Thank you for your time spent on our question.
This quick start document,
https://gobblin.readthedocs.io/en/latest/case-studies/Kafka-HDFS-Ingestion/,
shows
“source.class=org.apache.gobblin.source.extractor.extract.kafka.KafkaSimpleSource”.
That class overrides method, getExtractor, to return “new
KafkaSimpleExtractor(state)”, and class, KafkaSimpleExtractor, overrides
method, decodeRecord, to return just the Kafka message value.
return kafkaConsumerRecord.getMessageBytes()
Since we want both key and value stored in HDFS, class,
KafkaSimpleJsonExtractor, appears to provide the desired decodeRecord method:
protected byte[] decodeRecord(ByteArrayBasedKafkaRecord messageAndOffset)
throws IOException {
long offset = messageAndOffset.getOffset();
byte[] keyBytes = messageAndOffset.getKeyBytes();
String key = (keyBytes == null) ? "" : new String(keyBytes, CHARSET);
byte[] payloadBytes = messageAndOffset.getMessageBytes();
String payload = (payloadBytes == null) ? "" : new String(payloadBytes,
CHARSET);
KafkaRecord record = new KafkaRecord(offset, key, payload);
byte[] decodedRecord = gson.toJson(record).getBytes(CHARSET);
return decodedRecord;
}
The architecture diagram leads us to think that the exactor is the point where
both Kafka key and value are visible in the Gobblin pipeline:
https://gobblin.readthedocs.io/en/latest/Gobblin-Architecture/#gobblin-constructs
We are eager to learn from you.
From: Vicky Kak [mailto:vicky....@gmail.com]
Sent: Thursday, April 12, 2018 9:45 AM
To: user@gobblin.incubator.apache.org
Subject: Re: KafkaSimpleJsonExtractor
For writing the data to the HDFS you need to take a look at the Writer
Implementation, please look for it. The Extractor is used in pulling the data
which is thereafter passed through various stages before it is stored via the
Writer.
What I mean by the other subscriber was to add one more consumer which will
read the key/value e.g kafka-console-consumer.sh which comes with the kafka.
I was not earlier aware that you wanted to store the data in HFDS as you had
given the reference of the Extractor so it was not clear to me.
Please take a look at the Kafka to HDFS writer and see if that helps, in case
it is not doing what is exactly required by you then you may have to plugin the
customized writer.
On Thu, Apr 12, 2018 at 6:47 PM, Kidwell, Jack
<jack_kidwel...@comcast.com<mailto:jack_kidwel...@comcast.com>> wrote:
We want to extract both key and value from a Kafka message and publish the
combined information to HDFS. Keys contain numeric ids for the strings
contained in values.
Please explain “other subscriber”. Are you proposing a different Kafka message
structure?
KafkaSimpleJsonExtractor.java caught my attention because it extracts both keys
and values and puts them in decodedRecord.
From: Vicky Kak [mailto:vicky....@gmail.com<mailto:vicky....@gmail.com>]
Sent: Thursday, April 12, 2018 1:17 AM
To: user@gobblin.incubator.apache.org<mailto:user@gobblin.incubator.apache.org>
Subject: Re: KafkaSimpleJsonExtractor
I am not sure what you are asking for. Do you want to see the keys/values
rendered in the logs while the extraction is being done?
Why can't you have the other subscriber to the kafka which will render the
values rather than KafkaExtractor implementation rendering the same?
On Wed, Apr 11, 2018 at 11:17 PM, Kidwell, Jack
<jack_kidwel...@comcast.com<mailto:jack_kidwel...@comcast.com>> wrote:
Hi,
Using gobblin_0.10.0, we want to use module, KafkaSimpleJsonExtractor.java in
order to see both kafka record keys and values.
How does one configure a job to achieve it?
