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   <h1>Source code for apache_beam.io.external.kafka</h1><div class="highlight"><pre>
 <span></span><span class="c1">#</span>
 <span class="c1"># Licensed to the Apache Software Foundation (ASF) under one or more</span>
 <span class="c1"># contributor license agreements.  See the NOTICE file distributed with</span>
 <span class="c1"># this work for additional information regarding copyright ownership.</span>
 <span class="c1"># The ASF licenses this file to You under the Apache License, Version 2.0</span>
 <span class="c1"># (the &quot;License&quot;); you may not use this file except in compliance with</span>
 <span class="c1"># the License.  You may obtain a copy of the License at</span>
 <span class="c1">#</span>
 <span class="c1">#    http://www.apache.org/licenses/LICENSE-2.0</span>
 <span class="c1">#</span>
 <span class="c1"># Unless required by applicable law or agreed to in writing, software</span>
 <span class="c1"># distributed under the License is distributed on an &quot;AS IS&quot; BASIS,</span>
 <span class="c1"># WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.</span>
 <span class="c1"># See the License for the specific language governing permissions and</span>
 <span class="c1"># limitations under the License.</span>
 <span class="c1">#</span>
 <span class="sd">&quot;&quot;&quot;</span>
 <span class="sd">  PTransforms for supporting Kafka in Python pipelines. These transforms do not</span>
 <span class="sd">  run a Kafka client in Python. Instead, they expand to ExternalTransforms</span>
 <span class="sd">  which the Expansion Service resolves to the Java SDK&#39;s KafkaIO. In other</span>
 <span class="sd">  words: they are cross-language transforms.</span>

 <span class="sd">  Note: To use these transforms, you need to start a Java Expansion Service.</span>
 <span class="sd">  Please refer to the portability documentation on how to do that. Flink Users</span>
 <span class="sd">  can use the built-in Expansion Service of the Flink Runner&#39;s Job Server. The</span>
 <span class="sd">  expansion service address has to be provided when instantiating the</span>
 <span class="sd">  transforms.</span>

 <span class="sd">  If you start Flink&#39;s Job Server, the expansion service will be started on</span>
 <span class="sd">  port 8097. This is also the configured default for this transform. For a</span>
 <span class="sd">  different address, please set the expansion_service parameter.</span>

 <span class="sd">  For more information see:</span>
 <span class="sd">  - https://beam.apache.org/documentation/runners/flink/</span>
 <span class="sd">  - https://beam.apache.org/roadmap/portability/</span>
 <span class="sd">&quot;&quot;&quot;</span>

 <span class="kn">from</span> <span class="nn">__future__</span> <span class="k">import</span> <span class="n">absolute_import</span>

 <span class="kn">from</span> <span class="nn">apache_beam</span> <span class="k">import</span> <span class="n">ExternalTransform</span>
 <span class="kn">from</span> <span class="nn">apache_beam</span> <span class="k">import</span> <span class="n">pvalue</span>
 <span class="kn">from</span> <span class="nn">apache_beam.coders</span> <span class="k">import</span> <span class="n">BytesCoder</span>
 <span class="kn">from</span> <span class="nn">apache_beam.coders</span> <span class="k">import</span> <span class="n">IterableCoder</span>
 <span class="kn">from</span> <span class="nn">apache_beam.coders</span> <span class="k">import</span> <span class="n">TupleCoder</span>
 <span class="kn">from</span> <span class="nn">apache_beam.coders.coders</span> <span class="k">import</span> <span class="n">LengthPrefixCoder</span>
 <span class="kn">from</span> <span class="nn">apache_beam.portability.api.external_transforms_pb2</span> <span class="k">import</span> <span class="n">ConfigValue</span>
 <span class="kn">from</span> <span class="nn">apache_beam.portability.api.external_transforms_pb2</span> <span class="k">import</span> <span class="n">ExternalConfigurationPayload</span>
 <span class="kn">from</span> <span class="nn">apache_beam.transforms</span> <span class="k">import</span> <span class="n">ptransform</span>


 <div class="viewcode-block" id="ReadFromKafka"><a class="viewcode-back" href="../../../../apache_beam.io.external.kafka.html#apache_beam.io.external.kafka.ReadFromKafka">[docs]</a><span class="k">class</span> <span class="nc">ReadFromKafka</span><span class="p">(</span><span class="n">ptransform</span><span class="o">.</span><span class="n">PTransform</span><span class="p">):</span>
   <span class="sd">&quot;&quot;&quot;</span>
 <span class="sd">    An external PTransform which reads from Kafka and returns a KV pair for</span>
 <span class="sd">    each item in the specified Kafka topics. If no Kafka Deserializer for</span>
 <span class="sd">    key/value is provided, then the data will be returned as a raw byte array.</span>

 <span class="sd">    Note: Runners need to support translating Read operations in order to use</span>
 <span class="sd">    this source. At the moment only the Flink Runner supports this.</span>

 <span class="sd">    Experimental; no backwards compatibility guarantees.</span>
 <span class="sd">  &quot;&quot;&quot;</span>

   <span class="c1"># Returns the key/value data as raw byte arrays</span>
   <span class="n">byte_array_deserializer</span> <span class="o">=</span> <span class="s1">&#39;org.apache.kafka.common.serialization.&#39;</span> \
                             <span class="s1">&#39;ByteArrayDeserializer&#39;</span>

   <span class="k">def</span> <span class="nf">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">consumer_config</span><span class="p">,</span>
                <span class="n">topics</span><span class="p">,</span>
                <span class="n">key_deserializer</span><span class="o">=</span><span class="n">byte_array_deserializer</span><span class="p">,</span>
                <span class="n">value_deserializer</span><span class="o">=</span><span class="n">byte_array_deserializer</span><span class="p">,</span>
                <span class="n">expansion_service</span><span class="o">=</span><span class="s1">&#39;localhost:8097&#39;</span><span class="p">):</span>
     <span class="sd">&quot;&quot;&quot;</span>
 <span class="sd">    Initializes a read operation from Kafka.</span>

 <span class="sd">    :param consumer_config: A dictionary containing the consumer configuration.</span>
 <span class="sd">    :param topics: A list of topic strings.</span>
 <span class="sd">    :param key_deserializer: A fully-qualified Java class name of a Kafka</span>
 <span class="sd">                             Deserializer for the topic&#39;s key, e.g.</span>
 <span class="sd">                             &#39;org.apache.kafka.common.</span>
 <span class="sd">                             serialization.LongDeserializer&#39;.</span>
 <span class="sd">                             Default: &#39;org.apache.kafka.common.</span>
 <span class="sd">                             serialization.ByteArrayDeserializer&#39;.</span>
 <span class="sd">    :param value_deserializer: A fully-qualified Java class name of a Kafka</span>
 <span class="sd">                               Deserializer for the topic&#39;s value, e.g.</span>
 <span class="sd">                               &#39;org.apache.kafka.common.</span>
 <span class="sd">                               serialization.LongDeserializer&#39;.</span>
 <span class="sd">                               Default: &#39;org.apache.kafka.common.</span>
 <span class="sd">                               serialization.ByteArrayDeserializer&#39;.</span>
 <span class="sd">    :param expansion_service: The address (host:port) of the ExpansionService.</span>
 <span class="sd">    &quot;&quot;&quot;</span>
     <span class="nb">super</span><span class="p">(</span><span class="n">ReadFromKafka</span><span class="p">,</span> <span class="bp">self</span><span class="p">)</span><span class="o">.</span><span class="fm">__init__</span><span class="p">()</span>
     <span class="bp">self</span><span class="o">.</span><span class="n">_urn</span> <span class="o">=</span> <span class="s1">&#39;beam:external:java:kafka:read:v1&#39;</span>
     <span class="bp">self</span><span class="o">.</span><span class="n">consumer_config</span> <span class="o">=</span> <span class="n">consumer_config</span>
     <span class="bp">self</span><span class="o">.</span><span class="n">topics</span> <span class="o">=</span> <span class="n">topics</span>
     <span class="bp">self</span><span class="o">.</span><span class="n">key_deserializer</span> <span class="o">=</span> <span class="n">key_deserializer</span>
     <span class="bp">self</span><span class="o">.</span><span class="n">value_deserializer</span> <span class="o">=</span> <span class="n">value_deserializer</span>
     <span class="bp">self</span><span class="o">.</span><span class="n">expansion_service</span> <span class="o">=</span> <span class="n">expansion_service</span>

 <div class="viewcode-block" id="ReadFromKafka.expand"><a class="viewcode-back" href="../../../../apache_beam.io.external.kafka.html#apache_beam.io.external.kafka.ReadFromKafka.expand">[docs]</a>  <span class="k">def</span> <span class="nf">expand</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">pbegin</span><span class="p">):</span>
     <span class="k">if</span> <span class="ow">not</span> <span class="nb">isinstance</span><span class="p">(</span><span class="n">pbegin</span><span class="p">,</span> <span class="n">pvalue</span><span class="o">.</span><span class="n">PBegin</span><span class="p">):</span>
       <span class="k">raise</span> <span class="ne">Exception</span><span class="p">(</span><span class="s2">&quot;ReadFromKafka must be a root transform&quot;</span><span class="p">)</span>

     <span class="n">args</span> <span class="o">=</span> <span class="p">{</span>
         <span class="s1">&#39;consumer_config&#39;</span><span class="p">:</span>
             <span class="n">_encode_map</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">consumer_config</span><span class="p">),</span>
         <span class="s1">&#39;topics&#39;</span><span class="p">:</span>
             <span class="n">_encode_list</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">topics</span><span class="p">),</span>
         <span class="s1">&#39;key_deserializer&#39;</span><span class="p">:</span>
             <span class="n">_encode_str</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">key_deserializer</span><span class="p">),</span>
         <span class="s1">&#39;value_deserializer&#39;</span><span class="p">:</span>
             <span class="n">_encode_str</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">value_deserializer</span><span class="p">),</span>
     <span class="p">}</span>

     <span class="n">payload</span> <span class="o">=</span> <span class="n">ExternalConfigurationPayload</span><span class="p">(</span><span class="n">configuration</span><span class="o">=</span><span class="n">args</span><span class="p">)</span>
     <span class="k">return</span> <span class="n">pbegin</span><span class="o">.</span><span class="n">apply</span><span class="p">(</span>
         <span class="n">ExternalTransform</span><span class="p">(</span>
             <span class="bp">self</span><span class="o">.</span><span class="n">_urn</span><span class="p">,</span>
             <span class="n">payload</span><span class="o">.</span><span class="n">SerializeToString</span><span class="p">(),</span>
             <span class="bp">self</span><span class="o">.</span><span class="n">expansion_service</span><span class="p">))</span></div></div>


 <div class="viewcode-block" id="WriteToKafka"><a class="viewcode-back" href="../../../../apache_beam.io.external.kafka.html#apache_beam.io.external.kafka.WriteToKafka">[docs]</a><span class="k">class</span> <span class="nc">WriteToKafka</span><span class="p">(</span><span class="n">ptransform</span><span class="o">.</span><span class="n">PTransform</span><span class="p">):</span>
   <span class="sd">&quot;&quot;&quot;</span>
 <span class="sd">    An external PTransform which writes KV data to a specified Kafka topic.</span>
 <span class="sd">    If no Kafka Serializer for key/value is provided, then key/value are</span>
 <span class="sd">    assumed to be byte arrays.</span>

 <span class="sd">    Experimental; no backwards compatibility guarantees.</span>
 <span class="sd">  &quot;&quot;&quot;</span>

   <span class="c1"># Default serializer which passes raw bytes to Kafka</span>
   <span class="n">byte_array_serializer</span> <span class="o">=</span> <span class="s1">&#39;org.apache.kafka.common.serialization.&#39;</span> \
                           <span class="s1">&#39;ByteArraySerializer&#39;</span>

   <span class="k">def</span> <span class="nf">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">producer_config</span><span class="p">,</span>
                <span class="n">topic</span><span class="p">,</span>
                <span class="n">key_serializer</span><span class="o">=</span><span class="n">byte_array_serializer</span><span class="p">,</span>
                <span class="n">value_serializer</span><span class="o">=</span><span class="n">byte_array_serializer</span><span class="p">,</span>
                <span class="n">expansion_service</span><span class="o">=</span><span class="s1">&#39;localhost:8097&#39;</span><span class="p">):</span>
     <span class="sd">&quot;&quot;&quot;</span>
 <span class="sd">    Initializes a write operation to Kafka.</span>

 <span class="sd">    :param consumer_config: A dictionary containing the producer configuration.</span>
 <span class="sd">    :param topic: A Kafka topic name.</span>
 <span class="sd">    :param key_deserializer: A fully-qualified Java class name of a Kafka</span>
 <span class="sd">                             Serializer for the topic&#39;s key, e.g.</span>
 <span class="sd">                             &#39;org.apache.kafka.common.</span>
 <span class="sd">                             serialization.LongSerializer&#39;.</span>
 <span class="sd">                             Default: &#39;org.apache.kafka.common.</span>
 <span class="sd">                             serialization.ByteArraySerializer&#39;.</span>
 <span class="sd">    :param value_deserializer: A fully-qualified Java class name of a Kafka</span>
 <span class="sd">                               Serializer for the topic&#39;s value, e.g.</span>
 <span class="sd">                               &#39;org.apache.kafka.common.</span>
 <span class="sd">                               serialization.LongSerializer&#39;.</span>
 <span class="sd">                               Default: &#39;org.apache.kafka.common.</span>
 <span class="sd">                               serialization.ByteArraySerializer&#39;.</span>
 <span class="sd">    :param expansion_service: The address (host:port) of the ExpansionService.</span>
 <span class="sd">    &quot;&quot;&quot;</span>
     <span class="nb">super</span><span class="p">(</span><span class="n">WriteToKafka</span><span class="p">,</span> <span class="bp">self</span><span class="p">)</span><span class="o">.</span><span class="fm">__init__</span><span class="p">()</span>
     <span class="bp">self</span><span class="o">.</span><span class="n">_urn</span> <span class="o">=</span> <span class="s1">&#39;beam:external:java:kafka:write:v1&#39;</span>
     <span class="bp">self</span><span class="o">.</span><span class="n">producer_config</span> <span class="o">=</span> <span class="n">producer_config</span>
     <span class="bp">self</span><span class="o">.</span><span class="n">topic</span> <span class="o">=</span> <span class="n">topic</span>
     <span class="bp">self</span><span class="o">.</span><span class="n">key_serializer</span> <span class="o">=</span> <span class="n">key_serializer</span>
     <span class="bp">self</span><span class="o">.</span><span class="n">value_serializer</span> <span class="o">=</span> <span class="n">value_serializer</span>
     <span class="bp">self</span><span class="o">.</span><span class="n">expansion_service</span> <span class="o">=</span> <span class="n">expansion_service</span>

 <div class="viewcode-block" id="WriteToKafka.expand"><a class="viewcode-back" href="../../../../apache_beam.io.external.kafka.html#apache_beam.io.external.kafka.WriteToKafka.expand">[docs]</a>  <span class="k">def</span> <span class="nf">expand</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">pvalue</span><span class="p">):</span>
     <span class="n">args</span> <span class="o">=</span> <span class="p">{</span>
         <span class="s1">&#39;producer_config&#39;</span><span class="p">:</span>
             <span class="n">_encode_map</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">producer_config</span><span class="p">),</span>
         <span class="s1">&#39;topic&#39;</span><span class="p">:</span>
             <span class="n">_encode_str</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">topic</span><span class="p">),</span>
         <span class="s1">&#39;key_serializer&#39;</span><span class="p">:</span>
             <span class="n">_encode_str</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">key_serializer</span><span class="p">),</span>
         <span class="s1">&#39;value_serializer&#39;</span><span class="p">:</span>
             <span class="n">_encode_str</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">value_serializer</span><span class="p">),</span>
     <span class="p">}</span>

     <span class="n">payload</span> <span class="o">=</span> <span class="n">ExternalConfigurationPayload</span><span class="p">(</span><span class="n">configuration</span><span class="o">=</span><span class="n">args</span><span class="p">)</span>
     <span class="k">return</span> <span class="n">pvalue</span><span class="o">.</span><span class="n">apply</span><span class="p">(</span>
         <span class="n">ExternalTransform</span><span class="p">(</span>
             <span class="bp">self</span><span class="o">.</span><span class="n">_urn</span><span class="p">,</span>
             <span class="n">payload</span><span class="o">.</span><span class="n">SerializeToString</span><span class="p">(),</span>
             <span class="bp">self</span><span class="o">.</span><span class="n">expansion_service</span><span class="p">))</span></div></div>


 <span class="k">def</span> <span class="nf">_encode_map</span><span class="p">(</span><span class="n">dict_obj</span><span class="p">):</span>
   <span class="n">kv_list</span> <span class="o">=</span> <span class="p">[(</span><span class="n">key</span><span class="o">.</span><span class="n">encode</span><span class="p">(</span><span class="s1">&#39;utf-8&#39;</span><span class="p">),</span> <span class="n">val</span><span class="o">.</span><span class="n">encode</span><span class="p">(</span><span class="s1">&#39;utf-8&#39;</span><span class="p">))</span>
              <span class="k">for</span> <span class="n">key</span><span class="p">,</span> <span class="n">val</span> <span class="ow">in</span> <span class="n">dict_obj</span><span class="o">.</span><span class="n">items</span><span class="p">()]</span>
   <span class="n">coder</span> <span class="o">=</span> <span class="n">IterableCoder</span><span class="p">(</span><span class="n">TupleCoder</span><span class="p">(</span>
       <span class="p">[</span><span class="n">LengthPrefixCoder</span><span class="p">(</span><span class="n">BytesCoder</span><span class="p">()),</span> <span class="n">LengthPrefixCoder</span><span class="p">(</span><span class="n">BytesCoder</span><span class="p">())]))</span>
   <span class="n">coder_urns</span> <span class="o">=</span> <span class="p">[</span><span class="s1">&#39;beam:coder:iterable:v1&#39;</span><span class="p">,</span>
                 <span class="s1">&#39;beam:coder:kv:v1&#39;</span><span class="p">,</span>
                 <span class="s1">&#39;beam:coder:bytes:v1&#39;</span><span class="p">,</span>
                 <span class="s1">&#39;beam:coder:bytes:v1&#39;</span><span class="p">]</span>
   <span class="k">return</span> <span class="n">ConfigValue</span><span class="p">(</span>
       <span class="n">coder_urn</span><span class="o">=</span><span class="n">coder_urns</span><span class="p">,</span>
       <span class="n">payload</span><span class="o">=</span><span class="n">coder</span><span class="o">.</span><span class="n">encode</span><span class="p">(</span><span class="n">kv_list</span><span class="p">))</span>


 <span class="k">def</span> <span class="nf">_encode_list</span><span class="p">(</span><span class="n">list_obj</span><span class="p">):</span>
   <span class="n">encoded_list</span> <span class="o">=</span> <span class="p">[</span><span class="n">val</span><span class="o">.</span><span class="n">encode</span><span class="p">(</span><span class="s1">&#39;utf-8&#39;</span><span class="p">)</span> <span class="k">for</span> <span class="n">val</span> <span class="ow">in</span> <span class="n">list_obj</span><span class="p">]</span>
   <span class="n">coder</span> <span class="o">=</span> <span class="n">IterableCoder</span><span class="p">(</span><span class="n">LengthPrefixCoder</span><span class="p">(</span><span class="n">BytesCoder</span><span class="p">()))</span>
   <span class="n">coder_urns</span> <span class="o">=</span> <span class="p">[</span><span class="s1">&#39;beam:coder:iterable:v1&#39;</span><span class="p">,</span>
                 <span class="s1">&#39;beam:coder:bytes:v1&#39;</span><span class="p">]</span>
   <span class="k">return</span> <span class="n">ConfigValue</span><span class="p">(</span>
       <span class="n">coder_urn</span><span class="o">=</span><span class="n">coder_urns</span><span class="p">,</span>
       <span class="n">payload</span><span class="o">=</span><span class="n">coder</span><span class="o">.</span><span class="n">encode</span><span class="p">(</span><span class="n">encoded_list</span><span class="p">))</span>


 <span class="k">def</span> <span class="nf">_encode_str</span><span class="p">(</span><span class="n">str_obj</span><span class="p">):</span>
   <span class="n">encoded_str</span> <span class="o">=</span> <span class="n">str_obj</span><span class="o">.</span><span class="n">encode</span><span class="p">(</span><span class="s1">&#39;utf-8&#39;</span><span class="p">)</span>
   <span class="n">coder</span> <span class="o">=</span> <span class="n">LengthPrefixCoder</span><span class="p">(</span><span class="n">BytesCoder</span><span class="p">())</span>
   <span class="n">coder_urns</span> <span class="o">=</span> <span class="p">[</span><span class="s1">&#39;beam:coder:bytes:v1&#39;</span><span class="p">]</span>
   <span class="k">return</span> <span class="n">ConfigValue</span><span class="p">(</span>
       <span class="n">coder_urn</span><span class="o">=</span><span class="n">coder_urns</span><span class="p">,</span>
       <span class="n">payload</span><span class="o">=</span><span class="n">coder</span><span class="o">.</span><span class="n">encode</span><span class="p">(</span><span class="n">encoded_str</span><span class="p">))</span>
 </pre></div>

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