79 lines
3.8 KiB
Java
79 lines
3.8 KiB
Java
/**
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* The MIT License
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* Copyright (c) 2014-2016 Ilkka Seppälä
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* <p>
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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* <p>
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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* <p>
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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package com.iluwatar.databus;
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import com.iluwatar.databus.data.MessageData;
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import com.iluwatar.databus.data.StartingData;
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import com.iluwatar.databus.data.StoppingData;
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import com.iluwatar.databus.members.MessageCollectorMember;
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import com.iluwatar.databus.members.StatusMember;
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import java.time.LocalDateTime;
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/**
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* The Data Bus pattern
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* <p>
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* @see <a href="http://wiki.c2.com/?DataBusPattern">http://wiki.c2.com/?DataBusPattern</a>
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* <p>The Data-Bus pattern provides a method where different parts of an application may
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* pass messages between each other without needing to be aware of the other's existence.</p>
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* <p>Similar to the {@code ObserverPattern}, members register themselves with the {@link DataBus}
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* and may then receive each piece of data that is published to the Data-Bus. The member
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* may react to any given message or not.</p>
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* <p>It allows for Many-to-Many distribution of data, as there may be any number of
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* publishers to a Data-Bus, and any number of members receiving the data. All members
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* will receive the same data, the order each receives a given piece of data, is an
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* implementation detail.</p>
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* <p>Members may unsubscribe from the Data-Bus to stop receiving data.</p>
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* <p>This example of the pattern implements a Synchronous Data-Bus, meaning that
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* when data is published to the Data-Bus, the publish method will not return until
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* all members have received the data and returned.</p>
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* <p>The {@link DataBus} class is a Singleton.</p>
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* <p>Members of the Data-Bus must implement the {@link Member} interface.</p>
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* <p>Data to be published via the Data-Bus must implement the {@link DataType} interface.</p>
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* <p>The {@code data} package contains example {@link DataType} implementations.</p>
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* <p>The {@code members} package contains example {@link Member} implementations.</p>
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* <p>The {@link StatusMember} demonstrates using the DataBus to publish a message
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* to the Data-Bus when it receives a message.</p>
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*
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* @author Paul Campbell (pcampbell@kemitix.net)
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*/
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class App {
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public static void main(String[] args) {
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final DataBus bus = DataBus.getInstance();
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bus.subscribe(new StatusMember(1));
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bus.subscribe(new StatusMember(2));
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final MessageCollectorMember foo = new MessageCollectorMember("Foo");
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final MessageCollectorMember bar = new MessageCollectorMember("Bar");
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bus.subscribe(foo);
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bus.publish(StartingData.of(LocalDateTime.now()));
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bus.publish(MessageData.of("Only Foo should see this"));
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bus.subscribe(bar);
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bus.publish(MessageData.of("Foo and Bar should see this"));
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bus.unsubscribe(foo);
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bus.publish(MessageData.of("Only Bar should see this"));
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bus.publish(StoppingData.of(LocalDateTime.now()));
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}
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}
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