/*
 * Created on Apr 28, 2005
 */
package javax.sql;

/**
 * An object that registers to be notified of events that occur on PreparedStatements
 * that are in the Statement pool.
 * <p>
 * The JDBC 3.0 specification added the maxStatements 
 * <code>ConnectionPooledDataSource</code> property to provide a standard mechanism for 
 * enabling the pooling of <code>PreparedStatements</code>
 * and to specify the size of the statement 
 * pool.  However, there was no way for a driver to notify an external 
 * statement pool when a <code>PreparedStatement</code> becomes invalid.  For some databases, a 
 * statement becomes invalid if a DDL operation is performed that affects the 
 * table.  For example an application may create a temporary table to do some work 
 * on the table and then destroy it.  It may later recreate the same table when 
 * it is needed again.  Some databases will invalidate any prepared statements 
 * that reference the temporary table when the table is dropped.
 * <p>
 * Similar to the methods defined in the <code>ConnectionEventListener</code> interface,
 * the driver will call the <code>StatementEventListener.statementErrorOccurred</code> 
 * method prior to throwing any exceptions when it detects a statement is invalid.
 * The driver will also call the <code>StatementEventListener.statementClosed</code> 
 * method when a <code>PreparedStatement</code> is closed.
 * <p>
 * Methods which allow a component to register a StatementEventListener with a 
 * <code>PooledConnection</code> have been added to the <code>PooledConnection</code> interface.
 * <p>
 * @since 1.6   
 */
public interface StatementEventListener extends java.util.EventListener{
  /**
   * The driver calls this method on all <code>StatementEventListener</code>s registered on the connection when it detects that a 
   * <code>PreparedStatement</code> is closed.
   *
   * @param event an event object describing the source of 
   * the event and that the <code>PreparedStatement</code> was closed. 
   * @since 1.6
   */
  void statementClosed(StatementEvent event);
	
	/**
	 * The driver calls this method on all <code>StatementEventListener</code>s
         * registered on the connection when it detects that a 
         * <code>PreparedStatement</code> is invalid. The driver calls this method 
         * just before it throws the <code>SQLException</code>, 
	 * contained in the given event, to the application.
	 * <p>
	 * @param event		an event object describing the source of the event, 
	 * 					the statement that is invalid and the exception the 
	 * 					driver is about to throw.  The source of the event is 
	 * 					the <code>PooledConnection</code> which the invalid <code>PreparedStatement</code>
         * is associated with.
	 * <p>
	 * @since 1.6
	 */
	void statementErrorOccurred(StatementEvent event);
		
}