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On Design for Testability

Sunday, April 18th, 2010

keeping balanceAlmost at every conference, event, training, or consulting engagement someone asks for my opinion on the whole design for testability thing. I’m not quite sure why I haven’t blogged on this topic, especially at the time that a lot of the other bloggers were weighing in, but better late than never.

Before getting into that, I want to start with a slightly broader scope of discussion.

You see, I get asked about “best practices” on all sorts of things. And I try not to be the kind of consultant that responds with “it depends”, but the context of the question often makes the answer irrelevant. And the unspoken context of a best-practice question is:

Given infinite time and budget

The biggest problem that I see with well-intentioned, best-practices-following developers and architects is that they don’t ask the question “is this the right thing for us to be focusing on right now?” Understandably, that is a difficult question to answer – but it needs to be asked, since you don’t have infinite time or budget to do everything according to best practices (assuming those even exist).

About testing

The biggest issue I have with the “design for testability” topic is the extremely narrow view it takes of the word “testability”, usually in the form of more code written by a developer which invokes the production code of the system, also known as “unit tests”.

There are many different kinds of testing – unit, integration, functional, load, performance, exploratory, etc… where some may be automated and others not. Should we not discuss what “design for testability” means for not-just-unit-testing?

And what’s the point of testing anyway?

It’s not to find bugs.

Research has shown that testing (of all kinds) is not the most effective way of finding bugs. I don’t have the reference handy but I’m pretty sure that it’s from Alistair Cockburn’s work. Code reviews are (on average) about 60% more effective.

Don’t get me wrong – testing can provide indications that the software has bugs in it, but not necessarily where in the code those bugs are.

The purpose of testing is to provide quantitative and qualitative information about the system that can help various stakeholders in their decision-making processes. The relevance of that information indicates the quality of the testing. Here are some examples:

  • The system supports 100 concurrent users, with the expected user-type distribution (X% role A, Y% role B, etc), performing expected use-case distributions, and collaboration scenarios.
  • Time to proficiency for new users in role A is expected to be 3 days
  • Alternate #2 of use case #12 fails on step #3

As you can see, the relevance of the above information is dependent on what decisions the various stakeholders need to make. The bullet on load can help us decide if more machines are needed or if developers need to tune the performance of the systems. The bullet on time to proficiency can help us decide if larger investment in usability is required. Information like the last bullet can be used in conjunction with the first two to decide on the timing and type of a release.

The timeliness of this relevant information is critical to the success of a project.

Choosing which and how much of the various testing activities to perform when is something that needs to be revisited several times throughout the lifetime of a project, taking into account the current risks (threats and probabilities) and time and resource investment to mitigate them.

Let me reiterate – we’re not going to have enough time to do everything.

On iterations

If the only part of your organization that is doing iterations are your developers, you’re not agile.

In order to capitalize on the information that testers are providing, you need them in your iterations.

The same goes for the other roles involved in the project – business analysts, DBAs, sysadmins, etc.

I know that 99% of organizations aren’t structured in a way to do this.

I never said doing this would be easy.

On design

Figuring out what kind of design and how much to do when is just as important, and just as hard. Design for testability is one part of that, but not the only one, or necessarily the most important one at any point of time.

Within that design for testability topic is the “design for unit-testing” sub-topic which seems to be the popular one. Before getting into the design aspects of it, let’s take a closer look at the unit-testing side of things.

On unit-testing

The assumption is that having more unit tests will lead to a code-base with less bugs, thus requiring shorter time to get the system into production, which will pay back the time it took to write those unit tests to begin with.

In practice, what tends to happen is that as development progresses, testing code breaks as the structure of the production code changes. Now one of two things happens – either the testing code is removed or rewritten. In either case, we didn’t get the return on investment we expected on the first bit of testing code. Unfortunately, rare is the case where the relevant people in the organization understand why, resulting in the same situation repeating itself over and over again.

Those projects would have been better off without unit testing, though the organization as a whole might have used those experiences to learn and improve. It’s been my experience that if the organization wasn’t conscious enough in the context of the project to notice the situation, it is unlikely to do so at higher levels.

On fragile unit tests

The reason that a unit test ends up being rewritten (or removed) is that its code was coupled to the production code in such a way that it broke when the production code changed. This tendency to break (fragility) is a critical property of a unit test. A fragile unit test will slow down a developer doing work on some existing code – it actually makes the system less maintainable.

For a unit test code to be stable (not fragile) it needs to be coupled to stable properties of the production code. The question of whether the production code is designed in such a way that it has stable properties – is a design question. Is it a unit? If not, you will not be able to write a unit-test against it.

And anyway, who said that every class is a unit, or should be a unit? Domain models (when done right) are good examples of a unit, yet the classes that make them up may not be units. Unit-testing should only be attempted with things which are units.

I think too much weight is put on whether a dependency of a class is a concrete or interface type, and not nearly enough on the nature of the dependency. I wouldn’t blame the hammer for pounding my thumb, and by the same token I think that blame should not be directed towards tools like those from TypeMock.

On tools

There is so much more depth to both design and testability that needs to be more broadly understood. No tool has yet been created to handle either design or testing in such a way that humans can give up responsibility for the outcome.

Over the years I’ve noticed that tools are most significant when used by skilled practitioners, which makes sense in retrospect. Giving a novice carpenter a laser-guided saw probably won’t significantly change the outcome of their work. Ultimately, the skilled practitioners are the ones that create tools – not the novices. And no tool, no matter how advanced, will make a novice perform at levels like the skilled practitioner.

In the case of a project too big for a single skilled practitioner to complete in the time required (or at all), the balance of importance shifts away from tools to the project management topics described above.

In summary

I hope that this post has shed some light on the context in which decisions with respect to testing need to be made. Design is one activity that can support certain kinds of testing, but not the only one, or even the most important one for the given type of testing necessary at that time in the project.

Design is hard. Project management is hard. Testing is hard.

Getting the right mix of people that together have enough experience and skills in these activities isn’t easy.

Don’t expect that sprinkling some interfaces in your code base will be enough.
That doesn’t count much in the way of design, just as writing code in a testing namespace doesn’t count much in the way of testability.

Looking forward to hearing your comments.



Estimate Individually – Fail Globally?

Saturday, September 1st, 2007

After reading Derek Hatchard’s post, The Art and War of Estimating and Scheduling Software, I wanted to follow up on my previous post on the topic, Don’t Trust Developers with Project Management. The problem lies with individualistic thinking.

Developers, and managers too for that matter, by and large are concerned with “productivity”. Developers want the latest tools and technologies so that they can churn out more code faster. Managers create schedules trying to get the maximum efficiency out of each one of their developers. They consider resource utilization and other terms that sound manager-ish.

Fact is, on medium to large sized projects, if you look at the studies you’ll find that developer productivity when measured as total lines of (non-blank) code of the system in production divided by the total number of developer days comes in roughly at 6. Maybe 7.

7 lines of code a day.

Let that sink in for a second.

I can hear the managers screaming already. OMFG, what were they doing all day long?! It takes, what, 10 minutes to put out 7 lines of code? An hour even, if it’s complicated recursive code and stuff. And they say they don’t like us micro-managing them?! Now we know why. It’s because they’re goofing off all day long.

Well, managers, that’s not really the way it goes. You see, you have to take into account the time it took to learn the technology, tools, frameworks, etc. Add to that the time of understanding the requirements, which is really sitting through boring meetings that don’t explain much. Finally, our poor developer actually gets to implement the requirement. Maybe run the system a couple of times, trying out the feature they implemented, and checking the code in.

Well, that’s actually the easy part. Now comes the part which kills most of the time. After a bunch of features have been developed by the team, the testers start banging away at it and find a bunch of bugs. Now the developer has to reverse-engineer some bizarre system behavior and figure out which part of the system is to blame. That involves usually some educated guessing (unless they’ve just joined the team and have been put in the bug-fixer role to “learn the system”, in which case it is thoroughly UNeducated guessing). They change some code, run the system, which looks like its been fixed, check the new code in, and close the bug.

But the bugs keep coming. And as the project progresses towards production, more and more of the developers time is spent looking through code and changing existing code, that actually writing new code.

And the larger the system, the more bugs. And I don’t mean that the number of bugs linearly increases with lines of code, or number of features. It’s probably closer to exponential. If it’s a mission critical system, the performance bugs will be taking an order of magnitude more time to fix than other bugs.

So, as you can see, getting a system into production is a team effort. It includes the developers and testers, of course, but also management, and the customer, and how they manage scope. This is kind of a “duh” statement, but we’re getting to the punch-line.

If getting a system into production involves the entire team, isn’t that obviously true for each feature too?

In which case, why are we asking just the developers to estimate the time it takes to get a feature “done”? Why are we trying so hard to measure their productivity?

I know why. It’s so we can get rid of the less productive ones and give bonuses to the more productive ones!

Back to the main issue. I don’t “trust” developer estimates because I need to see the team’s capability to put features in production. The involves all aspects, and often many team members, in some cases multiple developers going through the same code. This involves all overhead and cross team communication, sick days, etc. It’s also why I try to get multiple data points over time to understand the team’s velocity.

While I care about the quality of my developers, and testers, and everybody on my team and would like them to be able to estimate their work as best they can, I’ve got a project to put into production. And the best way I’ll know when it’ll go into production is by having data that’ll enable me to state to my management:

“Our team is finishing 20 feature-units a month, we’ve got 200 feature-units to go, so we’ll be done in around 10 months.”

If I’m busy micro-measuring each developers estimates, I won’t have the time to see the forest. By first taking a harsh look at the reality of what the team can do, I can start looking for ways to make it better. Maybe the bottleneck is between analysts and developers, maybe we’re seeing the same bugs regressing many times, but until we know where we are, we can’t run controlled experiments to see what makes us better.

Focusing on the individual developer, getting them the latest and greatest tools may be great for their morale, but it probably won’t make a bit of difference to their actual productivity.

Next time – what to do when management asks you what it’ll take to be done sooner.



What? You mean, for free?

Wednesday, January 24th, 2007

Responding to change – it’s one of the primary agile values. This topic came up over lunch with Sébastien in a rather round about way. Sébastien mentioned that, in French, when his clients communicate with him (and he with them) using the informal address “tu” he finds himself more obliged to comply with their requests than when using the more formal “vous”. The agilists quickly chimed in on the importance of responding to change but my fixed-price background wouldn’t let that go.

 

For starters, let me say that I’m all for giving the greatest value possible to a client. However, when I’ve got a schedule that can’t slip and can’t recruit a larger team (for whatever reason) and my client asks me if we could also handle some new XYZ scenario, I sometimes answer “no”. My agile friends were even more astonished when I told them that quite a few of my customers respect me for that answer. Just so you understand, the long version of that “no” is:

 

“Since we can’t slip the schedule any, and we’ve already done away with all the features that could have been cut, and we can’t bring in any new people, I really can’t promise you that if we try to do that additional work the project will stay on track.”

 

With clients with whom I’ve worked for quite a while, I sometimes use the more glib “what? You mean, for free?”, and we usually have a good laugh over it.

 

Anyway, bottom line is that change costs. Somebody has to pay, sometimes a little, sometimes a lot. If you’re a week or two from shipping, dropping a feature to “make room” for the new feature might not help. So much work may have already been done that to take the old feature out might be more work than leaving it in.

 

One big thing that I will give to agile over the fixed-price projects is that by forcing customers to define up-front all requirements, and “threatening” with a high cost of subsequent change, customers are made to put in many requirements that they think that they just might need. This is scope creep even before any work’s been done. By allowing the customer to change their mind during the project you are, in one feel swoop, decreasing (often drastically) that scope of the project making it cheaper and easier to give high value.

 

You’d be surprised by the number of times that clients are just trying to figure out if the cost of additional feature XYZ now is outweighed by its value. Giving an unqualified “yes” short-circuits the necessary discussions around risk that keep the business in the driver’s seat on the project. Sometimes “no” really is the best answer.



Money?! Schedule?! But I’m an architect, not a PM!

Friday, January 5th, 2007

After all contestants presented their solutions in the Iron Architect contest at TechEd Developers in Barcelona, and the judges left the room to deliberate, I put a question to them:

“When can you have your solution in production and how much would it cost?”

You could see the shock on their faces. Architects weren’t supposed to answer these kinds of questions, were they? That’s what project managers are for, right? Eventually, they settled on one month for the schedule question, with only one developer. That’s one month in terms of calendar time. I was shocked by that.

Unless you’re Superman, in the span of one month you cannot learn an existing system, figure out all the new requirements, design, develop, test, and deploy, debug, etc, etc, and keep stakeholders happy and in the loop throughout the whole process. And it doesn’t matter how many developers you have.

And on that point, like you’re really going to be able to find a developer who’s any good at the drop of a hat, get them to leave whatever they’re doing for a month, for a short term project like that.

This topic came up in the speaker dinner when I was talking to Pooya and Jurgen (one of the judges). Architects need to be the glue that connect everything together – business, management, technical, test, operations, etc. They need to fully understand project lifecycle issues. When business comes along with a new requirement, the architect is the one who says if it can be just slipped in or needs to be separately budgeted – not the PM. The PM may have the final call, but the architect is the one who provides the information about the ramifications of changes to the project.

Money? Schedule? All in a day’s work for an architect.



On Prototypes

Thursday, December 11th, 2003

Prototypes. They’re everywhere. Sometimes they grow into full-fledged systems. Sometimes they’re thrown away. But they can be considered a project in their own right. I’ve decided to write this entry after reading Fabrice’s thoughts on the same subject. Before getting into my own thoughts on the matter, I’d like to quickly sum up the main points I found there, including the comments posted.


The main issue originally revolved around web apps, and whether HTML or ASP.NET should be used for prototypes. Powerpoint, Visio, Paper – yes that stuff that comes out of printers, Photoshop, Illustrator, and Denim were all brought up. Arguments for and against were made. Before I pick a side, I thought I’d return to the basics.


A prototype, by definition, should be thrown away. The lessons learned, obviously, should not.


I bring this point up as it is the most basic. When thinking about prototypes, the last thing that should concern us is if we can “reuse” pieces of it for the actual system. Now, if the point of the prototype is to learn, and learning is most facilitated by short feedback loops (tons of research back this up, think pavlov), we should be looking for the “technology” that allows for the quickest feedback.


What do I mean by feedback ? What the client thinks about what we’re doing. And what’s the fastest form of “do something, get feedback” ? Talking. What we need is a way to actually DO the prototype WHILE talking to the client. This pretty much reduces the number of contending technologies down to 1. Paper.


Paper prototyping, when done well, brings to light SO many issues and unspoken assumptions in SO little time, that, from my experience, it just doesn’t make sense to go any other route. There is so much information out there on paper prototyping that I can’t even begin to list it here. Just google it.


So, how can paper prototyping be done well ? Well, it requires preparation, and, obviously, lots of paper. Plan for about a 1 hour sessions at a time with the client, no more. These sessions are VERY tiring. If possible, try to get someone to write down everything that came up during the session, and what resolutions were reached. This person should not be involved in the session beyond being an observer.


Now, let’s consider the alternative. Using a computer + some software, be it Visio, Photoshop, whatever. The problem with these approaches is that we get to focused on what we’re building, and lose focus of the lessons we should be learning. These approaches obviously increase the time between a decision we make about the system, and getting the client’s reaction. It therefore also increases the time we waste when we get a decision wrong.


The Agile world has already come to this conclusion and makes every attempt to get a real, live customer/client/user on-site for the development of the actual system. When building actual systems, obviously, paper can’t be used. But where it can, and it’s most appropriate, it should.


To sum up, when a prototype is done, we should know more about the real system that we’re building than when we started. Short feedback loops with our clients is what gives us the most information. And paper is the medium most suited to short feedback loops when dealing with prototypes.





Update:


Six Signs That You Should Use Paper Prototyping from Java.Net


Sign 1. There are many different ideas about the design


Sign 2. You find yourself defending a particular design


Sign 3. There are parts of the design you’re unsure about


Sign 4. You’re changing the way that the users perform a task


Sign 5. The concepts or terminology are new to the users


Sign 6. You’re feeling uncreative



Busy busy BUSY

Wednesday, November 26th, 2003

Things have been quite frantic recently ( for a glimpse of what’s going on see Udi Dahan’s Projects under the categories ) so I haven’t had much time for blogging. I know that everyone gets bogged down in work now and again, and apologizes for not blogging, but I’m actually quite happy that business is going so well that a large portion of my time can now be billable. If this keeps up, I’ll have to reconsider non-work blogging.


So, although I doubt that this will be my “last” entry, I will probably be going into a dry spell.



Udi Dahan’s Projects

Thursday, November 20th, 2003

Recently I’ve started thinking about other potential uses for blogging and rss in general. One thought that came to my mind is the use of a blog for managing projects. Before I get into the managing projects thing, I guess that I should give a little background about myself. I am a standalone programmer / consultant. This really means that I am a team of one. I meet with clients, market my services, sign the contracts, meet with the users, dig for requirements, decide on architecture, design the UI, code the system ( test first ), deploy, manage user expectations, etc… Not only that, but I do this on several projects at the same time. This is what I mean by managing projects. I need a way to be most effective at doing all of these things. Just think of the possibilities if all of the stakeholders on a project had an rss aggregator. Communicating status on an ongoing basis would be simple. Mocking up a UI and getting the users comments would be simple. If you could get wiki technology integrated, you could work on all sorts of requirements docs/xp stories/whatever simply. To make a long story short, its all about effective asynchronous communication. Anyway, after all of these thoughts I came to a decision. Just do it. Try it. What’s the worst thing that could happen ? It’ll flop, and I’ll stop it pretty quick. On the other hand, maybe it really could be good for something, even a subset of the things listed above. Maybe other things that I didn’t think of. Maybe the project stakeholders will come up with other ways to use this technology. So… I am officially anouncing the opening of Udi Dahan’s Projects, the blog that will change the way we work – well, the way I work. The first experiment of its kind – that I know of. Tell me what you think ! How can blogging be used to manage projects, or, more generally, to improve the way projects are run ? Any ideas, crazy ones are exactly what I’m looking for, on other uses for this technology ? Am I totally wrong and going on the path to destruction ?



   


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Udi Dahan is the real deal.

We brought him on site to give our development staff the 5-day “Advanced Distributed System Design” training. The course profoundly changed our understanding and approach to SOA and distributed systems.

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“Udi is a world renowned software architect and speaker. I met Udi at a conference that we were both speaking at, and immediately recognized his keen insight and razor-sharp intellect. Our shared passion for SOA and the advancement of its practice launched a discussion that lasted into the small hours of the night.
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Aaron Jensen Aaron Jensen, VP of Engineering at Eleutian Technology
Awesome. Just awesome.

We’d been meaning to delve into messaging at Eleutian after multiple discussions with and blog posts from Greg Young and Udi Dahan in the past. We weren’t entirely sure where to start, how to start, what tools to use, how to use them, etc. Being able to sit in a room with Udi for an entire week while he described exactly how, why and what he does to tackle a massive enterprise system was invaluable to say the least.

We now have a much better direction and, more importantly, have the confidence we need to start introducing these powerful concepts into production at Eleutian.”

Gad Rosenthal Gad Rosenthal, Department Manager at Retalix
“A thinking person. Brought fresh and valuable ideas that helped us in architecting our product. When recommending a solution he supports it with evidence and detail so you can successfully act based on it. Udi's support "comes on all levels" - As the solution architect through to the detailed class design. Trustworthy!”

Chris Bilson Chris Bilson, Developer at Russell Investment Group
“I had the pleasure of attending a workshop Udi led at the Seattle ALT.NET conference in February 2009. I have been reading Udi's articles and listening to his podcasts for a long time and have always looked to him as a source of advice on software architecture.
When I actually met him and talked to him I was even more impressed. Not only is Udi an extremely likable person, he's got that rare gift of being able to explain complex concepts and ideas in a way that is easy to understand.
All the attendees of the workshop greatly appreciate the time he spent with us and the amazing insights into service oriented architecture he shared with us.”

Alexey Shestialtynov Alexey Shestialtynov, Senior .Net Developer at Candidate Manager
“I met Udi at Candidate Manager where he was brought in part-time as a consultant to help the company make its flagship product more scalable. For me, even after 30 years in software development, working with Udi was a great learning experience. I simply love his fresh ideas and architecture insights.
As we all know it is not enough to be armed with best tools and technologies to be successful in software - there is still human factor involved. When, as it happens, the project got in trouble, management asked Udi to step into a leadership role and bring it back on track. This he did in the span of a month. I can only wish that things had been done this way from the very beginning.
I look forward to working with Udi again in the future.”

Christopher Bennage Christopher Bennage, President at Blue Spire Consulting, Inc.
“My company was hired to be the primary development team for a large scale and highly distributed application. Since these are not necessarily everyday requirements, we wanted to bring in some additional expertise. We chose Udi because of his blogging, podcasting, and speaking. We asked him to to review our architectural strategy as well as the overall viability of project.
I was very impressed, as Udi demonstrated a broad understanding of the sorts of problems we would face. His advice was honest and unbiased and very pragmatic. Whenever I questioned him on particular points, he was able to backup his opinion with real life examples. I was also impressed with his clarity and precision. He was very careful to untangle the meaning of words that might be overloaded or otherwise confusing. While Udi's hourly rate may not be the cheapest, the ROI is undoubtedly a deal. I would highly recommend consulting with Udi.”

Robert Lewkovich, Product / Development Manager at Eggs Overnight
“Udi's advice and consulting were a huge time saver for the project I'm responsible for. The $ spent were well worth it and provided me with a more complete understanding of nServiceBus and most importantly in helping make the correct architectural decisions earlier thereby reducing later, and more expensive, rework.”

Ray Houston Ray Houston, Director of Development at TOPAZ Technologies
“Udi's SOA class made me smart - it was awesome.

The class was very well put together. The materials were clear and concise and Udi did a fantastic job presenting it. It was a good mixture of lecture, coding, and question and answer. I fully expected that I would be taking notes like crazy, but it was so well laid out that the only thing I wrote down the entire course was what I wanted for lunch. Udi provided us with all the lecture materials and everyone has access to all of the samples which are in the nServiceBus trunk.

Now I know why Udi is the "Software Simplist." I was amazed to find that all the code and solutions were indeed very simple. The patterns that Udi presented keep things simple by isolating complexity so that it doesn't creep into your day to day code. The domain code looks the same if it's running in a single process or if it's running in 100 processes.”

Ian Cooper Ian Cooper, Team Lead at Beazley
“Udi is one of the leaders in the .Net development community, one of the truly smart guys who do not just get best architectural practice well enough to educate others but drives innovation. Udi consistently challenges my thinking in ways that make me better at what I do.”

Liron Levy, Team Leader at Rafael
“I've met Udi when I worked as a team leader in Rafael. One of the most senior managers there knew Udi because he was doing superb architecture job in another Rafael project and he recommended bringing him on board to help the project I was leading.
Udi brought with him fresh solutions and invaluable deep architecture insights. He is an authority on SOA (service oriented architecture) and this was a tremendous help in our project.
On the personal level - Udi is a great communicator and can persuade even the most difficult audiences (I was part of such an audience myself..) by bringing sound explanations that draw on his extensive knowledge in the software business. Working with Udi was a great learning experience for me, and I'll be happy to work with him again in the future.”

Adam Dymitruk Adam Dymitruk, Director of IT at Apara Systems
“I met Udi for the first time at DevTeach in Montreal back in early 2007. While Udi is usually involved in SOA subjects, his knowledge spans all of a software development company's concerns. I would not hesitate to recommend Udi for any company that needs excellent leadership, mentoring, problem solving, application of patterns, implementation of methodologies and straight out solution development.
There are very few people in the world that are as dedicated to their craft as Udi is to his. At ALT.NET Seattle, Udi explained many core ideas about SOA. The team that I brought with me found his workshop and other talks the highlight of the event and provided the most value to us and our organization. I am thrilled to have the opportunity to recommend him.”

Eytan Michaeli Eytan Michaeli, CTO Korentec
“Udi was responsible for a major project in the company, and as a chief architect designed a complex multi server C4I system with many innovations and excellent performance.”


Carl Kenne Carl Kenne, .Net Consultant at Dotway AB
“Udi's session "DDD in Enterprise apps" was truly an eye opener. Udi has a great ability to explain complex enterprise designs in a very comprehensive and inspiring way. I've seen several sessions on both DDD and SOA in the past, but Udi puts it in a completly new perspective and makes us understand what it's all really about. If you ever have a chance to see any of Udi's sessions in the future, take it!”

Avi Nehama, R&D Project Manager at Retalix
“Not only that Udi is a briliant software architecture consultant, he also has remarkable abilities to present complex ideas in a simple and concise manner, and...
always with a smile. Udi is indeed a top-league professional!”

Ben Scheirman Ben Scheirman, Lead Developer at CenterPoint Energy
“Udi is one of those rare people who not only deeply understands SOA and domain driven design, but also eloquently conveys that in an easy to grasp way. He is patient, polite, and easy to talk to. I'm extremely glad I came to his workshop on SOA.”

Scott C. Reynolds Scott C. Reynolds, Director of Software Engineering at CBLPath
“Udi is consistently advancing the state of thought in software architecture, service orientation, and domain modeling.
His mastery of the technologies and techniques is second to none, but he pairs that with a singular ability to listen and communicate effectively with all parties, technical and non, to help people arrive at context-appropriate solutions. Every time I have worked with Udi, or attended a talk of his, or just had a conversation with him I have come away from it enriched with new understanding about the ideas discussed.”

Evgeny-Hen Osipow, Head of R&D at PCLine
“Udi has helped PCLine on projects by implementing architectural blueprints demonstrating the value of simple design and code.”

Rhys Campbell Rhys Campbell, Owner at Artemis West
“For many years I have been following the works of Udi. His explanation of often complex design and architectural concepts are so cleanly broken down that even the most junior of architects can begin to understand these concepts. These concepts however tend to typify the "real world" problems we face daily so even the most experienced software expert will find himself in an "Aha!" moment when following Udi teachings.
It was a pleasure to finally meet Udi in Seattle Alt.Net OpenSpaces 2008, where I was pleasantly surprised at how down-to-earth and approachable he was. His depth and breadth of software knowledge also became apparent when discussion with his peers quickly dove deep in to the problems we current face. If given the opportunity to work with or recommend Udi I would quickly take that chance. When I think .Net Architecture, I think Udi.”

Sverre Hundeide Sverre Hundeide, Senior Consultant at Objectware
“Udi had been hired to present the third LEAP master class in Oslo. He is an well known international expert on enterprise software architecture and design, and is the author of the open source messaging framework nServiceBus. The entire class was based on discussion and interaction with the audience, and the only Power Point slide used was the one showing the agenda.
He started out with sketching a naive traditional n-tier application (big ball of mud), and based on suggestions from the audience we explored different solutions which might improve the solution. Whatever suggestions we threw at him, he always had a thoroughly considered answer describing pros and cons with the suggested solution. He obviously has a lot of experience with real world enterprise SOA applications.”

Raphaël Wouters Raphaël Wouters, Owner/Managing Partner at Medinternals
“I attended Udi's excellent course 'Advanced Distributed System Design with SOA and DDD' at Skillsmatter. Few people can truly claim such a high skill and expertise level, present it using a pragmatic, concrete no-nonsense approach and still stay reachable.”

Nimrod Peleg Nimrod Peleg, Lab Engineer at Technion IIT
“One of the best programmers and software engineer I've ever met, creative, knows how to design and implemet, very collaborative and finally - the applications he designed implemeted work for many years without any problems!

Jose Manuel Beas
“When I attended Udi's SOA Workshop, then it suddenly changed my view of what Service Oriented Architectures were all about. Udi explained complex concepts very clearly and created a very productive discussion environment where all the attendees could learn a lot. I strongly recommend hiring Udi.”

Daniel Jin Daniel Jin, Senior Lead Developer at PJM Interconnection
“Udi is one of the top SOA guru in the .NET space. He is always eager to help others by sharing his knowledge and experiences. His blog articles often offer deep insights and is a invaluable resource. I highly recommend him.”

Pasi Taive Pasi Taive, Chief Architect at Tieto
“I attended both of Udi's "UI Composition Key to SOA Success" and "DDD in Enterprise Apps" sessions and they were exceptionally good. I will definitely participate in his sessions again. Udi is a great presenter and has the ability to explain complex issues in a manner that everyone understands.”

Eran Sagi, Software Architect at HP
“So far, I heard about Service Oriented architecture all over. Everyone mentions it – the big buzz word. But, when I actually asked someone for what does it really mean, no one managed to give me a complete satisfied answer. Finally in his excellent course “Advanced Distributed Systems”, I got the answers I was looking for. Udi went over the different motivations (principles) of Services Oriented, explained them well one by one, and showed how each one could be technically addressed using NService bus. In his course, Udi also explain the way of thinking when coming to design a Service Oriented system. What are the questions you need to ask yourself in order to shape your system, place the logic in the right places for best Service Oriented system.

I would recommend this course for any architect or developer who deals with distributed system, but not only. In my work we do not have a real distributed system, but one PC which host both the UI application and the different services inside, all communicating via WCF. I found that many of the architecture principles and motivations of SOA apply for our system as well. Enough that you have SW partitioned into components and most of the principles becomes relevant to you as well. Bottom line – an excellent course recommended to any SW Architect, or any developer dealing with distributed system.”

Consult with Udi

Guest Authored Books
Chapter: Introduction to SOA    Article: The Enterprise Service Bus and Your SOA

97 Things Every Software Architect Should Know



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