Generate Apache Avro schemas for BrAPI

[guydavenport]

Generate Apache Avro schemas for BrAPI. Make use of schema evolution from one version of BrAPI to another.

[tyrwh]

The total size of JSON responses can be very large compared to the size of the deserialized data, given the repetition of field names. This is noticeable when a client is requesting phenotypic evaluation data, which typically involves requests to both /observations/ and /observationUnits/ endpoints.

A more efficient serialization schema like Avro might make it faster to transmit large volumes of data.

Avro's native support for aliases seems useful in the context of cross-program data exchange and synchronization. If a group has used certain field names for a long time (Accession mapping to germplasmName, for example), then many of their workflows are probably built around this. When they view data fetched by a client, they presumably would like this data to use their local aliases. Aliases accompanying every message may simplify this process of field renaming.