content: /**
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you under the Apache License, Version 2.0 (the
   * "License"); you may not use this file except in compliance
   * with the License.  You may obtain a copy of the License at
   *
   *   http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing,
   * software distributed under the License is distributed on an
   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   * KIND, either express or implied.  See the License for the
   * specific language governing permissions and limitations
   * under the License.
   */
  package org.apache.apex.malhar.contrib.zmq;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  import org.zeromq.ZMQ;
  
  import com.datatorrent.api.Context.OperatorContext;
  import com.datatorrent.common.util.BaseOperator;
  
  /**
   * This is the base implementation of a ZeroMQ output adapter.&nbsp;
   * This operator will behave like a publisher that replies to requests.&nbsp;
   * A concrete operator should be created from this skeleton implementation.
   * <p>
   * <br>
   * Ports:<br>
   * <b>Input</b>: Can have any number of input ports<br>
   * <b>Output</b>: no output port<br>
   * <br>
   * Properties:<br>
   * <b>url</b>:the url for the publisher to listen to subscriber <br>
   * <b>syncUrl</b>: the url for the publisher to synchronize with subscriber<br>
   * <b>SUBSCRIBERS_EXPECTED</b>: the expected number of subscribers<br>
   * <br>
   * Compile time checks:<br>
   * None<br>
   * <br>
   * Run time checks:<br>
   * None<br>
   * <br>
   * <b>Benchmarks</b>: Blast as many tuples as possible in inline mode<br>
   * <table border="1" cellspacing=1 cellpadding=1 summary="Benchmark table for AbstractBaseZeroMQOutputOperator&lt;K,V extends Number&gt; operator template">
   * <tr><th>In-Bound</th><th>Out-bound</th><th>Comments</th></tr>
   * <tr><td>One tuple per key per window per port</td><td><b>400 thousand K,V pairs/s</td><td>Out-bound rate is the main determinant of performance. Operator can process about 400 thousand unique (k,v immutable pairs) tuples/sec as ZeroMQ DAG. Tuples are assumed to be
   * immutable. If you use mutable tuples and have lots of keys, the benchmarks may differ</td></tr>
   * </table><br>
   * </p>
   * @displayName Abstract Base ZeroMQ Input
   * @category Messaging
   * @tags output operator
   * @since 0.3.2
   */
  public abstract class AbstractBaseZeroMQOutputOperator extends BaseOperator
  {
    private static final Logger logger = LoggerFactory.getLogger(AbstractBaseZeroMQInputOperator.class);
    protected transient ZMQ.Context context;
    protected transient ZMQ.Socket publisher;
    protected transient ZMQ.Socket syncservice;
    protected int SUBSCRIBERS_EXPECTED = 1;
    private String url;
    private String syncUrl;
    protected boolean syncStarted = false;
  
    public void setUrl(String url)
    {
      this.url = url;
    }
  
    public void setSyncUrl(String syncUrl)
    {
      this.syncUrl = syncUrl;
    }
  
    public void setSUBSCRIBERS_EXPECTED(int expected)
    {
      SUBSCRIBERS_EXPECTED = expected;
    }
  
    public int getSUBSCRIBERS_EXPECTED()
    {
      return SUBSCRIBERS_EXPECTED;
    }
  
    @Override
    public void setup(OperatorContext ctx)
    {
      logger.debug("O/P setup");
      context = ZMQ.context(1);
      publisher = context.socket(ZMQ.PUB);
      publisher.bind(url);
      syncservice = context.socket(ZMQ.REP);
      syncservice.bind(syncUrl);
    }
  
  /**
   * necessary for publisher side to synchronize publisher and subscriber, must run after setup()
   * make sure subscribers all connected to the publisher, then the publisher send data after that
   */
    public void startSyncJob()
    {
      for (int subscribers = 0; subscribers < SUBSCRIBERS_EXPECTED; subscribers++) {
        syncservice.recv(0);
        syncservice.send("".getBytes(), 0);
      }
      syncStarted = true;
    }
  
    @Override
    public void teardown()
    {
      publisher.close();
      context.term();
    }
  }
  