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From conflue...@apache.org
Subject [CONF] Apache Camel > RX
Date Mon, 04 Mar 2013 08:50:00 GMT
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    <h2><a href="https://cwiki.apache.org/confluence/display/CAMEL/RX">RX</a></h2>
    <h4>Page <b>edited</b> by             <a href="https://cwiki.apache.org/confluence/display/~jstrachan">James
Strachan</a>
    </h4>
        <br/>
                         <h4>Changes (1)</h4>
                                 
    
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            <tr><td class="diff-snipped" >...<br></td></tr>
            <tr><td class="diff-unchanged" >In RX you work with an [Observable&lt;T&gt;|http://netflix.github.com/RxJava/javadoc/rx/Observable.html]
which behaves quite like a Collection&lt;T&gt; in Java 8 so you can filter/map/concat
and so forth. The Observable&lt;T&gt; then acts as a typesafe composable API for working
with asynchronous events in a collection-like way. <br> <br></td></tr>
            <tr><td class="diff-added-lines" style="background-color: #dfd;">Once
you have an Observable&lt;T&gt; you can then  <br> <br>* [filter events|https://github.com/Netflix/RxJava/wiki/Filtering-Operators]
<br>* [transform events|https://github.com/Netflix/RxJava/wiki/Transformative-Operators]
<br>* [combine event streams|https://github.com/Netflix/RxJava/wiki/Combinatorial-Operators]
<br>* [other utility methods|https://github.com/Netflix/RxJava/wiki/Utility-Operators]
<br> <br></td></tr>
            <tr><td class="diff-unchanged" >h2. Observing events on Camel endpoints
 <br> <br></td></tr>
            <tr><td class="diff-snipped" >...<br></td></tr>
    
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    </div>                            <h4>Full Content</h4>
                    <div class="notificationGreySide">
        <h1><a name="RX-CamelRX"></a>Camel RX</h1>

<p>The camel-rx library provides Camel support for the <a href="https://rx.codeplex.com/"
class="external-link" rel="nofollow">Reactive Extensions</a>&nbsp;(RX) using
the <a href="https://github.com/Netflix/RxJava/wiki" class="external-link" rel="nofollow">RxJava</a>
library so that:</p>

<ul>
	<li>Camel users can use the <a href="http://netflix.github.com/RxJava/javadoc/"
class="external-link" rel="nofollow">RxJava API</a> for processing messages on endpoints
using a typesafe composable API</li>
	<li><a href="https://github.com/Netflix/RxJava/wiki" class="external-link" rel="nofollow">RxJava</a>
users get to use all of the <a href="/confluence/display/CAMEL/Components" title="Components">Camel
transports and protocols</a> from within the <a href="http://netflix.github.com/RxJava/javadoc/"
class="external-link" rel="nofollow">RxJava API</a></li>
</ul>


<h2><a name="RX-BackgroundonRX"></a>Background on RX</h2>

<p>You can think of RX as providing an API similar to Java 8 / Groovy / Scala collections
(methods like filter, map, zip etc) - but which operates on an asynchronous stream of events
rather than a collection. So you could think of RX as like working with asynchronous push
based collections (rather than the traditional synchronous pull based collections).</p>

<p>In RX you work with an <a href="http://netflix.github.com/RxJava/javadoc/rx/Observable.html"
class="external-link" rel="nofollow">Observable&lt;T&gt;</a> which behaves
quite like a Collection&lt;T&gt; in Java 8 so you can filter/map/concat and so forth.
The Observable&lt;T&gt; then acts as a typesafe composable API for working with asynchronous
events in a collection-like way.</p>

<p>Once you have an Observable&lt;T&gt; you can then </p>

<ul>
	<li><a href="https://github.com/Netflix/RxJava/wiki/Filtering-Operators" class="external-link"
rel="nofollow">filter events</a></li>
	<li><a href="https://github.com/Netflix/RxJava/wiki/Transformative-Operators" class="external-link"
rel="nofollow">transform events</a></li>
	<li><a href="https://github.com/Netflix/RxJava/wiki/Combinatorial-Operators" class="external-link"
rel="nofollow">combine event streams</a></li>
	<li><a href="https://github.com/Netflix/RxJava/wiki/Utility-Operators" class="external-link"
rel="nofollow">other utility methods</a></li>
</ul>


<h2><a name="RX-ObservingeventsonCamelendpoints"></a>Observing events on
Camel endpoints </h2>

<p>You can create an Observable&lt;Message&gt; from any endpoint using the ReactiveCamel
helper class and the <b>toObservable()</b> method.</p>

<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
<span class="code-keyword">import</span> org.apache.camel.rx.*;

ReactiveCamel rx = <span class="code-keyword">new</span> ReactiveCamel(camelContext);
Observable&lt;Message&gt; observable = rx.toObservable(<span class="code-quote">"activemq:MyMessages"</span>);

<span class="code-comment">// we can now call filter/map/concat etc
</span>filtered = observable.filter(m -&gt; m.getHeader(<span class="code-quote">"foo"</span>)
!= <span class="code-keyword">null</span>).map(m -&gt; <span class="code-quote">"Hello
"</span> + m.getBody()); 
</pre>
</div></div>

<p>If you know the type of the body of the message, you can use an overloaded version
of toObservable() to pass in the class and get a typesafe Observable&lt;T&gt; back:</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
<span class="code-keyword">import</span> org.apache.camel.rx.*;

ReactiveCamel rx = <span class="code-keyword">new</span> ReactiveCamel(camelContext);
Observable&lt;Order&gt; observable = rx.toObservable(<span class="code-quote">"seda:orders"</span>,
Order.class);

<span class="code-comment">// now lets filter and map using Java 7
</span>Observable&lt;<span class="code-object">String</span>&gt;
largeOrderIds = observable.filter(<span class="code-keyword">new</span> Func1&lt;Order,
<span class="code-object">Boolean</span>&gt;() {
    <span class="code-keyword">public</span> <span class="code-object">Boolean</span>
call(Order order) {
        <span class="code-keyword">return</span> order.getAmount() &gt; 100.0;
    }
}).map(<span class="code-keyword">new</span> Func1&lt;Order, <span class="code-object">String</span>&gt;()
{
    <span class="code-keyword">public</span> <span class="code-object">String</span>
call(Order order) {
        <span class="code-keyword">return</span> order.getId();
    }
});
</pre>
</div></div>

<h2><a name="RX-SendingObservable%3CT%3EeventstoCamelendpoints"></a>Sending
Observable&lt;T&gt; events to Camel endpoints</h2>

<p>If you have an <a href="http://netflix.github.com/RxJava/javadoc/rx/Observable.html"
class="external-link" rel="nofollow">Observable&lt;T&gt;</a> from some other
library; or have created one from a <a href="http://netflix.github.com/RxJava/javadoc/rx/Observable.html#toObservable(java.util.concurrent.Future)"
class="external-link" rel="nofollow">Future&lt;T&gt; using RxJava</a> and
you wish to send the events on the observable to a Camel endpoint you can use the <b>sendTo()</b>
method on ReactiveCamel:</p>

<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
<span class="code-keyword">import</span> org.apache.camel.rx.*;

<span class="code-comment">// take some observable from somewhere
</span>Observable&lt;T&gt; observable = ...;
ReactiveCamel rx = <span class="code-keyword">new</span> ReactiveCamel(camelContext);

<span class="code-comment">// lets send the events to a message queue
</span>rx.sendTo(observable, <span class="code-quote">"activemq:MyQueue"</span>);
</pre>
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