Udi Dahan   Udi Dahan – The Software Simplist
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WCF Everywhere? Not on my watch.

Saturday, December 29th, 2007.

silver bullets The other day I was at Juval’s presentation where the main message was WCF is a better .NET. In other words, if you use WCF on every one of your classes, you’ll benefit. I don’t know about you, but I’m quite wary of silver bullets – they tend to inflict quite a bit of pain when used indiscriminately. This post is my response to all the people who came up to me at the end of the presentation and wanted to know if I agreed with these far-reaching architectural statements.

oz First of all let me say that Juval is indeed a master presenter. The “looks like a class, walks like a class, quacks like a class” bit was excellent. I could tell that most people didn’t notice the speedy hands quickly deleting all attributes from the classes before the “looks like a class…” bit. At times, I got flashbacks from the Wizard of Oz – “pay no attention to the man behind the curtain”. If all attributes in WCF only went on the interfaces, then this might actually fly, but we all know that that’s not the case.

One of the interesting comparisons Juval made with WCF was the introduction of .NET. Few people in the audience seemed to remember (or maybe were just professionally younger than .NET’s 8 years), but when it came out .NET was marketed as being mainly about XML Web Services. Juval stated that this was done to play down the fact that .NET made the previous Windows programming technologies obsolete. He then drew the same conclusion about WCF – that it’s as much .NET 3.0 as .NET was the next version of MFC; besides being written in a language that resembles the previous technology, it’s really all different. I don’t think that anyone would argue the difference, but is it really a “plain .NET” killer?

The answer seemed to come around the overhead of WCF – yet Juval deftly deflected that issue with a demo showing WCF doing 200 calls a second. And everybody just bought it – I was shocked. That’s 5ms per call. If you actually take Juval’s advice and use WCF on all your classes, you’ve bought yourself one hell of a performance nightmare. Say you have around 20 of your objects involved in a sequence to handle a user action – not that many actually. With a 5ms lag per object interaction, that user action is going to take 100ms – not including any database or webservice stuff you might be doing. If you do that in a server environment, you’ll be doing roughly 10 concurrent users per core. And that’s not even doing any heavy calculations or anything. Moderately sized systems are running upwards of 1000 concurrent users – if they needed 100 cores (or dozens of servers) for that, I’m guessing that they’d be out of business.

Let’s cut this short – WCF everywhere doesn’t scale, doesn’t perform, isn’t maintainable, or testable either. In other words – don’t do it. I know Juval is a brilliant guy, and an amazing presenter – but I don’t believe he would be employing this with his own clients. This actually bears repeating. WCF is a fine technology for your application’s boundaries, but don’t be pushing it in.

Don’t do it.

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  1. WCF Everywhere? Not on my watch. - Udi Dahan - The Software Simplist Says:

    […] The answer seemed to come around the overhead of WCF… Posted: Dec 29 2007, 05:06 PM by UdiDahan | with no comments Filed under: Architecture, .Net 2.0 3.0 WPF WCF WF […]

  2. Scott Bellware Says:


    Are the perf considerations here due to every method call being done as a message (a la Ruby) rather than an directly-addressed block of behavior?

  3. udidahan Says:


    All calls going through WCF go through 32 steps which can be independently configured. All client code interacts with is a proxy.

    You can guess what happens when each and every call is encrypted at the caller and decrypted at the receiver.

    The thing is that I’m not even sure that 5ms is the worst-case scenario.

  4. Mark Seemann Says:

    I haven’t seen the original presentation, but if I understand this correctly, Juval recommends that all objects should be talking to each other via WCF.

    I completely agree with you that this is going to kill performance. According to some experiments I did a few years back, even the fastest WCF call is approximately 100 times slower than an in-proc call (which is often so fast that you can’t really measure it).

    But wait: WCF anywhere? Doesn’t that sound a lot like implementing an object hierarchy with DCOM, let alone .NET Remoting or CORBA? Then you’d be able to distribute your objects according to some arbitrary boundary you draw at deployment time…

    We’ve already been there in the 90s, which led to Fowlers first law of distributed objects (“Don’t distribute your objects”) as well as the first SOA tenet (“Boundaries are explicit”). It may be fine in theory, but doesn’t work in practice.

    So, I totally agree with you, Udi – I just wanted to provide some extra arguments against the “WCF everywhere” notion 🙂

  5. Johan Says:

    I’m doing lots of WCF, but WCF everywhere sounds weird. I would like to see Juval’s presentation before I say anything more about this though. Is it available online mayhap? I have the deepest respect for Juval’s skills as a developer and software architect, so it really makes me wonder what he means.

  6. udidahan Says:


    The thing is that Juval was suggesting to apply it in in-process calls between objects. I would say “in-thread” as well, but since that’s not possible in WCF, you might just find yourself in multi-threaded hell. Of course WCF synchronizes all access to service code, but what about if you have something like a customer object that needs to be used by two WCF objects? Are you going to be copying it all the time between the threads? That seems like a step-function in terms of complexity.

    Thanks for backing me up.

  7. udidahan Says:


    I haven’t been able to get a copy of Juval’s presentation, but if I do I’ll post a link.

    Like I said in the post, I have a hard time believing that this is what he advises his clients, so I too wonder about the intent of his message.

  8. Arnon Rotem-Gal-Oz Says:

    I wasn’t at the presentation either – but you can hear Juval promote the same idea in one of the Arcasts http://channel9.msdn.com/ShowPost.aspx?PostID=347010

    I think (hope) he just wants to make a provocative statement and doesn’t mean it in the literal sense


  9. Colin Jack Says:

    You are also not going to need all the cpabilities that WCF gives you on every class, for example I don’t really see me needing to use it in the domain.

  10. Ollie Riches Says:

    I definitely smell a silver bullet here…

    People are aware of PI (Persistence Ignorance) why not go for CI – Communication Ignorance) as well. I don’t like the idea of attributing my domain model with a specific framework attributes.


  11. Oran Says:

    Conceptually, this is where Volta is heading. Not everything is a service, but most things can declaratively opt in to being a service.

    I thought I remembered hearing Don Box suggest taking WCF in a similar direction (in-process services in the small), but the best I can find is his comment here http://pluralsight.com/blogs/dbox/archive/2004/10/13/2762.aspx#2765

    As far as in-process performance, the NullTransport for WCF is interesting while we wait for Microsoft to find the time to implement it properly:
    Roman says it’s about 2.5ms to 3ms faster than named pipes, I assume per call. His in-process WCF-workflow integration scenario is also quite interesting.

    My personal opinion is that most of the supposed benefits of in-process WCF can be better accomplished using dependency injection with decorators, or AOP. You can do both of these with custom WCF programming, but it’s a lot more work. And since you can use existing DI and AOP tools to shim things into the service instances themselves, why bother getting WCF intimately involved?

  12. udidahan Says:

    Colin – agreed.

    Ollie – that one of the main concepets behind nServiceBus.


    “most of the supposed benefits of in-process WCF can be better accomplished using dependency injection with decorators, or AOP”

    Totally agreed.

  13. Juan Suero Says:

    I think Juval is being sensational just to get people to think.
    Think about the future perhaps? There was a time some people argued that you would never need more than something K of memory. There was a time when people thought webservices would never perform well enough for anything more than a demo. If every class was automatically a WCF Service you’d have enormous flexibility in carving that thing up into boundary explicit SOA by just flipping some switches or firing up Visual Studio 2030, drawing a circle around some subset of classes and dragging those things across your model of the cloud to some other server where they would run the minute you deployed your new application model. What Juval is proposing is not a reality, its a vision.

  14. udidahan Says:


    The way Juval speaks, he makes it sound like this is what you should be doing today.

    Even if it is a vision, it seems to remind many of the distributed object fiascos around a decade ago. The main thing that Juval didn’t get into was the architectural implications of working the way he describes. Flexibility is one desirable architectural property, but it’s not the only one, and needs to be balanced against others.

  15. Adron Says:

    I was on a project that started WCF development with this mentality early in the beta release. We kept along with that mentality for some time until things finally started getting cleaned up.

    I have to say following the SOA tenant that SOA Services should be business use inclusive, doesn’t mean every single object needs to be WCF’ed. So I’m agreeing with you Udi, WCF should be used more in a business case SOA type perspective instead of a WCF everywhere approach.

    …been there, done that, not doing it again.

  16. Patrik Löwendahl Says:

    Pingback: http://www.lowendahl.net/showShout.aspx?id=180

  17. Cornerstones utvecklarblogg : WCF As The Next Object Runtime in .NET? Says:

    […] applications I’ve come across (thus far). Apparently Juval Löwy is of the same opinion. Via UDI ( http://udidahan.weblogs.us/2007/12/29/wcf-everywhere-not-on-my-watch/ ) I found an ARCast with Juval and Ron Jacobs where Juval has the radical suggestion that WCF […]

  18. GadiM Says:

    I was in Juval’s lecture too and there are several points I would like to comment about your blog entry.

    1. Juval never removed ANY attribute on any service. What he removed where implementation lines that were irrelevant to the points he was trying to make.
    2. Juval recommended that every cross-layer call is done on a service and not that every class is a service (the context is important).
    3. Juval demoed 200 calls/sec using every feature WCF have, on his laptop (which is not a server), assuming your eye need 30 frames per second for normal view, it is enough for a watch (but probably not enough for device driver).
    4. Juval did not say that you should actually use every class as a service today. He did say that it is where we are heading as an industry (again the time context is important).
    5. Juval also said that if you have to speculate where would a platform replacing .NET look like, class as a service would be the direction, based on the historical tread of always trading performance for productivity. I am not under NDA so I can direct you to http://www.microsoft.com/soa/products/oslo.aspx to see if Juval was right.

    Every one has the right to have its own opinion, and you don’t have to agree with Juval opinions, but you should at lease quote what he says and reflect what he did correctly before you disagree with him.

  19. Juan Suero Says:

    Im still learning about SOA from you and other luminaries so i didnt mean to sound so .. whatever i sounded like. Conceptually every object as a service doesnt work becuase as you say services are carved up by business capability. SOA is a business methodolgy first that then helps I.T. carve up the enterprise into something more agile than the EAIs we have out there today.(?) But a platform where every object or cog can be service enabled would be great. Juval does make it sound like you can do this today. Very matter-a-factly i might add. But the visionaries that created the world as we know it today looked passed that which is possible. Thanks for all the podcasts on SOA… i would like to recommend a book … Understanding Enterprise SOA by Eric Pullier. As well as SOA Security. SOA Security for the reason that I have learned alot about SOA itself from thinking along with the author about its security. I would also like to recommend people download the architectural document of the Neuron ESB. Its a product from Neudesic. In it there are discussions about the why and how of thier product but through this you can learn more about practical SOA.

  20. Outreal Says:

    This is a great debate, and one that I’ve been searching for answers for over the last few years. I took Juvals WCF Master Class back in 2006, where I was introduced to the concept of every class as a service.

    As everyone else that hears this for the first time does, I raised my hand and asked him to explain that again. Juval touches upon this again in his Architects Master Class when he talks about run-time processes allocation. This time I had two years of testing this theory behind me so I completely understand the benefits of what he is talking out.

    The key to understanding the benefits is to understand the context that his statements are placed. And don’t forget that the context isn’t always a distributed system using Big SOA and Little SOA…sometime it’s a desktop application using “Mini” SOA, making use of WCF services hosted in-proc and still reaping the rewards of layers, boundaries, isolation that SOA gives you.

    GadiM, you correctly highlighted three of the most important elements to the context in points 2, 4 and 5. Points 4 and 5 are clearly something in the (near and definite) future, whereas point 2 is something you can benefit from today.

    Yes, it requires a change in how you would usually design or architect your application, but then so does introducing a new design pattern (How much work is involved in implementing MVC??!!). A little bit of extra work goes a long way, especially when you have to consider fault isolation, security isolation, time-line isolation, transactions, throughput, responsiveness (more services doing small steps), and not forgetting consistency…in WCF you get all of that in a single programming model, straight out of the box.

    As a programmer, I don’t relish the thought of having to do any of that in my code, I would rather it was taken care of for me (and by people that are experts in security, transactions and threading). Whether you use the Microsoft Enterprise Library, WCF or write your own libraries. It all still needs to be done, so why not mitigate any implementation issues by using what you get for free in WCF.

    “Trading performance for productivity” is always a benefit…unless you’re writing 3D computer game graphic code ;o)

  21. udidahan Says:


    I suggest you read Juval’s article on the myriad of ways you can deadlock yourself when following that guidance. I’ve linked to it here:


    Lest we not forget, in the pursuit of our own productivity, that our users’ productivity comes first.

  22. Living in the Tech Avalanche Generation » Every Class a Class - Not JABOWS. Says:

    […] pointed out a while back that this approach gave cause for concern with regards to performance. If I make every […]

  23. Outreal Says:


    there’s nothing in that article that presents a problem. As Juval says and as WCF does, it solves the deadlock and any other concurrency issues you will get when not using WCF.

    WCF was designed to provide solutions to all those typical problems developers run into when they start using multiple threads and windows forms. It’s not just about making calls to a remote client anymore. This is something else Juval clearly points out in his presentation. And that’s why he suggests it is “a better .Net”.

    I’ve never had any deadlock or concurrency issues since using the iDesign techniques. Most of the problems were resolved without having to actually write any code, just the fact that .Net knows WCF is being used takes care of synchronization automatically for you.

    If you find your still having trouble with forms, threads and synchronization is probably an application design issue that needs to be resolved rather than a WCF issue. Juvals 2nd edition of his Programming WCF book goes a lot further into answering these very same issues (as I’m pretty sure iDesign were flooded with emails about them!).

    As I said in my previous post, to get the real benefits of WCF you really need to change how you architect your application. It just doesn’t work when you try to get WCF to do things how you “used” to do it. You need to embrace new technologies and use them how they were intended to be used.

    I’m still amazed at how may developers are developing .Net applications that require transactions, concurrency control, synchronization and multiple threading, and yet they haven’t considered using WCF!

    I’m also still amazed that Microsoft hasn’t spent more time educating the developer community on how to use their tools effectively. There are so many anti-Microsoft technology blogs, and only a few championing them. And yet the few championing them don’t have the same issues as the anti-Microsoft brigade 🙂

    Without going to far off-topic, I think this is Microsofts biggest problem. They need to reach the masses rather than focus on the few when it comes to these kind of debates.

    Don’t give up on WCF yet, it’s going to be around in one name or another for a while!!

  24. udidahan Says:


    First of all, I thank you for speaking up on this matter which impacts many developers and architects. I appreciate your position and would like to continue the conversation…

    “Don’t give up on WCF yet, it’s going to be around in one name or another for a while!!”

    COBOL’s still around too 🙂

    “to get the real benefits of WCF you really need to change how you architect your application”

    If you are suggesting that the architectural practice of finding the appropriate solution to the specific problem domain is made irrelevant by any technology – well, I’m afraid I strongly disagree.

    “WCF was designed to provide solutions to all those typical problems”

    Actually, I believe that WCF was created to replace ASMX web services, remoting, and enterprise services (aka COM+) – giving a single technological stack.

    Looking forward to hearing your reply,


  25. Barry Says:

    Hi Udi,

    Don’t you see parallels if you take your own argument and replace ‘WCF’ with C and ‘.NET’ with assembler?
    Or ‘WCF’ with C++/object orientation and ‘.NET’ with C?
    Or ‘WCF’ with COM and ‘.NET’ with C++?
    Or ‘WCF’ with .NET and ‘.NET’ with COM?
    We know how those arguments turned out!

  26. udidahan Says:


    Nice straw man – but it doesn’t fly.
    Neither do oranges and orangutans.

    .NET fully replaced all of COM and C++ as a developer API.
    WCF does not do that with .NET.

  27. Eisen Says:

    I work in an environment where we are forced to use the iDesign/WCF everywhere approach and it is so painful and unproductive. Udi – you are an island of hope in an ocean of quacking classes!

  28. udidahan Says:


    I sympathize with your pain.

  29. BobODoole Says:


    I don’t know if you still read these comments,
    But I do not get the point of this article to it’s full meaning.
    The first sentence
    ‘The other day I was at Juval’s presentation where the main message was WCF is a better .NET.’
    Makes not much sense because was or was not WCF intended to be used in Service Oriented Architectures mainly?

    So I don’t see the point to use ‘WCF’ in every single class like you mentioned in a normal application which does not even need such an architecture.

    So my main question is, is the above what you back then tried to say or you mean that in case you need a Service Oriented Architecture you should NOT rely on WCF, and go back to the days of ASP.Net web services (Which prove that they are SLOWER than WCF services) or another way of web services?

    Thanks for clearing it up in case you still read this.

  30. udidahan Says:

    Hey Bob,

    I do continue reading comments, even on my older blog posts 🙂

    With regards to the original intention of WCF, my understanding was that it was designed as a replacement for .NET Remoting, ASMX Web Services, and (COM+) Enterprise Services. Later on, when the industry starting getting hot for SOA, some people tried to stretch it in that direction, but that never got much traction – either in Microsoft internally or in the market.

    I agree with your statement “I don’t see the point to use ‘WCF’ in every single class” – and that was what I was arguing against in this post.

    If you want to know my stance on Service Oriented Architecture, there are many other blog posts to read – here are some to get you started:




    Hope that helps.

  31. Chris Marisic Says:

    Udi, WCF was meant to change programming as we know it. It was only after fear from the other groups in Microsoft that changing programming as you know it was too radical for how new .NET even was at that point. After fear of the message “changing programming as we know it” emerged it somehow morphed into “web sevices”.

    There’s a reason it’s WINDOWS Communication Foundation and not Web Communication Foundation or anything else. The fact you could bolt on support for the WS-* “standards” (with WS-* a resounding failure in hindsight) was due to the agility of WCF not anything else.

    WCF is best with in memory transport, tcp transport, queue transport, and the service bus. If you’re not using those, you’re missing the entire value of WCF. It’s unfortunate Microsoft carried the flag 90% of the way but flinched thereby forcing Juval to publish ServiceModelEx for how it was truly intended to be used.

  32. udidahan Says:


    Well, it’s been several years since then, and it doesn’t look like enough other people in Microsoft, or out in the industry for that matter, bought into that perspective.

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“Udi delivered a 5 hour long workshop on SOA for aspiring architects in Norway. While keeping everyone awake and excited Udi gave us some great insights and really delivered on making complex software challenges simple. Truly the software simplist.”

Motty Cohen, SW Manager at KorenTec Technologies
“I know Udi very well from our mutual work at KorenTec. During the analysis and design of a complex, distributed C4I system - where the basic concepts of NServiceBus start to emerge - I gained a lot of "Udi's hours" so I can surely say that he is a professional, skilled architect with fresh ideas and unique perspective for solving complex architecture challenges. His ideas, concepts and parts of the artifacts are the basis of several state-of-the-art C4I systems that I was involved in their architecture design.”

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.”

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