Monthly Archives: January 2011

Interesting links from 2011-01-22 (Kanban)

Atlasian Bitbbucket: a free and private Mercurial repository for small teams

I was looking at open source / free applications to do Agile with a Kanban flavor, here are the places I found:

FDD Project management application

Express – Agile project management

Agilefant

Agilo – Flexible software for project management (Python download)

Digaboard – Task board gone digital (PHP and mySQL download)

Radtrack – Agility with cards (free service)

Apropos – Agile Product Portfolio Scheduler (launch in May)

SeeNowDo – Digital dashboard for distributed agile teams (free service)

SimpleKanban – A Kanban board in simply one HTML file

Scrum Agile Software Project Management Open Source Tools Directory

And I went around other things as well:

Collaborative fund

Drive: the surprising truth about what motivate us (video)

Top ten reasons to run your own business (Inc magazine article)

PeopleRank: Quora Is Developing An Algorithm To Determine And Rank User Quality (Techcrunh)

A Modest Proposal for America: Build 500 Accelerators (Launch)

Backlit photography samples

Cloud9 Javascript IDE

The truth about real estate (Inc magazine article from the guys in 37 Signals)

National Geographic Magazine: 50 Years of Covers

Entrepreneurship survey in Ireland

And some notes about DDDD:

The generic repository

Repository is the new Singleton

Long live repository

More on repository

Hexagonal architecture (notes from a chat in a book club)

Learn REST: a tutorial (fast, easy and educating)

The Pragmatic Programmers magazine (free PDF download)

Exiting the zone of pain: static analysis with NDepend

The reactive extensions (LINQ libraries for push operations)

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Interesting links from 2011-01-21

Put a Flex UI On Your Application

CQRS Starting page

Uniqueness validation in CQRS architecture

Layered architecture (going towards Hexagonal)

Inversion of control patterns for the .NET Framework

Steve Fenton – Javascript

Container tutorials

Dynamic DNS providers: DynDNS – Pricing

Dynamic DNS providers: DNSMadeEasy – Pricing

The World of Notch – blog from the programmer behind Minecraft

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The Hexagonal Architecture and the pot of gold

As part of my research, I was trying to see how the big traffic sites are implemented. A lot of things are going around, a few diagrams are popular, but the main point seems to be able to distribute your code in as many machines as practical, as cheaply as possible.

That is good and reasonable, but in the end, my question was still ‘how do you do your code?’. Going specifically to it, the spectrum is broader, and you can find from massive spaghetti code, to massive structures done under industrial ideas and everything in between.

From all those approaches I liked most the DDDD approach, it being a distributed domain driven design. I knew DDD already, and the distribution part just made sense.

There are again a few different approaches to it, but being in .NET NServiceBus is the one I choose to follow, so I spent some time around it, and again, it makes sense when you look at the problems it is trying to solve.

But even than it makes sense, something was missing in the picture, at least the picture from the web site and mailing list. It looks more than a bunch of libraries (with very good reasons behind), but still suspiciously close to ‘use this technology and everything will be great’. I know that each one making that statement probably mean it, but I heard it too many times to believe in ‘technology’ solutions.

And then, I found CQRS, and from some video got the magical words ‘hexagonal architecture‘. It is a pattern, and as usual with them is deceptively simple. Instead of being concerned about a long line of code blocks calling one to the other, make it a single, tightly coupled core dealing with the outside using adapters. In particular, take the data layer outside of your model, and make it an external service.

I just loved the idea even before reaching the end of the article, but found it difficult to explain it to others. ‘What is the new thing about it, compared with any other data access layer?’, I was asked, and heard me babbling as I usually do when too many ideas jump in my head, obvious for me and nobody else around.

Now, the important thing for me is (and I just realized it a couple of hours ago) that instead of the situation from the last ten years with an object model and a relational model living in the same chunk of code (being it a single library or an arbitrary number of them but all related and interdependent), you can have only one model on each application. One for the domain, one for data storage, one for the external API, one for UI, one for Santa Claus if required. That is brilliant!

Do you have a business operation that you want to model? Do it disregarding anything about data storage or user interfaces. Make your model, make it the best you can, as simple or complicated as you need, and then request services from others (the main suspect the database) and provide services for something else (a UI or an external consumer).

The magic is, in your domain model now you really, but really really, don’t care about relational data. It does not matter if you have SQL or not, if you use an ORM or directly call ODBC. Data providing will have its own application, and the model in it will be only relational (or whatever you want). No business logic there, you don’t care in data storage about validating, or cascading activities, or logging or anything else. Your data storage application will only be concerned about storing and retrieving data. Just data. Genius!

There is nothing new in there. That should have been the role of the data layer. but the thing is, I never saw it so clearly separated until now. The theory was right, the implementation always ended as a mess and a bigger or smaller monolithic application.

The philosophy is even older, I still remember talking with people in FidoNet about the theory of Unix, and being thinking ‘what is a theory of an operating system? It is just a big program!’ without realizing that probably a very important concept was the fact that each operation is auto contained. You have twenty small applications and you pipe the results from one to the other. There is no need to solve the big problem (taking months or years of development), just do an application as small as possible, involving one activity to model, and off you go. It is a different implementation, but the concept is the same, and I love it.

How do this translate to my daily practice? Well, now I can focus in one thing at a time. I can do the model for something I need, finish it, and forget it. Then I can do the data storage. Or the UI, or some other atomic model. I can keep the external references outside, and prepare a bit of code to emulate the real thing until I have time to do it properly. Basically, I can advance a step at a time, and not be concerned about a landslide sending me back to the starting point. And I even get an extra bonus, because now application distribution is trivial, everything is distributed from the start!

NB: I am talking again to you, monkeys, it looks like we stroke gold here. Instead of being concerned about how long we will need to work until having something useful, we can make it as small as needed to be done in the available time, and still get something of value. Solid, commercial value, not just learning something new or doing something interesting. Are we going to stay sleeping or can we take the opportunity to eat an elephant a bit at a time? It is soft, it is golden, can we check if it is real gold with code?

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New laptop, twice the fun

Apart from the cluster and the other dozen of computers at home, I got my last work horse in 2003, an Inspiron 5160 from Dell.

The thing was expensive, badly designed (it spent three months in service, one for each new motherboard it required until I clipped the insides of the case to stop it ripping the board apart) and lived miserably until a couple of years ago when I stopped using it. Before that I even tried to upgrade it a bit with more memory and a new hard disk, but finally the external wifi card failed and I didn’t bother getting a new one (a few Eee PCs replaced it, thank you very much).

But now the Colmenar is working, Visual Studio 2010 has a good number of nice features, and after a few months thinking I decided to get a new laptop. I got an HP ProBook 6550b, and I am liking it nearly as much as the Eee PC.

It came with Windows 7 64 bits, and a sledge of applications that I didn’t want, so after a few hours trying to remove them I wiped the disk and installed Ubuntu instead. The setup was fast and detected everything but the finger print scanner (which I don’t care).

After installing VirtualBox I went for Windows, and found that the disk that came with the machine had a 32 bits version instead of 64. I imagine that I could have called the guys in HP, but it is not a big deal (as other .NET people are doing, I wonder how longer will I stay in the lands of Uncle Bill) and the setup of Windows 7 32 bits in Virtual box worked without flaws. Visual Studio, SQL 2008 and the usual suspects went in without protests, and now I finally have a machine where I can run Python and mySQL on their natural neighborhood, as well as doing C# as fast as usual in Visual Studio.

The only point a bit annoying is that on the first boot, when Windows asked for my details, some of the dozen weird applications wrote the BIOS with a username and password related to the Mickey Mouse network I said I was using. After wiping everything, when I accessed the BIOS setup to change some details for virtualization, I found that those user details were used and now I can not change them. I didn’t spend too much time investigating, but I guess that I will be in trouble if I want to do a BIOS upgrade, but I think that it will not be another period of seven years until the next laptop. Hopefully, that upgrade will never be required.

All in all I am very happy with the ProBook, it is solid, good looking, the keyboard is surprisingly good for a laptop (I am writing this on it, even than the Natural Keyboard 4000 is my interface with the processor), and the screen is great.

Now, the only bit missing is to do some real programming :)

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3 weeks to live

In the last few days I started following the progress of the guys in 3 weeks to live, a blog where a couple of engineers post a video recapping a working day in a project which has only three weeks to go live before everyone goes to other gigs.

Apart from the fact that I love the adventure (and feel very envious of them doing it, after so many times that I had good ideas and did nothing with them), they are sharing their experiences with tools and languages. One of them is AgileZen, and online project management styled as kanban, HipChat is another, and a few minutes ago I learnt that at least some of them are .NET programmers, but are using Rails just to learn while driving.

I hope they go well, and feeling more envious by the minute.

NB: you monkeys know who you are, when are we going to do anything at all? :)

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Development speed

Just read two interesting articles about development in Facebook (How Facebook Ships Code and LAUNCH002: What I Learned from Zuckerberg’s Mistakes). Apparently the programmers choose what interest them, implement and deploy. A lot less ‘design, discuss, evaluate, prototype, etc.’ Just write the code and see how it goes. Even one week cycles!

Associated with that is a very alert operations team, checking for problems, and changes in user behavior (I wonder how they measure it).

I still remember that approach of ‘write the program and visit the customer’, but lost it many years ago. It is refreshing to see it again, and I wonder how long will it take to me to go back to that situation, given than I am more eager every day to write some code and make it fly. Could be anyone in Ireland working like that?

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