69 lines
3.1 KiB
Java
69 lines
3.1 KiB
Java
/**
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* The MIT License
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* Copyright (c) 2014 Ilkka Seppälä
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*
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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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*
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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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*
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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.publish.subscribe;
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import org.apache.camel.CamelContext;
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import org.apache.camel.ProducerTemplate;
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import org.apache.camel.builder.RouteBuilder;
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import org.apache.camel.impl.DefaultCamelContext;
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/**
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*
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* There are well-established patterns for implementing broadcasting. The Observer pattern describes
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* the need to decouple observers from their subject (that is, the originator of the event) so that
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* the subject can easily provide event notification to all interested observers no matter how many
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* observers there are (even none). The Publish-Subscribe pattern expands upon Observer by adding
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* the notion of an event channel for communicating event notifications.
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* <p>
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* A Publish-Subscribe Channel works like this: It has one input channel that splits into multiple
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* output channels, one for each subscriber. When an event is published into the channel, the
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* Publish-Subscribe Channel delivers a copy of the message to each of the output channels. Each
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* output end of the channel has only one subscriber, which is allowed to consume a message only
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* once. In this way, each subscriber gets the message only once, and consumed copies disappear from
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* their channels.
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* <p>
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* In this example we use Apache Camel to establish a Publish-Subscribe Channel from "direct-origin"
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* to "mock:foo", "mock:bar" and "stream:out".
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*
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*/
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public class App {
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/**
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* Program entry point
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*/
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public static void main(String[] args) throws Exception {
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CamelContext context = new DefaultCamelContext();
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context.addRoutes(new RouteBuilder() {
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@Override
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public void configure() throws Exception {
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from("direct:origin").multicast().to("mock:foo", "mock:bar", "stream:out");
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}
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});
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ProducerTemplate template = context.createProducerTemplate();
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context.start();
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context.getRoutes().stream().forEach(r -> System.out.println(r));
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template.sendBody("direct:origin", "Hello from origin");
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context.stop();
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}
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}
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