Virtual Surreality

You can hear my dulcet tones at Ruby5 eposide 106 hosted with Jon “Lark” Larkowski.

It was great fun – he made me do the accent at the beginning and we had a lot of laughs over the “it’s gonna rain” part.

Hope you find it of use and if you have some Ruby news, please do submit stories to Lark.

Came across this twice in the past two weeks.

How NOT to do it:

$('form :submit').click(function() {
    $(this).attr("disabled", true);
    $(this).val("wait...");
    $(this).addClass("disabled");
});

Doing it the above way, the click event will indeed fire, but on some browsers the submit event will not.

The event to bind to is submission of a form, not clicking of a submit button.

How to do it:

$('form').submit(function() {
    $(":submit").attr("disabled", "disabled");
    $(":submit").val("wait...");
    $(":submit").addClass("disabled");
});

Also, the :submit selector is a jQuery cross-browser selector for input and button elements that could submit the form, used in preference to input[type="submit"]

A little “remember me later” for conditionally deploying a Rails 3 app running on Ruby 1.9 on Heroku.

$ruby_version = `ruby --version`.split[1].to_f
$heroku = ENV['USER'].match(/^repo\d+/)

source :rubygems
source 'http://gems.github.com'

gem 'rails', '3.0.0.beta4'
# gem 'rails', :git => 'git://github.com/rails/rails.git'

gem 'bson_ext', '~> 1.0.1'
gem 'decent_exposure'
gem 'haml'
gem 'mongoid', '>= 2.0.0.beta.9'

unless $heroku
  if $ruby_version < 1.9
    gem 'ruby-debug'
  else
    gem 'ruby-debug19'
  end

  group :development, :test do
    gem 'rspec-rails', '>= 2.0.0.beta.17'
    gem 'rails3-generators' #for HAML
  end
end

The --without=test option isn’t (yet) being used on Heroku deploys, thus the :test group is in the unheroku block. Update: check if .bundle/config WITHOUT="" works.

Update: Mongoid changed gem versioning for lexicographical sorting (a “dot” between “beta” and the number
Update: Latest mongoid (beta.16 and something after beta.9) requires Rails 3.0.0.rc which doesn’t support Ruby 1.9.1 which isn’t yet on Heroku
Update: Heroku user doesn’t have “repo” in it anymore and USER env var isn’t available – find new mechanism if bundler config WITHOUT option doesn’t work

Also:

• Only the --colo(u)r and --format options work in the .rspec file
• use_transactional_fixtures=false in spec_helper.rb (talk to Chelimsky about transactional fixtures in non-ActiveRecord environments)
• In application.rb:
  • require 'mongoid/railtie'
  • require 'decent_exposure/railtie'
  • g.orm :mongoid
  • g.template-engine :haml
  • g.text_framework :rspec, :fixture => false, :views => false

WindyCityDB – great conference!

I did a lightning talk on squealer, and here is the PDF of the slides (1.7MB)

squealer Lightning Talk slides

One evening in May, 2006 at a ThoughtWorks Sydney company meeting, Richard McLaren (then a Senior VP of ThoughtWorks) and I made a bet with Jon Tirsen (now Google überwunderkind) and Roy Singham (still Chairman of ThoughtWorks) about Ruby in the Enterprise.

The claim from Roy and Jon was that within five years, 10% of applications running in the Enterprise would be written in Ruby. Richard and I bet against that. The prize is a case each of the winners’ favourite potable.

I’ve since been steadily working to try to lose that bet, and now code daily in Ruby at Hashrocket.

Alas, with just one year to go, I think Richard and I are going to win. Although there’s been a decent growth in Ruby’s adoption in the Enterprise, my esteemed colleagues underestimated the lack of capability, talent, and intellect of the majority of corporate IT decision makers.

Object/Relational Mappings (ORM’s) are in the wrong place in the architecture.

An application should have minimal impedance mismatch with the persistence of its own data. External or ancillary systems should bear the cost of mapping between paradigms. If you are writing an application with the concepts modelled in an object-oriented fashion, then the state of those objects should be stored in an object-oriented fashion. Mapping from the object-oriented structure to a relational structure should be done where and when it’s needed. If you want to access application data in a relational way for reports, do the mapping for the report.

There has been a low uptake of OODBMS’s. Why is outside the scope of this post. However, there are other, older (albeit feeling newer) data storage techniques available that more readily persist an object graph than a relational database. A flurry of open-source implementations have come along. You may have heard of MongoDB, neo4j, Redis, Hadoop, CouchDB, Memcached, and Raven DB (a native .NET document database). These are all under active development, and almost all have been proven on many large commercial projects (Raven was being developed by Oren while he was at speakerconf 2010!).

For an introductory look at evaluating the landscape, check out Sarah Mei’s RailsConf presentation slides.

One of the projects I’ve worked on at Hashrocket involved a large MongoDB database. The reasons for the choice for MongoDB were clear:

• the way the users handled most of the data more naturally fitted an embedded document model;
• the scale and speed required were far greater than relational databases could achieve; and
• the need for ACID transactions was almost nil

Additionally, the data was mostly read, rather than written (although MongoDB writes blazingly fast too). I’m hoping to address the equivocations in those reasons in a subsequent post.

MongoDB uses a binary form of JSON. As JSON is a serialization format for object state, it’s a good candidate for persisting an object graph. JavaScript, remember, uses composition rather than inheritance, so there is also a tendency to “embed” document instances within other document instances. So, for MongoDB, most of the object graph is stored a tree structure. Cyclic graphs and associated objects (those that aren’t aggregated with composition) are handled with references to identifiers.

As a consequence of using Rails and MongoDB, the team looked to various ways of manipulating the JSON structures from Ruby: directly through the driver, MongoMapper, MongoDoc, and Mongoid. The rationales behind these libraries and their different and interesting approaches are the subject of additional blogs (hopefully jointly with Nunemaker, Hill, and Jordan respectively). The needs and makeup of the project we were on fell into the lap of mongoid to solve.

DBAs want to interact directly with the database. Because of this “new-fangled” approach to data storage that has been around since before SQL, some are unwilling or unable to learn the query language to interact directly with the database. So, to make their world a less scary place and let them retire without the stress of intellectual endeavour, I built a simple, declarative language where the mapping from the tree structure of MongoDB to the tuple space in an RDBMS can be scripted.

Durran Jordan (author of Mongoid) and I paired on “squealer” (and on emptying bottles) in our evenings while he was stationed in the Chicago office of Hashrocket. The name came from “SQL” (which some of us still pronounce “squeal” rather than “sequel”) and the facetious notion that it turned the data into a pig.

We decided to focus on mySQL as the target and MongoDB as the source as these are the technologies we were using. Upcoming targets will include PostgreSQL, SQL Server, Oracle. Upcoming sources will include Redis and CouchDB.

UPDATE: squealer 2.2 now supports PostgreSQL!

Matt Yoho provided multiple insights into implementing the Ruby DSL, and Bernerd Schaefer helped me reduce the DSL syntax and provide sensible defaults (as well as the righteous progress bar). Bernerd then struck on the idea of reflecting on the Mongoid declarations in the Rails domain model classes to generate an initial squealer script and SQL DDL to build the target SQL database. He then set about writing it overnight and we tweaked it over lunch. We called this tool “skewer”, because that’s what you do to something to make it squeal . It’s part of the squealer RubyGem.

Next time: how to use skewer and squealer.

After 4.5 years at ThoughtWorks, I’ve put down the purple elephant and donned my spacesuit to join Hashrocket and open the Chicago office.

Hashrocket is the world’s best Ruby on Rails shop — a world-class team of spectacular developers, lead by my former and now current colleague Obie Fernandez.

Our Chicago office has been set up to help draw in more talent to meet our growing client needs. Some devs would prefer to live in a big city and Chicago has a strong Ruby community.

If you’re a Rubyist in Chicago, you can look forward to Hashrocket soon hosting some of the user groups and other events. We will be open at 661 W Lake St on Feb 1, 2010.

Announcing PreparedEval, prepared statements for generating JavaScript (and the like) from Java. It prepares Java strings for JavaScript evaluation, similar to SQL prepared statements. Saves you from quote escape nightmares! Great for Selenium tests and Rhino JavaScript.

As a follow-up to my post on escaped, quoted strings, Taking the idea of using a different encoding scheme further (and not being super happy about the need to pump the string through unescape()) I thought about interpolation and wondered about prepared statements in SQL. Some quick research turned nothing up, but while chatting with Ola Bini he also mentioned prepared statements, so this convinced me to knock something together that might be useful.

More information is at http://wiki.github.com/delitescere/PreparedEval.

There’s no runtime dependencies so it’s nice and tiny if you just want the JAR.

Let me know if you use if to help with CSS / XPath selectors for Selenium or if you have any suggestions on improving the API.

When you have more backslashes than words in the strings you are constructing, perhaps it’s time to look at another way of handling special characters like quotes.

The problem

You’re generating JavaScript code from another language with C-like quoting and escaping syntax (e.g. Java).

As part of that code generation, you’re substituting strings that have both double quotes (“) and single quotes (‘). My team’s actual problem stems from using XPath locators which include quoted text and sending that to Selenium so we can obtain the particular element that contains the text^*.

Let’s say we want to pop up an alert within which are some double quotes:

String original = "Hello \"stranger\", how are you?";
String quoted = original.replaceAll("\"", "\\\"");
String script = "alert(\"" + quoted + "\")";
eval(script);

We then expect the browser to have this JavaScript code to process:

alert("Hello \"stranger\", how are you?")

and when then expect the alert to display the string:

Hello “stranger”, how are you?

But why doesn’t it work?
continue reading…

I’m visiting our India operation for a few months, mostly at our Pune office. I’m trying my hand at various coaching activities on a number of fronts, including working with some of our technical leads, aspiring architects, business development team, and recruitment.

I’ve always been a fan of our teams in India and China. In the early days of the ThoughtWorks Sydney office, to help fill the rapidly growing demand pipeline, we were able to bring people in from TW offices around the world, including some from India (Nitesh rocks!). We also had to distribute some delivery work to India (and later, China too) on some large projects. This was an eye-opening time for us in learning how to make Agile software development work across teams in different places and timezones. (People like Ben Hogan, Naresh Jain, Shyam Mohan, and Jane Robarts have been able to share some of that experience at conferences.)

It wasn’t the reduced rates that these projects were able to offer to clients that appealed to them – it was the large capacity of ThoughtWorks talent available that we simply couldn’t fill quickly enough locally. ThoughtWorks and clients alike insisted on top grade delivery team members, no matter where they happened to be located during any given iteration (we rotated people through the locations quite a bit to engender better collaboration, shared understanding, and teamwork).

Being a senior member of the company for four years, I had always felt a little incomplete in not having visited any offshore teams – based on the stories from others who had visited, I was missing out. I’m pleased now I’m here and I can experience for myself the atmosphere, attitude and aptitude of the Pune office and I’ll get to meet everyone from Chennai and Bangalore at the ThoughtWorks India Away Day in a few weeks.

It’s also pleasing that we have evolved the offshore capability to the point it is a compelling set of offerings that really appeal to companies looking for top quality, technical innovation, agile software delivery, and commitment to results within leaner budgets. http://offshore.thoughtworks.com/

I’m very excited to be here right now. Amanda is knocking out her “F# In Action” book from Manning as fast as an autorickshaw darts between pedestrians, I’m working with some awesome new and old faces, and the dal makhani is delicious!

However, I’m not having much luck getting people to call me “RoganJoshG”…