Udi Dahan   Udi Dahan – The Software Simplist
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UI Composition Techniques for Correct Service Boundires

Saturday, June 23rd, 2012.

PrismOne of the things which often throws people off when looking to identify their service boundaries is the UI design. Even those who know that the screen a user is looking at is the result of multiple services working together sometimes stumble when dealing with forms that users enter data into.

Let’s take for example a screen from the Marriott.com online reservation system (below). This screen collects information about the guest staying at the hotel (name, phone number, address, etc) and credit card information.


While we might have wanted to keep guest information in a separate service from the credit card information (which may very well be the corporate card of someone responsible for travel), the above screen would seem to indicate that the data would be collected together, validated together, and would also have to be processed together.

The traditional way

In standard layered architectures you would have all the data submitted by the user passed in a single call from a controller to some “service layer” (possibly running on a different machine), which would then persist that data in one transaction.

Even if some attempt was made to separate things out, there likely would be some “orchestration service” that received the full set of data and it would make calls to the other “services”, passing in the specific data that each “service” is responsible for.

I am putting quotes around the word “service” to indicate that I don’t consider these proper services in the SOA sense (as they lack the necessary autonomy) – they are more like functions or procedures, whether or not they’re invoked XML over HTTP is besides the point.

What to do?

Like so many other things, the solution is simple but a bit counter-intuitive as it doesn’t follow the way most web development is done, i.e. one submit button => one call to the server.

Let’s say the “Red” service is responsible for guest information and the “Blue” service is responsible for credit card data. In this case, each service would have its own javascript come down with the page and that script would register itself for a callback on the click of the submit button. Each service would take the data the user entered into its part of the page and independently make a call to “the” server (could be to 2 separate servers) where the data is persisted (potentially to 2 different databases).

This raises other questions, of course.

Now that the data submitted is being processed in 2 transactions rather than just one, we may need to figure out how to correlate the data. In this specific case, it’s not such a big deal as there is no direct relationship between the guest and the credit card – both need to be independently correlated to some reservation ID.

That reservation ID would likely have been “created” on a button click on a previous screen by some other service. The reason why I put the word “created” in quotes is that this could be as simple as having the client generate a new GUID and put that in a cookie (which would cause the reservation ID to end up being submitted along with subsequent requests). Another alternative would be to put the reservation ID in the session.

It’s quite possible that the reservation ID would only be persisted much later in the service that owns it when the user actually confirms the reservation on the website.

In any case, what we can see is that each of the commands of our respective services can now be processed independently of the others in an entirely asynchronous fashion thus vastly improving the autonomy of our services.

Some words on CQRS

This style of UI composition where services leverage javascript code running in the browser isn’t technically difficult in the slightest. The rest of the implementation of each service – having a controller that takes that data and passes it on for persistence can be quite simple.

I’d say even more strongly, most of the time you shouldn’t need to use any fancy-dancy messaging to get that data persisted – that is, unless you’re still stuck with the big relational database behind 23 firewalls type data tier. Embrace NoSQL databases for the simplicity and scalability they provide – don’t try to re-invent that using messaging, CQRS, persistent view models, event-sourcing, and other crap.

There are other very valid business reasons to embrace CQRS, but they have nothing to do with persistence.

Also notice, this is all happening within a service boundary / bounded context.

In closing

If you aren’t leveraging these types of composite UI techniques, it’s quite likely that your service boundaries aren’t quite right. Do be aware of the UI design and use it to inform your choices around boundaries, but be aware of certain programming “best practices” that may lead you astray with your architecture.

Also, if you’re planning on coming to my course in Toronto to learn more about these topics, just wanted to let you know that there’s one week left for the early-bird discount.

Finally, it’s good I have a birthday that comes around once a year to remind me that my time here isn’t unlimited and that I had better get off my rear and do something meaningful with the time I do have. If you get value from these posts, leave a comment or send me a tweet to let me know – it does wonders for my motivation.

Thanks a bunch.

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  1. Pawel Pabich Says:

    Yep, keep them coming.

  2. Sean Kearon Says:

    I always love reading your posts. I even have an Instapaper subscription for your blog sent to my Kindle. So, thank you, do keep them coming and have a good birthday too!

  3. Yaron Wittenstein Says:

    great post as always!!

  4. Marcin Deryło Says:

    Udi, many thanks for all the insights you’re sharing. It really affected the way me & my colleagues are designing our system and I’m happy to see this post confirming our understanding of how UI composition should be done. Happy birthday!

  5. Stacy Says:

    Multiple submit buttons on the form shown could be confusing to most users, especially since the tasks are “obviously related and dependent” from the user’s viewpoint. The only purpose here is to enable some under-the-hood technical stuff, at the expense of user experience.

    In this kind of case, maybe a wizard interface might be more user-friendly, and still allow for multiple submit buttons.

    Also we have to keep mobile interfaces in mind these days, and this composite ui-style is going in the opposite direction.

    One thing I found very helpful in this post is to think of each wizard step as a separate service, coupled only by an Id and not all the previous inputs. A very liberating thought to help me out of webforms wizard hell!

    I ALWAYS learn from you, even when I disagree. Thanks and Happy Birthday!

  6. Andy Says:

    @Stacy You wouldn’t need multiple submit buttons — you would submit to multiple services using a single submit button.

  7. Augi Says:

    Thank you for the great article (again) and happy B-day!

  8. Gabriel Schenker Says:

    “CQRS, persistent view models, ES and other crap…”
    These are strong words and IMHO not really helpful since they provoke people rather than helping them to find the best solution to a give problem. I have learned that ‘there are many ways that lead you to Rome’. There is no single best way of doing something. It’s rather an evolutionary process that leads us to a better and deeper understanding and consequently allows us to find more appropriate ways of solving the problems.

  9. Dan Turner Says:

    I’m sorry, but with all due respect I must strongly disagree. You haven’t avoided any orchestration work at all, you’ve just moved it in to client side script! How are you going to deal with the scenario that one of the service calls fails? Say a failed credit card payment, or no more rooms left? In more javascript?? I would much rather take the less brittle approach of introducing an orchestration service. Like it or not, however trivial it may be, there is a relationship between these services, if one call fails, they both fail. This should be reflected in the architecture, not hidden in javascript. With an orchestration service you also either get transactions for free provided by infrastructure, or alternatively if the underlying service doesnt support this, explicit and unit testable control over recovery.

  10. Rob Eisenberg Says:

    Happy Birthday! I tend to relish your blog posts, so please keep them coming.

  11. Parag Says:

    question is what if both of these services are interdependent, in this case reservation is only allowed if credit card is correctly charged.

  12. Kelly Summerlin Says:

    @stacy – don’t read two callbacks on the submit as multiple submit buttons. Just multiple callbacks for one button. Each callback uses a separate service using the generated ID value.

  13. Payman Says:

    I find your blogs highly educational and a great resource so please keep them coming. Happy birthday.

  14. Jimmy Sin Says:

    Happy birthday, Udi! I attended your “Advanced Distributed System Design with SOA& DDD” course in Sydney this year and must admit that the course has helped me understand and appreciate your posts even more. Hence, please keep posting, as this is something that I look forward to ever since I attended your course. Thumbs up!

  15. Sławek Sobótka Says:

    Udi, Your posts brings value and Your entire work is meaningful for me and people I pass this knowledge down.

    Hope to meet somewhere in our limited time span… maybe during one of “rabbit-hole” workshops someday.

    Thanks and happy birthday:)

  16. Mani Says:

    Thanks for the post – Keep up the good work and Happy B’day.

  17. Valeriob Says:

    @ Udi
    Happy birthday !

    @Dan Turner
    I understand your pov, because i made the same mistake at first, but
    if you analyze the use case, you will notice that there is no behaviour.
    This is about a “volatile” user buying something on the fly :
    the form is just storing data in two different services.
    Given that, Udi said that when you will need to add some behaviour (charge the client for example) you can use only later that correlationId for the payment process (that is only valid for a certain amount of time).

    This could be wrapped out with KISS and do not gold plate when there is no complexity involved more than “don’t do CQRS/ES/SAGA use js instead” 😀

  18. Chris Says:

    What about users without Javascript?

  19. João P. Bragança Says:

    Or machine clients for that matter. I think it would be better (i.e., RESTful) to submit a composite command + a correlationId and let the controller handle the routing.

    Of course I also agree that there’s hardly any behavior here, command ( -> transaction script?) -> persist is good enough.

  20. Clava Says:

    Great post, this one has been a long time coming… Enjoy your birthday

  21. Matt Says:

    Really appreciate the good work you do here, and in other places – you’re a real boon to the community at large. Keep up the good work, and happy birthday!

  22. Tarun Kohli Says:

    Not sure if I agree with this design paradigm. All it does is move Controller/Orchestration/Facade Service responsibilities to the UI Layer.

    In this case, the UI layer needs to create the correlation ID and make it available to both the independent services. Also, the UI would have to be cognizant of the state of the entire transaction and the services participating in it. How would it let the user know when the job has been completed? Wouldn’t it have to listen to status from the registered services thus creating a pseudo-transaction?

    Also, there are times when you want to execute the business services in a specific order. For example, create the customer and then only charge the card. This would entail bloating the UI code to exactly do what the Orchestration service would have done.

    Needless to say, the same UI orchestration code would have to be duplicated for some other channel(like B2B) as well.

    BTW, hope you had a great birthday!


  23. Josh Kodroff Says:


    “Wouldn’t it have to listen to status from the registered services thus creating a pseudo-transaction?”

    Not really.

    You fire 2 AJAX POSTs, and if you don’t get an HTTP error you’re A-OK. Then you just set up a block of JS that redirects the user to the next page once both async calls have been completed successfully. (This code is very similar to how a saga works.) If you receive an error on either call, you alert the user to the error.

  24. Tarun Kohli Says:


    Thanks much for your response. Much appreciate it. I understand what you are saying but IMHO it might only be applicable for handful of scenarios. There are times when one has to do things sequentially.

    It could be that I’m taking Udi’s example literally but I think there are only handful of scenarios when this could of thing could work.

    Also, as I mentioned, this kind of code – invoking the registered services asynchronously, listening to the errors, doing basic error handling etc. would have to be repeated for every new UI channel.

  25. Jon Says:

    Who owns the HTML? Aren’t the services still coupled there? Or should we make ajax calls to get the html too? In which case who owns the CSS? We have to couple somewhere, so what does this approach actually buy you? You may as well couple the services on the server side. It makes things easier to serve the html/css/js as one thing, no? Or is this a deployment issue?

  26. Mr. Logic Says:

    One has to question everything when thinking of incorporating the latest buzz. The complexities will eat you alive if you do not have a good enough reason for moving in that direction.

    This is a very good post. I look forward to the next one.

  27. Josh Kodroff Says:


    If you have to do it sequentially, you may well either have your service boundaries wrong, or your assumption that things *have* to be done in a certain order is wrong. Also, it’s important to know that commands very rarely fail. You should generally assume that they’ll go through just fine. If a command failing is truly catastrophic (someone’s life is at risk or the organization stands to lose a lot of money), then you’ll need to do something like issue a compensating command.

    Don’t let the UI dictate the service boundaries. I made that mistake. Ideally the UI and the commands it invokes are seamless – 1 form, 1 command. But if you can’t get that across, don’t let the UI dictate the command/services structure. I made that mistake and it sucked.

  28. Josh Kodroff Says:


    HTML and CSS would be owned by the one context that can see all the services: IT Ops. (Udi’s name for it, not mine.) This approach buys you coupling at a single point, instead of spread out all over the code base.

    One way to implement this would be to use something like Knockout.js: you make direct calls to a very thin facade (or none at all) over the service that returns JSON (data only). The markup templates and code to map it to viewmodels all exist on the page as initially rendered. Once the page loads, Knockout code hits the services and grabs the data.

    Major advantages of this approach are:
    1. more scalable from a performance perspective
    2. more scalable from a development perspective (because a back-end developer could hand off the service to a front-end JS expert)
    3. easier to deploy (you could update a service to make it more performant and deploy it by itself so long as you don’t change the interface)

    (and probably more stuff I haven’t thought of)

    DISCLAIMER: I *personally* have never developed a site like this, but I believe that’s how sites like Twitter work. I believe MSFT (and possibly others) refer to this design style as “single page app”.

  29. Jørn Wildt Says:

    Keep it coming 🙂 I have always looked forward to your blog posts.

    Kind regards, Jørn Wildt

  30. Shay Ben-Sasson Says:

    Dear Udi,
    first of all happy birthday.

    After being in one of your fascinating courses, I’ve tried architechting one of my projects to be the SOA way (I know you don’t like the word “the”).
    Didn’t have any major problems on server side, but I’ve been struggling doing “UI composition” on the client side.
    Following this great link gave in an earlier post (http://blog.hansenfreddy.com/2011/07/07/tabular-data-composition-in-the-browser-for-soa/) – I’ve built the client using Knockout and Ajax (getting data from web api that is cleverly cached using CDNs).
    It seems that the major caveat of this approach is SEO (search engine bots, more precisely) unable to index the dynamic content generation (in my case mostly KO bindings of articles header, author and text).

    Have you heard of any solution to this problem?

    Thanks for you time,

  31. Jon Says:


    Couple of fair points around perf and scalability. I still do not really get the autonomous argument though. It seems to me the coupling is pretty much the same if you choose to compose client side or server side. It’s not “spread out all over the code base”, why can’t IT Ops own a server side component that composes the services?

    Regarding point 2, you could easily expose JSON if you couple on the service server side if you wanted to.

  32. Josh Kodroff Says:


    Let’s say you have a web app with an HTML front end and a RESTful API (a common scenario).

    If you turn the data into a viewmodel at the controller level and return that data as formatted markup to the browser:
    1. Multiple controllers will likely be dependent (either directly or indirectly) on the same service (coupling when reading) because they have to return 1 viewmodel. You’re stuck with either creating a service that takes the data from 2 services and returns the 1 viewmodel or doing a bunch of mapping code in the controllers.
    2. You’ll have to HTTP POST the entire viewmodel to a single action, then break that down into 2 commands to be issued at the controller level, so you now have an extra controller action exposed just because 2 unrelated forms appear in the same UI screen (coupling when writing).

    In the approach Udi’s detailing, your API and your controller actions are one and the same. The controllers don’t need to know anything about the structure of the UI’s viewmodels because you’ve pushed the ITOps farther down the chain into client-side JavaScript. It’s less code, less exposed methods, just simpler and cleaner IMO. Composition FTW.

    Disclaimer: This argument may not hold quite as much weight when working in a dynamic language server-side – I’ve only done thing with C# and ASP.NET MVC so far.

  33. Services are (still) not Remotely Callable Components Says:

    […] In fact, in a well designed Service-Oriented Architecture, we tend to see components from many services deployed in process with each other (as I showed in my recent post UI Composition for Correct Service Boundaries). […]

  34. Paul Davies Says:

    Udi, If you want to do something meaningful and have a lasting legacy, then I suggest you put all your theories and ideas down in a book. I believe if more people took on your concepts then it would vastly improve the quality of enterprise software globally. Unfortunately, not all of us work for companies who are prepared to send us on £3k training courses. I understand you make more money from the courses than you would a book, but until these ideas are available to a wider audience then they will continue to be the preserve of the elite.

  35. Jason Says:

    Thank you Udi. Very simple solution to a complex problem.

  36. Ash Says:


    How do you deal with temporal coupling when doing composite UIs? i.e. Do you fire the AJAX request directly to an endpoint exposed by the service (meaning that service has to be up) or do you send it to an endpoint on the web application that in turn forwards it to the appropriate service through a bus?

  37. udidahan Says:


    Temporal coupling (ie synchronous RPC) is perfectly alright between components within the same service – for example, from a component in the composite web UI to a component hosted in a WCF endpoint.

    The issue of availability is then handled technologically through means like load-balancing and clustering the endpoint.

  38. Terrence Joe Says:


    Just to confirm; syncronous RPC is OK if you are requesting information from a service, however if you are firing off commands, these should always go via a reliable ESB like NServiceBus?

    It seems an ESB helps mitigate many of the risks of commands being lost that load balancing alone cannot solve (network problems, bugs in the handlers, etc).

  39. udidahan Says:

    Hi Terrence,

    Yes, queries are OK to be blocking/synchronous calls.
    Commands should be delivered over reliable infrastructure.

  40. sunrayuser Says:

    Have you used .NET MEF to do UI Composition? Any good articles on best practices?

  41. udidahan Says:


    I haven’t tried .NET MEF for that. Sorry.

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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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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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