On 27 May 2013 20:00, Stefan Krawczyk <ste...@nextdoor.com> wrote: > So it's up to you what you stick into the body of that Avro event. It > could just be json, or it could be your own serialized Avro event - and as > far as I understand serialized Avro always has the schema with it (right?). >
In an Avro data file, yes, because you just need to specify the schema once, followed by (say) a million records that all use the same schema. And in an RPC context, you can negotiate the schema once per connection. But when using a message broker, you're serializing individual records and don't have an end-to-end connection with the consumer, so you'd need to include the schema with every single message. It probably doesn't make sense to include the full schema with every one, as a typical schema might be 2 kB whereas a serialized record might be less than 100 bytes (numbers obviously vary wildly by application), so the schema size would dominate. Hence my suggestion of including a schema version number or hash with every message. Be aware that Flume doesn't have great support for languages outside of the > JVM. > The same caveat unfortunately applies with Kafka too. There are clients for non-JVM languages, but they lack important features, so I would recommend using the official JVM client (if your application is non-JVM you could simply pipe your application's stdout into the Kafka producer, or vice versa on the consumer side). Martin
