Introduction

A Ruby gem for Google's Protocol Buffers messages using three different encodings JSON based syntax instead of the original binary protocol.

This gem extends the ruby_protobuf gem [1] to allow these new encodings in a protocol buffer message:

• [1] ruby_protobuf gem: link to github project

• [2] ProtoJson specification by DrSlump

Installation

gem install protojson -v0.2.0

Supported formats

• Hashmap: A tipical JSON message, with key:value pairs where the key is a string representing the field name.

• Tagmap: Very similar to Hashmap, but instead of having the field name as key it has the field tag number as defined in the proto definition. This can save much space when transferring the messages, since usually field names are longer than numbers.

• Indexed: Takes the Tagmap format a further step and optimizes the size needed for tag numbers by packing all of them as a string, where each character represents a tag, and placing it as the first element of an array.

How to use

Serialize a message

require 'protojson'
require 'examples/addressbook.rb'

book = Examples::AddressBook.new

person = Examples::Person.new
person.name = 'Juan de Bravo'
person.id = 21
book.person << person

Serialize using the default codec (binary)

data = Protojson.encode(book)

Serialize using a specific codec

[:json, :tagmap, :indexed].each{|codec|
    Protojson.encode(book, codec)
}

Unserialize a message

Unserialize using a specific codec

data = Protojson.encode(book, :json)
value = Protojson.decode(Examples::AddressBook, data, :json)
puts value.person[0].name # "Juan de Bravo"

Unserialize using the default codec

Protojson.set_default_codec(:json)
data = Protojson.encode(book)
value = Protojson.decode(Examples::AddressBook, data)
puts value.person[0].name # "Juan de Bravo"