Wrap It Thinly

The major concern about TDD in firmware development I hear is the hardware relation.

-"We don't have hardware to run the code in."
-"Every part of the code is hardware dependant."

I noticed I wrote about these approximately a year ago for the first time (I, II, and III). That was more on the theoretical side. This time I have a bit more experience on the subject. We have found Alistair Cocburn's article on hexagonal architecture valuable in philosophizing this issue. Many firmware developers are not familiar with design patterns, but a good starting point is above mentioned article. Writing adapters for your hardware, grouping them to ports, keeping the number of them low, and only allowing them to be responsible for the lowest-level of hardware interfacing, will help you isolate hardware dependant parts. Here is a picture of hexagonal architecture for the case project we are working on.




Then there is a philosophical issue of testing the adapters, or wrappers. In many cases binary input/output handlings are just like accessors, getters and setters. In TDD literature it is generally agreed that these do not need unit tests. When writing hardware wrappers we need to think a bit harder. We could understand the unit tests for hardware wrappers as our firmware/hardware interface specification. Then for sure it makes sense to write these tests. My thinking goes along with "to be able to judge what to unit test and what not to unit test, you have to be able to unit test everything".

Test the Goal of the Code

It is time to get technical again. We have been writing unit tests for some time. We have tried test-driven development. However we have never been disciplined in this. Sometimes we don't write tests at all. Sometimes we don't fix the test suite when code is needed to change. Sometimes we just decide that well, this project or that part of the project does not need tests (typically when it seems to get complex or difficult to test!). We have come to a conclusion that with this approach we will never totally master the skill, and not get the benefit it is supposed to bring.

We decided to try another approach. We are writing a very real hard-time constrained, very hardware related code with 100% test-driven development (TDD) in C. A code exists to do the job, but we are gonna completely re-write it. It is originally ported to C from assembly, and this is done maybe four years ago. Since then it has been improved, modified, and adapted to new situations. What has happened is the code has rotten, it is a jungle of conditional compilation, and so forth. So what is better place to do a tiny bit of always refreshing skunk work and completely re-write the whole piece of art?

Right after we made the decision that we are gonna write EVERYTHING with test-driven development we noticed a change in thinking. We constantly think for the simplest possible thing to do, constantly re-evaluate the module (C file) interfaces and so on. If you are gonna do everything in this manner, there just is no backdoor for you.

Another big change was (well, we still need constantly remind ourselves about this) the shift in thinking towards writing the tests as specification. We often ended up thinking about the solution and then writing tests to check the solution. This is maybe caused by the fact that one shot on the code exists and is thoroughly known. However, you will create novel, simple solutions for your tests only if you think about what you want your next small code-to-be do, not how it will do it. Keith Ray has listed questions to help you in this.

Sean Shubin has done a nice work and listed first guidelines to TDD. Again:

Test the goal of the code, not the implementation

Embedded TDD Link List

I created a del.icio.us bookmarks for web resources I have found useful for understanding TDD for embedded software.

my del.icio.us bookmarks for embedded TDD

Embedded Blogosphere

Yesterday was yet another record breaking hot day in Helsinki, and what did I do? That's right, searched the net for new embedded slash agile blogs. I periodically do this, but normally I come empty handed. This time I was happily surprised to find Low Country Software Ramblings by Benoit Lavigne. Benoit was also wondering "Am I alone?", and later found out that "I am not alone after all!"

Via Benoit's blog I discovered Embedded Cork by Ralph Depping and Embedded Gurus. Embedded gurus seem to be a bit quiet, but there is some recent stuff as well. Names behind Embedded Gurus group are impressive; Nigel Jones, Michael Barr, Larry Mittag, Mike Anderson, and Miro Samek.

Keep in mind the Atomic Object Spin Embedded Corner, and But Uncle Bob Archive (James Grenning).

I linked them in sidebar - give them a look.

Story: Spike Up Your Coctail

I posted earlier about short, 6 week, experiment where we had weekly deliveries of firmware and true parallel co-design of plastics, electronics, and software/firmware. I mentioned I would try to write down experience report. Well, it became more like story, and you can find the whole of it here (pdf). (LINK CORRECTED 27/6/2007)


Abstract. Agile development is a term used for wide variety of lightweight software development methods following shared values1. Many of these methods and practices however can be applied to more general new product development. This paper describes a six week project using some of the practices from agile development. These practices included self organizing team, collective ownership, continuous integration, iterative planning, iteration demos, team retrospective meetings, wall work queue, information radiator etc. The project crystallized a vague idea and a draft of electronics schematic into two fully functioning prototypes. It is shown that meaningful functionality can be developed in just six weeks. This is remarkable when reflected against the effort needed in so called traditional process models with formal analysis/design and theoretical proof of concept with heavy review processes. This is possible because of today’s advanced development tools and prototyping technology. Stefan Thomke (2001) calls this an era of enlightened experimentation. Building the working prototype is more cost effective way of reliable proof of concept. Using this approach already in the fuzzy front-end phase of the project would result in huge savings in overall project schedule and budget. It was also noticed that all stakeholders of this project appreciated the approach and considered it as “common sense”. The positive side effect was the team building effect this period had.

Camp Fire

A week ago on Tuesday we organized a camp fire event at our premises. Camp fire is an event about sharing agile experiences, and this was second of such events. Roughly twenty people gathered to an auditorium after the office hours. The audience consisted of people from few different organizations inside the company; developers, managers and marketers. We had two talks; Vasco Duarte from F-Secure was invited as quest storyteller and Mikko Kaijärvi from Schneider Electric volunteered to share his recent experience.




Vasco's presentation was strong, as usual. He talked about top-down agile adaptation at F-Secure in a very realistic way. He did everything but painted a pretty picture about the journey. This is according to his experience, and literature as well, expected. When everything is laid down on the table, it tends to get ugly from time to time. It was interesting to see how within top-down approach they were able to put the whole organization into "agile rhythm". Vasco mentioned that lack of outside help, or not getting outside support enough, was the main thing he would do differently if need ever arises. Vasco presented also some cold quantitative data from theirs and others agile adaptation to support the reasoning for change. It just happens to look like we have more data supporting agile than sequential models ever had. The presentation and especially the Q&A and discussion parts showed Vasco's deep knowledge and understanding of modern project work.




Mikko presented another interesting story in a lively style. His project has applied agile project management and Scrum practices in globally distributed embedded system development project. He estimated that only 5% of development effort is software and firmware, and in addition this is coming from non-agile team. Agile practices were seen as the only option for this project to be successful. The project was started with very vague requirements, barely a vision. Teams were pretty much given. One team in Shanghai, China and another in Monterrey, Mexico, and technology and software development in Europe. The offshore teams had minimal domain knowledge and a huge amount of knowledge needed to be transferred fast. Continuous integration of mechanical and electronics prototypes was a key catalyst for communication. Mikko further identified a clear transition in team behavior from hierarchical - through a single point communication - to self managing emergent behavior actively seeking for best possible solutions in this challenging environment. The project has only been active for five months, but they expect to deliver it in September as originally scheduled. Compared to average project that would be fast according Mikko. Furthermore active early participation of marketing is expected to result in better product as well. This has potential of making yet another example of agile project management practices being succesfull also outside pure software projects.

As conclusion both talks were excellent, delivered by guys that are experienced in both, the project work and giving presentations. Hopefully people were able to walk out with something new and to be able to connect some more dots in their thinking.




After the official part the discussion continued over snack and refreshments. It was agreed that lot of the agile adaptations outside so called agile homeground is about attitude. It is about the shift in thinking towards the art of possible. Just changing your de facto answer from starting with "Yes, but..." to "Yes, and..." offers a huge potential. Vasco's message was "if you really want it, you can do it." The reward demonstrably is there.

Enough of processes, let's do labels

The title of course follows the Dr.Dobbs article by Ivar Jacobsen, Pan-Wei Ng, and Ian Spence "Enough of Processes, let's do practices Part I".

Venkatesh Krishnamurthy has an article in March 2007 Agile Journal about top-down commitment in agile adaptation. He defines three layers of stakeholders in organization; Sponsors, Mid Level Management, and Development Team. As a conclusion he presents an argument that highest possibility for successful agile adaptation is a right mixture of bottom-up and top-down strategies. Dave Nicolette reviews the article in his post and shares his experience:

The agile group had started life as a skunkworks operation. When the group was brought back into the IT department formally, IT management dismantled the group and morphed the project process, management tools, and development methods back into conventional ones, although with "agile" labels.

There are propably a lot of stories like that. Based on the initial moderate success in agile adaptation on the technical level, agile gets to be the new silver bullet and buzz word. A new group of people are expected to automatically form a team, jell, and "just do agile". "Just do agile" means that traditional PM starts using agile jargon without bothering to look what these terms mean, not to mention that she would try to master the agile values, principles and practices, adjust them, and further develop them. "Just do agile" seems like a little bit too thin statement regarding that agile adaptation is described to be a paradigm shift, a completely new philosophy requiring a new mental package. "Just do agile" could be called doing practices, but that would be being nice. Instead it is only doing labels as Dave called the phenomenon. Few years back I was teached to avoid new labels, like agile ones, when introducing change. Now I have learned that some people only want new labels. That's probably why the silver bullet business is doing so well. Calling everything agile, Scrum, and/or Sprint is not much of a change, and will not automatically make everything visible, consistent, or reliable. Somehow the point is completely lost. Of course people who expected agile to be a silver bullet or magic wand are going to be disappointed and call agile just another fad. Some people who actual get agile, and understand that it is a bit more than "doing some stuff in 30 or so days and using words like agile, Scrum, and Sprint a lot", are also quite frustrated. Dave's post sets out the more than likely dark symptom of this:

As I write this, just over a year has elapsed since the process of dismantling agile began. Of the 60+ people who were part of the agile group at its peak, only 4 individuals who were in that group are still employed by the company.

It is equally true according to my experience that commitment from all three categories mentioned by mr. Krishnamurthy is needed to continue agile adaptation for any prolonged periods . Both orders in which this adaptation happens have been reported as successful, and yes indeed, also as failures. Mixture of both strategies sounds appealing.

Mike Vizdos writes about similar experiences in his RIP Scrum -post and cartoon. He calls this a "Death by a thousand copies".

Conference Programs Announced

Several agile conferences have their programs out.

Oresund Agile 2007
Copenhagen, 11-14 June

XP2007
Como, 18-22 June

Agile2007
Washington D.C., 13-17 August

At Agile2007 Dan Pierce and James Grenning are giving a talk "Embedded Agile - Issues and Practices". Should be valuable, as these two gentlemen have been talking about and practicing agile development in embedded domain for a long time. Of course lots of other interesting stuff as well, 5 days with 8 or more tracks...

Edward Bear Does Not Have Time to Improve.

In many companies the software assets and practices are left to rot. This indifference to fundamental quality issues is justified with phrases like "we are in a hurry", "we need to create new stuff", and other nonsense. Software is going to require maintenance and further development for its whole life. If you neglect to keep it fit it is going to haunt you back for sure. And it gets worse. If you leave your code base and practices to rot, you will eventually paralyse your whole productiveness. See Ken Schwaber explain it in this InfoQ video.

I have used the story about timber jack being so late at his logging site, that he does not have time to sharpen his saw. Some time ago I bumped into another quote that makes the same point.

“HERE is Edward Bear, coming downstairs now, bump, bump, bump, on the back of his head, behind Christopher Robin. It is, as far as he knows, the only way of coming downstairs, but sometimes he feels that there really is another way, if only he could stop bumping for a moment and think of it.”

It really gets painful sometimes.

It's less chaotic today than it was yesterday

SD Times reviews the new, 2006 Chaos Report from the Standish Group. According the article:

35 percent of software projects started in 2006 can be categorized as
successful, meaning they were completed on time, on budget and met user
requirements.

I'm not sure if 35 percent is a good number, but it surely beats 16.2 percent in the 1994 report.

It would be nice to know how the size and complexity of average software project has developed during those 12 years. Maybe that is in the report, we just have to wait a bit more (and get 500$ for the report from somewhere).

The report lists three reasons for the improvement:

• better project management,
• iterative development, and
• the emerging Web infrastructure.

I don't know if better project management in this context means agile project management. A quote “Managers have a better understanding of the dynamics of a project.” hints to that direction. Iterative development at least is something that we believe is essential for success, and it is nice to get more and more data to show that. Web infrastructure plays quite insignificant role in firmware development.

If you happen to know recent data about new product development success rate in general, or maybe even embedded software numbers, I would be most interested seeing them.

What does it mean to be agile?

OK, the ESC2007 Conference is over. Many of the classes and especially Peer Roundtable discussions at the conference, Beer Roundtable discussions at the bars after conference hours, and long flight hours with a colleague, woke several questions, among them:

-What does it mean to be agile?
-When is an organization/team considered agile?

In his review (pdf) Dr. Pekka Abrahamsson showed the software life-cycle support of different agile methods. We know that Scrum does not have any engineering practices described in detail, but focuses on project management. That's why it has been adapted also outside software development. It is simple. This is why majority of the so called agile adaptations at least say they follow Scrum. As have we; we have used it with cross-disciplined embedded system development teams to develop a complete embedded system as fast paced iterative development. I have also written in my paper how I saw reflective iterative development as a tool itself for figuring out what practices you need. This said I share Simon Baker's post

Are you missing the point?

As long as you share the underlying values of agile development, and keep the obvious practices like short iteration, demonstrable progress and retrospectives, you are going to figure out the rest of it - or die trying or at least you figure out the need for something and can start looking. If your survival anxiety in your current environment is high, but you have juniority prevailing in your team, you can still gain a lot from practicing "just" Scrum. Scrum puts the basic structure in place with its simple rules and in my experience this is an immediate relief to chaos. This does not mean that it is easy. It will make everything visible; good and bad and needs a lot of discipline and nurturing.

With this approach, you being now out of the chaos and anarchy, it is time to bring in the engineering practices. Our case has shown that they are needed. We have experienced with eXtreme Programming (XP) practices; collocated team, pair programming (development), test driven development, coding standard, metaphor, and so on. We have seen the value in them, but not been able to actually master them in firmware or embedded system development in order to put the discipline into using them. Still we feel that we gain from practicing Scrum, and agile development as learning-driven thinking. This is the very reason why we still keep learning more skills and practices.

Are we agile? I do not know.

If your environment is functioning and open minded, and you have master mind developers in your team, why not go full blown XP right away? We have manifested that those practices are of high value, but they are hard for beginners. We now have also hard evidence to support the effectiveness of these methos (see for example the AGILE-ITEA project, run by the same Dr. Pekka Abrahamsson btw). It may be that with this approach you find out that you need some project management practices from Scrum. Who knows.

I wrote in my original paper about agile firmware development that lot of the agile programming practices for firmware development need innovative thinking. I think last week at the ESC2007 I met some of the people capable doing this. In the front line James Grenning from Object Mentor and Mike Karlesky and Greg Williams from Atomic Object. They have put these engineering practices into full use (also) in low end firmware projects. They are also willing to share their knowledge by publishing their tools as open source, and having discussions about the methods. Maybe we even become clients of these guys some day... Furthermore during the classes and discussions I got the feeling that a fair amount of people are actually practicing.

We have just scratched the surface, but after last week I believe that it is time to put some serious effort into agile programming practices, and actual firmware development. After all that is where we started this journey. It just kind a slipped into system development.

Are we agile after adapting these practices? I do not know.

The Vacation is Over - Officially

It's Monday. Back at work after seven weeks of vacation. It actually feels almost as bad as it sounds. I did spend over six weeks in Thailand. Lots of sun, beer, good food, nice people, and of course technical diving. Technical diving is a nicely balancing hobby for an agile proponent, as it relies so much in up-front plan:

Plan the dive, dive the plan.

There are very few situations where this rule may be broken. It is the opposite to my beliefs in new product development. I'm a strong believer in:

Plans are useless, planning is everything.

This Friday I'm off to Embedded Systems Conference 2007. We're planning to get together with people from AgileEmbedded Yahoo group during the conference. If you you are planning to be in San Jose keep an eye for that. If you are not planning to be there, it's better get started.

ESC2007

Embedded Systems Conference 2007 in San Jose, California, is having some interesting events. James Grenning is giving several sessions and people from Atomic Object are coming to tell about their low level system agile testing methods.

The best news is that right after my vacation (still have some three to four weeks to burn) I'm going to attend the conference with a colleague. Talking about nice return to work! I'll try to have energy to write something about the conf'.

Scrum Simulation Rocks

Last week I gave an introduction to agile development and Scrum for a global project organization in Shanghai, China. After the lunch on first day it was time for 59min Scrum simulation. I have written about bad experiences when trying to achieve too much, so it was back to the basics.

There were participants from Finland, China, and Mexico. We used the product backlog for Family Cookbook. Only addition to original Scrum simulation was the use of relative complexity estimations on product backlog items. This time it worked. Estimating the tasks in numbers gave birth to discussion on whether something is simple, or not, not just dividing an item into tasks. Some items were also soon identified to be too large to fit in one 14 minutes Sprint. Team was immediately forced to seek for collaboration with Product Owner.

On retrospective the main thing experienced was the time pressure. I do not see this as a bad thing, it is just the beginning of understanding the discipline needed for time-boxed development. Time pressure will decrease when the team builds trust and improves estimating.

Everyone valued the exercise and though that it was a good lesson. I might consider adding a separate exercise for planning and estimating before the final Scrum Simulation. With this early experience I do not think that I will ever try meaningful work inside the simulation again. The difference was so clear.

TDD'ing State Machines

I'm an electrical engineer. Everything in programming seems to be very very hard for me. Last week I spent 40 hours in aeroplanes, so I had some quality reading time. I did read Agile Estimating and Planning and Test-Driven Development from cover-to-cover. I had quickly gone through them earlier, but this was enlightening experience.

First of all, I have told that we have been trying to figure out effective TDD for our FW development. To be honest, we've struggled. We wrote tests for a state machine implementation. We expected the tests to be run in certain sequence, and that the state was always left where it should be after the test. We of course ended up in lot of rework on test code when our state machine design emerged. We thought that we need to design the state machine up-front in order to be able effectively write tests for it. This did not sound like test driven development at all. This required some more thorough thinking.

So back to my flight. Kent Beck writes that coupling is bad also between tests. A test should leave the system as it was. So writing unit tests in the same sequence as you expect your state machine to work does not seem like a right thing to do. You should be able to execute individual tests and to change the order of individual tests. So instead we are starting to recognize a single state as something to test.

Ph.D. Miro Samek writes about state machines being a killer app for function pointers. He further defines a design pattern for state chart implementation. Our state chart interface has become to be something like:

construct()
dispatch(event)

construct is self explaining and dispatch dispatches new event. We have specific event tick that gives resource time to state machine every 10ms (based on our 50Hz mains). We could also implement a timeout as OS service, and not to have local counters for timed events. Anyway, if we implement each state as a function as Mr. Samek proposes, and we hold our state as a function pointer we can write

dispatch( me, event )
{
me.myState(event);
}

We get rid of cryptic switch -structures. This solution helps us to unit test each state as a function with natural feel.

I'm going to write some benchmarking code to see the actual overhead, but at the moment I like this idea.