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'''
spark/bin/spark-submit \
--master local --driver-memory 4g \
--num-executors 2 --executor-memory 4g \
--packages org.apache.spark:spark-sql-kafka-0-10_2.11:2.4.0 \
sstreaming-spark-out.py
'''
from pyspark.sql import SparkSession
from pyspark.sql.types import *
spark = SparkSession.builder \
.appName("Spark Structured Streaming from Kafka") \
.getOrCreate()
sdfRides = spark \
.readStream \
.format("kafka") \
.option("kafka.bootstrap.servers", "localhost:9092") \
.option("subscribe", "taxirides") \
.option("startingOffsets", "latest") \
.load() \
.selectExpr("CAST(value AS STRING)")
sdfFares = spark \
.readStream \
.format("kafka") \
.option("kafka.bootstrap.servers", "localhost:9092") \
.option("subscribe", "taxifares") \
.option("startingOffsets", "latest") \
.load() \
.selectExpr("CAST(value AS STRING)")
taxiFaresSchema = StructType([ \
StructField("rideId", LongType()), StructField("taxiId", LongType()), \
StructField("driverId", LongType()), StructField("startTime", TimestampType()), \
StructField("paymentType", StringType()), StructField("tip", FloatType()), \
StructField("tolls", FloatType()), StructField("totalFare", FloatType())])
taxiRidesSchema = StructType([ \
StructField("rideId", LongType()), StructField("isStart", StringType()), \
StructField("endTime", TimestampType()), StructField("startTime", TimestampType()), \
StructField("startLon", FloatType()), StructField("startLat", FloatType()), \
StructField("endLon", FloatType()), StructField("endLat", FloatType()), \
StructField("passengerCnt", ShortType()), StructField("taxiId", LongType()), \
StructField("driverId", LongType())])
def parse_data_from_kafka_message(sdf, schema):
from pyspark.sql.functions import split
assert sdf.isStreaming == True, "DataFrame doesn't receive treaming data"
col = split(sdf['value'], ',') #split attributes to nested array in one Column
#now expand col to multiple top-level columns
for idx, field in enumerate(schema):
sdf = sdf.withColumn(field.name, col.getItem(idx).cast(field.dataType))
return sdf.select([field.name for field in schema])
sdfRides = parse_data_from_kafka_message(sdfRides, taxiRidesSchema)
sdfFares = parse_data_from_kafka_message(sdfFares, taxiFaresSchema)
query = sdfRides.groupBy("driverId").count()
query.writeStream \
.outputMode("complete") \
.format("console") \
.option("truncate", False) \
.start() \
.awaitTermination()
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