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https://issues.apache.org/jira/browse/AVRO-1704?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15712508#comment-15712508
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Ryan Blue commented on AVRO-1704:
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With a spec like this, we want to be careful about having too many things that
must be implemented. I think there would have to be a very good reason to add
additional hashes to the spec.
If you're interested in using the Avro MessageEncoder and MessageDecoder, then
that shouldn't be too difficult because the code is modular enough you can
implement a decoder for your message format fairly easily.
> 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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