Mobile.UdiDahan.com
Posted in General
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Comments Posted on Tuesday, July 15th, 2008. |
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Udi Dahan – The Software Simplist
Enterprise Development Expert & SOA Specialist |
MSDN Magazine Article On Losing Data
Posted in Articles
Now I can die happy.
I’ve made the cover of the latest issue of MSDN magazine.
OK, enough of that.
I really am thrilled that Microsoft has taken a non-technological article and promoted it in such a way. Change is happening, and I like it.
With a name as long as most of my variables, this article is quite the failure-fest:
Build Scalable Systems That Handle Failure Without Losing Data
No drag and drop, no wizards, code completion, or anything.
Real world problems with no magic solutions. A real analysis of message loss over HTTP, what additional problems durable messaging brings with it, how integrated systems can lose consistency as the result of database deadlocks, and more.
The solutions described are first and foremost about thought processes – knowing the nature of the problem, how to design a solution that addresses it, and what new problems now need to be dealt with. You’ll see exception management strategies (no, you shouldn’t be try-catching), how that feeds into deserialization exceptions, error queues, and finally into a versioning strategy that also addresses the human element. There’s a lot of architectural meat. I had to cut out a lot of filler in order to get it all into the 7 page limit.
If you haven’t yet read the book Release It! this article might be considered the Cliff Notes version. But you still should read the book. It really is worth your time.
Comments and questions are most welcome.
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Comments [7] Posted on Monday, July 7th, 2008. |
Make WCF and WF as Scalable and Robust as NServiceBus
This topic is getting more play as more people are using WCF and WF in real-world scenarios, so I thought I’d pull the things that I’ve been watching in this space together:
Reliability
Locking in SqlWorkflowPersistenceService (via Ron Jacobs) where, if you want predictable persistence (MS: ‘none of our customers asked for this to be easy’), you need to use a custom activity (which Ron was kind enough to supply).
“Given what I learned today I’d have to say that I’d be very careful about using workflows with an optimistic locking. Detecting these types of situations is not that simple.”
Let’s think about that. If we’re doing pessimistic locking, we get into the problem of, if a host restarts (as the result of a critical windows patch or some other unexpected occurrence), that the workflow won’t be able to be handled by any other host in the meantime (you didn’t care so much about your SLA, did you?).
Luckily, someone’s come up with a hack that works around this robustness problem in Scalable Workflow Persistence and Ownership.
“So this code will attempt to load workflow instances with expired locks every second. Is it a hack? Yes. But without one of two things in the SqlWorkflowPersistenceService its the sort of code you have to write to pick up unlocked workflow instances robustly.”
This will seriously churn the table used to store your workflows, decreasing performance of workflows that haven’t timed out. Oh well.
Testability
Implementing WCF Services without Referencing WCF (via Mark Seemann):
“More than a year ago, I wrote my first post on unit testing WCF services. One of my points back then was that you have to be careful that the service implementation doesn’t use any of the services provided by the WCF runtime environment (if you want to keep the service testable). As soon as you invoke something like OperationContext.Current, your code is not going to work in a unit testing scenario, but only when hosted by WCF.”
After pointing out some of the more basic difficulties in testability a straightforward WCF implementation brings, Mark turns the heat up in his follow-up post, Modifying Behavior of WCF-Free Service Implementations:
“Perhaps you need to control the service’s ConcurrencyMode, or perhaps you need to set UseSynchronizationContext. These options are typically controlled by the ServiceBehaviorAttribute. You may also want to provide an IInstanceProvider via a custom attribute that implements IContractBehavior. However, you can’t set these attributes on the service implementation itself, since it mustn’t have a reference to System.ServiceModel.”
Wow – all the things required to make a WCF service scalable and thread-safe make it difficult to test. In the end, we’re beginning to see how many hoops we have to go through in order to get separation of concerns, but until we can take all this and get it out of our application code, it’s an untenable solution. I hope Mark will continue with this series, if only so I can take the framework that might grow out of it and use it as a generic WCF transport for NServiceBus.
Comparison
After the Neuron-NServiceBus comparison that Sam and I had, we talked some more. After going through some of the rational and thinking, Sam even put nServiceBus into his WCF-Neuron comparison talk. Sam had this to say about nServiceBus:
“The bottom line is: I like what I see. Although it’s a framework, not an ESB product like Neuron, it’s a powerful framework that takes the right approach on SOA and enforces a paradigm of reliable one-way, *non-blocking* calls. That is the point of the talk tonight overall; we need to get away from the stack world of synchronous RPC calls to true asynchronous non-blocking message based SOA systems.”
The main concern I have with a WCF+WF based solution is that developers need to know a lot in order to make it testable, scalable, and robust. In nServiceBus, that’s baked into the design. It would be extremely difficult for a developer writing application logic to interfere with when persistence needs to happen, or the concurrency strategy of long-running workflows. The fact that message handlers in the service layer don’t need concurrency modes, instance providers, or any of that junk make them testable by default.
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Comments Posted on Monday, June 30th, 2008. |
Object Relational Mapping Sucks!
For reporting, that is.
And doesn’t handle concurrency!
Unless you don’t expose setters.
I guess it depends, doesn’t it?
Well, that was Ted’s assertion in his recent Pragmatic Architecture column on data access.
But, “it depends” doesn’t get the system built, does it?
So, here are some rules for using o/r mapping that will get you 99% of the way there.
Yes, you heard me.
Rules.
They do not depend.
If you’re doing something significantly bigger than enterprise-scale development, and you are already doing this, and it isn’t enough, give me a call. Here we go.
- No reporting.
I mean it. Don’t report off of live data.
This isn’t just a o/r mapping thing.
Users can tolerate some, if not quite a lot of latency.And it’s not like objects are even used. It’s just rolled up data. Not a single behaviour for miles.
- Don’t expose setters
You want multiple users sharing and collaborating on data, right? Then don’t force them to either overwrite each others data, or throw away their own. There is one simple way to avoid that: Get an object, call a method. Once the object has the most up to date data, pass all the client data in via a method call. The object will decide if its valid, from a business perspective as well, and then update the appropriate fields.
Now your DBAs can vertically partition tables accordingly, and improve throughput. After that, you can increase the isolation level, to improve safety, without hurting throughput.
This will also keep your logic encapsulated, bringing you closer to a true Domain Model.
If your O/R mapping tool requires you to have setters on your domain classes, hide those from your service layer behind an interface.
- Grids are like reports.
No o/r mapping required there either. While you probably won’t be showing grids of yesterday’s data to users in an interactive environment, it’s still just data – no behaviour.
However, users should NOT update data in those grids. This gets back to rule 2. Have users select a specific task they want to perform, pop open a window, and have them do it there. Change customer address. Discount order. You get the picture. That way you’ll know what method to call on those objects you designed in rule 2.
Before wrapping up, one small thing.
You can use an O/R mapping tool to do reporting, just, for the love of Bill, don’t use the same classes you designed for your OLTP domain model. But, just because you can, doesn’t necessarily mean you should. Datasets datatables are probably just as viable a solution.
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Comments [23] Posted on Wednesday, June 25th, 2008. |
Sagas Solve Stupid Transaction Timeouts
It turns out that there was a subtle, yet dangerous problem in the use of System.Transactions – a transaction could timeout, rollback, and the connection bound to that transaction could still change data in the database. 
Think about that a second.
Scary, isn’t it?
At TechEd Israel I had a discussion with Manu on this very issue, just under a different hat:
What’s the difference between a short-running workflow and a long-running one?
Manu suggested that we look at the actual time that things ran to differentiate between them. I asserted that if any external communication was involved in some part of state-management logic, that logic should automatically be treated as long-running.
Manu’s reasoning was that the complexity involved in writing long-running workflows was not justified for things that ran quickly, even if there was communication involved. Many developers don’t think twice about synchronously calling some web services in the middle of their database transaction logic. In the many Microsoft presentations I’ve been at on WF, not once has it been mentioned that state machines should be used when external communication is involved.
The problem that I have with this guidance is how do you know how quickly a remote call will return?
Do you just run it all locally on your machine, measure, and if it doesn’t take more than a second or so, then you’re OK?
The fact of the matter is that we can never know what the response time of a remote call will be. Maybe the remote machine is down. Maybe the remote process is down. Maybe someone changed the firewall settings and now we’re doing 10KB/s instead of 10MB/s. Maybe the local service is down and we’re communicating with the backup on the other side of the Pacific Ocean.
But the thing is, Manu’s right.
Writing long-running workflows (with WF) is more complex than is justified. My guess is that since WF wasn’t specifically designed for long-running workflows only, that this complexity crept in.
Sagas in nServiceBus were specifically designed for long-running workflows only.
Maybe that’s what kept them simple.
Since all external communication is done via one-way, non-blocking messaging only, each step of a saga runs as quick as if no communication were done at all. This keeps the time the transaction in charge of handling a message is open as short as possible. That, in turn, leads to the database being able to support more concurrent users.
In short, sagas are both more scalable and more robust.
No need to worry about garbaging-up your database.
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Comments [2] Posted on Monday, June 23rd, 2008. |
[Podcast] Highly Scalable Web Architectures
For those people who couldn’t come to TechEd USA and didn’t see my talks on how to build highly scalable web architectures, you’re in luck – Craig, the man behind the Polymorphic Podcast sat down with me and we chatted about what the problems, common solutions, and effective tactics there are in this space. For those of you who were at TechEd and still didn’t come to my talk – what were you thinking?!
🙂
Some of this stuff is a bit counter-intuitive (and not readily supported by the tools available in Visual Studio) so please, do feel free to ask questions (in the comments below).
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Comments Posted on Thursday, June 19th, 2008. |
External Value Configuration with IoC
One of the things I haven’t like about using IoC containers, AKA dependency injection frameworks, was the string-based configuration model they exposed. In order to set these values, developers had 2 options: either use XML config (usually without the benefit of intellisense or refactoring support), or use code (still quoting property names – again, no intellisense or refactoring support).
In short, there seemed to be a hole in the development model.
Here’s an example from how nServiceBus used to do this:
builder.ConfigureComponent(typeof(HttpTransport), ComponentCallModelEnum.Singleton)
.ConfigureProperty(“DefaultNumberOfWorkerThreads”, 10)
.ConfigureProperty(“DefaultNumberOfSenderThreads”, 10);
The problem was that if a developer got the case of the property wrong, misspelled it in some way, or somebody later refactored/renamed that property, the system would break. It would also be very difficult to figure out why.
Then, a couple of weeks ago, it dawned on me.
This was the same problem we used to have with testing using mock objects – before we had today’s more advanced frameworks. So, the solution must be to use the same techniques. The container should give the developer an object that looks just like their class, but that would intercept all calls. Then, that interceptor could turn those into the config calls shown above. Here’s what the new config model looks like:
HttpTransport transport = builder.ConfigureComponent<HttpTransport>
(ComponentCallModelEnum.Singleton);transport.DefaultNumberOfSenderThreads = 10;
transport.DefaultNumberOfWorkerThreads = 10;
Granted, you’re not going to have tons of code like this. However, for all those parameters which are factory-configured and that customers/integrators shouldn’t tinker with, it makes a difference. The biggest difference is during that time of development where you’ve gotten into preliminary integration tests but the systems components are still being “polished”.
Aside: On the current project that has adopted this model, we’ve probably saved (conservatively) about 3 months of effort with this tiny (?) thing, and this isn’t a huge project. If that’s more than you would’ve thought, well, I was surprised myself. First, understand that in the old config model, everything still compiles and unit tests pass, even though its broken.
Just consider what happens in the lab when this occurs. You have N testers that can’t test the new version, waiting. You have the person who installed the version, trying to figure out what’s wrong. They then call in one of the developers where most of the new development occurred since the previous version. They fiddle around with it, looking at exception traces and whatnot. In the best case, we’re talking about 2 hours from noticing its broken until a new version comes out fixed. Multiply that by N+3 people. Then multiply by the number of versions you do integration tests on in the lab.
Caveat: In the current version, properties must be virtual in order for this to work.
For those of you who want just this feature without nServiceBus, I’ve put up all the binaries here. For the source, you’ll need to go to here.
Let me know what you think – especially if you can take the implementation to the point where it won’t need virtual properties to work 🙂
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Comments [12] Posted on Friday, June 13th, 2008. |
Prism – Occasionally Connected?
Prism, AKA Composite Application Guidance + Composite Application Library, is rolling towards a release. I’ve been talking with Glenn Block quite a bit about Prism, and am even on the advisory board (what were they thinking?).
One of the topics not covered by Prism is occasional connectivity, and I would like to say a word or two about that. First of all, if you’re building a standalone client (one that doesn’t communicate with anything), then there’s a good chance that Prism isn’t for you, although you could be composing other standalone client modules. So, if your client isn’t communicating with anything, well, then this post probably won’t interest you that much. Let’s start with…
Physics
Networks fail. Period.
This means that your client machine will not always be connected to other servers.
Also, servers fail – critical Windows patches and just regular power outages.
Ergo, your “smart” client will be occasionally connected, whether you planned for it or not.
And please don’t take this post as a “dumping on Prism” post – it isn’t intended that way. Rather, it is about how you should think about designing modules in Prism, and why.
Modules and Connectivity
Consider the case where we have two modules being composed in a single client. Each module communicates with a different server. Let’s call these modules Ma and Mb, and the servers Sa and Sb respectively. Now, let’s discuss what occurs given that the modules weren’t designed with occasional connectivity in mind.
User clicks something in Mb which requires communication.
Mb tries to call Sb, say, over HTTP, using a regular web service invocation.
The calling thread, in this case, the one used for user interaction, is blocked waiting for a response from Sb.
Sometime in this call, Sb fails, connectivity goes down, whatever.
30 seconds after the call, the HTTP connection times out.
If something important were happening in Ma at the same time, the user couldn’t even see it, let alone do anything about it since the user interaction thread is stuck. This is a serious concern for the financial services domain, but in many others as well.
You mean there’s more?
I can go on, but I think that that’s enough to paint the picture that if you are building a smart client, there are a lot more things to think about than just learning Prism. That’s my main concern after witnessing what happened around the CAB. Given the learning curve around these frameworks many developers don’t seek to deepen their understanding beyond just becoming proficient with them. This isn’t just centered on the developers, evangelists in Microsoft tend to paint the picture this way:
Once you understand X (CAB, Prism, BizTalk, whatever), all your problems are solved.
That’s not to say there aren’t good things in those technologies, but that’s just it, they’re just tools. Silver hammers and “laser” guided saws do not a master carpenter make. There’s actually a pretty good chance the regular guy will saw their arm off.
Help
I do hope more “instruction manuals” will be coming out of Microsoft on these topics. That’s not to say there aren’t any. Specifically on the topic of occasional connectivity, there is Chapter 4 of the Smart Client Architecture & Design Guide. Unfortunately, it doesn’t say anything about how that connects with the MVC/MVP being used client side (the bits affected by Prism). Chapter 6 of the same guide deals with the client-side threading, but doesn’t address issues like:
- Which model object instance are views bound to.
- Do other threads have access to that object at the same time.
- Which controller/presenter is responsible for giving that object to the view.
- Do they need to clone it.
- How deep should the clone be.
- How do various controllers/presenters (which may be showing the same object in different views at the same time) communicate changes to their various independent clones.
I haven’t yet documented all the patterns that answer these questions, but until I do (or Microsoft does), let me offer these few resources which I’ve put out over the years:
- Occasionally Connected Systems Architecture: The Client
- Occasionally Connected Systems Architecture: Concurrency
- Threading issues when smart clients reconnect
- [Podcast] Occasionally Connected Smart Clients and ADO.NET Sync Services
There’s also some more links under the Smart Client link of my “First time here?” page.
Also, please join me in asking Microsoft for an update to these guides – comments below or your own blog posts would be great.
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Comments Posted on Monday, June 9th, 2008. |
Web Scalability Slides and Code
Posted in Presentations
For all the people who came to my talk on Web Scalability with Asynchronous Systems Architecture, thanks for coming and being such a great audience. For all my other readers and loyal subscribers, I’ve updated the code since last it was published so you can find the new stuff here.
Here’s the powerpoint
And here’s the code
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Comments [7] Posted on Friday, June 6th, 2008. |
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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
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A man I respect immensely.”
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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.”
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“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.”
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“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.”
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I am honored to have Udi as a colleague and a friend (plus having his cell phone on my speed dial).”
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“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.”
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“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.”
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“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.”
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“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.
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It was a distinct pleasure and a unique opportunity to learn from someone who is among the best at what he does.”
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“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.
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I cannot recommend Udi, and his courses, highly enough.”
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“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.”
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“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.
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With Udi's attention to details, and knowledge we avoided pit falls that would cost us dearly.”
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“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.”
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“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
“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
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© Copyright 2005-2011, Udi Dahan. email@UdiDahan.com