001/**
002 *
003 * Copyright 2015-2017 Florian Schmaus
004 *
005 * Licensed under the Apache License, Version 2.0 (the "License");
006 * you may not use this file except in compliance with the License.
007 * You may obtain a copy of the License at
008 *
009 *     http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018package org.jivesoftware.smack.roster;
019
020import org.jivesoftware.smack.packet.Presence;
021
022import org.jxmpp.jid.Jid;
023
024
025/**
026 * Handle incoming requests to subscribe to our presence. The
027 * {@link #processSubscribe(Jid, Presence)} method may return a subscribe
028 * answer. If no subscribe answer is returned, the next listener will be
029 * notified and asked. If no listener returns an answer, then nothing happens.
030 *
031 */
032public interface SubscribeListener {
033
034    enum SubscribeAnswer {
035        /**
036         * Approve the subscription request.
037         */
038        Approve,
039
040        /**
041         * Approve the subscription request and also request subscription from the other party if not already subscribed.
042         * @since 4.2.2
043         */
044        ApproveAndAlsoRequestIfRequired,
045
046        /**
047         * Deny the subscription request.
048         */
049        Deny,
050    }
051
052    /**
053     * Handle incoming presence subscription requests.
054     *
055     * @param from the JID requesting the subscription.
056     * @param subscribeRequest the presence stanza used for the request.
057     * @return a answer to the request, or <code>null</code>
058     */
059    SubscribeAnswer processSubscribe(Jid from, Presence subscribeRequest);
060
061}