Query.java

package org.prevayler;
import java.util.Date;

/** 
 * Represents a query that can be executed on a Prevalent System.
 * @see org.prevayler.Prevayler#execute(Query)
 */
public interface Query {
  /** 
 * @param prevalentSystem The Prevalent System to be queried.
 * @param executionTime The "current" time.
 * @return The result of this Query.
 * @throws Exception Any Exception encountered by this Query.
 */
  public Object query(  Object prevalentSystem,  Date executionTime) throws Exception ;
}