streaming-mqtt/python/mqtt.py

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#    http://www.apache.org/licenses/LICENSE-2.0
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from py4j.protocol import Py4JJavaError

from pyspark.storagelevel import StorageLevel
from pyspark.serializers import UTF8Deserializer
from pyspark.streaming import DStream

__all__ = ['MQTTUtils']


class MQTTUtils(object):

    @staticmethod
    def createStream(ssc, brokerUrl, topic,
                     storageLevel=StorageLevel.MEMORY_AND_DISK_2):
        """
        Create an input stream that pulls messages from a Mqtt Broker.

        :param ssc:  StreamingContext object
        :param brokerUrl:  Url of remote mqtt publisher
        :param topic:  topic name to subscribe to
        :param storageLevel:  RDD storage level.
        :return: A DStream object
        """
        jlevel = ssc._sc._getJavaStorageLevel(storageLevel)
        helper = MQTTUtils._get_helper(ssc._sc)
        jstream = helper.createStream(ssc._jssc, brokerUrl, topic, jlevel)
        return DStream(jstream, ssc, UTF8Deserializer())

    @staticmethod
    def _get_helper(sc):
        try:
            return sc._jvm.org.apache.spark.streaming.mqtt.MQTTUtilsPythonHelper()
        except TypeError as e:
            if str(e) == "'JavaPackage' object is not callable":
                MQTTUtils._printErrorMsg(sc)
            raise

    @staticmethod
    def _printErrorMsg(sc):
        scalaVersionString = sc._jvm.scala.util.Properties.versionString()
        import re
        scalaVersion = re.sub(r'version (\d+\.\d+)\.\d+', r'\1', scalaVersionString)
        sparkVersion = re.sub(r'(\d+\.\d+\.\d+).*', r'\1', sc.version)
        print("""
________________________________________________________________________________________________

  Spark Streaming's MQTT libraries not found in class path. Try one of the following.

  1. Include the MQTT library and its dependencies with in the
     spark-submit command as

     ${SPARK_HOME}/bin/spark-submit --packages org.apache.bahir:spark-streaming-mqtt_%s:%s ...

  2. Download the JAR of the artifact from Maven Central http://search.maven.org/,
     Group Id = org.apache.bahir, Artifact Id = spark-streaming-mqtt, Version = %s.
     Then, include the jar in the spark-submit command as

     ${SPARK_HOME}/bin/spark-submit --jars <spark-streaming-mqtt.jar> ...
________________________________________________________________________________________________
""" % (scalaVersion, sparkVersion, sparkVersion))