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Archive for the ‘WCF’ Category



NBus now supporting long running workflow

Thursday, July 12th, 2007

This is a backwards-compatible update to the last drop of my messaging infrastructure – NBus. For more information on what it’s about read what such an infrastructure should do.

This update includes support for long-running workflows and includes persistent timer functionality. Workflow persistence is abstracted behind an IWorkflowPersister. The current drop includes an in-memory persister, but you could easily implement it over a database, or a distributed in-memory datagrid / space.

Other important details. To have a message kick off a workflow, just put the StartsWorkflow attribute on it. To define a message type as being involved in workflows, have it implement IWorkflowMessage instead of just IMessage. If you do these two things, the infrastructure will be able to generically dispatch messages to your workflow; you will not have to write any message handlers for your workflow, just the workflow class itself. This is done by implementing IWorkflow<T> for every message type received.

Persistent timers are activated from within your workflow like so:

this.reminder.ExpireIn(TimeSpan.FromSeconds(5), this, state);

As always, dependency injection is used – via my simple ObjectBuilder. The implementation provided delegates to Spring, but, once again, that can be easily substituted with whatever you want.

Download (509 KB) (sometimes problematic with IE, try FireFox before emailing me).

Finally, I’m leaning towards changing the name to NServiceBus. Anyone against, please leave a comment. Questions and comments are more than welcome.

Next step: implementing a WCF transport.



[Podcast] Passing Data Between Layers in SOA Model/Smart Client Application

Thursday, July 12th, 2007

This week we discuss the different options that are available for passing data between a client and a service, as well as common pitfalls around trying to use the same objects for both presentation to the user and persistence to the database.

Download via the Dr. Dobb’s site.

Or download directly here.

And here’s the question that gets us started:

Hello there,

We are developing an application in .NET Smart Client application which connects to a WCF service and then to the data access layer. The issue we have here is on the type of data which can be passed between the client side and web service.

1. Can it be a dataset (No!), custom entity or XML or anything else ?

Which is the best one ?

2. Ofcourse , a dataset can’t be used coz it can’t be used in non-.NET environment?

3. If we go for custom-entity or XML how do we ensure the changes happen to the data during client-side actions ? For example, binding the XML or custom entity to a data grid can be done. But if user makes any changes to the same, how do we identify ?

4. If we use custom entities / XM L, the same can not be passed to the Data Access Application Block which invokes the data objects.

Note : All the above are based on assumption without using a translator in between any of the layers.

Please provide a better solution if you have come across any.

Additional References:



Coming soon: MSMQ Bus without the MSMQ

Thursday, June 14th, 2007

I’m getting close to finally disconnecting all the code from my ESB implementation from MSMQ specifics.

You get this simple yet rich API:

public interface IBus : IDisposable
{
void Start();

void Publish(IMessage message);
void Publish(params IMessage[] messages);

void Subscribe(Type messageType);
void Subscribe(Type messageType, Predicate condition);
void Unsubscribe(Type messageType);

void Send(IMessage message);
void Send(params IMessage[] messages);
void Send(IMessage message, string destination);
void Send(IMessage[] messages, string destination);
void Send(IMessage message, CompletionCallback callback, object state);
void Send(IMessage[] messages, CompletionCallback callback, object state);
void Send(IMessage message, string destination, CompletionCallback callback, object state);
void Send(IMessage[] messages, string destination, CompletionCallback callback, object state);

void Reply(IMessage message);
void Reply(params IMessage[] messages);

void Return(int errorCode);

string SourceOfMessageBeingHandled { get; }
}

Currently, I have only MSMQ implementations for the transport of messages, the storage of subscription information, and for an error queue. This coming release will make it possible for you to customize each implementation. The release after that will be focusing on WCF implementations.

I’m also going to start releasing some more structured guidance on working with this infrastructure – getting started, configuration, etc. If I can this anywhere near what Jeremy has done with StructureMap or his MVP series, that would be an enormous achievement.

Also, now would be a great time to start telling me about additional things you’d like to see in the API, or other transports you’d like to see supported.

This is going to be a huge effort so any support that you can offer would be more than welcome.



Testing services the hard way with WCF

Thursday, May 17th, 2007

I just read the kind of hoops you have to go through in order to test your WCF service implementations. Oh. My. GOD.

If that’s the best there is, NOBODY is going to be testing their WCF services. That’s scary.

When using this message-based design, your service implementations tend to look like this:

public class WorkflowMessageHandler : IMessageHandler
{
	public void Handle(Stage1Msg msg)
	{
		using (IDBScope scope = this.DbServices.GetScope(TransactionOption.On))
		{
			IWorkflow wf = this.DbServices.Get(msg.WorkFlowID);
			wf.Handle(msg);

			scope.Complete();
		}
	}
}

And it’s this easy to test them:

[TestMethod]
public void TestWorkflowMessageHandler()
{
	WorkflowMessageHandler handler = new WorkflowMessageHandler();
	handler.Bus = this.MockBus;

	// set up expectations on bus in terms of messages returned

	Stage1Msg msg = new Stage1Msg();
	// fill msg with data

	handler.Handle(msg);

	// verify expectations on bus
}

That’s right, it’s just plain old unit testing the way we test everything else these days.

I’m beginning to get the impression that the new suite of technologies that is coming out of Microsoft is making things more complicated than they need to be.

Well, maybe that’s just me.



Service-Enabled Workflows with WF and WCF

Saturday, May 12th, 2007

I’ve looked over the example Guy put up in his blog on how to interact with external services from a workflow, and tried it out using asynchronous APIs with WCF. This is done quite simply by having our service accept an object as a parameter that it can call methods on (which has availability issues, but whatever). The object that we pass in is quite simply a reference to our own service. Anyway, I haven’t been able to get the SendActivity in WF to work with it. Bummer. I guess I’m “stuck” doing things the “old fashioned” way.

By having messages dealing with workflow contain the ID of the specific instance they refer to, we can do simple message to workflow mapping. When a message handler receives a message containing a workflow ID, it just goes to the workflow store and retrieves the object by its ID. Finally, it calls the Handle method on that object, and I’m done. Workflow classes are just state machines whose triggers are the arrival of a message.

Here’s some example code so you can see how simple it really is:

public class WorkflowMessageHandler : IMessageHandler<Stage1Msg>
{
	public void Handle(Stage1Msg msg)
	{
		using (IDBScope scope = this.DbServices.GetScope(TransactionOption.On))
		{
			IWorkflow wf = this.DbServices.Get(msg.WorkFlowID);
			wf.Handle(msg);

			scope.Complete();
		}
	}
}

You can see how easy it would be to take this and make it generic. Just define an IWorkflowMessage that inherits from IMessage and has a single property – WorkFlowID. Then we could have a BaseWorkflowMessageHandler<T> which would inherit from IMessageHandler<T> where T : IWorkflowMessage.

After that, it would be enough to have a class inherit from the base for a specific message and you’d be done, just like this:

public class Stage1Message : IWorkflowMessage { // WorkFlowID and other data };

public class WorkflowMessageHandler : BaseWorkflowMessageHandler<Stage1Msg> {}

I could even automate the creation of these message handlers given the set of messages that correspond to a workflow. I could then create all sorts of sexy designers on top of that.

But, seeing as there’s so little extra code to get long-running workflows to work with “asynchronous services”, I don’t think I’ll bother. I mean, why do I even need a “SendActivity”? It’s just a simple little call:

this.Bus.Send(msg);

It appears that clean designs don’t leave much to be draggy-dropped. Oh well. Your mileage may vary.



Service-Layer Separation of Concerns

Sunday, April 1st, 2007

The idea of having a generic bus object that dispatches message objects to their appropriate message handler objects seems to have struck a chord with Ayende (aka Oren). It is definitely one way of doing the Unit-of-Work Pattern that also partly goes along with the idea of Consumer-Driven Contracts, in that the consumer “defines” the transaction boundary. These two topics are directions that the Bus API was not originally intended to cover, but I’ve found them useful in many cases.

One of the strengths of this approach that isn’t immediately apparent is that you can have multiple classes that handle the same message type. These classes are then configured in the Bus to run in a certain order – very similar to the channel model in WCF, or the HTTP Handlers in ASP.NET. Each message handler in the chain can stop processing of the message if it should so choose.

The use of this strength is that it allows for a strong separation of concerns in the message handling logic. Need to do some pessimistic lock checking first? No problem – have a separate message handler class that does that. Want to add some custom auditing before and after all other processing, configure in a couple more message handlers. Have some complex validation logic that you’d like to keep separate from the rest of the business logic? Put it in its own message handler class.

For those thinking about more advanced messaging scenarios, you could have each message handler in the chain do some Content Enrichment and have that data available in down-stream handlers.

I’ll address the issue of sending messages using this pattern in a coming post, so stay tuned J



Queues, Scalability, & Availability

Friday, February 2nd, 2007

Dr. Nick has a great post up on scalability, queues, and WCF. For some reason, everybody’s always talking about scalability, but availability gets much less play. For many systems, availability is actually the more important *ility.

Anyway, when it comes to scaling out queues help a lot. Although not explicitly mentioned in the above post, having multiple machines feeding off of the same queue is the key to scalability and is known as the Competing Consumer pattern. The added benefit of such a design is that you get availability without any additional work, given that you have more than one consuming machine per queue.

One thing to keep in mind about the Microsoft platform today is that MSMQ does not currently support remote, transactional receives (Update MSMQ 4 released as a part of Vista / Server 2008 now supports this, yet people in the know have told me to avoid this feature). What this means is that, in the above design, you cannot make sure that if one of the servers fails while processing a message from the queue, that that message will return to the queue. For some kinds of messages this isn’t a big deal (like stock prices), but in other cases (like money transfers) this isn’t acceptable.

So, bottom line is that queues and other asynchronous transports (JMSs and topics) enable robust systems to be built using proven patterns, but be aware of any limitations of the technology and what ramifications they may have.



Web Service Software Factory – Data Access CRUD!

Sunday, September 24th, 2006

And I don’t mean CRUD as in Create,Read,Update,Delete.

I haven’t been following the factories much but David Hayden’s recent post pulled me back in. Here’s an example of the kind of solution that the factory creates:

I thought that object orientation was already accepted as good practice, but here comes Microsoft splitting up data and behavior once again. Business components that have only behavior, and business entities that contain only data (relationships between entities doesn’t count as behavior) <shudder/>.

If anything, the business components, when you actually look at the code in them, are more service layer objects than anything else. Which kind of makes you wonder why there is a separate Service Implementation layer. Is it because the service implementation is technology dependent? The answer is yes.

Wouldn’t it be great if we could have service layer objects that were technology independent? Then we could take the code in the “business components” and put it there, and do away with an entire layer.

You know where this is heading. The tried and true Domain Model pattern and its friends. Its just that this whole “data access” paradigm that Microsoft keeps pushing gets on my nerves. It just does not hold up in complex domains – I know, I’ve tried. I’ve also consulted on many other projects that have tried, and seen them get to the point of no return. The point where programmers just don’t know what the domain logic is – because its spread all over the place: service implementation, business components, entities, data access, stored procedures… Its at that point when they have to “ship” so that the project won’t be called a failure. Then they scrap the whole thing, and start working on version 2.0 which will be totally different! They use a rules engine! I’ve already wrote about the kinds of successes I’ve seen there.

OK, enough whining. Do your own design. There are other patterns besides what Microsoft puts out. Read them, use them. Just because there’s a factory that autogenerates thousands of lines of code, doesn’t mean that they’re the right thousands of lines of code.



Can Indigo be my bus?

Friday, June 2nd, 2006

Updates:

Download the MSMQ implementation.

Service-Layer Separation of Concerns achieved by using Bus API.

How the Bus API handles the connection between messages and transactions

How information from one request can be used elsewhere


You’d think that with Indigo/WCF/WinCom out now, people like me who develop distributed systems would be overjoyed. Finally, a single technology stack to deal with, right?

Well, maybe if the API wasn’t so cumbersome.

I know that Indigo tries to be almost everything to all people through its pervasive extensibility model, but I’d really like to have my (rather simple) needs handled well, without having to special case a lot of the low-level mechanisms.

The thing is, I’ve already found a much better API. The reason its turned out so simple is the result of accepting a certain way of working – the SOA way. Once you give up the desire to tightly couple, the fog clears. You start to see the following simple elements combining in well defined ways…

The only data that goes between services are messages. In other words, any class that implements the IMessage marker interface. If you want XML or SOAP serialization, that class should probably be serializable.

The thing you use to send message implements the IBus interface. IBus exposes the following methods:

void Send(IMessage message);
void Send(IMessage message, CompletionCallback callback, object cookie);
void Reply(IMessage message);
void Reply(IMessage message, int errorCode);

void Start();

void LoadTypesFromAssembly(Assembly a);

** void CompletionCallback(int errorCode, object cookie);

There is one more interface to mention, and that is IMessageHandler where T : IMessage. It has a single method – void Handle(T message);

Before we get too mired down in the details, you’ll probably notice that the “Send” methods don’t take a destination parameter. That’s because there’s no way in hell that application code can/should know where a message should go. Here’s the reasoning:

A message schema, a group of classes that implement IMessage, aren’t just available. An autonomous service “published” that schema, in essence saying “this is how you speak to me”. The corrollary of that statement is that an instance of one of those classes should always be sent to an endpoint of that autonomous service. The implementation of the bus, probably with a config file, will know which endpoints are for which message type.

Another thing you’ll probably notice is that there’s no “Receive” method. What happens is this:

Since the bus implementation will deal with the underlying technology, it will know when a message has arrived. It now needs to inform the application of this. While it could expose a MessageReceived event, what we’d really like it to do is to dispatch that message to the appropriate message handler. The bus could easily reflect on the generic type parameter of the message handler in order to build a map from message types to message handler types.

When we start to think about message handlers, they really are one shot deals. There’s no reason to keep them in memory when they’re not handling messages. So, the bus would do per-message instantiation. Since the communication is based one asynchronous messages, there really is no meaning to the term “session”.

And about the messages – there really isn’t any need to decorate their fields with attributes or anything, is there? All the data is passed, always.

The “Reply” method is there so that a message handler, as a part of its logic, can send a message back to the client that sent it the request. Alternatively, it could just “Send” one of its own messages (like CustomersUpdatedMessage) to all clients subscribed.

How would we know that a client subscribed? Simple – it has a message handler for a message defined as belonging to someone else (the autonomous service). The client bus could then send its own specific subscription messages to the bus running on the service, which would then save that subscription.

I could go on, but I think that you can see that Indigo wasn’t designed to make this kind of scenario easy. Of course it’s possible to implement this on top of, and inside of Indigo, but, to put it mildly, its a bitch. The hard part is getting rid of the need to use all those ugly attributes.

The real thing that gets under my skin is having to explain to technical business types why we aren’t using Indigo either as an API or implementation. It’s just too much complexity! Look at all the examples out there on the blogosphere, did you see how much techno-crap you have to write to get something working. And the resulting application level code is mired in technologically specific details. Yuck. I barely have enough time to develop the system itself without wasting any on debugging infrastructure code just to find out I forgot yet another attribute (YAA). How’s that for a replacement for WCF?

Just to fill in the description of the API, the LoadTypesFromAssembly method scans a given assembly and loads and maps all the types that implement IMessage and IMessageHandler. The Start method tells the bus to start listening for messages – in essence spawning the appropriate number of worker threads. For client side buses, you probably only need a single worker thread. Service buses will probably have more.

The Send method that accepts the callback and cookie is used so that when the bus receives a response message (possibly identified by a correlationId field, but that’s an implementation detail), it would activate the callback passed before. The cookie is there so that the initiator can differentiate between different messages that it sent. For instance, if we had two CustomerDetailsForms open, and from each we initiated an update, when we get two responses back, we need to know which response goes with which form. If we were to pass the form object in as a cookie, which we’d get back in the callback, that would be just dandy. The errorCode passed in the reply would also be passed to the callback.

This asynchronous request/response pattern, combined with pub/sub – event-based communication is at the heart of loosely coupled systems. The API I described does a fine job of enabling it in a technology neutral fashion. Indigo does a much poorer job, in my opinion.

So, I’m afraid that I’ll have to keep using my MSMQ implementation – it seems that Indigo never really wanted to be a bus anyway. Although it does a fine job of uniting the technology stacks that were previously out there, WCF/YAA appears to have a long way to go.

BTW, my podcast on ESBs is up on Dr. Dobbs now.



   


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

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

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

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

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

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

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

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

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


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

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

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

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

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

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

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

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

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

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

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

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

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

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

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