I was building a small app to stream messages from kafka via spark. The message was an xml, every message is a new xml. I wrote a simple app to do so[ this app expects the xml to be a single line]
from __future__ import print_function from pyspark.sql import Row import xml.etree.ElementTree as ET import sys from pyspark import SparkContext from pyspark import SparkConf from pyspark.streaming import StreamingContext from pyspark.streaming.kafka import KafkaUtils ## This is where you parse the XML dict ={} def create_dict(rt,new=None): global parent_tag for child in rt: if new == None : parent_tag = child.tag else : parent_tag = parent_tag if child.getchildren(): create_dict(child,parent_tag) else: # if child.tag in dict.keys(): # tag = tag + child.tag # else: # tag=child.tag dict[parent_tag]=child.text return dict def parse_xml_to_row(xmlString): dct={} root = ET.fromstring(xmlString.encode('utf-8')) dct = create_dict(root) return Row(**dct) def toCSVLine(data): return ','.join(str(d) for d in data) ## Parsing code part ends here #sc.stop() # Configure Spark conf = SparkConf().setAppName("PythonStreamingKafkaWordCount") conf = conf.setMaster("local[*]") sc = SparkContext(conf=conf) sc.setLogLevel("WARN") ssc = StreamingContext(sc, 10) zkQuorum, topic = 'localhost:2182', 'topic-name' kvs = KafkaUtils.createStream(ssc, zkQuorum, "spark-streaming-consumer", {topic: 1}) lines = kvs.map(lambda x: x[1]).map(parse_xml_to_row).map(toCSVLine) # lines.pprint() lines.saveAsTextFiles('where you want to write the file ') ssc.start() ssc.awaitTerminationOrTimeout(50) ssc.stop() Hope this is helpful. Puneet From: Hyukjin Kwon [mailto:gurwls...@gmail.com] Sent: Monday, August 22, 2016 4:34 PM To: Diwakar Dhanuskodi Cc: Darin McBeath; Jörn Franke; Felix Cheung; user Subject: Re: Best way to read XML data from RDD Do you mind share your codes and sample data? It should be okay with single XML if I remember this correctly. 2016-08-22 19:53 GMT+09:00 Diwakar Dhanuskodi <diwakar.dhanusk...@gmail.com<mailto:diwakar.dhanusk...@gmail.com>>: Hi Darin, Ate you using this utility to parse single line XML? Sent from Samsung Mobile. -------- Original message -------- From: Darin McBeath <ddmcbe...@yahoo.com<mailto:ddmcbe...@yahoo.com>> Date:21/08/2016 17:44 (GMT+05:30) To: Hyukjin Kwon <gurwls...@gmail.com<mailto:gurwls...@gmail.com>>, Jörn Franke <jornfra...@gmail.com<mailto:jornfra...@gmail.com>> Cc: Diwakar Dhanuskodi <diwakar.dhanusk...@gmail.com<mailto:diwakar.dhanusk...@gmail.com>>, Felix Cheung <felixcheun...@hotmail.com<mailto:felixcheun...@hotmail.com>>, user <user@spark.apache.org<mailto:user@spark.apache.org>> Subject: Re: Best way to read XML data from RDD Another option would be to look at spark-xml-utils. We use this extensively in the manipulation of our XML content. https://github.com/elsevierlabs-os/spark-xml-utils There are quite a few examples. Depending on your preference (and what you want to do), you could use xpath, xquery, or xslt to transform, extract, or filter. Like mentioned below, you want to initialize the parser in a mapPartitions call (one of the examples shows this). Hope this is helpful. Darin. ________________________________ From: Hyukjin Kwon <gurwls...@gmail.com<mailto:gurwls...@gmail.com>> To: Jörn Franke <jornfra...@gmail.com<mailto:jornfra...@gmail.com>> Cc: Diwakar Dhanuskodi <diwakar.dhanusk...@gmail.com<mailto:diwakar.dhanusk...@gmail.com>>; Felix Cheung <felixcheun...@hotmail.com<mailto:felixcheun...@hotmail.com>>; user <user@spark.apache.org<mailto:user@spark.apache.org>> Sent: Sunday, August 21, 2016 6:10 AM Subject: Re: Best way to read XML data from RDD Hi Diwakar, Spark XML library can take RDD as source. ``` val df = new XmlReader() .withRowTag("book") .xmlRdd(sqlContext, rdd) ``` If performance is critical, I would also recommend to take care of creation and destruction of the parser. If the parser is not serializble, then you can do the creation for each partition within mapPartition just like https://github.com/apache/spark/blob/ac84fb64dd85257da06f93a48fed9bb188140423/sql/core/src/main/scala/org/apache/spark/sql/DataFrameReader.scala#L322-L325 I hope this is helpful. 2016-08-20 15:10 GMT+09:00 Jörn Franke <jornfra...@gmail.com<mailto:jornfra...@gmail.com>>: I fear the issue is that this will create and destroy a XML parser object 2 mio times, which is very inefficient - it does not really look like a parser performance issue. Can't you do something about the format choice? Ask your supplier to deliver another format (ideally avro or sth like this?)? >Otherwise you could just create one XML Parser object / node, but sharing this >among the parallel tasks on the same node is tricky. >The other possibility could be simply more hardware ... > >On 20 Aug 2016, at 06:41, Diwakar Dhanuskodi ><diwakar.dhanusk...@gmail.com<mailto:diwakar.dhanusk...@gmail.com>> wrote: > > >Yes . It accepts a xml file as source but not RDD. The XML data embedded >inside json is streamed from kafka cluster. So I could get it as RDD. >>Right now I am using spark.xml XML.loadstring method inside RDD map >>function but performance wise I am not happy as it takes 4 minutes to >>parse XML from 2 million messages in a 3 nodes 100G 4 cpu each environment. >> >> >> >> >>Sent from Samsung Mobile. >> >> >>-------- Original message -------- >>From: Felix Cheung >><felixcheun...@hotmail.com<mailto:felixcheun...@hotmail.com>> >>Date:20/08/2016 09:49 (GMT+05:30) >>To: Diwakar Dhanuskodi >><diwakar.dhanusk...@gmail.com<mailto:diwakar.dhanusk...@gmail.com>> , user >><user@spark.apache.org<mailto:user@spark.apache.org>> >>Cc: >>Subject: Re: Best way to read XML data from RDD >> >> >>Have you tried >> >>https://github.com/databricks/ spark-xml >>? >> >> >> >> >> >>On Fri, Aug 19, 2016 at 1:07 PM -0700, "Diwakar Dhanuskodi" >><diwakar.dhanusk...@gmail.com<mailto:diwakar.dhanusk...@gmail.com>> wrote: >> >> >>Hi, >> >> >>There is a RDD with json data. I could read json data using rdd.read.json . >>The json data has XML data in couple of key-value paris. >> >> >>Which is the best method to read and parse XML from rdd. Is there any >>specific xml libraries for spark. Could anyone help on this. >> >> >>Thanks. dunnhumby limited is a limited company registered in England and Wales with registered number 02388853 and VAT registered number 927 5871 83. Our registered office is at Brook Green, 184 Shepherds Bush Road, London, W6 7NL, United Kingdom. The contents of this message and any attachments to it are confidential and may be legally privileged. If you have received this message in error you should delete it from your system immediately and advise the sender. dunnhumby may monitor and record all emails. The views expressed in this email are those of the sender and not those of dunnhumby.