Package: MessageBus

MessageBus

Coverage

1: /*
2: * *************************************************************************************************************************************************************
3: *
4: * TheseFoolishThings: Miscellaneous utilities
5: * http://tidalwave.it/projects/thesefoolishthings
6: *
7: * Copyright (C) 2009 - 2025 by Tidalwave s.a.s. (http://tidalwave.it)
8: *
9: * *************************************************************************************************************************************************************
10: *
11: * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License.
12: * You may obtain a copy of the License at
13: *
14: * http://www.apache.org/licenses/LICENSE-2.0
15: *
16: * 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
17: * CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.
18: *
19: * *************************************************************************************************************************************************************
20: *
21: * git clone https://bitbucket.org/tidalwave/thesefoolishthings-src
22: * git clone https://github.com/tidalwave-it/thesefoolishthings-src
23: *
24: * *************************************************************************************************************************************************************
25: */
26: package it.tidalwave.messagebus;
27:
28: import javax.annotation.Nonnull;
29:
30: /***************************************************************************************************************************************************************
31: *
32: * A simple message bus for a local publish/subscribe facility.
33: *
34: * @author Fabrizio Giudici
35: *
36: **************************************************************************************************************************************************************/
37: public interface MessageBus
38: {
39: /***********************************************************************************************************************************************************
40: * A listener to receive notifications from a {@link MessageBus}.
41: *
42: * @stereotype Listener
43: **********************************************************************************************************************************************************/
44: public static interface Listener<T>
45: {
46: /***************************************************************************************************************
47: *
48: * Notifies the reception of the given message.
49: *
50: * @param message the event
51: *
52: **************************************************************************************************************/
53: public void notify (@Nonnull T message);
54: }
55:
56: /***********************************************************************************************************************************************************
57: * Publishes the given event. The topic is the class of the event.
58: *
59: * @param <T> the static type of the topic
60: * @param message the event
61: **********************************************************************************************************************************************************/
62: public <T> void publish (@Nonnull T message);
63:
64: /***********************************************************************************************************************************************************
65: * Publishes the given message and topic. Passing an explicit topic can be useful when dealing with a hierarchy of
66: * events (so, perhaps a subclass is passed but the topic is the root of the hierarchy).
67: *
68: * @param <T> the static type of the topic
69: * @param topic the topic
70: * @param message the message
71: **********************************************************************************************************************************************************/
72: public <T> void publish (@Nonnull Class<T> topic, @Nonnull T message);
73:
74: /***********************************************************************************************************************************************************
75: * Subscribes a {@link Listener} to a topic.
76: *
77: * @param <T> the static type of the topic
78: * @param topic the topic
79: * @param listener the listener
80: **********************************************************************************************************************************************************/
81: public <T> void subscribe (@Nonnull Class<T> topic, @Nonnull Listener<T> listener);
82:
83: /***********************************************************************************************************************************************************
84: * Unsubscribes a {@link Listener}.
85: *
86: * @param listener the listener
87: **********************************************************************************************************************************************************/
88: public void unsubscribe (@Nonnull Listener<?> listener);
89: }