Udi Dahan   Udi Dahan – The Software Simplist
Enterprise Development Expert & SOA Specialist
 
  
    Blog Consulting Training Articles Speaking About
  

[Podcast] Parallel Processing and SOA


Posted in Ask Udi Podcast | SOA

In this podcast we address non-functional requirements in SOA, such as throughput and latency. We’ll discusses a whitepaper on the topic, as well as the use of pipeline architecture within a service to comply with SLA’s that define these non-functional requirements. (MP3)

Resources

1. Whitepaper on Using Intelligent Parallel Processing in SOA
2. Ask Udi a question on SOA
3. 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 Friday, October 13th, 2006.



DDD – why bother?


Domain Driven Design (DDD), alongside its growing popularity, is experiencing some growing pains. The Domain Model pattern, documented in the Patterns of Enterprise Application Architecture book, is at the heart of DDD yet the division of responsibility between it and other DDD patterns like Service Layer isn’t quite clear. To make matters worse, the value of the Domain Model pattern relative to simpler code-generation techniques remains vague. The one thing that has reached a wide consensus is that it requires a higher level of skill to employ these techniques than continue using the widespread procedural programming practices. There is one overwhelming reason to do it anyway, though, and that is that it is the cheapest way to get a system up and running right. The reasoning behind this has to do with business rules.

An exceedingly large number of systems are being built and modified today in order to support business rules. Beyond just computerizing the management of data in the enterprise, today’s systems are required to computerize the business processes that use that data, and these processes are built upon business rules.

A rule is composed of two main elements, a clause and an action. The clause defines under what circumstances the action is to be activated. An example of a rule employed in the business environment might be “if the customer is a preferred customer, then give them a 5% discount on all orders”. The rich behavior of an enterprise is governed by these interacting rules. Consider the result of adding another business rule like “if the customer has ordered $100,000 or more in the last year, then they are to be considered a preferred customer”. If a customer is not preferred, but then sends in a new order that puts them over the limit, how is the system to behave? Conversely, what if a preferred customer cancels an order bringing them under the limit?

I’ve seen too many projects that have been tasked with implementing these kinds of behaviors yet were unable to get the system running right. Customers that should have gotten discounts didn’t in some cases, and those that should not have enjoyed a discount did at times. After much time was spent trying to track down what part of the code was wrong, changing some code, testing, over and over again, an executive decision was made to put the system into production as is. The harm to the business was deemed cheaper in this case then not putting the system in production. Is it any wonder that business is skeptical of IT’s ability to handle the agile enterprise of the future where, not only will the business rules be more complex, they will be changing all the time.

The Domain Model pattern encapsulates these business rules in such a way that they will be run even when not directly invoked. This is especially critical when one rule triggers another. Intelligent use of OO principles when designing the domain can help you altogether avoid the jump in complexity found in Business Rules Engines.

Finally, we need to understand that supporting techniques like Object/Relational (O/R) mapping are but a means, and not the end. The discussions around DDD often get mired down in the relative costs of O/R mapping and procedural code generation. Persistence is a solved problem, a technical problem that has no meaning to business. Is it not time to raise the discussion to the level of business? If the only problem you are trying to solve is the manipulation of data in a database, then don’t bother with DDD and its descendents. It won’t make your life any easier. If, on the other hand, business has gotten sick of IT deciding for them how to run their business; if you are the one tasked with building the right system, you just won’t be able to do it unless you build the system right – DDD won’t be a bother, but a necessity.

Comments
Posted on Saturday, October 7th, 2006.



Hype busting truth?


Posted in SOA

Taken from Ron Jacobs (of ArCast fame) “Patterns and Anti-Patterns for Service-Oriented Architectures”:


3 Hype Busting Truths:

1. Tight coupling has its place
2. Prefer explicit behavior over implicit
3. Services are the interface to business processes

The successes that I’ve seen on projects were those where business processes were designed across services. Those projects that took the discrete steps of each business processes and designed each step as a service, reusing those services between processes got mired down in integration, and often suffered horrible performance problems.

What I mean by “designed across services” is this:

One service would “hear” an event being published. It would perform some internal logic, and publish an event of its own. Another service would “hear” that event, and do something similar. This chaining of published events implemented one given business process. Other sequences of events embodied other processes. Changing a given process hardly ever changed service interaction, but rather was almost always implemented as a local change to logic internal to one service.

I would hardly describe this top-level design by using the phrase “Services are the interface to business processes”. I don’t think there really is an interface to a business process. A business process is what happens as a result of a given event and a pre-existing state. The same event, under a different pre-existing state, would probably cause different behavior – a different business process to occur.

About state, there really is no such thing. It is amorphous, changing all the time, never synchronized across all parties. When the first event occurs, the service that receives (and handles) that event is in state A, but the rest of the services’ states are not known. Those services could already be handling other events, their states changing while the first service is doing its part of some business process.

My experience has been that this large-scale, concurrently running ecosystem of services is too complex to be modeled only in terms of flow-charted business processes. Business processes tell us how the ecosystem should behave in certain circumstances, but have not been effective design tools in my experience.

Command-and-control tactics that were once the mainstay of modern armies, are being replaced with more organic rules of engagement to respond more quickly to uncertain and changing battlefield conditions. It is time that we too give up the appearance of control found in orchestration and choreography in order to respond more quickly to the changing needs of business, lest we find ourselves extinct.

Comments
Posted on Saturday, October 7th, 2006.



AJAX & SOA to merge? puh-lease!


Posted in SOA

This came up on my radar, its from the WebSphere Power Magazine.


“Although technologists have been calling for the marriage of hot technologies such as SOAs and AJAX to help users better leverage Web services, the industry is only now beginning to see products that fully support this integration. At the AJAXWorld conference, JackBe and TIBCO Software are unveiling initiatives to more tightly link service-oriented architectures and Asynchronous JavaScript and XML.”

First of all, as we already know, SOA is not a technology.

Second, SOA is not dependent on Web Services, but can be implemented with them.

As for integration between AJAX and SOA, from the service’s perspective, anyone can send it a message, and the service will then decide based on certain criteria (policy if you will) whether or not to handle the message or send a response. So, AJAX doesn’t change anything in terms of SOA. As for the ability to send a message to a service, AJAX has certain limitations security-wise since it’s run out of the browser, but these shouldn’t be a problem.

So, it appears for lack of anything important to do, the vendors decided to invest in integrating stuff that can already work together just fine, maybe a point-and-click interface for developers?

Comments
Posted on Friday, October 6th, 2006.



.Net 2.0 vs. 3.0 – the debate continues


Posted in Development

Jesse quickly rebutted my claims on the value of WPF. We don’t seem to be disagreeing so much as coming from different domains:


“If you, being a developer, do all of your design work and your UI code is really just 5% of your apps, then WPF probably isn’t going to do you much good, because you obviously don’t care enough about your UI anyway. (or maybe your apps really need to be 95% backend, which is fine, but that’s certainly not the type of apps we are building).”

I think that I’ll have to make it clear that the 5% number was for smart client development effort (time spent), and does not take into account server side effort. Second, the smart clients I work on usually have a very rich interface from the user perspective – including 2D and sometimes 3D maps, with powerful interactive capabilities. That said, we rely on a 3rd party map control for that, and by employing MVP style separation, are able to keep most of our code independent of UI widgets.

I do care very much about the usability of the systems I work on, as do most developers, I imagine. The fact that I structure my code in such a way as to keep most of it independent of visual elements only lends itself to being more testable.

I’d actually like to call out to Microsoft to add something that’s been paining me for a while into the Avalon timeframe. The designers for menus and toolbars require them to be hosted on a form. I don’t work that way. The menu that we have is an isolated component – its items being tied to commands. The same goes for the toolbars in the system. The form on which they will sit is in entirely different solution, and is not dependent on the specific menu or toolbar classes. I could swap out one menu and replace it with another by changing a config file. I could support different modes of work very easily this way. But what I end up having to do is design the menu and toolbar on a form, and then rip them out of the form, and package them separately. This is a pain to maintain (put back on a form, fix, rip out, repeat). I hope that Microsoft didn’t bind the whole designer framework in the IDE to having a form available.

To Jesse’s final question, “so why not just wait out another extra year or two on the 1.1 Framework and then move to 3.0?”

Because I have to ship at the end of this year and 2.0 makes me and my team much more productive than 1.1.

Comments
Posted on Thursday, October 5th, 2006.



Two strikes against SDO


Posted in SOA

Arnon wonders “what were you thinking?”. I also wrote this up on the Web Services blog on Dr. Dobb’s.

It’s no wonder, really. Me and Arnon see things quite similarly – you should see us when we’re both part of the architectural review team on a project. Picture something like this:

That’s right, Arnon is Waldorf, and I’m Statler.

Comments
Posted on Thursday, October 5th, 2006.



.Net 2.0 no big deal?


Posted in BizTalk | Development | OO | Workflow

Jesse seems to be swallowing the Microsoft party line without missing a drop in his latest post Screw 2.0, I’m Going Straight to 3.0.

From his post:


“The 2.0 framework doesn’t really give you a massive amount of really new really cool features. There is one-click, which we probably wouldn’t use anyway, generics (which are useful as a time saver, but don’t really do much that you can’t do without them), and some other little features… but the best part about the 2.0 framework is probably the IDE/dev experience, not what customers get out of it.”

Granted, One-Click is nothing to write home about, but the runtime level additions, they just totally changed the way I write code. I’m talking about generics, anonymous methods, delegate inference, and the rest. The rest of 2.0, like the enhancements of the provider model in ASP.Net, well you would have developed the same kind of framework yourself if you were doing serious web development.

The whole 3.0 story, I’ve got to tell you, I’m pretty underwhelmed. Everybody seems to be jumping up and down about WPF, and yes, it’s new and shiny, but there still the clunkety Windows message pump in the background. No real changes in how you’re going to write multi-threaded UIs, which seem to be the real future given the rise in multi-core processing. The visual aspects of client side code in the systems I write run at around 5% of the overall effort. So the UI will look better, I dunno, 4D buttons and stuff, sorry for not falling over with enthusiasm.

And then there’s WCF. Ah, wait, no publish/subscribe. Bummer, most of my systems being asynchronous in nature are built on the pub/sub model. An OO interface for interprocess communication? Who wants it – I need a message-based interface.

Don’t forget WF – what was that for again? The main place where WF can fit my needs is for handling long-running workflows between systems, since I don’t use Biztalk. But the performance of WF doesn’t seem to fit this environment, it seems to be more suited for human workflow times.

If anything, I’d have to say that .Net 2.0 was a relatively big deal. 3.0 will probably be just as important with the runtime level enhancements like lambda expressions, extension methods, anonymous types, and implicitly typed variables. All the rest of the hyped up stuff in 3.0, I don’t really expect it to change anything in how I work today.

Comments
Posted on Thursday, October 5th, 2006.



Data Services – oh no! not again!


Posted in SOA

Every once in a while, I see this pick up. Data services are not a part of SOA. Keeping data separate from behavior was recognized as bad practice, oh, plus or minus 3 decades ago, when OO came out. Dressing it up as service-oriented does not change anything.

Comments
Posted on Monday, October 2nd, 2006.



SQL Injection attacks & O/R mapping


You’ve probably never thought of SQL Injection Attacks and O/R mapping in the same context. I know I haven’t, that is, until today. I saw Scott’s post on how to “Guard Against SQL Injection Attacks” and started wondering how long it’s been since I’ve given it any thought. Then I realized that it was around the same time I switched to O/R mapping.

Since data received from the user is put in domain objects, and then those objects are mapped to tables (or views) in the database, the O/R mapper just handles it all for me. I assume that all the mappers out there use parameterized SQL, but I know for sure that NHibernate does (from peeking at the logs every once in a while).

Anyway, just wanted to mention this added side benefit of moving to the Domain Model pattern – no more SQL injection worries.

Comments
Posted on Saturday, September 30th, 2006.



Re: XML vs. Web Service, Who Wins?


Posted in Uncategorized

I flagged this for followup some time ago, but it just got lost in the shuffle. Brent (?) put up a great post called “XML vs. Web Service, Who Wins?” where he dispells the WebServices Everything Everywhere anti-pattern. In the example he uses, a read-only XML file ended up being a much simpler, and almost definitely more performant solution than using Web Services.

If there was one thing that I’d add to his solution is to use some kind of notification mechanism (publish) that would let all subscribers know that the data in the XML file had changed. This would be preferable to having each subscriber polling for changes. You could use Web Services to implement such a mechanism, but shucks, the WS-Eventing spec is only now getting nailed down and it might take some time for the implementations to get out, not to mention the kinks worked out of them. I’ll bet you could use some other, simple notification mechanism instead.

So, the question isn’t really XML vs. Web Services, but rather today’s stable, already in use techniques vs. tomorrow’s hyped up, not yet stable technologies. If you had to build a mission critical system, what would you bet your job on?

Comments
Posted on Saturday, September 30th, 2006.



   


Don't miss my best content
 

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





Ian Robinson 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 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 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 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 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 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 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 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 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 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 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 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 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 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 Aaron Jensen, VP of Engineering at Eleutian Technology
Awesome. Just awesome.

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

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

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

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

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

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

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

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

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

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

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

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

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

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


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

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

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

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

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

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

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

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

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

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

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

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

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

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

Consult with Udi

Guest Authored Books



Creative Commons License  © Copyright 2005-2011, Udi Dahan. email@UdiDahan.com