= CBOR for Ruby

This is a Ruby implementation of the CBOR[http://cbor.io] encoding, based on
the (polished) high-performance msgpack-ruby code.

Documentation will follow, but generally, if you replace MessagePack
and msgpack with CBOR and cbor in the text cited from MessagePack
below, you will be on the right track.  For a starter:

    require 'cbor'
    s = [1, 2, 33.5, 4].to_cbor  #=> "\x84\x01\x02\xF9P0\x04"
    CBOR.decode(s)  #=> [1, 2, 33.5, 4]

Use RubyGems to install:

    gem install cbor

CBOR is an object representation format defined by the IETF[http://ietf.org].
The specification[http://tools.ietf.org/html/rfc8949]
is an IETF Standards-Track specification
and has been published as RFC 8949 (superseding the older RFC 7049).

This is all based on wonderful work by frsyuki, and I have no idea how
to acknowledge him appropriately.  This gem is not intended to fork or
supersede MessagePack[http://msgpack.org], which has a vibrant
ecosystem.  It is just making use of the high-quality code that is
available in this community.  If MessagePack works for you, go for it.
If you need CBOR, you need this.

Todos:

* This code has not yet been fully optimized, so it is still a few
  percent slower than msgpack-ruby.

* Properly document things, in particular the classes CBOR::Simple and
  CBOR::Tagged.  If you check out the source, you can +rake+ +doc+ to
  get some documentation in the directory +doc+ (see +index.html+ there).

* Cover more rubies.
  * \[✔✔✔✔] tested on MRI (1.9.3, 2.0.0, 2.1.10, 2.2.10, 2.3.7, 2.4.4 and 2.5.1).
  * (\[✔] There now also is some basic MRI 1.8.7 compatibility, however 1.8.7 does not support differentiation between byte and text strings.)
  * \[✔] tested on Rubinius 2.4.1.
  * \[_] Publish the pure-ruby version and make it work the same way on JRuby.

* Find and implement good ways to offer CBOR's indefinite length
  ("streaming") capability at the Ruby API level.  (Decoding is fully
  supported, just no streaming or indefinite length encoding.)

* Rename some of the internals from msgpack to cbor.  Right now, much
  of the code still uses the name msgpack in its identifiers, to
  facilitate merging upstream fixes.  (The msgpack and cbor gems
  coexist nicely in one MRI instance due to the magic in +renamer.h+.)

Same Apache 2.0 License applies to the changes as to the original.
For the changes:

Author::    Carsten Bormann <cabo@tzi.org>
Copyright:: Copyright (c) 2013, 2014 Carsten Bormann
License::   Apache License, Version 2.0

{<img src="https://travis-ci.org/cabo/cbor-ruby.svg?branch=master" />}[https://travis-ci.org/cabo/cbor-ruby] {<img src="https://badge.fury.io/rb/cbor.svg" alt="Gem Version" />}[http://badge.fury.io/rb/cbor]

For the original, see below.

= MessagePack

MessagePack[http://msgpack.org] is an efficient binary serialization format.
It lets you exchange data among multiple languages like JSON but it's faster and smaller.
For example, small integers (like flags or error code) are encoded into a single byte,
and typical short strings only require an extra byte in addition to the strings themselves.

If you ever wished to use JSON for convenience (storing an image with metadata) but could
not for technical reasons (binary data, size, speed...), MessagePack is a perfect replacement.

    require 'msgpack'
    msg = [1,2,3].to_msgpack  #=> "\x93\x01\x02\x03"
    MessagePack.unpack(msg)   #=> [1,2,3]

Use RubyGems to install:

    gem install msgpack

or build msgpack-ruby and install:

    bundle
    rake
    gem install --local pkg/msgpack


= Use cases

* Store objects efficiently serialized by msgpack on memcached or Redis
  * In fact Redis supports msgpack in EVAL-scripts[http://redis.io/commands/eval]
* Upload data in efficient format from mobile devices such as smartphones
  * MessagePack works on iPhone/iPad and Android. See also Objective-C[https://github.com/msgpack/msgpack-objectivec] and Java[https://github.com/msgpack/msgpack-java] implementations
* Design a portable protocol to communicate with embedded devices
  * Check also Fluentd[http://fluentd.org/] which is a log collector which uses msgpack for the log format (they say it uses JSON but actually it's msgpack, which is compatible with JSON)
* Exchange objects between software components written in different languages
  * You'll need a flexible but efficient format so that components exchange objects while keeping compatibility


= Portability

MessagePack for Ruby should run on x86, ARM, PowerPC, SPARC and other CPU architectures.

And it works with MRI (CRuby) and Rubinius.
Patches to improve portability is highly welcomed.


= Serializing objects

Use *MessagePack.pack* or *to_msgpack*:

    require 'msgpack'
    msg = MessagePack.pack(obj)  # or
    msg = obj.to_msgpack

== Streaming serialization

Packer provides advanced API to serialize objects in streaming style:

    # serialize a 2-element array [e1, e2]
    pk = MessagePack::Packer.new(io)
    pk.write_array_header(2).write(e1).write(e2).flush

See {API reference}[http://ruby.msgpack.org/MessagePack/Packer.html] for details.

= Deserializing objects

Use *MessagePack.unpack*:

    require 'msgpack'
    obj = MessagePack.unpack(msg)

== Streaming deserialization

Unpacker provides advanced API to deserialize objects in streaming style:

    # deserialize objects from an IO
    u = MessagePack::Unpacker.new(io)
    u.each do |obj|
      # ...
    end

or event-driven style which works well with EventMachine:

    # event-driven deserialization
    def on_read(data)
      @u ||= MessagePack::Unpacker.new
      @u.feed_each(data) {|obj|
         # ...
      }
    end

See {API reference}[http://ruby.msgpack.org/MessagePack/Unpacker.html] for details.


= Buffer API

MessagePack for Ruby provides a buffer API so that you can read or write data by hand, not via Packer or Unpacker API.

This {MessagePack::Buffer}[http://ruby.msgpack.org/MessagePack/Buffer.html] is backed with a fixed-length shared memory pool which is very fast for small data (<= 4KB),
and has zero-copy capability which significantly affects performance to handle large binary data.

= How to build and run tests

Before building msgpack, you need to install bundler and dependencies.

    gem install bundler
    bundle install

Then, you can run the tasks as follows:

* Build

    bundle exec rake build

* Run tests

    bundle exec rake spec

* Generating docs

    bundle exec rake doc

= Copyright

Author::    Sadayuki Furuhashi <frsyuki@gmail.com>
Copyright:: Copyright (c) 2008-2013 Sadayuki Furuhashi
License::   Apache License, Version 2.0

