001/*
002 * Copyright 2006 - 2013
003 *     Stefan Balev     <stefan.balev@graphstream-project.org>
004 *     Julien Baudry    <julien.baudry@graphstream-project.org>
005 *     Antoine Dutot    <antoine.dutot@graphstream-project.org>
006 *     Yoann Pigné      <yoann.pigne@graphstream-project.org>
007 *     Guilhelm Savin   <guilhelm.savin@graphstream-project.org>
008 * 
009 * This file is part of GraphStream <http://graphstream-project.org>.
010 * 
011 * GraphStream is a library whose purpose is to handle static or dynamic
012 * graph, create them from scratch, file or any source and display them.
013 * 
014 * This program is free software distributed under the terms of two licenses, the
015 * CeCILL-C license that fits European law, and the GNU Lesser General Public
016 * License. You can  use, modify and/ or redistribute the software under the terms
017 * of the CeCILL-C license as circulated by CEA, CNRS and INRIA at the following
018 * URL <http://www.cecill.info> or under the terms of the GNU LGPL as published by
019 * the Free Software Foundation, either version 3 of the License, or (at your
020 * option) any later version.
021 * 
022 * This program is distributed in the hope that it will be useful, but WITHOUT ANY
023 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
024 * PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more details.
025 * 
026 * You should have received a copy of the GNU Lesser General Public License
027 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
028 * 
029 * The fact that you are presently reading this means that you have had
030 * knowledge of the CeCILL-C and LGPL licenses and that you accept their terms.
031 */
032package org.graphstream.stream.net;
033
034import java.io.IOException;
035import java.net.URL;
036
037import org.graphstream.stream.Source;
038
039/**
040 * Graph event input source from an URL.
041 */
042public interface URLSource extends Source {
043        /**
044         * Read the whole URL in one big non-interruptible operation.
045         * 
046         * @param url
047         *            The URL to fetch.
048         * @throws IOException
049         *             If an I/O error occurs while fetching the URL.
050         */
051        void fetchAll(URL url) throws IOException;
052
053        /**
054         * Begin fetching the URL stopping as soon as possible. Next graph events
055         * from the URL will be send by calling {@link #nextEvents()}. Once begin()
056         * as been called, you must finish the reading process using {@link #end()}.
057         * You cannot call begin() twice without having called {@link #end()} in
058         * between.
059         * 
060         * @param url
061         *            The URL to fetch.
062         * @throws IOException
063         *             If an I/O error occurs while reading.
064         */
065        void begin(URL url) throws IOException;
066
067        /**
068         * Try to process one graph event, or as few as possible, if more must be
069         * read at once. For this method to work, you must have called
070         * {@link #begin(URL)}. This method return true while there are still events
071         * to read.
072         * 
073         * @return true if there are still events to read, false as soon as the file
074         *         is finished.
075         * @throws IOException
076         *             If an I/O error occurs while reading.
077         */
078        boolean nextEvents() throws IOException;
079
080        /**
081         * Finish the reading process (even if {@link #nextEvents()} did not
082         * returned false). You must call this method after reading.
083         * 
084         * @throws IOException
085         *             If an I/O error occurs while closing the file.
086         */
087        void end() throws IOException;
088}