Hi Akhil, Vyas, Helena,
Thank you for your suggestions.
As Akhil suggested earlier, i have implemented the batch Duration into
JavaStreamingContext and waitForTermination(Duration).
The approach Helena suggested is Scala oriented.
But the issue now is that I want to set Cassandra as my output.
I have created a table in cassandra "test_table" with columns "key:text primary
key" and "value:text"
I have mapped the data successfully into JavaDStream<Tuple2<String,String>>
data :
JavaSparkContext sc = new JavaSparkContext("local[4]", "SparkStream",conf);
JavaStreamingContext jssc = new JavaStreamingContext(sc, new Duration(3000));
JavaPairReceiverInputDStream<String, String> messages =
KafkaUtils.createStream(jssc, args[0], args[1], topicMap );
JavaDStream<Tuple2<String,String>> data = messages.map(new Function<
Tuple2<String,String>, Tuple2<String,String> >()
{
public Tuple2<String,String> call(Tuple2<String, String> message)
{
return new Tuple2<String,String>( message._1(), message._2() );
}
}
);
Then I have created a List:
List<TestTable> list = new ArrayList<TestTable>();
where TestTable is my custom class having the same structure as my Cassandra
table, with members "key" and "value":
class TestTable
{
String key;
String val;
public TestTable() {}
public TestTable(String k, String v)
{
key=k;
val=v;
}
public String getKey(){
return key;
}
public void setKey(String k){
key=k;
}
public String getVal(){
return val;
}
public void setVal(String v){
val=v;
}
public String toString(){
return "Key:"+key+",Val:"+val;
}
}
Please suggest a way how to I add the data from
JavaDStream<Tuple2<String,String>> data into the List<TestTable> list.
I am doing this so that I can subsequently use
JavaRDD<TestTable> rdd = sc.parallelize(list);
javaFunctions(rdd, TestTable.class).saveToCassandra("testkeyspace",
"test_table");
to save the RDD data into Cassandra.
I had tried coding this way:
messages.foreachRDD(new Function<Tuple2<String,String>, String>()
{
public List<TestTable> call(Tuple2<String,String> message)
{
String k = message._1();
String v = message._2();
TestTable tbl = new TestTable(k,v);
list.put(tbl);
}
}
);
but seems some type mis-match happenning.
Please help.
Thanks and Regards,
Md. Aiman Sarosh.
Accenture Services Pvt. Ltd.
Mob #: (+91) - 9836112841.
________________________________
From: Helena Edelson <[email protected]>
Sent: Friday, December 5, 2014 6:26 PM
To: Sarosh, M.
Cc: [email protected]
Subject: Re: Spark-Streaming: output to cassandra
You can just do
You can just do something like this, the Spark Cassandra Connector handles the
rest
KafkaUtils.createStream[String, String, StringDecoder, StringDecoder](
ssc, kafkaParams, Map(KafkaTopicRaw -> 10), StorageLevel.DISK_ONLY_2)
.map { case (_, line) => line.split(",")}
.map(RawWeatherData(_))
.saveToCassandra(CassandraKeyspace, CassandraTableRaw)
- Helena
@helenaedelson
On Dec 4, 2014, at 9:51 AM,
[email protected]<mailto:[email protected]> wrote:
Hi,
I have written the code below which is streaming data from kafka, and printing
to the console.
I want to extend this, and want my data to go into Cassandra table instead.
JavaStreamingContext jssc = new JavaStreamingContext("local[4]", "SparkStream",
new Duration(1000));
JavaPairReceiverInputDStream<String, String> messages =
KafkaUtils.createStream(jssc, args[0], args[1], topicMap );
System.out.println("Connection done!");
JavaDStream<String> data = messages.map(new Function<Tuple2<String, String>,
String>()
{
public String call(Tuple2<String, String> message)
{
return message._2();
}
}
);
//data.print(); --> output to console
data.foreachRDD(saveToCassandra("mykeyspace","mytable"));
jssc.start();
jssc.awaitTermination();
How should I implement the line:
data.foreachRDD(saveToCassandra("mykeyspace","mytable"));?
so that data goes into Cassandra, in each batch. And how do I specify a batch,
because if i do Ctrl+C on the console of streaming-job-jar, nothing will be
entered into cassandra for sure since it is getting killed.
Please help.
Thanks and Regards,
Md. Aiman Sarosh.
Accenture Services Pvt. Ltd.
Mob #: (+91) - 9836112841.
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