środa, 23 maja 2012

33rd Degree conference - day 3

Looking at the agenda, I knew exactly which talks I wanted to attend on last day of the conference.

Integrating JVM languages 

by Venkat Subramaniam

Once again, Venkat gave a very entertaining talk, this time about the integration of various languages running on Java Virtual Machine (Java,Groovy,Scala,JRuby) and the problems one can get into when trying to do it. In general, the integration is quite smooth, but there are some edge cases when the solution is not really trivial. From what I've seen Groovy seems to have the most smooth integration, but things don't look bad with Scala or JRuby. While I didn't gained any immediately enlightening knowledge I got a good introduction into the subject and now I know that it's not that hard to do and knowing a few languages that run on JVM one can pick the one most suitable for the problem at hand and don't suffer too much when integrating it with the rest of the application. That's cool, especially that after Venkat's talk about Scala on the 2nd day our manager gave us green light to use it in our project when we learn the language a bit.

MongoDB : Scaling web applications

by Ken Sipe

This one was another eye-opener, not really for me - because I investigated the topic a bit before - but for some of my colleagues for sure. My boss got quite excited about it as he recognized immediately a part of our system that could be easily implemented using MongoDB as storage (and which has been in development for about 2 years now and still very far from being perfect or even production-ready). Ken shown us an example of real web site with Mongo storing it's data. He offered a few useful bits of advice, like modelling the documents based on the specific use cases, so that there's no need to fetch multiple documents for a single thing. He mentioned ways to scale Mongo and to fine tune its performance. Talk was very informative and as a result I was asked to create a proof-of-concept for replacing the mentioned part of our system with Mongo-based implementation (more on that in another post).

The Three Laws of Test Driven Development

by Uncle Bob

I guess I was not the only one really looking forward to this talk. That was the very first time I could meet Uncle Bob live (and I regret I didn't have any of his books for him to sign). As I have read a lot of Uncle's posts and watched a few presentations as well I knew what I could expect, but even then his live performance was an awesome thing to watch, listen & learn from. I guess that almost every phrase could be used as a really good quote.
Introduction of TDD began with some sad numbers, as only about 5% of the industry is doing TDD. This number is however improving rapidly, and in a few years we can expect it to be much better.
Uncle Bob dealt quickly with the myth that developers don't have time to write tests/do TDD. As he said, it's childish to think that we have to make a mess to be quick, even if this mess is going to slow us down in the longer run. When mess in the code base grows, more effort is put into moving it from place to place instead of developing new features. That's not the situation we want to have in our projects as it often ends with a redesign of the whole systems, made by the experienced guys (the "Tiger" team)  - the same who made the whole mess in the first place. Of course, team doing the redesign has to be quick to catch up with the feature set of the system they are going to replace. And to be quick, they need to make some mess of course... See the pattern?
Instead of falling into the trap of the big redesign, we should rather concentrate on clearing thes mess one little bit at a time. That's of course the famous Boy Scout Rule that Uncle Bob often mentions. Each time we touch our code, we should make some improvements. Even small ones. Even very small ones. And of course, when writing new code, we should avoid creating mess. Don't even dare to think to yourself: "I'll fix it later". Later does not exist. We all know it.
"Bad mgmt can be suffered through but the bad code is the anchor that is bringing the company down"
Unfortunately, we are often reluctant to clean up the mess we find in the code we read. We think if we clean it and break it in the process we'll be responsible for it from now on. Or we might be afraid of touching it because we've got no idea what will happen (break) if we do. As Uncle Bob said:

"We have created the monster and now the monster rules us"  
That's unfortunately sad reality for many (most?) software projects. As professionals we should have control over our creations. Our software can't just work (any idiot can do that). It must be continuously flexible, easy to maintain & modify at any point in its life.
"You don't want to be good at debugging. It's not a skill to be desired"
"You don't want to spend time debugging. You want to spend time not bugging"
Debugging is hard. And takes a lot of time. The good news is - we can avoid it. Maybe not 100% but most of the time. How? Use the Force, Luke. I mean, use TDD. With TDD done well (that's the trick - you have to do it well otherwise your code will suck as much as it would if you haven't. But to do it well you have to practice it!).
Additional benefits we get when doing TDD are the formal design docs (yup, your tests), nice & decoupled code. And the possibility to refactor with fear.

Uncle Bob also said more than a few words about fast tests. The suite of unit tests of FitNesse (1892 unit tests) is running on his Mac in under 50s. That's pretty awesome and shows how short feedback loop unit tests give. In our project a suite of 700 tests runs for a few minutes (~3) - most of them are functional tests and it's not very useful for doing TDD. And we have to change our mindset regarding such tests - there's no reason for acceptance tests to be slow. They even can't be slow. It's our job to make them blazing fast. There's no excuse for it.
"If you want control over your code you'd better get yourself a suite of tests"
Another important thing is the trust you are willing to put into your test suite. It's like jumping out of a plane with a parachute - you'd better now have any holes in it. Software can be extremely easily broken, just flip a single bit and it's done (unlike your brain which can loose a couple of thousands of cells in a single drinking session and not be affected by this loss). You need a really good suite of tests, one that you can trust your life to. When it runs and passes, you should be convinced that your software works. If you're not and have to check it manually - what good are your tests for?

And for the end, a few Questions & Answers, which made the whole audience laugh:
Q: But we have a testing department, I don't have to write tests!
A: Screw you!
Q: What about refactorings?
A: It's a good idea to refactor your code. Next question"
Q: How you start TDD culture in company that doesn't have it?
A: You start shooting people at random. Don't get your hopes high regarding developing a TDD culture in your company. And remember - you can always change your organization or change your organization.

Code Craft

by Nat Schutta

Next talk was very nice, going back to the basics - good code, bad code and how to improve it (tip: write less of it, less is more). While nothing earth-shattering, it was a real pleasure to listen to a good speaker, got reminded of many things that we might not think about too often. We got reminded to simplify the code, to talk to each other about it (most of us prefers to write code, not to read it, and it's critical to read code) - but we need to remember that we have to be critical of the code, not the people.
Nat also warned us against thinking too much about code reuse - it should be a byproduct, not a rationale (but too often I participate in meetings when we talk about reusing the code that is not even written yet!).
Nat also touched the topic of tests - we should treat them the same way we treat production code and if a developer is not writing them he's not really doing his job.
And the last advice was where to start improving code - we should let the feat guide us. We should start where the code is really scary. That's where the biggest mess is, just begging us to get it cleaned up.

Demanding Professionalism

by Uncle Bob

I was really sad when this last keynote started, as I knew that I will have to leave early to catch my train back home.
The talk started with a question what is the software crisis? As Uncle Bob put it:
It's so hard to get the damn software done right
One of the major problems is the lack of professionalism in our industry. We see bugs as normal thing that happens rather than "OMG A BUG!". And we live in an illusion that there's no demand for professionalism in software. But thinking about it - how else are we going to deliver features fast, if not by being professional and carefully crafting software?
There's an analogy often made, that building software is a bit like creating buildings. But in fact it's not - a normal architect creates the plans for the building because it's damn expensive to make changes after you started to lay the bricks down. In software, it's cheap so there's no point in having big design up-front. We've got to remember that we're not the masons - our code is not the product, it's the specification the compiler uses to build the product. We're more like architects, preparing plans for the compiler to follow.
Unfortunately, changing your design often works only if the build step is cheap. If we make it expensive (for example long - with slow builds!) the cost of building increases and we have to do more up-front planning. Therefore it's our duty as developers to keep the builds short, so that they don't get in our way when you want to change our design. We cannot submit to the idea that build just takes that much time...

... and unfortunately this is where 33rd degree conference ended for me. I left the presentation and went back home, with 'REST in practice' book I bought on the O'Reilly stand (James Lewis recommended this book and I must admit that it's a really good read).

I'm looking forward to coming back for the next edition of 33rd degree, if it will be possible. In the meantime, I'll probably join Confitura conference in Warsaw, in June.

poniedziałek, 14 maja 2012

33rd Degree Conference - Day 2

Okay, a long time since I wrote the first part of my 33rd degree journal and even a longer time since the conference itself. Still, I will try to write down what I learned, just to refresh my own memory.

Agile, Lean and Startups Practice & Principles to create ultimate value creation machine

by Barry O'Reilly

Starting early (not really, but I had some late night discussions with my colleagues) in the morning with a non-technical talk. I'm (unfortunately?) from the corporate world rather than from startup environment so I picked this talk to get a better understanding of how startups work (maybe one day I'll need this knowledge, who knows?). Barry started by introducing (?) waterfall, agile, lean and startup and highlighting some of the differences. He presented how the Deming cycle applies to startups and gave a handful of useful tips:
Ask: What's the smallest thing I can build that will give me a lot of feedback?
"Validate that what you're trying to build is the right thing to build.
In startup you don't have infinite time to do useless things as you might have in corporate world (oh yeah, I know something about it...).
 You need good understanding of the potential users to design a system suiting their needs  
Street surveys: help the team interact with end users to understand their motivations  
Developers don't just write code now, they have to understand their users
Get out of the building. Go to a coffee shop and talk to someone: Hey, I'm building something... 
Barry suggested doing street surveys - the very thought of it scares the s**t out of me but I guess that would be a scary & insightful exercise, as it would take me as far from my comfort zone as possible. That's how we learn after all. There's a few things to remember when doing it:
"Always ask Who? Why? How? What? and that kind of questions" 
"Ask demographic questions first to check if you're talking to the right person"
He also presented a few useful tools that can help people to understand their business (Business Model Canvas, personas, User value stream maps) and make it work better. And he stressed how important for startups is learning how are you doing (various metrics) & learning from mistakes:
Understanding what your customer wants is pure gold
Measure - data is the new oil
Don't waste your failures - don't celebrate failures but what you learned from them

I'll finish here as you can find the slideshow located here. I think that the talk, while concentrating on startups, has a lot of value for people coming from corporate world. I think that many of the patterns/tips applied to such environment would only make it better.

Micro Services - Java, the Unix Way

by James Lewis

Just noticed today - the slides are finally available! Yay!

The title of the talk intrigued me when I first saw it some time before the conference and I knew I'll participate. I think that was the best talk I've been to in the conference - maybe not the best show but I think most valuable from my point of view.
James shared with us the story of a project he participated in - they've build a huge application out of tiny, independent services (divided along the business capabilities of the system - one or more service per capability), implementing using various technologies (individual teams was free to choose whatever technology worked for them), all communicating in the same way - via HTTP.

"Micro service - small enough to fit in your head. Small enough so you can throw it away"
The services were small enough so that they could be discarded & rimplemented at any time. In fact, rewritting them would be even faster & cheaper than applying bigger modifications to them, should the need arise ("Rewrite over Maintain").

"Organize your teams around your business capabilities"
Such divide & conquer approach allowed them to share the workload among many teams, not conflicting with one another (and remember the Conway's law!). Otherwise, they wouldn't be able to meet tight deadlines they had. Additional benefit of this architecture:

  • can adjust the architecture of individual services according to the specific requirements (like huge data sets or low latency)
  • adhering to SRP (each application doing only one thing)
"If the class on the screen is bigger than by head it's too big"
  • individual services fits in one's head (simplicity!)

"Be of the web, not behind the web"
The services were talking to each other via REST APIs, using regular request-response calls and publishing ATOM-based event logs.
The services were distributes as standalone JAR files (with Unix rc.d scripts), along with their configuration. To prevent developers from seeing the similarities in the code & extracting tons of common code, they were put in different VCS roots (with some library/infrastructure code being shared as separate artifacts, maintained in a open-source-like way).
Later, James explained how such system scales (see the presentation), what tools have they used. He also stressed that the uniform interface of the services is critical and how to deal with eventual consistency in this case. He didn't manage to talk about versioning but he was asked about it after the talk and explained that they were using automated tests as contracts between the systems - as long as the tests were passing the applications could communicate with their collaborators. I find this a wonderfully simple (conceptually) way to ensure that systems can change & still work together.

The presentation was a great example how huge things can built from small parts, using well-known, open technologies, without a need to spend years to develop an internal framework that nobody will be familiar with. Additionally, I found it interesting to see the same concepts Greg Young was talking about during his DDD/CQRS training were coming out in this talk (eventual consistency, bounded contexts, simplicity!). I guess great minds think alike and those techniques are not something new, that people could be afraid to use or have troubles with understanding.

After the talk, I bought the 'REST in Practice' book that James recommended. I'm reading it right now and I see it will make me smarter, even if we're not doing REST in our projects at work.

Concurrency Without Pain in Pure Java

by Venkat Subramaniam

I arrived really late for this talk (stayed a bit longer near the TouK room to listen & talk to James Lewis after his presentation). As for every talk Venkat gave, the room was suffering from a heavy participants overflow so I wasn't really able to see/hear everything. I only saw Venkat showing how to use STM (using Refs) in Java (and Clojure, IIRC). While entertaining (as always!) this talk didn't bring much value to me. Maybe if I had participated from the beginning.

What's new in Groovy 2.0?

by Guillaume Laforge

This was one of those presentation I wasn't paying 100% of my attention to. I don't know Groovy too well so learning what's new wasn't of much use to me but what I've seen looks like a really nice language. I'm a bit surprised that Groovy developers are going in the direction of allowing Groovy code to be statically compiled - I know performance might be an issue (and it certainly is for Groovy 1.x) but that's the tradeoff you make when using a dynamic language - sacrificing performance & compiler checks for reduced development friction & more expressiveness. But anyway, I like the dot- and parentheses-less code you can write with Groovy.

And of course - attending this presentation enabled to get me a seat for the next talk:

Scala for the Intrigued

by Venkat Subramaniam

This one I was really looking for. First - you know the show will be great if Venkat is the presenter (no free seats 15 minutes before the presentation start). Second - from what I have seen so far, Scala looked like a nice language. Maybe not entirely familar, but kind of luring me to give it a try. Therefore I wanted to see what cool features of the language Venkat will show us.
First class support for XML, no primitives, implicits are only some of the goodies you get if you run away from Java language to embrace Scala. As Venkat said - Scala is Java with its flaws fixed. An expressive, low-ceremony language that doesn't need an IDE that will produce hundreds of lines of code for getters, setters etc for you:
"Java: I just declare fields and my IDE magically vomit the rest of the getters, setters and constructors"
Additionally, Scala has traits (~ mixins) - something I was often missing when hacking Java code.
Of course, the show was as good as expected and this presentation was a good ending for the second day of the presenatation (at least for me). Scala seems to be really promising and we even get support from our manager to learn Scala and use it (as a proof of concept initially) at work! Good news indeed.