jackdaw.serdes.avro — fundingcircle/jackdaw 0.7.2

DEPRECATION NOTICE:

This namespace is deprecated and will soon be removed. Please use jackdaw.serdes.avro.confluent.

Generating Serdes mapping Clojure <-> Avro.

The intentional API of this NS has three main features - SchemaCoercion, the intentional type registry (of which #'+base-schema-type-registry+ is an example) and #'avro-serde.

avro-serde is the primary entry point to this namespace for users. It's a function of a schema-registry configuration, a schema type registry, and a serde configuration to be instantiated.

The intent is that an end user will partial the avro-serde function with their schema registry details and desired type registry, and use the partial'd function as en entry in a registry as used by jackdaw.serdes/serde.

This allows serdes and avro-serde to be agnostic to application or environment specific configuration details.

But what's this type registry?

Apache Avro "logical types" - a tool for annotating fields in an avro record as having some complex interpretation beyond their serialized format. The type-registry for the purposes of the avro-serde function a mapping of addresses to functions which will when invoked build and return a SchemaCoercion instance.

When a Serde is instantiated, a stack of SchemaCoercion coersion helpers is built which will - given a simply deserialized Avro record - walk its tree coercing its to Clojure types as defined by the SchemaCoercion helpers.

The SchemaCoercion stack is built by statically inspecting the parsed Avro schema, and using the type (if any) and potentially logical type to select a handler in the type-registry which will, given a function with which to recurse and the schema of that node, build and return a SchemaCoercion handler.

This registry pattern is deliberately chosen so that Avro coercion will be customizable by the user. As an example, the +UUID-type-registry+ is included, which defines a mapping from two different logical UUID refinements of the binary string type to an appropriate handler.

A user who wanted to opt into these handlers could simply call avro-serde with (merge +base-schema-type-registry+ +UUID-type-registry+)

Users are HIGHLY encouraged to use the +base-schema-type-registry+ as the base for their type registries, as it defines sane handlings for all of Avro's fundamental types and most of its compounds.

+base-schema-type-registry+ clj

Provides handlers for all of Avro's fundamental types besides fixed.

Fixed is unsupported.

+UUID-type-registry+ clj

A type constructor registry.

Provides the logical types uuid and jackdaw.serdes.avro.UUID coded as strings with coercion to round-trip java.util.UUID instances.

as-edn clj

(as-edn {:keys [type-registry coercion-cache avro-schema] :as coercion-stack}
        json+avro)

Returns the edn representation of the supplied json+avro

json+avro is an avro object represented as a json string

as-json clj

(as-json {:keys [type-registry avro-schema coercion-cache] :as coercion-stack}
         edn+avro)

Returns the json representation of the supplied edn+avro

edn+avro is an avro object represented as an edn object (compatible with the jackdaw avro serde)

avro-bytes? clj

Returns true if the object is compatible with Avro bytes, false otherwise

• byte[] - Valid only as a top level schema type
• java.nio.ByteBuffer - Valid only as a nested type

class-name clj

(class-name x)

Returns a human readable description of x's type

make-coercion-stack clj

(make-coercion-stack type-registry)

Given a registry mapping Avro type specs to 2-arity coercion constructors, recursively build up a coercion stack which will go clj <-> avro, returning the root coercion object.

(satisfies SchemaCoercion)

num-coercable? clj

(num-coercable? x coercion-fn)

Checks whether x can be coerced to a number with coercion-fn (such as long).

parse-schema-str clj

SchemaCoercion clj protocol

avro->clj clj

(avro->clj schema-type avro-data)

clj->avro clj

(clj->avro schema-type clj-data path)

match-avro? clj

(match-avro? schema-type avro-data)

match-clj? clj

(match-clj? schema-type clj-data)

serde clj

(serde type-registry
       {:keys [avro.schema-registry/client avro.schema-registry/url]
        :as registry-config}
       {:keys [avro/schema avro/coercion-cache key? deserializer-properties]
        :as topic-config})

Given a type and logical type registry, a schema registry config with either a client or a URL and an Avro topic descriptor, build and return a Serde instance.

serialization-error-msg clj

(serialization-error-msg x expected-type)

single-float? clj

(single-float? x)

validate-clj! clj

(validate-clj! this x path expected-type)