booch · February 10, 2014 22:19 · Feb 10, 2014
diff --git a/Ruby ORMs.md b/Ruby ORMs.md
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+Ruby ORMs
+=========
+
+
+Abstract
+--------
+
+Rails is really a collection of pieces that can be put together to create a web app.
+You can enhance or replace many of the components - how you write views, how controllers
+work, and how you build models. While models are built on top of ActiveRecord in the 
+default Rails stack, you've got a lot of other choices.
+
+In this presentation, we'll take a look at ActiveRecord and alternative ORMs.
+We'll discuss the pros and cons of each, and take a look at what the future will bring us.
+
+
+ORMs
+----
+
+* ActiveRecord
+* DataMapper
+* Sequel
+* ROM
+* Perpetuity
+* Mongoid
+* MongoMapper
+* Mince
+
+
+ActiveRecord Pros
+-----------------
+
+ActiveRecord is the 800-pount gorilla.
+
+* Ubiquitous
+  * Everyone knows it
+  * Lots of people improving on it
+  * Plugins usually assume you're using it
+  * Plenty of documentation
+* Well-tested
+* Well-understood
+* Super easy to get started
+  * It's included in Rails by default
+* ARel behind the scenes
+
+
+ActiveRecord Cons
+-----------------
+
+* Class inheritance
+  * Not (current) idiomatic Ruby
+  * Prevents a hierarchical class structure
+    * TODO: Show an example where this would be useful
+* Persistence and behavior in one class
+  * Violates SRP
+  * Makes testing harder and slower
+    * TODO: Show examples of slow tests and fast test
+* Validations are also included (another responsibility)
+* No Identity Map
+  * TODO: Show example of where this is a problem
+* Have to look 2 places to find everything:
+  * Attributes (fields) are declared in the schema
+  * Relations are declared in the model itself
+
+
+ActiveRecord Add-Ons
+--------------------
+
+* Includable ActiveRecord
+  * Solves the inheritance issue
+* Annotated Models (TODO: or its replacement)
+  * Kind of solves the problem of fields and relations in different places
+* Virtus::ActiveRecord or mini_record
+  * Solves the problem of fields and relations in different places
+* Squeel
+  * Gives a more Ruby-like API for scopes
+* Attachments (Paperclip, etc.)
+* Authentication (Devise, etc.)
+
+
+DataMapper
+----------
+
+* Actually uses the Active Record pattern
+* Supports a lot more than just SQL on the back end
+* No further development (last updated 2012-08-27)
+
+
+[Sequel](http://sequel.jeremyevans.net/)
+------
+
+* Probably the best alternative right now
+* Good documentation
+* Leverages database features (like foreign key constraints)
+* Supports almost any SQL database you can think of
+* Thread safety, connection pooling
+
+* Awesome feature - set a model to a subset of a table:
+```ruby
+DB = Sequel.connect('sqlite://blog.db')
+class Post < Sequel::Model
+  set_primary_key [:category, :title]
+  set_dataset DB[:my_posts].where(category: 'ruby').select(:category, :title, :content).order(:date)
+end
+```
+
+
+ROM
+---
+
+* Should be the best alternative in the future
+* Previously was called DataMapper 2
+  * But has diverged a lot since the name change
+* Truly implements the Data Mapper pattern
+* Taking longer to get to 1.0 than hoped
+  * Developers seem to be low-level / bottom-up types
+* Supports in-memory (PostgreSQL in the works)
+* More pieces:
+  * Axiom
+  * ROM::Relation
+  * ROM::Mapper
+  * ROM::Session
+  * Model
+* Identity Map
+
+
+Perpetuity
+----------
+
+* Worth looking at
+* Simple
+* Implements the Data Mapper patter
+* Supports MongoDB, PostgreSQL, in-memory
+* Identity Map
+
+
+Mongoid and MongoMapper
+-----------------------
+
+* See Sarah Mei's essay on why to avoid MongoDB in most cases
+* Mongoid
+  * Pretty simple
+  * Be sure to turn on MongoDB persistence!
+  * Pretty stable
+* TODO: Why to avoid MongoMapper
+
+
+Mince
+-----
+
+* Simple and light-weight (no relations)
+* Supports MongoDB, Hashy (in-memory), and DynamoDB
+* Multi-tier architecture
+  * Collections and items
+  * Causes some un-DRYness declaring fields
+* No further development (last updated 2013-06-07)
+
+```ruby
+	require 'mince'
+
+	class BookDataModel
+	  include Mince::DataModel
+	  data_collection :books
+	  data_fields :title, :publisher
+	end
+
+	class Book
+	  include Mince::Model
+	  data_model BookDataModel
+	  fields :title, :publisher
+	end
+
+	book = Book.new title: 'The World In Photographs', publisher: 'National Geographic'
+	book.save
+```
+
+
+Others
+------
+
+* [Swift](https://github.com/shanna/swift)
+* ORM Adapter
+  * Gives a standard API, sitting atop AR, DM, MM, or Mongoid
+
+
+NoORM
+-----
+
+* POROs
+* Sometimes you don't need persistence for all your models
+  * TODO: Show examples
+* MagLev
+
+
+The Future
+----------
+
+* ROM will reach 1.0 and be usable in production
+* Hopefully ROM will become the go-to ORM many cases
+* Perpetuity might become useful before ROM
+* MageLev might gather a following
+* Virtus::ActiveRecord might be a stepping-stone to ROM
+* ActiveRecord will continue to improve
+* We'll learn how to better use ActiveRecord
+
+
+References
+----------
+
+* http://solnic.eu/2011/11/29/the-state-of-ruby-orm.html
+* http://rhnh.net/2011/11/29/datamapper-retrospective
+* http://rosenfeld.herokuapp.com/en/articles/ruby-rails/2013-12-18-sequel-is-awesome-and-much-better-than-activerecord
+* Sarah Mei on MongoDB
+* http://java.dzone.com/articles/martin-fowler-orm-hate
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