My highlights of YOW! 2011 Melbourne

I attended the YOW! 2011 Conference in Melbourne on 1-2 December 2011.

The talks

There were many great talks, and some not-so-great. For me, two talks in particular stood out as special. If I only got to listen to these two and nothing else, it would've been worth it.

Product Engineering :- Mike Lee

I first saw Mike Lee's talk on InfoQ several months ago and was really inspired by the passion of that guy, and was so happy to discover he was making an appearance at YOW.



He didn't impart any novel technical knowledge to us, nor did he tell us about the latest agile technique. In fact, everything he said in YOW was common-sense in hindsight, and virtually identical to the talks on InfoQ. And yet, it was pure pleasure to watch this man share his vision of what constituted a good product. I just did not get bored listening to this same talk for the 3rd time! Maybe it was his costume.

Two things that stood out from the talk:

• The hook :- the thing that makes a product special
• Appsterdam :- New IT hub for freedom loving developers

Temporally Quaquaversal Virtual Nanomachine Programming In Multiple Topologically Connected Quantum-Relativistic Parallel Timespaces...Made Easy! :- Damian Conway

Speaking of the hook, the title of this talk did the job. Ever since I watched Fred Simon's JavaPosse lightning talk on Positronic Variables a few months ago, I was curious about the Damian Conway's original work. As luck would have it, Damian came to tell us all about positronic variables.



Damian's Perl (and Rod logic) code was not very familiar to me, but his tongue-in-cheek introduction to quantum physics and the multi-verse was pure entertainment. Personally, I was not convinced that an Einstein-Rosenberg bridge could be harnessed as described for running computer programs due to excessive energy requirements. A computer program using positronic variables would probably be unstable and generate incoherent results due to the unpredictable superposition of multiple variations of positronic values from an indeterminate number of future multi-verses.

Other notable talks

Jim Webber gave his usual talk on RESTful systems. I'd listened to his similarly themed talks before, but it was still entertaining to watch Jim Webber's performance. The one lesson that stuck in my mind was: Use an ATOM feed to publish events so that different clients could independently maintain / reconstruct their own internal states.



Another interesting talk was Dan Ingalls telling us about Lively Kernel. Dan built a simple online load monitoring service simply using drag-on-drop from the Lively Kernel interface... cool.

The games

As usual, there were lots of fun and games between talks. Sensis developed a online (mobile) quiz game, CodeJuicer, that morphed into to be a fun hacking game instead. Too bad I did not have a laptop with me to hack on it all day, though I did manage to hack it to zero-time from home at the end of Day 1. Thoughtworks put up a quiz game and a movie title matching game, plus frozen nitrogen ice cream... all very popular. Atlassian let us shoot Nerf guns... hard to beat that.

The food

First day's food was not too good, but got better on the second day. The Beef Stroganoff was delicious.



The best parts were the free (real) coffee paid for by Aconex, and the desserts, especially the mango mousse.



Looking forward to YOW! 2012.

Personal recollections of the YOW Melbourne Conference

I attended the YOW!2010 Australia Software Developer Conference in Melbourne last week, and here is some recollection of my favourite talks. Please note this is all from memory, so I might some parts wrong.

Main themes

From the sessions I attended, some of the main recurring technical themes in this conference were:

• Consistency should be traded for Availability in typical distributed systems
• Eventual consistency over ACID
• Always expect network failures, i.e. systems must be able to tolerate partitioning
• NoSQL

Most informative talks

The Rich Get Richer: Rails 3 :- Obie Fernadez

Obie gave a enlightening summary of the events leading to and the people involved in the merging of the Merb and Rails codebases, resulting in the newly released Rails 3.0. The main drivers behind the new release were decoupling, modularity and prevention of code bloat. Many components of Rails 2 had been abstracted out and managed as third-party plug-in projects. He described Rack, Bundler, Arel and the upgrade process from Rails 2.x to 3.0. I look forward to the day when I get the chance to put all these into practice.

Integrated Tests Are A Scam :- J. B. Rainsberger

Having written myriads of tests over the years, it was easy to lose sight of the different roles of tests in different parts of the system. JB gave an excellent refresher on two fundamentals of unit tests : interaction testing and contract testing.


Interaction tests were the "normal" unit tests that I've been writing, where the external dependencies were replaced with stubs/mocks . In the example, he described interaction tests for a client assessing an external supplier. These tests were concerned with the pattern in which the system-under-test (SUT) called out to the external system (mocked out), and how the SUT responded to various return values from the external system (stubbed).


Contract tests referred to tests that verified that an external system satisfied a certain API and expected behaviour, i.e. the contract. In a strongly-typed language like Java, this contract could be abstracted out from the actual implementation of the external system into a public interface, that our code could depend on. In fact, our code would only depend on this public interface, with no knowledge of the implementation. In a strongly-typed language, any implementation of this interface would then satisfy the minimum requirements of the contract, therefore, the real implementation could be replaced with a stub. As long as the stub passed the contract tests, it would in theory make no difference to our code. Hence, we could then write integrated tests for our SUT that used the stub instead of the real implementation, which would make such tests extremely fast.

Personally, I was not too convinced that interaction and contract tests could fully replace the need for integrated tests against real external systems. There would always be unexpected surprises lurking in system configuration, and some behaviour could not be adequately captured by the abstracted interface. Furthermore, in dynamically typed languages, it would be much harder to enforce that the stub fully implemented the public interface.

Designing and Implementing RESTful Application Protocols :- Ian Robinson

Ian walked us through an example from his new book, REST in Practice, to illustrate the interactions of a client program ordering coffee beans from a coffee supplier via a RESTful interface.

The client first asked the server for a list of allowed operations. After that, it requested a quote of available product prices. It then placed an order by resubmitting all the pricing data it had previously received back to the server. In this way, the client could maintain conversation state over a stateless protocol. A checksum of the data was used to prevent price tampering by the client. Finally, the server immediately returned a HTTP 202 response, before kicking off the long-running order fulfillment process asynchronously.

Ian explained several basic concepts such as the use of media types, link relations and XForms in driving the process flow.

I found Ian's talk to be clear and concise, therefore I'm putting his book on my wish-list.

Most interesting talks

Exploring NoSQL :- Erik Meijer

This talk started a bit a slowly with an (mostly unecessary) explanation of how an object graph was represented in memory using pointers. This type of representation was embodied by noSQL, whereas SQL embodied a fully normalized relational view of data.

Things became interesting when Erik started describing Category Theory. Erik reasoned that because the direction of parent-child relationships was reversed between SQL and noSQL, they were duals of each other according to Category Theory. In other words, noSQL was actually "coSQL", i.e. for any statement that was true of SQL, the dual-statement (opposite meaning) would hold true for noSQL. Some examples of this duality were:

SQL	noSQL
The identity is embodied in the row, i.e. primary key (extensional)	Identity of an object depended on other objects in the environment (intensional)
Closed-world view of data	Open-world view of data
Synchronous operations	Asynchronous operations

A very interesting concept indeed. Furthermore, this talk had the most obscure slide ever...

Computational Information Design :- Ben Fry

This talk was worth attending just for the visual candy itself. Ben talked about data visualization using his Processing programming language (IMO really a DSL over Java 2D/3D). Some of the examples shown were really amazing, such as:

• Mapping the program flow in old cartridge-based video games
• Tracking changes to six editions of Charles Darwin's work
• Comparing the human genome with other mammals

Ben then introduced Processing.js that allowed code written in Processing to be run on any HTML5 compatible browser. People could simply go to sketch.processing.org to write and run Processing code all within a Web browser. What was even more exciting was a port of the Processing runtime to Android, which meant I could run Processing programs on my smartphone. Super cool!

Workshop

For me, the best part of the conference was the iPhone workshop. Having done some Android development, I was eager to see how things worked on the iPhone side. In this half-day workshop, I learned some basic syntax of Objective-C, basic usage of xcode IDE, some iPhone frameworks, and finally put together a simple iPhone application. My verdict of Objective-C :- dynamic typing and late binding were nice, but the extremely verbose syntax really sucked. I guess I'll stick with Android for now.