library/src/main/java/org/apache/apex/malhar/lib/io/PubSubWebSocketAppDataQuery.java

/**
 * 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.lib.io;

import java.net.URI;
import javax.validation.constraints.Min;

import org.codehaus.jettison.json.JSONException;
import org.codehaus.jettison.json.JSONObject;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import org.apache.apex.malhar.lib.appdata.StoreUtils.BufferingOutputPortFlusher;
import org.apache.apex.malhar.lib.appdata.query.WindowBoundedService;
import org.apache.apex.malhar.lib.utils.PubSubHelper;

import com.datatorrent.api.Context.OperatorContext;
import com.datatorrent.api.DAG;
import com.datatorrent.api.DefaultOutputPort;
import com.datatorrent.common.experimental.AppData;
import com.datatorrent.common.experimental.AppData.EmbeddableQueryInfoProvider;
import com.datatorrent.common.util.PubSubMessage;

/**
 * This is an App Data pub sub query operator. This operator is used to receive queries from
 * App Data dashboards and forward queries to App Data store operators.
 *
 * @displayName App Data Pub Sub Query
 * @category DT View Integration
 * @tags input, app data, query
 * @since 3.0.0
 */
public class PubSubWebSocketAppDataQuery extends PubSubWebSocketInputOperator<String> implements AppData.ConnectionInfoProvider, EmbeddableQueryInfoProvider<String>
{
  private static final Logger logger = LoggerFactory.getLogger(PubSubWebSocketAppDataQuery.class);

  private static final long serialVersionUID = 201506121124L;
  public static final long DEFAULT_EXECUTE_INTERVAL_MILLIS = 10;

  private boolean useEmitThread;
  @Min(0)
  private long executeIntervalMillis = DEFAULT_EXECUTE_INTERVAL_MILLIS;

  private transient WindowBoundedService windowBoundedService;

  public PubSubWebSocketAppDataQuery()
  {
    this.skipNull = true;
  }

  @Override
  public void setup(OperatorContext context)
  {
    setUri(uriHelper(context, getUri()));
    logger.debug("Setting up:\nuri:{}\ntopic:{}",this.getUri(), this.getTopic());
    super.setup(context);

    if (useEmitThread) {
      windowBoundedService = new WindowBoundedService(executeIntervalMillis,
                                                      new BufferingOutputPortFlusher<>(this.outputPort));
      windowBoundedService.setup(context);
    }
  }

  @Override
  public void beginWindow(long windowId)
  {
    super.beginWindow(windowId);

    if (windowBoundedService != null) {
      windowBoundedService.beginWindow(windowId);
    }
  }

  @Override
  public void endWindow()
  {
    if (windowBoundedService != null) {
      windowBoundedService.endWindow();
    }

    super.endWindow();
  }

  @Override
  public void teardown()
  {
    if (windowBoundedService != null) {
      windowBoundedService.teardown();
    }

    super.teardown();
  }

  public static URI uriHelper(OperatorContext context, URI uri)
  {
    if (uri == null) {
      if (context.getValue(DAG.GATEWAY_CONNECT_ADDRESS) == null) {
        throw new IllegalArgumentException("The uri property is not set and the dt.attr.GATEWAY_CONNECT_ADDRESS is not defined");
      }

      try {
        uri = PubSubHelper.getURI(context);
      } catch (Exception ex) {
        throw new RuntimeException(ex);
      }
    }

    return uri;
  }

  /**
   * Gets the URI for WebSocket connection.
   *
   * @return the URI
   */
  @Override
  public URI getUri()
  {
    return super.getUri();
  }

  /**
   * The URI for WebSocket connection. If this is not set, the value of the dt.attr.GATEWAY_CONNECT_ADDRESS DAG attribute is used. If neither this
   * property or dt.attr.GATEWAY_CONNECT_ADDRESS attribute is set, then this operator will fail with an {@link IllegalArgumentException}.
   *
   * @param uri
   */
  @Override
  public void setUri(URI uri)
  {
    super.setUri(uri);
  }

  @Override
  protected String convertMessage(String message)
  {
    String data;

    try {
      JSONObject jo = new JSONObject(message);
      data = jo.getString(PubSubMessage.DATA_KEY);
    } catch (JSONException e) {
      return null;
    }

    return data;
  }

  @Override
  public String getAppDataURL()
  {
    return "pubsub";
  }

  @Override
  public DefaultOutputPort<String> getOutputPort()
  {
    return outputPort;
  }

  @Override
  public void enableEmbeddedMode()
  {
    useEmitThread = true;
  }

  /**
   * Get the number of milliseconds between calls to execute.
   * @return The number of milliseconds between calls to execute.
   */
  public long getExecuteIntervalMillis()
  {
    return executeIntervalMillis;
  }

  /**
   * The number of milliseconds between calls to execute.
   * @param executeIntervalMillis The number of milliseconds between calls to execute.
   */
  public void setExecuteIntervalMillis(long executeIntervalMillis)
  {
    this.executeIntervalMillis = executeIntervalMillis;
  }
}