spring-cloud-function/getting-started.html

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<div id="header">
<div id="toc" class="toc2">
<div id="toctitle">Table of Contents</div>
<ul class="sectlevel1">
<li><a href="#_building_and_running_a_function">Building and Running a Function</a></li>
</ul>
</div>
</div>
<div id="content">
<div id="preamble">
<div class="sectionbody">
<div class="paragraph">
<p>Build from the command line (and "install" the samples):</p>
</div>
<div class="listingblock">
<div class="content">
<pre>$ ./mvnw clean install</pre>
</div>
</div>
<div class="paragraph">
<p>(If you like to YOLO add <code>-DskipTests</code>.)</p>
</div>
<div class="paragraph">
<p>Run one of the samples, e.g.</p>
</div>
<div class="listingblock">
<div class="content">
<pre>$ java -jar spring-cloud-function-samples/function-sample/target/*.jar</pre>
</div>
</div>
<div class="paragraph">
<p>This runs the app and exposes its functions over HTTP, so you can
convert a string to uppercase, like this:</p>
</div>
<div class="listingblock">
<div class="content">
<pre>$ curl -H "Content-Type: text/plain" localhost:8080/uppercase -d Hello
HELLO</pre>
</div>
</div>
<div class="paragraph">
<p>You can convert multiple strings (a <code>Flux&lt;String&gt;</code>) by separating them
with new lines</p>
</div>
<div class="listingblock">
<div class="content">
<pre>$ curl -H "Content-Type: text/plain" localhost:8080/uppercase -d 'Hello
&gt; World'
HELLOWORLD</pre>
</div>
</div>
<div class="paragraph">
<p>(You can use <code><sup>Q</sup>J</code> in a terminal to insert a new line in a literal
string like that.)</p>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_building_and_running_a_function"><a class="link" href="#_building_and_running_a_function">Building and Running a Function</a></h2>
<div class="sectionbody">
<div class="paragraph">
<p>The sample <code>@SpringBootApplication</code> above has a function that can be
decorated at runtime by Spring Cloud Function to be an HTTP endpoint,
or a Stream processor, for instance with RabbitMQ, Apache Kafka or
JMS.</p>
</div>
<div class="paragraph">
<p>The <code>@Beans</code> can be <code>Function</code>, <code>Consumer</code> or <code>Supplier</code> (all from
<code>java.util</code>), and their parametric types can be String or POJO.</p>
</div>
<div class="paragraph">
<p>Functions can also be of <code>Flux&lt;String&gt;</code> or <code>Flux&lt;Pojo&gt;</code> and Spring
Cloud Function takes care of converting the data to and from the
desired types, as long as it comes in as plain text or (in the case of
the POJO) JSON. There is also support for <code>Message&lt;Pojo&gt;</code> where the
message headers are copied from the incoming event, depending on the
adapter. The web adapter also supports conversion from form-encoded
data to a <code>Map</code>, and if you are using the function with Spring Cloud
Stream then all the conversion and coercion features for message
payloads will be applicable as well.</p>
</div>
<div class="paragraph">
<p>Functions can be grouped together in a single application, or deployed
one-per-jar. It&#8217;s up to the developer to choose. An app with multiple
functions can be deployed multiple times in different "personalities",
exposing different functions over different physical transports.</p>
</div>
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