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An American actress, Kristen Jaymes Stewart (born April 9, 1990) is best known for playing Bella Swan in The Twilight Saga. She has also starred in Panic Room (2002), Zathura (2005), In the Land of Women (2007), The Messengers (2007), Adventureland (2009) and The Runaways (2010). Josh Tyler of Cinema Blend hailed her as "a modern day James Dean". Stewart will playing the leading role in the upcoming film Snow White and the Huntsman.

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Formula 1 2011 Australian Grand Prix (2011)

Formula 1 2011 Australian Grand Prix (2011)



The 2011 Formula 1 TM Qantas Australian event is the country's most spectacular sporting event and will feature an impressive array of both on-track and off-track activities for people of all ages to enjoy. If you've never experienced the thrill of a Formula 1 TM car racing by at speeds of more than 300 km/h, make 2011 your opportunity to witness this unforgettable phenomenon.



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WICSA 2011

I was at WICSA last week. I am a lousy trendspotter, but here is what I have seen as “trends” so far:

There seems to be several efforts, especially on the tool side, that focuses on capturing and navigating architectural information. Is this a sign that architecture information is getting bigger and bigger and is distributed among different sources/artefacts? I thought one of the tangible deliverables from an architect was a comprehensive documentation/model/wiki/whatever with architecture information. As a contrast there wa a tutorial the last day by George Fairbanks on writing a 1-page architecture document. I would say this was a highlight of the conference, to bad most people had gone home by then.

In general it seems architects are more aware of the need to adopt to agile development. I don’t think there is any contradiction, contrary I believe that it is necessary for agile developers to be more aware of “architectural thinking” and what benefits there is of having an explicitly defined architecture. But I do agree that often architecture is the same as Big Upfront Design. At the panel debate I understood better the historical background; many of the originators of the agile manifesto were active developers already in the late eighties and nineties when a lot of focus where on software design. people who started as developers in the last decade don’t have that background and think that the last years focus on process is all that is necessary for developing good software.

There was some discussions  on architecture-based testing (this is a good strategy to define a new research area, combine two or more buzzwords), but it was confusing. some people seemed to mean an architecture where it was easy to verify the quality attributes it was designed to achieve. others seemed to mean an architecture for a systems that was easy to test for testers. I like the latter better, and hope there will emerge more patterns for this than the general patterns of encapsulation etc.

Compared to the last WICSA in 2009 I think the acceptance rate was much higher, above 40%. I think this could be one explanation to why some papers had a rather weak scientific methodology. One other thing I did not like at all were some studies based on industrial practice where the results were too polished. if you present a case study you should include all the small (and big) problems that occur in real settings, otherwise the cases are not of more interest than textbook examples.

Reference architecture, what is it?

I am at WICSA 2011 and the words “reference architecture” come up now and then in discussions. I am not sure I like the definition in Wikipedia, I think relies too much that you already have knowledge or experience of a reference architecture.
One simile (parable?) would be to a building code, a set or rules that underlie the actual architecture and construction of a house. The architect is free to build any type of house, as long as the code is adhered to.
But I like to use cooking as an example. A recipe is like an architecture, when you actually cooks the recipe and serve it is the implementation of software. You need to do certain things that are implementation specific, like tasting to see if the amount of salt suits your taste etc, and maybe you need to double all the ingredients to fit your  dinner party.
Julia Child writes in her book Mastering the Art of French Cooking that there are 6 principal ways to make a sauce, one being an emulsion of melted butter with egg yolks, which is common the common method for béarnaise, hollandaise and choron sauces. The type of emulsion is similar to a pattern while the three different recipes are designs.
For a restaurant; a product line architecture would be the menu they have based on the ingredients they stock, for example chicken could be used in more than one dish.
So what is a reference architecture for a restaurant? It would be the “rules” that guides and controls what is possible or desirable. It could be for example driven by the business domain, e.g. it should focus on French or Hunan cuisine. Woking as a “development method” would not be relevant in the former, but certainly in the latter.
Or it could be driven what is technically possible, e.g if the kitchen has no deep fryer it is impossible to for example make french fries.
Or there could be other restrictions, such a desire to only use locally produced ingredients.
Maybe I went to far with this simile (parable)?

Architectural views in practice

My research is not really focused on identifying the “best” architectural views for in-vehicle software. But as a side effect to the studies I am presently doing I got to think about three views that could actually make a difference in how well large projects succeeds (or fails). I have thought about the need of addiitonal views, but cannot think of an immediate need of more.

Integration is always an in issue in large projects that has some form of iterative development. With the increasing inter-dependencies between various parts of the system it is almost impossible to know what should be integrated when, for example what can actually be tested. There actually is already an architectural view defined that addresses this concern, the anatomy. I would describe the anatomy as visualisation of the complete system seen from an integration perspective, for example if a feature depends on a MOST interface it is no use to test it if the interface is not implemented. The visual picture means everybody should have the same understanding of the “.
The anatomy should dictate the order of development, delivery schedules and integration order. And the progress should be measured in how much of the anatomy is implemented, not in customer features. There is a relationship between customer features and the anatomy, but it is not one-to-one. you can read more about “Integration Centric Development and Anatomies” in a PowerPoint presentation or the article “Manifesting Shared Affordances in System Development – the System Anatomy” by L. Taxén and J. Lilliesköld.

The second view is the systems view, i.e. how the complete system is decomposed in smaller parts. I prefer to see this view as equivalent to the development view in Kruchten’s 4+1 views, i.e. it is aligned with the development teams. One can discuss if the system decomposition follows the organisation, as predicted by Conway’s law. The other extreme is that the development teams follow the most “logical” decomposition, i.e. ECUs, which is the most common unit to be outsourced to suppliers in the automotive domain.

The functional content of a vehicle is often defined by a list of customer features, which can be quite long, and this in itself can be considered an architectural view that concerns for example the business project, the marketing department and the end customer.
What is important for the development project is the relationship between this feature list and the two other views, i.e. what systems/development teams are responsible to implement the features and how the features relate to the anatomy. I don't know if these two relationships/mapping between views should be considered as separate views, which would make the total number of views 3+2.

What is a "good" architecture?

Hopefully you recognise it when you see it...

I believe every system has an architecture, documented or not, and intended or not. So I think it is reasonable to discuss if the architecture of a system is good or not, and that the question if the architecture description is good is a different, but related question.

So what criteria could you use to establish if an architecture is good? Is it suitable for it's purpose is a more precise question? But this probably differs depending on the stakeholder, a system could be very nice and intuitive for the user, but very difficult to develop and maintain for the developers. In the rest of this blog post I will writing about goodness from a developer perspective (including the architect, if one is involved).

I think there are different levels of how well the architecture suits it's purpose to guide and control the implementation.

The ideal level is where the developer understands the architecture and following the architecture is the obvious way to implement something. Doing it differently is seen as more difficult and less elegant.

The next level is where the developer understands the architecture, is able to follow it on her own and can evaluate if the implementation follows the architecture or not. The developer also understands the "debt" that would occur if she deviates from the architecture, for example in terms of compromising some quality attributes. At both this and the previous level the developer can contribute to the design of the architecture itself, and an appointed architect doing the design may not always be necessary.

The developer may need continuous support from the architect to be able to understand the architecture when working. This is very common and requires more work and puts limits on the the ratio between the number of architects and developers in large projects.

The worst level is where the developer cannot understand the architecture and the only one that can determine if the implementation follows the architecture is the architect by reviews. This is very work intensive on the part of the architect. The architect is also viewed as a police that interferes with the developers rather than supporting them.

I have worked at all this four levels in various projects, and I think that you need to be on the upper two if you talk about a good architecture from a developer perspective. I also think that if you want to be truly agile in a self-organising team it is at the two top levels you nee to be.

Embedding Linux for an Automotive Environment

I thought this presentation was interesting enough to share, even if i have absolutely nothing to do with it: Embedding Linux for an Automotive Environment. I guess you need to have a thorough understanding of Linux to understand how the optimisations were implemented.

You can watch a videorecording of the talk as well.