Inter-schema references

This is a feature release 🎊

From the very beginning, this library was heavily inspired by avro_turf simplicity and features. Now it's time to say – Avrora moves one step closer to the feature set avro_turf provides.

The must-have feature inter-schema references comes to Avrora. Now you can split your huge schema into smaller pieces and glue them together via references.

What is a reference?

Reference is a canonical full name of a schema. Accordingly to Avrora name to location rules if you have schema under io/confluent/Message.avsc its full name (namespace + name) will be io.confluent.Message.

How do references work?

Technically Avro specification doesn't support inter-schema references, only local-schema references. Because of this limitation, inter-schema references implemented via embedding referenced schema into the schema which contains reference and replacing all other references within this schema with local-references.

How to use references?

For example, you have a Messenger schema which contains references to
the Message schema:

priv/schemas/io/confluent/Messenger.avsc

{
  "type": "record",
  "name": "Messenger",
  "namespace": "io.confluent",
  "fields": [
    {
      "name": "inbox",
      "type": {
        "type": "array",
        "items": "io.confluent.Message"
      }
    },
    {
      "name": "archive",
      "type": {
        "type": "array",
        "items": "io.confluent.Message"
      }
    }
  ]
}

priv/schemas/io/confluent/Message.avsc

{
  "type": "record",
  "name": "Message",
  "namespace": "io.confluent",
  "fields": [
    {
      "name": "text",
      "type": "string"
    }
  ]
}

Final compiled schema which will be stored and registered in the Confluent
Schema Registry, will looks like this:

{
  "type": "record",
  "name": "Messenger",
  "namespace": "io.confluent",
  "fields": [
    {
      "name": "inbox",
      "type": {
        "type": "array",
        "items": {
          "type": "record",
          "name": "Message",
          "fields": [
            {
              "name": "text",
              "type": "string"
            }
          ]
        }
      }
    },
    {
      "name": "archive",
      "type": {
        "type": "array",
        "items": "Message"
      }
    }
  ]
}

💢 In case of avro_turf field archive will keep its canonical items
type reference io.confluent.Message instead of local reference Message.