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<p>The tuple is Heron's core data type. Heron's native
<a href="/api/org/apache/heron/api/tuple/Tuple.html"><code>Tuple</code></a> interface supports
a broad range of <a href="guides-data-model#using-tuples">basic data types</a>, such as
strings, integers, and booleans, out of the box, but tuples can contain values
of any type. You can use data types beyond the core types by providing a custom
serializer using the instructions below.</p>
<h2><a class="anchor" aria-hidden="true" id="kryo"></a><a href="#kryo" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Kryo</h2>
<p>Heron uses <a href="https://github.com/EsotericSoftware/kryo">Kryo</a> for tuple
serialization and deserialization. You can create a custom tuple serializer by
extending Kryo's abstract
<a href="http://code.google.com/p/kryo/source/browse/trunk/src/com/esotericsoftware/kryo/Serializer.java"><code>Serializer</code></a>
class. More information can be found in <a href="https://github.com/EsotericSoftware/kryo#serializers">Kryo's
documentation</a>.</p>
<h2><a class="anchor" aria-hidden="true" id="registering-a-serializer"></a><a href="#registering-a-serializer" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Registering a Serializer</h2>
<p>Once you've created a custom Kryo serializer for a type:</p>
<ol>
<li>Make sure that the code for the serializer is on Heron's
<a href="../compiling/compiling/#classpath">classpath</a>.</li>
<li>Register the class with Kryo using the <code>topology.kryo.register</code> parameter for
your topology. Here's an example:</li>
</ol>
<pre><code class="hljs css language-yaml"><span class="hljs-attr">topology.kryo.register:</span>
  <span class="hljs-bullet">-</span> <span class="hljs-string">biz.acme.heron.datatypes.CustomType1</span> <span class="hljs-comment"># This type will use the default FieldSerializer</span>
  <span class="hljs-bullet">-</span> <span class="hljs-attr">biz.acme.heron.datatypes.CustomType2:</span> <span class="hljs-string">com.example.heron.serialization.CustomSerializer</span>
</code></pre>
<p>Once your custom serializer is on Heron's classpath and Heron is aware of its
existence, you must <a href="compiling-overview">re-compile</a> Heron.</p>
</span></div></article></div><div class="docs-prevnext"><a class="docs-prev button" href="/docs/guides-data-model"><span class="arrow-prev">← </span><span>Heron Data Model</span></a><a class="docs-next button" href="/docs/guides-ui-guide"><span>Heron UI Guide</span><span class="arrow-next"> →</span></a></div></div></div><nav class="onPageNav"><ul class="toc-headings"><li><a href="#kryo">Kryo</a></li><li><a href="#registering-a-serializer">Registering a Serializer</a></li></ul></nav></div><footer class="nav-footer" id="footer"><div class="apache-disclaimer">Apache Heron is an effort undergoing incubation at <a target="_blank" href="https://apache.org/">The Apache Software Foundation (ASF)</a> sponsored by the Apache Incubator PMC. Incubation is required of all newly accepted projects until a further review indicates that the infrastructure, communications, and decision making process have stabilized in a manner consistent with other successful ASF projects. While incubation status is not necessarily a reflection of the completeness or stability of the code, it does indicate that the project has yet to be fully endorsed by the ASF.<br/><br/>Apache®, the names of Apache projects, and the feather logo are either <a rel="external" href="https://www.apache.org/foundation/marks/list/">registered trademarks or trademarks</a> of the Apache Software Foundation in the United States and/or other countries.<br/><br/><div class="copyright-box">Copyright © 2023 the Apache Software Foundation, Apache Heron, Heron, 
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