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Avro-repository for Clojure

CircleCI Clojars Project

A little library for managing Avro schemas in your Clojure projects.

This is a part of thdr/kfk project: clients and helpers for working with Apache Kafka in Clojure.

Install

Boot / Leiningen

[io.thdr/avro-repo "0.1.0"]

Maven

<dependency>
  <groupId>io.thdr</groupId>
  <artifactId>avro-repo</artifactId>
  <version>0.1.0</version>
</dependency>

Usage

Loading schemas.

Make sure you schemas directory is accessible somewhere on the classpath.

Use (load-schemas! schemas-path) to load Avro schemas into your app. load-schemas! returns a map where the key by default is a kebab-cased and keywordized schema's filename and the value is an org.apache.avro.Schema instance.

You can provide :key-fn option to customize keys in a resulting map:

(load-schemas! schemas-path 
               {:key-fn (fn [basename schema] (.getName schema))})

Sharing custom types and schemas

If types or includes directories are present on provided schemas-path, they will be loaded first. Avro-repo loads schemas in the following order:

:schemas-path:/types/**/*.avsc
:schemas-path:/includes/**/*.avsc
everithing else on :schemas-path:

Using schemas

A map with schemas can be accessed directly though it's better to create a record with proto/SchemaRepo protocol implemented and use it with something like Component library.

Note that values are raw Schema instances and JSON-serialization is quite expensive. If you need each Schema to be serialized to JSON (for example, when working with Confluent's schema-registry), be sure to implement some kind of caching mechanism. In future versions I'm thinking of adding this feature to this library.

(ns schema-repo
  (:require [com.stuartsierra.component :as component]
            [thdr.avro-repo
			  [core :refer [load-schemas!]]
			  [proto :as proto]]))
		     
(defrecord Schemas [schemas]
  component/Lifecycle
  
  (start [this]
	(assoc this :schemas (load-schemas!)))

  (stop [this]
    (assoc this :schemas {}))
	
  proto/SchemaRepo
  
  (get-schema [this k]
    (get schemas k)))

Contributing

Feel free to open an issue or PR.

License

Copyright © 2016 Theodore Konukhov me@thdr.io

Distributed under the Eclipse Public License either version 1.0 or (at your option) any later version.