src/org/apache/xalan/lib/sql/ConnectionPool.java

/*
 * The Apache Software License, Version 1.1
 *
 *
 * Copyright (c) 1999 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
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 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Xalan" and "Apache Software Foundation" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written
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 *
 * 5. Products derived from this software may not be called "Apache",
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 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
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 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation and was
 * originally based on software copyright (c) 1999, Lotus
 * Development Corporation., http://www.lotus.com.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

package org.apache.xalan.lib.sql;

import java.util.Properties;
import java.lang.String;
import java.sql.Connection;
import java.sql.SQLException;
import java.sql.*;

/**
 * An interface used to build wrapper classes around existing
 * Connection Pool libraries.
 * Title:     ConnectionPool<p>
 * @author John Gentilin
 * @version 1.0
 */
public interface ConnectionPool
{

  /**
   * Determine if a Connection Pool has been disabled. If a Connection pool
   * is disabled, then it will only manage connections that are in use.
   * @return
   */
  public boolean isEnabled( );

  /**
   * The Driver and URL are the only required parmeters.
   * @param d
   * @return
   */
  public void setDriver( String d );

  /**
   * @param url
   * @return
   */
  public void setURL( String url );

  /**
   * Start downsizeing the pool, this usally happens right after the
   * pool has been marked as Inactive and we are removing connections
   * that are not currently inuse.
   * @return
   */
  public void freeUnused( );


  /**
   * Provide an indicator to the PoolManager when the Pool can be removed
   * from the Pool Table.
   * @return
   */
  public boolean hasActiveConnections( );

  /**
   * The rest of the protocol parameters can eiter be passed in as
   * just Username and Password or as a property collection. If the
   * property collection is used, then the sperate username and password
   * may be ignored, it is up to the wrapper implementation to handle
   * the situation. If the connection information changes while after the
   * pool has been established, the wrapper implementation should ignore
   * the change and throw an error.
   * @param p
   * @return
   */
  public void setPassword( String p );

  /**
   * @param u
   * @return
   */
  public void setUser( String u );


  /**
   * Set tne minimum number of connections that are to be maintained in the
   * pool.
   * @param n
   * @return
   */
  public void setMinConnections( int n );

  /**
   * Test to see if the connection info is valid to make a real connection
   * to the database. This method may cause the pool to be crated and filled
   * with min connections.
   * @return
   */
  public boolean testConnection( );

  /**
   * Retrive a database connection from the pool
   * @return
   * @throws SQLException
   */
  public Connection getConnection( )throws SQLException;

   /**
   * Return a connection to the pool, the connection may be closed if the
   * pool is inactive or has exceeded the max number of free connections
   * @param con
   * @return
   * @throws SQLException
   */
  public void releaseConnection( Connection con )throws SQLException;

   /**
   * Provide a mechinism to return a connection to the pool on Error.
   * A good default behaviour is to close this connection and build
   * a new one to replace it. Some JDBC impl's won't allow you to
   * reuse a connection after an error occurs.
   * @param con
   * @return
   * @throws SQLException
   */
  public void releaseConnectionOnError( Connection con )throws SQLException;


  /**
   * The Pool can be Enabled and Disabled. Disabling the pool
   * closes all the outstanding Unused connections and any new
   * connections will be closed upon release.
   * @param flag Control the Connection Pool. If it is enabled
   * then Connections will actuall be held around. If disabled
   * then all unused connections will be instantly closed and as
   * connections are released they are closed and removed from the pool.
   * @return
   */
  public void setPoolEnabled( final boolean flag );

  /**
   * Used to pass in extra configuration options during the
   * database connect phase.
   */
  public void setProtocol(Properties p);


}