Extension library to enable easier tapping of pails.
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Extension library to enable easier tapping of pails.

Built on top of David Cuddeback's clj-pail.


Add clj-pail to your project's dependencies. If you're using Leiningen, your project.clj should look something like this:

(defproject ...
  :dependencies [[clj-pail-tap VERSION]])

Where VERSION is the latest version on Clojars.

Defining a PailStructure

You can generate classes that implement the PailStructure interface with the gen-structure macro from the clj-pail-tap.structure namespace. The PailStructure interface is used by Pail to serialize, deserialize, and keep organized your data.

(ns ...
  (:require [clj-pail-tap.structure :as s]))

(s/gen-structure com.example.pail.DefaultPailStructure)

gen-structure uses gen-class. So any namespace that uses gen-structure needs to be AOT-compiled. In Leiningen, add your namespace to the :aot key in project.clj:

(defproject ...
  :aot [myproj.ns.that.uses.clj-pail.structure])


By default, a PailStructure class generated with gen-structure will do nothing. It will be defined to handle byte[]; serialization and deserialization will do nothing (because your data is already a byte array); and no vertical partitioning will be defined.

These behaviors can be specified with options to gen-structure:

(s/gen-structure com.example.pail.CustomPailStructure
                 :type DataUnit-A-Thrift-Class.
                 :schema DataUnit-Some-Prismatic-Schema-definition.
                 :serializer (CustomDateSerializer. DataUnit-A-Thrift-Class)
                 :partitioner (DailyDatePartitioner.)
                 :tapmapper (DataUnit-tapmapper)
                 :property-path-generator (DataUnit-property-paths)
                 :prefix "date-")

Type and schema are mutually exclusive. Type should be used for objects, whereas Schema is for the situation when the serializer is Fressian instead of thrift and the schema is Prismatic schema rather than graph schema.

Property-path-generator should be a function which takes whichever is being used, type or schema, and returns a list of property path vectors.

Tap Mapper should be a function that can be mapped to output of the property-path-generator and provides property path which correlates to the path the partitioner would create.

The Pail Graph library uses graph schema and thrift. Where the Pail Schema library uses Prismatic Schema and Fressian.

Both libraries provide full tap mapping features.


Copyright © 2014 Eric Gebhart

Distributed under the MIT License.