/**
 *
 *  Copyright 2005 The Apache Software Foundation or its licensors, as applicable.
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
package org.apache.tuscany.das.rdb;

import commonj.sdo.DataObject;

/**
 * An iterator-like interface to conveniently move through chunks of data. The
 * idea is that a Pager works with a read Command. The read command returns a
 * large amount of data and the client wants to work with chunks of it at a
 * time. So the Pager is created on the command and each call to next returns
 * the next chunk of data. This is done completely disconnected. No cursor is
 * maintained between calls to #next.
 * 
 * TODO - This is very preliminary. We need to look at this interface in the
 * context of disonnected scenarios such as a web app. The Pager instance will
 * probably be saved in session so it must be very light and cannot reference a
 * connection. Also, we probably need to define a factory or add a method to set
 * page size.
 * 
 * 
 */
public interface Pager {

	/**
	 * Get the next page of data
	 * 
	 * @return the next page of data
	 */
	public DataObject next();

	/**
	 * Get the page prior to the last page returned
	 * 
	 * @return the previous page
	 */
	public DataObject previous();

	/**
	 * Return a specific identified page.
	 * 
	 * @param page
	 *            The number of the page to return
	 * @return the indicated page
	 */
	public DataObject getPage(int page);

}