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Date: Sun, 4 Sep 2016 20:44:21 +0000 (UTC)
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Subject: [jira] [Commented] (AVRO-1704) Standardized format for encoding
 messages with Avro
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archived-at: Sun, 04 Sep 2016 20:44:24 -0000


    [ https://issues.apache.org/jira/browse/AVRO-1704?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15463476#comment-15463476 ] 

ASF subversion and git services commented on AVRO-1704:
-------------------------------------------------------

Commit 30408a9c192c5f4eaaf42f01f0ffbfffd705aa57 in avro's branch refs/heads/master from [~rdblue]
[ https://git-wip-us.apache.org/repos/asf?p=avro.git;h=30408a9 ]

AVRO-1704: Add single-record encoding spec. (Contributed by Niels Basjes)


> Standardized format for encoding messages with Avro
> ---------------------------------------------------
>
>                 Key: AVRO-1704
>                 URL: https://issues.apache.org/jira/browse/AVRO-1704
>             Project: Avro
>          Issue Type: Improvement
>          Components: java, spec
>            Reporter: Daniel Schierbeck
>            Assignee: Niels Basjes
>             Fix For: 1.9.0, 1.8.3
>
>         Attachments: AVRO-1704-2016-05-03-Unfinished.patch, AVRO-1704-20160410.patch, AVRO-1704.3.patch, AVRO-1704.4.patch
>
>
> I'm currently using the Datafile format for encoding messages that are written to Kafka and Cassandra. This seems rather wasteful:
> 1. I only encode a single record at a time, so there's no need for sync markers and other metadata related to multi-record files.
> 2. The entire schema is inlined every time.
> However, the Datafile format is the only one that has been standardized, meaning that I can read and write data with minimal effort across the various languages in use in my organization. If there was a standardized format for encoding single values that was optimized for out-of-band schema transfer, I would much rather use that.
> I think the necessary pieces of the format would be:
> 1. A format version number.
> 2. A schema fingerprint type identifier, i.e. Rabin, MD5, SHA256, etc.
> 3. The actual schema fingerprint (according to the type.)
> 4. Optional metadata map.
> 5. The encoded datum.
> The language libraries would implement a MessageWriter that would encode datums in this format, as well as a MessageReader that, given a SchemaStore, would be able to decode datums. The reader would decode the fingerprint and ask its SchemaStore to return the corresponding writer's schema.
> The idea is that SchemaStore would be an abstract interface that allowed library users to inject custom backends. A simple, file system based one could be provided out of the box.


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