001/*
002 * flattr4j - A Java library for Flattr
003 *
004 * Copyright (C) 2012 Richard "Shred" Körber
005 *   http://flattr4j.shredzone.org
006 *
007 * This program is free software: you can redistribute it and/or modify
008 * it under the terms of the GNU General Public License / GNU Lesser
009 * General Public License as published by the Free Software Foundation,
010 * either version 3 of the License, or (at your option) any later version.
011 *
012 * Licensed under the Apache License, Version 2.0 (the "License");
013 * you may not use this file except in compliance with the License.
014 *
015 * This program is distributed in the hope that it will be useful,
016 * but WITHOUT ANY WARRANTY; without even the implied warranty of
017 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
018 */
019package org.shredzone.flattr4j.model;
020
021import java.io.Serializable;
022
023/**
024 * A {@link UserIdentifier} is used to identify a user of a web site. This user can
025 * collect Flattr even when he is not registered there, and will be able to claim the
026 * Flattr clicks he gained.
027 * <p>
028 * {@link UserIdentifier} is only useful for Partner Site Integration. You need to
029 * register your site with Flattr before.
030 *
031 * @author Richard "Shred" Körber
032 * @since 2.0
033 */
034public interface UserIdentifier extends Serializable {
035
036    /**
037     * User identifier string.
038     * <p>
039     * Examples:
040     * <ul>
041     *   <li><tt>email:05f8b3480b04f6a516bb1a46e556323c</tt></li>
042     *   <li><tt>twitter:user:id:123</tt></li>
043     * </ul>
044     */
045    String getUserIdentifier();
046
047}