[
https://issues.apache.org/jira/browse/KAFKA-3744?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15300130#comment-15300130
]
Ismael Juma commented on KAFKA-3744:
------------------------------------
Also, I took a look at the PR and it's not clear to me why `avro-binary` is
given preferential treatment:
{code}
0 and 1 specify two payload encodings (text and avro-binary); key format is
unspecified.</li>
+ <li>2 specifies that the key must be a JSON object with a property "t" c
{code}
> Message format needs to identify serializer
> -------------------------------------------
>
> Key: KAFKA-3744
> URL: https://issues.apache.org/jira/browse/KAFKA-3744
> Project: Kafka
> Issue Type: Improvement
> Reporter: David Kay
> Priority: Minor
>
> https://issues.apache.org/jira/browse/KAFKA-3698 was recently resolved with
> https://github.com/apache/kafka/commit/27a19b964af35390d78e1b3b50bc03d23327f4d0.
> But Kafka documentation on message formats needs to be more explicit for new
> users. Section 1.3 Step 4 says: "Send some messages" and takes lines of text
> from the command line. Beginner's guide
> (http://www.slideshare.net/miguno/apache-kafka-08-basic-training-verisign
> Slide 104 says:
> {noformat}
> Kafka does not care about data format of msg payload
> Up to developer to handle serialization/deserialization
> Common choices: Avro, JSON
> {noformat}
> If one producer sends lines of console text, another producer sends Avro, a
> third producer sends JSON, and a fourth sends CBOR, how does the consumer
> identify which deserializer to use for the payload? The commit includes an
> opaque K byte Key that could potentially include a codec identifier, but
> provides no guidance on how to use it:
> {quote}
> "Leaving the key and value opaque is the right decision: there is a great
> deal of progress being made on serialization libraries right now, and any
> particular choice is unlikely to be right for all uses. Needless to say a
> particular application using Kafka would likely mandate a particular
> serialization type as part of its usage."
> {quote}
> Mandating any particular serialization is as unrealistic as mandating a
> single mime-type for all web content. There must be a way to signal the
> serialization used to produce this message's V byte payload, and documenting
> the existence of even a rudimentary codec registry with a few values (text,
> Avro, JSON, CBOR) would establish the pattern to be used for future
> serialization libraries.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
