a given scope, and to return the locator of a resultset which contains the unparsed result serialisations.
<RESULT,QUERY extends ISQuery<RESULT>> QUERY	getQuery(Class<QUERY> clazz) Returns a query from the interface or class which defines its type.
protected Class<? extends AbstractQuery>	getQueryBaseClass() Returns the subtype of AbstractQuery used as the base class for query implementations.
protected abstract void	loadGenericQueries(Map<String,String> queryMap) Implement to load query implementations in a map which indexes by their standard interfaces.
protected abstract void	loadQueries(Map<Class<? extends ISQuery<?>>,Class<? extends ISQuery<?>>> queryMap) Implement to load query implementations in a map which indexes by their standard interfaces.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.gcube.common.core.informationsystem.client.ISClient

getQuery

Field Detail

logger

protected GCUBELog logger

Object logger.

implementationMap

protected static Map<Class<? extends ISQuery<?>>,Class<? extends ISQuery<?>>> implementationMap

Query implementations indexed by their standard interface.

genericQueries

protected static Map<String,String> genericQueries

Query implementations indexed by their implementation-defined name.

Constructor Detail

AbstractClient

public AbstractClient()

Creates a new instance and loads query implementations if not previously done.

Method Detail

loadQueries

protected abstract void loadQueries(Map<Class<? extends ISQuery<?>>,Class<? extends ISQuery<?>>> queryMap)

Implement to load query implementations in a map which indexes by their standard interfaces.

Parameters:

queryMap - the map.

loadGenericQueries

protected abstract void loadGenericQueries(Map<String,String> queryMap)

Implement to load query implementations in a map which indexes by their standard interfaces.

Parameters:

queryMap - the map.

getQuery

public <RESULT,QUERY extends ISQuery<RESULT>> QUERY getQuery(Class<QUERY> clazz)
                                       throws ISClient.ISUnsupportedQueryException,
                                              InstantiationException,
                                              IllegalAccessException

Returns a query from the interface or class which defines its type. The method is intended as a means to bind query interfaces to concrete implementations provided along with implementations of this interface.

Specified by:

getQuery in interface ISClient

Type Parameters:

RESULT - the type of the query results.

QUERY - the type of the query which produces results of type RESULT.

Parameters:

clazz - the query interface or class.

Returns:

the query.

Throws:

ISClient.ISUnsupportedQueryException

InstantiationException

IllegalAccessException

execute

public abstract <RESULT> List<RESULT> execute(ISQuery<RESULT> query,
                                              GCUBEScope scope)
                              throws ISClient.ISUnsupportedQueryException,
                                     ISException

Evaluates a query in a given scope and returns its results a local list.

Specified by:

execute in interface ISClient

Type Parameters:

RESULT - The type of the query results.

Parameters:

query - the query.

scope - the scope.

Returns:

the results.

Throws:

ISMalformedResultException

ISClient.ISMalformedQueryException - if the query is incorrectly formulated and cannot produce results.

ISException - if the evaluation could not be completed.

ISClient.ISUnsupportedQueryException

checkQuery

protected void checkQuery(ISQuery<?> query)
                   throws ISClient.ISMalformedQueryException,
                          ISClient.ISUnsupportedQueryException

Invoked internally by execute(ISQuery, GCUBEScope) to check that a can be handled by the implementation and is in fact well-formed. By default it checks that the query is an AbstractQuery and can thus be handled by subclasses. Subclasses may wish to override the method to enforce more specific checks.

Parameters:

query - the query.

Throws:

ISMalformedQueryException - if the query is not well-formed.

ISInvalidQueryException - if the query if of a type which cannot be processed by the implementatio

ISClient.ISMalformedQueryException

ISClient.ISUnsupportedQueryException

executeByRef

public abstract <RESULT> ISInputStream<RESULT> executeByRef(ISQuery<RESULT> query,
                                                            GCUBEScope scope)
                                            throws ISClient.ISMalformedQueryException,
                                                   ISClient.ISUnsupportedQueryException,
                                                   ISException

Implement to execute the query against the associated Information System in a given scope, and to return the locator of a resultset which contains the unparsed result serialisations. Note that, if required, the query can be safely cast to the subtype of AbstractQuery used by the implementation, as runtime checks. have already been performed.

Specified by:

executeByRef in interface ISClient

Type Parameters:

RESULT - The type of the query results.

Parameters:

query - the query.

scope - the scope.

Returns:

the ISInputStream.

Throws:

ISException - if the query could not be executed

ISClient.ISMalformedQueryException - if the query is incorrectly formulated and cannot produce results.

ISClient.ISUnsupportedQueryException

getQueryBaseClass

protected Class<? extends AbstractQuery> getQueryBaseClass()

Returns the subtype of AbstractQuery used as the base class for query implementations. This is used by the client to check the validity of queries once and where most convenient on behalf of its subclasses.

Returns:

the base class.