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package org.apache.cayenne.access;

import java.util.Collection;

import org.apache.cayenne.map.EntityResolver;
import org.apache.cayenne.query.Query;

/**
 * Defines methods used to run Cayenne queries.
 * 
 */
public interface QueryEngine {

    /**
     * Executes a list of queries wrapping them in its own transaction. Results of
     * execution are passed to {@link OperationObserver}object via its callback methods.
     * 
     * @since 1.1 The signature has changed from List to Collection.
     */
    void performQueries(
            Collection<Query> queries,
            OperationObserver resultConsumer);

    /**
     * Returns a resolver for this query engine that is capable of resolving between
     * classes, entity names, and obj/db entities
     */
    EntityResolver getEntityResolver();
}
