YOW will be making the presentations and videos available online in due course.
1 - What I Learnt
- Continuous Delivery of Business Value
- JS everywhere, REST, push technologies, HTML5
- Having fun with technology
Continuous Delivery/Business Value sessions
Continuous Design - Mary Poppendieck
- Assemble Diverse Team
- Frame the problem
- Ideation - prototype
- Iterate back to 3, or Reformat the problem/pivot back to 2
Continuous Design puts coding into this loop
The Learning Cycle. Learn -> Model -> Build -> Measure -> Learn ...
The fastest learner wins.
A small, experienced, dedicated, self empowered team can introduce 4x more product - George Stalk, competing against time.
Need good people, whole team (marketing, design, dev, test, ops, support)
Measure product metrics not project metrics
Amazon.com, working backwards:
- Write a press release
- Write FAQs
- Describe customer experience
- (Write User Manual)
- Start with hypothesis - a business growth model
- Establish a baseline - the Minimum Viable Product
- Target every initiative at a Growth Metric
- Split Test A/B
- Definition of Done includes feature value validated
- Measure a cohort of new users every week
- Track behaviour of each cohort against product events and changes
Mary then covered some continuous delivery principles - which made Jez Humble and Martin Fowler adjust their subsequent presentation somewhat :-)
- Low Dependency Architecture
- Feature Toggles
- Trunk-based development
- Branch by abstraction
- Canary releasing
Continuous Delivery - Jez Humble, Martin Fowler
This covered many of the concepts from the excellent Continuous Delivery book. I won't repeat this content - go read the book. Some useful soundbites from the talk:
- On acquisition, Flickr were initially told by Yahoo to stop continuous deployment. The Flickr team then gained stats that they had less downtime than any of the other Yahoo services. Flickr deploy approx 10x/day to production. Downtime was 4 x 6mins per year.
- Mingle has 20 hours of acceptance tests. Running in parallel across 70 boxes, these complete in 45 minutes.
- On any acceptance test failure you should find out how it got through, and beef up your commit tests to catch the failure earlier.
- The job of the deployment pipeline is to kill code that isn't suitable for release
- Devops - development is measured on throughput, operations on stability. Need to establish a culture of collaboration, automation, measurement, sharing.
- Dark launching - deploy back end service first before switching it on
- Benefits in decoupling deployment and release (eg. using feature toggles). Facebook has every major feature to be released in the next 6 months already deployed to production, and waiting to be released.
Introducing Continuous Delivery
- Focus on behaviours, not tools
- People are the key
- Get everyone together at the beginning
- Keep meeting
- Make it easy for everyone to see what's happening (eg. big visible display)
- Kaizen. Continuous Delivery should be part of continuous improvement process. It's going to take months. Do it step-by-step.
ITIL and Continuous Delivery
Jez provided an excellent answer to a question about using Continuous Delivery with ITIL. See the last 5 minutes of the video (when it comes out).
- The deployment pipeline is a superior way to manage risk (over paperwork)
- Under ITIL v3, continuous delivery can be approved as a standard change with known low risk.
- 2 other strategies for integrating with ITIL v3
- Need to work closely with auditor
- Auditors love deployment pipelines, everything you could possibly audit is available and version controlled.
Adventures in Infrastructure as code - Julian Simpson
Julian demonstrated code using Puppet and Chef, that installs Ubuntu, nginx, jetty and deploys a war file. In short, Puppet is configuration-based and appeals more to sysadmins who like to see all the moving parts. Chef is convention-based and tends to appeal to developers more.
He discussed testing using cucumber-puppet and cucumber-nagios, and mentioned cfengine, vagrant and the veewee plugin.
The Limited Red Society - Joshua Kerievsky
Parallel to the Limited WIP Society, the goal is to minimise the development time spent in the red (failing tests), or in the pink (code that won't compile).
By visualising the development flow, developers get feedback for improvement. Analogies with sports visualisations. Joshua recommended "The art of winning an unfair game" book, on which the Moneyball movie was based.
Measure and practice the Shortest Longest Red Etude. A good retreat is better than a bad stand.
Refactoring strategies missed in Joshua's book:
- Parallel Change - write refactored code alongside current code and gradually switch over (like building a 2nd bridge)
- Narrowed Change - reduce the number of change points (eg. using Extract Method), before making the change. This is preferred over parallel change.
We had covered these in depth on Joshua's excellent Refactoring Workshop on Wednesday. The eLearning package that Industrial Logic have put together is exceptional, with IDE plugins to allow us to visualise our refactoring sessions and provide feedback on our work.
The development visualisation is available in Industrial Logic's Sessions tool.
Domain-driven design for RESTful Systems - Jim Webber
HTTP is an Application Protocol. You have to narrow it down to your Domain Application Protocol.
PUT is idempotent. Always use it rather than POST for financial transactions.
Jim presented some of the Restbucks examples from his book.
His talk was very engaging. It was somewhat alarming to find that only 1 of the audience had played a PS/1 or later as their first computer game, while over 50% of the audience had first played games that were loaded from cassette tape.
The Live Web - Drag n' drop in the Cloud - Dan Ingalls
It's like Squeak (and Scratch, BYOB, Snap) but runs behind firewall
Kit approach - components, connections, encapsulation
Parts bin - cloud based repository of active content
Live connect, dataflow binding
The IDE runs using Lively Web, and saves using WebDAV (to node.js, to svn)
Not sure how I'd use this for commerical projects yet, but it's a lot of fun and I'll be trying it out with my son.
Better testing with less work - John Hughes
I've previously looked at (and discounted) QuickCheck in Java, but the Erlang version does so much more that I'll be looking at it again. There is a lot of difference between the different language implementations.
QuickCheck allows us to write general properties that a system should meet. The properties should hold true across a range of values (similar to JUnit Theories). It then generates random inputs to test those properties. On failure it will retry with simpler test cases until it finds the minimal test case that fails. This simplifies debugging.
A particular sweet spot for QuickCheck is finding race conditions. It's easy to convert sequential to parallel tests. John used QuickCheck to easily find some race conditions in a database implementation that had been eluding the developers for months.
Matthew discussed how they're using Node at Yammer. Three of their customer-facing services use Node - the Upload service, the collaborative document editing service and an undisclosed new service.
Internally, Yammer use Jake and FooUnit for build and test. It's good to see Yammer developers open sourcing some of their work on Github.
Matthew described the Geddy web framework and showed how they use the yammer.util.promise framework for async code.
Webbit - a lightweight WebSocket web server for Java - Aslak Hellesoy
Webbit is a single-threaded, non-blocking, Java-based, high throughput web server (no servlet API). It supports 3 models:
- HTTP request-response
- WebSocket (long-lived 2 way connections)
- EventSource (long-lived push server->client connections)
EventSource is a W3C standard and is implemented in most decent browsers. It's more lightweight than WebSockets.
At DRW, Aslak's team ported a trading app to Webbit, Chrome, WebSockets.
Aslak coded a HTTP client app in less than 100 lines (including Java, JS, HTML, CSS). See https://gist.github.com/1421652.
Blocking or long operations must be offloaded to another thread.
Webbit has no hot-deploy capability out-of-the-box, and does not support HTTPS. (Aslak recommended stud as a HTTPS terminating proxy).
For testing, Webbit provides StubRequest, StubResponse and StubConnection classes. For end-to-end tests, the server can be started and stopped in 1.5ms.
Webbit tends to be embedded in an app (rather than the app being embedded in the web server). It has a small footprint, using about 100kb RAM and almost no CPU when idle. It has REST (JAX/RS) and RPC add-ons.
Above the Clouds - Introducing Akka - Peter Vlugter
It was a surprise to find out that NZ has a developer working for Typesafe as part of the core Akka development team.
Peter introduced the core features - Actors, STM (Software Transactional Memory) and Dataflow (a way of composing futures, inspired by the Oz framework). They are looking at supporting Agents and Transactors (2 phase commit STM).
Akka supports Scala and Java APIs.
Peter gave a good, detailed introduction to Scala Actors.
Akka integrations include Camel, Spring, ZeroMQ, AMQP, Play framework, REST. It has a testing toolkit (and Peter is keen to explore a QuickCheck for actors), It is open-source, except for the commercial Atmos tool (trace, monitor, manage, provision).
The keynotes were entertaining and insightful. Hearing Cameron Prudy describe potential JVM enhancements gave me some warm and fuzzies about Java's future as a platform.
Mike Lee, Damian Conway, Mary Poppendieck, Simon Peyton-Jones and Jim Webber were outstanding speakers.
Thanks to the great company - especially John Hurst, Martin Paulo, Paul and Luke (the AEMOs) and Balaji, and to everyone else that made this great.
And above all, thanks to Dave Thomas, the YOW committee, the volunteers and speakers who made YOW happen.
WOW - that turned into an epic. Illustrating just how much I got out of YOW!
2 - What I will do next
Books to read
The Lean Startup - Eric Ries
REST in Practice - Jim Webber
Technologies to play with
Presentations to watch online (that I missed)
The Post-Java Virtual Machine - Ola Bini
JRuby for the win - Ola Bini
Three 'Tall' Tales - Kevin O'Neill (mobile dev and testing)
3 - Impediments
Above all, the speakers brought out the joy of programming (especially Damian Conway!)
My main impediment is time. I really need to re-instate my "20% time" for research, play, innovation and general hacking.
Must be about time for my new year's resolutions..