United Thoughts of a Distributed Mind

This is the first real conference day, as the last two were mere tutorial days. So here small report one the day’s session from my perspective:

I opted for concentrating on architecture in the morning, after the keynote of Amazon’s CTO Werner Vogels, on how Amazon’s single web application (yes, the famous online book shop) evolved into a application development platform that Amazon now is opening and making available to the software development community.

What stood out of his talk? Four things:

• To scale: No direct access to the database anymore. Instead data access is encapsulated in services (code and data together), with a stable, public interface.
• To decouple: Services are aggregateable from other services or very “thin” web application, allowing to mesh different services together and leave out, what you do not need, so supporting many different applications and uses.
• One small team own a service in all its aspects. This has the advantage to make the team responsible for the functioning of the service and at the same time giving it the freedom to do whatever it takes to implement it and make it work.
• Scale later. It is soooo difficult to make it right, that sometimes the effort to do it up front is not justified. Or leave it to somebody, that has the knowhow and has done it already…like Amazon (remember S3 - Virtual Disk, etc.).

Then Kevlin Henney introduced as host the architecture track, talking about architecture quality attributes, something I need currently also look at.

The session of Martin Fowler talking about “Modifiability”. His approach to hold the session, made him even more sympathetic for me. He downplayed his role as Agile fore-thinker by taking a backseat during the session and let instead five of Thoughworks’ senior software designers (or architects, if you like) illustrate different ideas around evolutionary architecture.

More detailed notes on this will be published on these pages as soon as I have transcribed them.

In the afternoon I attended the “Performance & Scalability” talk of Cameron Purdy of Tangorsol. Besides that he put up just too many slide for a talk of one hour (more than 70) and his talking stile is somewhat monotonous, his talk was very information-rich. Especially I liked his list of architectural “Don’t’s”. Recognized several of them in our own architecture on the current project we are doing. We really have to throw out the legacy code, that is lurking in all corners of the current framework we are using.

In one point Cameron made somewhat contradictory statement in contrast to the keynote of Werner Vogels: Architect for performance and scalability up front, because it will cost you way too much to put it in at a later point in a project. So who is right? Well, when I try to consolidate those two talks overall message I come to this conclusion: Include thoughts on performance and scalability in your initial draft of your architecture, but be ready to revide it and to optimize it at a later point, when you know a.) more about the real requirement for your system, and b.) when you are able to see with your own eyes (or mesure), where the effective bottlenecks hide.

The next talk was again by Werner Vogels, about “Availability & Consistency”. A very interesting talk, that needs further digging, because there a lot of ideas essential to high end web applications. More on that in a later entry.

The last talk was by Peter Sommerlad on “Security Patterns”, based on his new volume of the famous POSA (Pattern-Oriented Software Architecture) books. Unfortunately he was not able to present the theme in an involving manner, that would spark more interest in the auditorium. Partly this can be traced to him not being a native English speaker, so he was sometimes having difficulty finding words and he often lost the flow that is so important to a talk. At the same time he bothered to explain far an long what patterns are and instead of analyzing thoroughly only two pattern (an easy one and a complicated one), he wanted to give an overview over the whole book. An impossible task to accomplish in one hour. Too bad. It seamed more like a sales pitch, than a session, people can actually take something away. I know he can do better, especially in German.

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