Although S3's data storage and retrieval model looks presently better suited for larger units of data (e.g. media content), it would be interesting to investigate how it could be applied as an Object persistence service.

In the following example, we will use Ruby's AWS::S3 library to create a class resembling Ruby on Rails' ActiveRecord::Base, allowing Objects to be persisted to and retrieved from an S3 Bucket.

Objects need to be somehow serialized and de-serialized in order to be successfully stored and retrieved from S3. YAML is one of the standard means to object serialization in Ruby, so we will be making use of it.  

require 'yaml'
require 'aws/s3'

class S3Record
  attr_accessor :id
  
  def initialize(attrs = {})
    attrs.each { |k, v| instance_eval "self.#{k} = v" }
  end
end 

Requiring YAML provides S3Record with, among other functionality, a to_yaml instance method. Next, we add the ability to persist an instance of S3Record to S3. 

def create
  AWS::S3::S3Object.find(@id, self.class.name)
  raise "Object with key [#{@id}] already exists"
rescue AWS::S3::NoSuchKey
  AWS::S3::S3Object.store(@id, self.to_yaml, self.class.name)
end

The first parameter to the AWS::S3::S3Object#find method is the unique identifier by which the Object will be keyed when stored and will be the one used to find the object.

The second parameter is the name of the Bucket in which the object will be stored. Here, we use the name of our class as the bucket name. This implies that a bucket with a matching name to this of our class must exist before we can start storing objects. 

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