Udi Dahan - The Software Simplist; a blog on Service Oriented Architecture and Enterprise Software Development

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DDD the opposite of SOA? Uh, no.

Posted in DDD

Just recently the .Net Rocks crew interviewed Jimmy Nilsson on Domain Driven Design (DDD). In the first half, Richard Campbell describes SOA as the opposite of DDD, where SOA “very much is a set of technologies, that are going around trying to find a problem to solve”, and DDD is based on focusing on the problem and designing a solution for that problem.

Despite my high regard for Richard, I must say that he missed the boat on this one. Maybe the only thing that has achieved industry-wide agreement in terms of SOA is that it is NOT a technology.

Just so as there’s full disclosure here, I was the person to write the section on SOA for Jimmy’s book “Applying Domain Driven Design & Patterns”.

As for the relationship between DDD and SOA, they are not opposites. It would be more appropriate to say that they are orthogonal. You can employ DDD on an application without SOA, and conversely you could employ SOA without DDD. Although I believe that many principles of service-orientation are applicable in most distributed systems, I feel that DDD has much broader applicability and would suggest training your staff in DDD before going to SOA.

As for the question “where would you see DDD in a service-oriented solution?” Well, my answer would be that the domain model would be nicely encapsulated by a single service. The activities exposed by the domain model could also impact the message-exchange patterns that the service supports, although sometimes higher level constructs are needed. Paul Gielens’ last post on the subject, as well as a bit of the discussion on an eariler post shows just how trivial it ISN’T 🙂

Anyhow, I just wanted to straighten that out.

Comments [3]
Posted on Monday, September 4th, 2006.

Tech Ed Europe 2006

Posted in Presentations

I haven’t seen this begin circulating yet, so I just might get to be the first.

I’ll be doing a talk on SOA and workflow. More details coming soon…

Comments
Posted on Wednesday, August 30th, 2006.

[Podcast] Business and Autonomous Components in SOA

In this podcast, we describe the service oriented analysis process that leads to coherent services that are strongly business aligned. Verification techniques are also presented which can point to poor service decomposition. Finally, we drill down and show how services can be decomposed further into “Business Components” and “Autonomous Components”.

Resources:

1. Autonomous Services and Enterprise Entity Aggregation
2. Autonomous Services Podcast
3. Ask Udi a question on SOA
4. Subscribe to the Ask Udi podcast

Get it via the Dr. Dobb’s site here.

Or download directly here.

Want more? Go to the “Ask Udi” archives.

Comments
Posted on Monday, August 28th, 2006.

Re: Generics, Anonymous Methods, & Delegate inference

Posted in Development

In my previous post .Net 2.0 Generics, Anonymous Methods, and Delegate inference bug I bemoaned the difference in behavior between anonymous methods and delegates.

When using plain old event handlers, it is perfectly acceptable to subscribe and unsubscribe by doing the following:

Commands.Open.Activated += new EventHandler<OpenEventArgs>(Open_Activated);
Commands.Open.Activated -= new EventHandler<OpenEventArgs>(Open_Activated);

Even though the delegate that you are removing is a different object than the one you subscribed with, since delegates are immutable they behave like value types so this works. However, with anonymous delegates this is apparently not the case (as my previous post showed). The following code is incorrect, even for the same object ‘f’:

Commands.Open.Activated += this.GetOpenPolylineCallbackFor(f);
Commands.Open.Activated -= this.GetOpenPolylineCallbackFor(f);

Considering that anonymous methods are syntactic sugar for regular delegates, and the whole variable promotion is handled by the compiler, it is unclear why anonymous methods behave differently.

Anyway, here’s the correct code – courtesy of Ayende Rahien:

private void RouteForm_OnNeedPolyline(object sender, EventArgs e)
{
IRouteForm f = sender as IRouteForm;
if (f == null) return;

  EventHandler<OpenEventArgs> openCallback = delegate(object sender, OpenEventArgs e)
  {
    Polyline p = e.Entity as Polyline;
    if (p != null)
      f.Polyline = p;

Commands.Open.Activated -= openCallback;
};

Commands.Open.Activated += openCallback;

Commands.New.Activate(this, new NewEventArgs(typeof(Polyline)));
}

Comments
Posted on Wednesday, August 23rd, 2006.

.Net 2.0 Generics, Anonymous Methods, and Delegate inference bug

Posted in Development

I’m working on this system that allows the user to perform certain tasks on a map. For instance, building a route on the map is performed by quite simply clicking on the map to add waypoints. This action is done as a part of the RouteForm data entry – on the form there is a button that, when clicked, changes the map’s state to accept user input (the polyline map tool is selected). Of course, the user could have a number of these forms open at any time. Obviously, we’d need to route selected on the map to be passed back to the originating form, and not a different open RouteForm.

In this case, we’d have our RouteForm expose a “NeedPolyline” event. We wouldn’t want our forms or controlling logic (presenters) to be dependent on the map implementation, so we make heavy use of the command pattern to transfer data between them.

So, as a result of the “NeedPolyline” event raised by the RouteForm, the RouteController needs to communicate that it needs a new polyline to be created. This is done by activating the “New” command and passing “typeof(Polyline)” in the event args “EntityType” property. When the MapController gets called back on the command, it activates the relevant map tool. When the user finishes selecting the route on the map (signalled by a right click), the map controller needs to take the polyline from the map control and pass it back into the application. This is done by activating the “Open” command, and passing the polyline as a parameter to the event args. What the RouteController needs to do when its called back on that command is to pass the polyline back to the RouteForm that initiated the whole deal. Ay, there’s the rub.

Well, there’s an elegant solution that uses the new features of .net 2.0 to do just that, or so I thought. Here’s the code:

private void RouteForm_OnNeedPolyline(object sender, EventArgs e)
{
IRouteForm f = sender as IRouteForm;
if (f == null) return;

Commands.Open.Activated += this.GetOpenPolylineCallbackFor(f);
Commands.New.Activate(this, new NewEventArgs(typeof(Polyline)));
}

private EventHandler<OpenEventArgs> GetOpenPolylineCallbackFor(IRouteForm f)
{
  return delegate(object sender, OpenEventArgs e)
  {
    Polyline p = e.Entity as Polyline;
    if (p == null) return;

    f.Polyline = p;
    Commands.Open.Activated -= this.GetOpenPolylineCallbackFor(f);
  }
}

The nicest thing about the above code is that the management of which form requested the polyline is automatically handled – I don’t have to write any code that pipes the event back to the originating form. There’s only one eensy-weensy problem. Unsubscribing from the event doesn’t work – the code “Commands.Open.Activated -= this.GetOpenPolylineCallbackFor(f);” doesn’t do anything. In which case, only the first RouteForm works correctly, since the event is piped back to all forms ever opened.

Is this a bug? Well, it is in my book. I don’t get how the subscription can work while the inverse doesn’t. I know that there are workarounds – I’ve already implemented them and moved on. But I think that there’s a real missed opportunity here. This is the kind of code .net 2.0 is supposed to support – generic, concise, elegant.

I really hope that this gets rolled into SP1 of VS2005. I’d really hate to have to wait 3 years for a fix for this (re: VS2003 sp1).

Comments
Posted on Sunday, August 20th, 2006.

High volume event stream processing

Posted in Architecture

I ran into this post a couple of days ago on InfoQ which described some kind of product/technology that would enable a system to perform “high volume event correlation”.

These happen to be the kind of systems that I work on.

For some reason, the company behind this product thinks that databases don’t support these non-functional requirements well. I’d have to say that a naive implementation probably wouldn’t – but then a naive implementation in any domain would probably perform poorly.

In cases where you have to handle high volumes of information “streaming” at the system constantly, you’ll often find that it’s usually just the same data being constantly updated. I’ve seen this happen in systems that receive updates 50 times a second per source, with dozens of sources.

Would you believe that not only are databases capable of handling these loads but object-relational mapping too?

If you are building these kinds of systems, don’t buy in to the hype that some vendor’s product will solve you’re problems. True for any kind of system, apparently.

And a solution to getting the database to perform at that level? Simple really. Analyze the data coming in. Set up tables specifically for it. Put them on a separate volume/partition at the db level. Stick a 2 gig flash disk on the db server. Map the above partition to that disk. Move the data from those tables to archive tables on volumes on regular disks as the data gets older. Voila, a database that performs amazingly well at high loads.

Comments
Posted on Thursday, August 17th, 2006.

[Podcast] BPM vs. SOA

Posted in Ask Udi Podcast | BPM | Master Data Management | SOA

Udi analyzes the relationships between Master Data Management, Service Oriented Architectures and Business Process Management.

Get it via the Dr. Dobb’s site here.

Or download directly here.

Want more? Go to the “Ask Udi” archives.

Comments
Posted on Tuesday, August 8th, 2006.

This makes it all worth it

Posted in General

Today I got an email from Peter, a listener of my podcast with the subject “REST vs Web Services mp3 discussion – Thanks!”.

“Hello Mr. Dahan,

I just wanted to let you know that I found your discussion on REST vs. Web services very interesting. Two years ago, I got to learn about Web services and WSDL, in order to figure out if I can use that to communicate
between two application servers. Unfortunately, at that time, I discovered
the way we were accessing the server, was for development only, and there
was no production support for Web services on the server at that time.

Thinking for the future, after hearing your discussion on REST, I’m going
to start researching more information on it, to see if maybe I can use
that method to transport information.

Do you know of any websites I can go to to learn more about this?

About your show, please spell out your email and website for us. I was
listening to it in the car on mp3, and had no idea on how to contact you.

Thank you.

Peter *****
Web developer (XHTML, Java, Javascript, XML)”

Well, Peter, thank you for your kind words. It’s really great knowing that I’m not just shouting into the endless void of the internet and that what I’m saying makes a difference. And I will take your suggestions to heart about spelling out the site and email. Who knew people would have a hard time spelling UdiDahan? It sounds just how its spelled 🙂

About the sites on REST – well there are a lot. Although most are quite superficial – nothing that would show you how to implement anything but a trivial application. To tell you the truth, I’m not sure that the REST architectural style jives with transaction processing that well. I have yet to see an example that both models the system entities as URIs and can transactionally update several of them at once.

Anyway, Peter, thanks again. And best of luck with your REST excursions.

Comments
Posted on Friday, August 4th, 2006.

Polymorphism and the switch statement

Posted in Development

In my previous post, I contrivedly complained about how C# makes it hard for me to switch based on type. In the comments I got, rather quickly I might mention, Keith suggested the “replace switch statement with polymorphism” refactoring. While that refactoring is quite often what is needed when the switch is found in implementations of procedural business logic, the appropriate refactoring in this case is different.

First, some context. The code described was in an event handler for a specific command activation – the ‘new’ command. The command pattern is a common one in user interfaces so I won’t expound on it here. OK, so the user can via the menu or toolbar request to create a new entity. The menu, or toolbar, activate the ‘new’ command while passing along the type of entity to create in the EventArgs of the Activated event of the command.

The code shown in the previous post showed a single event handler that would decide based on the EntityType property of the event args what to do – open the customer form, order form, etc. What is needed is to perform the refactoring called (well, I call it): “replace switch statement in single event handler with multiple, specific type based event handlers”. I should probably find a better name for that 🙂

I’ll skip some of the interim steps and go directly to the generic solution. The new code would look more like this:

public class CommandHandler<T> where T : IEntity
{
  public CommandHandler()
  {
    NewCommand.Activated += delegate(object sender, EntityEventArgs e) {
      if (e.EntityType == typeof(T))
      {
        IView v = this.builder.Build<IEntityView<T>>();
        v.Show();
      }
    };
  }
}

and then you’d just instantiate a command handler for each entity type like so:

new CommandHandler<Customer>();
new CommandHandler<Order>();

and the forms would respectively implement IEntityView<Customer> and IEntityView<Order>. The builder that you use (I use Spring) would easily look up the type supporting that interface (you’d most probably only have one class like that in play) and instantiate it.

So, although in this case Microsoft does not make it easy to get the poorly designed code working, surprisingly they supply no guidance around this incredibly common Rich/Smart scenario – even in the CAB/Smart Client Factory. The solution is object oriented, generic, and results in less code. A winner all around.

What say you?

Comments
Posted on Friday, August 4th, 2006.

Switch statement angst

Posted in Development

The C# compiler doesn’t like the following code:

public void NewCommandActivatedCallback(object sender, EntityTypeEventArgs e);
{
switch(e.EntityType)
{
case typeof(Customer): // open new customer form; break;
case typeof(Order): // open new order form; break;
//and so on
}
}

It doesn’t like the fact that the values of the case elements aren’t constant. Well, logically speaking they are constant. Is the following code that much different?

public void NewCommandActivatedCallback(object sender, EntityTypeEventArgs e);
{
switch(e.EntityType.Name)
{
case “Customer”: // open new customer form; break;
case “Order”: // open new order form; break;
//and so on
}
}

Well, yes. For starters, it compiles. It’s also uglier. And less maintainable. But, its semantically equivalent.

My wish for Orcas is FIX IT!!! God! We’ve been carrying this crap through 2.5 versions of .net. Enough already. Hell, roll it into SP1 of VS2003 or VS2005. It’s not like it’ll break any existing code.

OK, I feel better now. Move along now. Nothing to see here.

Comments
Posted on Tuesday, August 1st, 2006.

Recommendations

Bryan Wheeler, Director Platform Development at msnbc.com
“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.

Consider some of the evidence: 1. Months later, developers still make allusions to concepts learned in the course nearly every day 2. One of our developers went home and made her husband (a developer at another company) sign up for the course at a subsequent date/venue 3. Based on what we learned, we’ve made constant improvements to our architecture that have helped us to adapt to our ever changing business domain at scale and speed If you have the opportunity to receive the training, you will make a substantial paradigm shift.

If I were to do the whole thing over again, I’d start the week by playing the clip from the Matrix where Morpheus offers Neo the choice between the red and blue pills. Once you make the intellectual leap, you’ll never look at distributed systems the same way.

Beyond the training, we were able to spend some time with Udi discussing issues unique to our business domain. Because Udi is a rare combination of a big picture thinker and a low level doer, he can quickly hone in on various issues and quickly make good (if not startling) recommendations to help solve tough technical issues.” November 11, 2010

Sam Gentile, Independent WCF & SOA Expert
“Udi, one of the great minds in this area.
A man I respect immensely.”

Ian Robinson, Principal Consultant at ThoughtWorks
"Your blog and articles have been enormously useful in shaping, testing and refining my own approach to delivering on SOA initiatives over the last few years. Over and against a certain 3-layer-application-architecture-blown-out-to- distributed-proportions school of SOA, your writing, steers a far more valuable course."

Shy Cohen, Senior Program Manager at Microsoft
“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.
It was evident through that discussion that Udi is one of the most knowledgeable people in the SOA space. It was also clear why – Udi does not settle for mediocrity, and seeks to fully understand (or define) the logic and principles behind things.
Humble yet uncompromising, Udi is a pleasure to interact with.”

Glenn Block, Senior Program Manager - WCF at Microsoft
“I have known Udi for many years having attended his workshops and having several personal interactions including working with him when we were building our Composite Application Guidance in patterns & practices. What impresses me about Udi is his deep insight into how to address business problems through sound architecture. Backed by many years of building mission critical real world distributed systems it is no wonder that Udi is the best at what he does. When customers have deep issues with their system design, I point them Udi's way.”

Karl Wannenmacher, Senior Lead Expert at Frequentis AG
“I have been following Udi’s blog and podcasts since 2007. I’m convinced that he is one of the most knowledgeable and experienced people in the field of SOA, EDA and large scale systems.
Udi helped Frequentis to design a major subsystem of a large mission critical system with a nationwide deployment based on NServiceBus. It was impressive to see how he took the initial architecture and turned it upside down leading to a very flexible and scalable yet simple system without knowing the details of the business domain. I highly recommend consulting with Udi when it comes to large scale mission critical systems in any domain.”

Simon Segal, Independent Consultant
“Udi is one of the outstanding software development minds in the world today, his vast insights into Service Oriented Architectures and Smart Clients in particular are indeed a rare commodity. Udi is also an exceptional teacher and can help lead teams to fall into the pit of success. I would recommend Udi to anyone considering some Architecural guidance and support in their next project.”

Ohad Israeli, Chief Architect at Hewlett-Packard, Indigo Division
“When you need a man to do the job Udi is your man! No matter if you are facing near deadline deadlock or at the early stages of your development, if you have a problem Udi is the one who will probably be able to solve it, with his large experience at the industry and his widely horizons of thinking , he is always full of just in place great architectural ideas.
I am honored to have Udi as a colleague and a friend (plus having his cell phone on my speed dial).”

Ward Bell, VP Product Development at IdeaBlade
“Everyone will tell you how smart and knowledgable Udi is ... and they are oh-so-right. Let me add that Udi is a smart LISTENER. He's always calibrating what he has to offer with your needs and your experience ... looking for the fit. He has strongly held views ... and the ability to temper them with the nuances of the situation.
I trust Udi to tell me what I need to hear, even if I don't want to hear it, ... in a way that I can hear it. That's a rare skill to go along with his command and intelligence.”

Eli Brin, Program Manager at RISCO Group
“We hired Udi as a SOA specialist for a large scale project. The development is outsourced to India. SOA is a buzzword used almost for anything today. We wanted to understand what SOA really is, and what is the meaning and practice to develop a SOA based system.
We identified Udi as the one that can put some sense and order in our minds. We started with a private customized SOA training for the entire team in Israel. After that I had several focused sessions regarding our architecture and design.
I will summarize it simply (as he is the software simplist): We are very happy to have Udi in our project. It has a great benefit. We feel good and assured with the knowledge and practice he brings. He doesn’t talk over our heads. We assimilated nServicebus as the ESB of the project. I highly recommend you to bring Udi into your project.”

Catherine Hole, Senior Project Manager at the Norwegian Health Network
“My colleagues and I have spent five interesting days with Udi - diving into the many aspects of SOA. Udi has shown impressive abilities of understanding organizational challenges, and has brought the business perspective into our way of looking at services. He has an excellent understanding of the many layers from business at the top to the technical infrstructure at the bottom. He is a great listener, and manages to simplify challenges in a way that is understandable both for developers and CEOs, and all the specialists in between.”

Yoel Arnon, MSMQ Expert
“Udi has a unique, in depth understanding of service oriented architecture and how it should be used in the real world, combined with excellent presentation skills. I think Udi should be a premier choice for a consultant or architect of distributed systems.”

Vadim Mesonzhnik, Development Project Lead at Polycom
“When we were faced with a task of creating a high performance server for a video-tele conferencing domain we decided to opt for a stateless cluster with SQL server approach. In order to confirm our decision we invited Udi.

After carefully listening for 2 hours he said: "With your kind of high availability and performance requirements you don’t want to go with stateless architecture."

One simple sentence saved us from implementing a wrong product and finding that out after years of development. No matter whether our former decisions were confirmed or altered, it gave us great confidence to move forward relying on the experience, industry best-practices and time-proven techniques that Udi shared with us.
It was a distinct pleasure and a unique opportunity to learn from someone who is among the best at what he does.”

Jack Van Hoof, Enterprise Integration Architect at Dutch Railways
“Udi is a respected visionary on SOA and EDA, whose opinion I most of the time (if not always) highly agree with. The nice thing about Udi is that he is able to explain architectural concepts in terms of practical code-level examples.”

Neil Robbins, Applications Architect at Brit Insurance
“Having followed Udi's blog and other writings for a number of years I attended Udi's two day course on 'Loosely Coupled Messaging with NServiceBus' at SkillsMatter, London.

I would strongly recommend this course to anyone with an interest in how to develop IT systems which provide immediate and future fitness for purpose. An influential and innovative thought leader and practitioner in his field, Udi demonstrates and shares a phenomenally in depth knowledge that proves his position as one of the premier experts in his field globally.

The course has enhanced my knowledge and skills in ways that I am able to immediately apply to provide benefits to my employer. Additionally though I will be able to build upon what I learned in my 2 days with Udi and have no doubt that it will only enhance my future career.

I cannot recommend Udi, and his courses, highly enough.”

Nick Malik, Enterprise Architect at Microsoft Corporation
“You are an excellent speaker and trainer, Udi, and I've had the fortunate experience of having attended one of your presentations. I believe that you are a knowledgable and intelligent man.”

Sean Farmar, Chief Technical Architect at Candidate Manager Ltd
“Udi has provided us with guidance in system architecture and supports our implementation of NServiceBus in our core business application.

He accompanied us in all stages of our development cycle and helped us put vision into real life distributed scalable software. He brought fresh thinking, great in depth of understanding software, and ongoing support that proved as valuable and cost effective.

Udi has the unique ability to analyze the business problem and come up with a simple and elegant solution for the code and the business alike.
With Udi's attention to details, and knowledge we avoided pit falls that would cost us dearly.”

Børge Hansen, Architect Advisor at Microsoft
“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, 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, 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, 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, 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, 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, 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, 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, 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, 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, .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, 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, 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, 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, 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, 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, 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, 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, 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

Article: The Enterprise Service Bus and Your SOA

97 Things Every Software Architect Should Know

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