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/*
* Query.java
*
* Created on February 25, 2000
*/
package com.sun.jdo.api.persistence.support;
import java.io.Serializable;
import java.util.Collection;
import java.util.Map;
/** The Query interface allows applications to obtain persistent instances
* from the data store.
*
* The @link PersistenceManager is the factory for Query instances. There
* may be many Query instances associated with a PersistenceManager. Multiple
* queries might be executed simultaneously by different threads, but the
* implementation might choose to execute them serially. In either case, the
* implementation must be thread safe.
*
* <P>There are three required elements in a Query:
* the class of the candidate instances,
* the candidate collection of instances, and the filter.
*
* <P>There are optional elements: parameter declarations, variable
* declarations, import statements, and an ordering specification.
*
* @author Craig Russell
* @version 0.1
*/
public interface Query extends java.io.Serializable
{
/** Set the class of the candidate instances of the query.
* <P>The class is a PersistenceCapable class which specifies the class
* of the candidates of the query. Elements of the candidate collection
* that are of the specified class are filtered before being
* put into the result Collection.
* @param cls the Class of the candidate instances.
*/
void setClass(Class cls);
/** Set the candidate Collection to query.
* @param pcs the Candidate collection.
*/
void setCandidates(Collection pcs);
/** Set the filter for the query.
*
* The filter is a Java-like boolean expression used to select elements of the
* candidate Collection.
* @param filter the query filter.
*/
void setFilter(String filter);
/** Set the import statements to be used to identify the package name of
* variables or parameters.
* @param imports import statements separated by semicolons.
*/
void declareImports(String imports);
/** Set the parameter list for query execution.
*
* The types and names of execution parameters are specified as a String
* separated by commas, similar to formal method declarations.
*
* @param parameters the list of parameters separated by commas.
*/
void declareParameters(String parameters);
/** Declare the unbound variables to be used in the query.
*
* @param variables the variables separated by semicolons.
*/
void declareVariables(String variables);
/** Bind the ordering declarations to the query instance.
* The ordering consists of one or more ordering declarations separated by commas.
* Each ordering declaration is the name of the field in the name scope of the
* candidate class followed by one of the following words: ascending or descending.
*
* @param ordering the ordering declarations separated by comma.
*/
void setOrdering (String ordering);
/**
* Set the result of the query.
* <p>
* The query result is an optional keyword distinct followed by a Java
* expression, which tells what values are to be returned by the JDO query.
* If the result is not specified, then it defaults to "distinct this",
* which has the effect of returning the elements of the candidates
* that match the filter.
*/
void setResult(String result);
/** Sets the prefetchEnabled option.
*
* The prefetchEnabled option specifies whether prefetch of relationship
* fields should be enabled for this query. The prefetch is enabled by
* default if such fields are part of DFG. A user needs to explicitely
* disable prefetch for any particular query if the related instances
* will not be used in this transaction.
*
* @param prefetchEnabled the setting of the prefetchEnabled option.
*/
void setPrefetchEnabled(boolean prefetchEnabled);
/** Set the ignoreCache option.
*
* The ignoreCache option setting specifies whether the query should execute
* entirely in the back end, instead of in the cache.
* @param ignoreCache the setting of the ignoreCache option.
*/
void setIgnoreCache(boolean ignoreCache);
/** Get the ignoreCache option setting.
* @return the ignoreCache option setting.
* @see #setIgnoreCache
*/
boolean getIgnoreCache();
/** Verify the elements of the query and provide a hint to the query to
* prepare and optimize an execution plan.
*/
void compile();
/** Execute the query and return the filtered Collection.
* @return the filtered Collection.
* @see #executeWithArray (Object[] parameters)
*/
Object execute();
/** Execute the query and return the filtered Collection.
* @return the filtered Collection.
* @see #executeWithArray (Object[] parameters)
* @param p1 the value of the first parameter declared.
*/
Object execute(Object p1);
/** Execute the query and return the filtered Collection.
* @return the filtered Collection.
* @see #executeWithArray (Object[] parameters)
* @param p1 the value of the first parameter declared.
* @param p2 the value of the second parameter declared.
*/
Object execute(Object p1, Object p2);
/** Execute the query and return the filtered Collection.
* @return the filtered Collection.
* @see #executeWithArray (Object[] parameters)
* @param p1 the value of the first parameter declared.
* @param p2 the value of the second parameter declared.
* @param p3 the value of the third parameter declared.
*/
Object execute(Object p1, Object p2, Object p3);
/** Execute the query and return the filtered Collection.
* @return the filtered Collection.
* @see #executeWithArray (Object[] parameters)
* @param parameters the Map containing all of the parameters.
*/
Object executeWithMap (Map parameters);
/** Execute the query and return the filtered Collection.
*
* <P>The execution of the query obtains the values of the parameters and
* matches them against the declared parameters in order. The type of
* the declared parameters must match the type of the passed parameters,
* except that the passed parameters might need to be unwrapped to get
* their primitive values.
*
* <P>The filter, import, declared parameters, declared variables, and
* ordering statements are verified for consistency.
*
* <P>Each element in the candidate Collection is examined to see that it
* is assignment compatible to the Class of the query. It is then evaluated
* by the boolean expression of the filter. The element passes the filter
* if there exist unique values for all variables for which the filter
* expression evaluates to true.
* @return the filtered Collection.
* @param parameters the Object array with all of the parameters.
*/
Object executeWithArray (Object[] parameters);
/** Get the PersistenceManager associated with this Query.
*
* <P>If this Query has no PersistenceManager return null.
* @return the PersistenceManager associated with this Query.
*/
PersistenceManager getPersistenceManager();
}