  <a class="anchor" href="#end-to-end-exactly-once-applications-with-apache-flink">#</a>
</h2>
<p>We&rsquo;ll walk through the two-phase commit protocol and how it enables end-to-end exactly-once semantics in a sample Flink application that reads from and writes to Kafka. Kafka is a popular messaging system to use along with Flink, and Kafka recently added support for transactions with its 0.11 release. <a href="//nightlies.apache.org/flink/flink-docs-release-1.4/dev/connectors/kafka.html#kafka-011">This me