我正在尝试访问Tuple2中的字段，编译器返回错误。该软件尝试在kafka主题中推送案例类，然后我想使用spark streaming恢复它，这样我就可以提供机器学习算法并将结果保存在mongo实例中。
解决！
我终于解决了我的问题，我将发布最终解决方案：
这是github项目：
name := "my-recommendation-spark-engine"
version := "1.0-SNAPSHOT"
scalaVersion := "2.10.4"
val sparkVersion = "1.6.1"
val akkaVersion = "2.3.11" // override Akka to be this version to match the one in Spark
libraryDependencies ++= Seq(
"org.apache.kafka" % "kafka_2.10" % "0.8.1"
exclude("javax.jms", "jms")
exclude("com.sun.jdmk", "jmxtools")
exclude("com.sun.jmx", "jmxri"),
//not working play module!! check
//jdbc,
//anorm,
//cache,
// HTTP client
"net.databinder.dispatch" %% "dispatch-core" % "0.11.1",
// HTML parser
"org.jodd" % "jodd-lagarto" % "3.5.2",
"com.typesafe" % "config" % "1.2.1",
"com.typesafe.play" % "play-json_2.10" % "2.4.0-M2",
"org.scalatest" % "scalatest_2.10" % "2.2.1" % "test",
"org.twitter4j" % "twitter4j-core" % "4.0.2",
"org.twitter4j" % "twitter4j-stream" % "4.0.2",
"org.codehaus.jackson" % "jackson-core-asl" % "1.6.1",
"org.scala-tools.testing" % "specs_2.8.0" % "1.6.5" % "test",
"org.apache.spark" % "spark-streaming-kafka_2.10" % "1.6.1" ,
"org.apache.spark" % "spark-core_2.10" % "1.6.1" ,
"org.apache.spark" % "spark-streaming_2.10" % "1.6.1",
"org.apache.spark" % "spark-sql_2.10" % "1.6.1",
"org.apache.spark" % "spark-mllib_2.10" % "1.6.1",
"com.google.code.gson" % "gson" % "2.6.2",
"commons-cli" % "commons-cli" % "1.3.1",
"com.stratio.datasource" % "spark-mongodb_2.10" % "0.11.1",
// Akka
"com.typesafe.akka" %% "akka-actor" % akkaVersion,
"com.typesafe.akka" %% "akka-slf4j" % akkaVersion,
// MongoDB
"org.reactivemongo" %% "reactivemongo" % "0.10.0"
)
packAutoSettings
//play.Project.playScalaSettings
build.sbt
package example.producer
import play.api.libs.json._
import example.utils._
import scala.concurrent.Future
import example.model.{AmazonProductAndRating,AmazonProduct,AmazonRating}
import example.utils.AmazonPageParser
import scala.concurrent.ExecutionContext.Implicits.global
import scala.concurrent.Future
/**
args(0) : productId
args(1) : userdId
Usage: ./amazon-producer-example 0981531679 someUserId 3.0
*/
object AmazonProducerExample {
def main(args: Array[String]): Unit = {
val productId = args(0).toString
val userId = args(1).toString
val rating = args(2).toDouble
val topicName = "amazonRatingsTopic"
val producer = Producer[String](topicName)
//0981531679 is Scala Puzzlers...
AmazonPageParser.parse(productId,userId,rating).onSuccess { case amazonRating =>
//Is this the correct way? the best performance? possibly not, what about using avro or parquet? How can i push data in avro or parquet format?
//You can see that i am pushing json String to kafka topic, not raw String, but is there any difference?
//of course there are differences...
producer.send(Json.toJson(amazonRating).toString)
//producer.send(amazonRating.toString)
println("amazon product with rating sent to kafka cluster..." + amazonRating.toString)
System.exit(0)
}
}
}
卡夫卡制片人
package example.model
import play.api.libs.json.Json
import reactivemongo.bson.Macros
case class AmazonProduct(itemId: String, title: String, url: String, img: String, description: String)
case class AmazonRating(userId: String, productId: String, rating: Double)
case class AmazonProductAndRating(product: AmazonProduct, rating: AmazonRating)
// For MongoDB
object AmazonRating {
implicit val amazonRatingHandler = Macros.handler[AmazonRating]
implicit val amazonRatingFormat = Json.format[AmazonRating]
//added using @Yuval tip
lazy val empty: AmazonRating = AmazonRating("-1", "-1", -1d)
}
这是必要案例类（UPDATED）的定义，该文件名为models.scala：
package example.spark
import java.io.File
import java.util.Date
import play.api.libs.json._
import com.google.gson.{Gson,GsonBuilder, JsonParser}
import org.apache.spark.streaming.{Seconds, StreamingContext}
import org.apache.spark.{SparkConf, SparkContext}
import org.apache.spark.sql.SQLContext
import org.apache.spark.sql.functions._
import com.mongodb.casbah.Imports._
import com.mongodb.QueryBuilder
import com.mongodb.casbah.MongoClient
import com.mongodb.casbah.commons.{MongoDBList, MongoDBObject}
import reactivemongo.api.MongoDriver
import reactivemongo.api.collections.default.BSONCollection
import reactivemongo.bson.BSONDocument
import org.apache.spark.streaming.kafka._
import kafka.serializer.StringDecoder
import example.model._
import example.utils.Recommender
/**
* Collect at least the specified number of json amazon products in order to feed recomedation system and feed mongo instance with results.
Usage: ./amazon-kafka-connector 127.0.0.1:9092 amazonRatingsTopic
on mongo shell:
use alonsodb;
db.amazonRatings.find();
*/
object AmazonKafkaConnector {
private var numAmazonProductCollected = 0L
private var partNum = 0
private val numAmazonProductToCollect = 10000000
//this settings must be in reference.conf
private val Database = "alonsodb"
private val ratingCollection = "amazonRatings"
private val MongoHost = "127.0.0.1"
private val MongoPort = 27017
private val MongoProvider = "com.stratio.datasource.mongodb"
private val jsonParser = new JsonParser()
private val gson = new GsonBuilder().setPrettyPrinting().create()
private def prepareMongoEnvironment(): MongoClient = {
val mongoClient = MongoClient(MongoHost, MongoPort)
mongoClient
}
private def closeMongoEnviroment(mongoClient : MongoClient) = {
mongoClient.close()
println("mongoclient closed!")
}
private def cleanMongoEnvironment(mongoClient: MongoClient) = {
cleanMongoData(mongoClient)
mongoClient.close()
}
private def cleanMongoData(client: MongoClient): Unit = {
val collection = client(Database)(ratingCollection)
collection.dropCollection()
}
def main(args: Array[String]) {
// Process program arguments and set properties
if (args.length < 2) {
System.err.println("Usage: " + this.getClass.getSimpleName + " <brokers> <topics>")
System.exit(1)
}
val Array(brokers, topics) = args
println("Initializing Streaming Spark Context and kafka connector...")
// Create context with 2 second batch interval
val sparkConf = new SparkConf().setAppName("AmazonKafkaConnector")
.setMaster("local[4]")
.set("spark.driver.allowMultipleContexts", "true")
val sc = new SparkContext(sparkConf)
val sqlContext = new SQLContext(sc)
sc.addJar("target/scala-2.10/blog-spark-recommendation_2.10-1.0-SNAPSHOT.jar")
val ssc = new StreamingContext(sparkConf, Seconds(2))
//this checkpointdir should be in a conf file, for now it is hardcoded!
val streamingCheckpointDir = "/Users/aironman/my-recommendation-spark-engine/checkpoint"
ssc.checkpoint(streamingCheckpointDir)
// Create direct kafka stream with brokers and topics
val topicsSet = topics.split(",").toSet
val kafkaParams = Map[String, String]("metadata.broker.list" -> brokers)
val messages = KafkaUtils.createDirectStream[String, String, StringDecoder, StringDecoder](ssc, kafkaParams, topicsSet)
println("Initialized Streaming Spark Context and kafka connector...")
//create recomendation module
println("Creating rating recommender module...")
val ratingFile= "ratings.csv"
val recommender = new Recommender(sc,ratingFile)
println("Initialized rating recommender module...")
//THIS IS THE MOST INTERESTING PART AND WHAT I NEED!
//THE SOLUTION IS NOT PROBABLY THE MOST EFFICIENT, BECAUSE I HAD TO
//USE DATAFRAMES, ARRAYs and SEQs BUT IS FUNCTIONAL!
try{
messages.foreachRDD(rdd => {
val count = rdd.count()
if (count > 0){
val json= rdd.map(_._2)
val dataFrame = sqlContext.read.json(json) //converts json to DF
val myRow = dataFrame.select(dataFrame("userId"),dataFrame("productId"),dataFrame("rating")).take(count.toInt)
println("myRow is: " + myRow)
val myAmazonRating = AmazonRating(myRow(0).getString(0), myRow(0).getString(1), myRow(0).getDouble(2))
println("myAmazonRating is: " + myAmazonRating.toString)
val arrayAmazonRating = Array(myAmazonRating)
//this method needs Seq[AmazonRating]
recommender.predictWithALS(arrayAmazonRating.toSeq)
}//if
})
}catch{
case e: IllegalArgumentException => {println("illegal arg. exception")};
case e: IllegalStateException => {println("illegal state exception")};
case e: ClassCastException => {println("ClassCastException")};
case e: Exception => {println(" Generic Exception")};
}finally{
println("Finished taking data from kafka topic...")
}
ssc.start()
ssc.awaitTermination()
println("Finished!")
}
}
这是火花流媒体流程的完整代码：
def predict(ratings: Seq[AmazonRating]) = {
// train model
val myRatings = ratings.map(toSparkRating)
val myRatingRDD = sc.parallelize(myRatings)
val startAls = DateTime.now
val model = ALS.train((sparkRatings ++ myRatingRDD).repartition(NumPartitions), 10, 20, 0.01)
val myProducts = myRatings.map(_.product).toSet
val candidates = sc.parallelize((0 until productDict.size).filterNot(myProducts.contains))
// get ratings of all products not in my history ordered by rating (higher first) and only keep the first NumRecommendations
val myUserId = userDict.getIndex(MyUsername)
val recommendations = model.predict(candidates.map((myUserId, _))).collect
val endAls = DateTime.now
val result = recommendations.sortBy(-_.rating).take(NumRecommendations).map(toAmazonRating)
val alsTime = Seconds.secondsBetween(startAls, endAls).getSeconds
println(s"ALS Time: $alsTime seconds")
result
}
谢谢大家，@ Yuval，@ Emecas和@ Riccardo.cardin。
Recommender.predict签名方法如下：
$ git stash
$ git stash show -p # here I see the diff and all is right with the world
$ git stash pop
//我觉得我已经尽可能清楚，告诉我你是否还需要更多东西，感谢你耐心教我@Yuval
答案 0 :(得分：1)
问题是声明rdd.take(count.toInt)返回Array[T]，如所述here
def take(num: Int): Array[T]
获取RDD的第一个num元素。
您正在向RDD说明其中的前n个元素。然后，与您猜测的不同，您不是Tuple2类型的对象，而是数组。
如果要打印数组的每个元素，可以使用mkString类型上定义的方法Array来获取包含数组所有元素的单个String。
答案 1 :(得分：1)
看起来你要做的只是map而不是DStream。 map操作是从A类型到B类型的投影，其中A是String（您从Kafka收到的），以及{ {1}}是您的案例类B。
我们为AmazonRating添加empty值：
AmazonRating现在让我们解析JSON：
case class AmazonRating(userId: String, productId: String, rating: Double)
object AmazonRating {
lazy val empty: AmazonRating = AmazonRating("-1", "-1", -1d)
}
答案 2 :(得分：1)
诊断
IllegalStateException表示您正在使用已经处于活动状态或已停止状态的StreamingContext。 see details here (lines 218-231)
java.lang.IllegalStateException: Adding new inputs, transformations, and output operations after starting a context is not supported
代码审核
通过观察您的代码AmazonKafkaConnector，您正在map，filter和foreachRDD上通过同一个foreachRDD对象进入另一个DirectStream ：messages
一般建议：
成为我的朋友的功能，通过将逻辑划分为您要执行的每个任务的小部分：
这将帮助您更轻松地理解和调试要实现的Spark管道。