Udi Dahan   Udi Dahan – The Software Simplist
Enterprise Development Expert & SOA Specialist
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#NoEstimates – Really?

Saturday, April 19th, 2014

estimatesThere has been some discussion online recently about the issue of estimates in software development, specifically under a meme called #NoEstimates.

This came up when I was in London for the DevWeek conference at the speaker dinner with Austin Bingham, Rob Smallshire, and Allen Holub and I wanted to share some of the ideas that came up, as well as some of my personal opinions on the matter.

Context matters

When you’re in an organization that is continuously developing and evolving a product, platform, or suite, your context is quite different than when you’re working on a project either for an external client or an internal one.

In short: product vs. project.

While in both contexts you’ll want frequent releases, the main difference is that a project is meant to achieve a certain state of “done-ness” in a bound period of time. A product is not ever meant to be “done” in that way. A successful product is one that continues to evolve over time, with that success (arguably) resulting in more resources being dedicated to its development.

If we were to zoom out our scope beyond that of the project, we’d probably see certain product-ish qualities at the level of a client’s entire IT environment – no state of “done-ness” and similar consequences of success.

Where estimates are needed

Whether you’re in a product development organization or the CIO of an enterprise, there are a certain number of features/projects (FP) that people in “the business” want done. Let’s assume that each FP has a certain amount of business value that its implementation would result in and that that value is known in advance.

Sidebar: Clearly, the business value of any feature or project can not be known with much certainty in advance of it being implemented. Still, for the purpose of keeping the analysis simple for now, let’s table this issue for a bit.

While you might think it’s reasonable to perform the work on these FPs in order of decreasing value, that is mistaking revenue for profit/return-on-investment (ROI).

In other words, we need to know roughly how much each of them costs to be able to calculate its predicted ROI (value – cost).

Only then can we decide in which order to do the work.

So, we need somebody technical to give an estimate.

High-level estimates

In this context, sometimes it’s enough to provide 3-4 buckets describing the amount of work – I like the approach of using shirt sizes: S, M, L, XL.

This can help the organization decide quickly to charter the development of the FPs with very high value and very low cost. These low hanging fruit are great for getting started, but when you’re done with them, then you have to decide between a bunch of FPs whose predicted ROI are all very close to each other.

Before doing that (!), it’s important that no projects with an XL size are fully chartered as is – no matter what the value.

When a technical person gives an XL estimate, that means “this is so big, I really have no idea how long it’ll take”. The variance can be huge here – in some cases, they might not even be certain if the request is doable without being given some time to do additional research first. And that is exactly why you need to carve out a certain chunk of time and resources for doing that research.

“But you don’t understand, Udi! We need this done ASAP.”

Believe me when I say that that ship has already sailed.

There’s a pretty good chance that before that extra-large FP is half-done, so much time will have gone by that business priorities will have shifted. Unfortunately, by that time so many resources will have been invested in it that nobody will have the guts (or political capital) to pull the plug on it. The best people will start leaving – sometimes to other FPs but, more often, the company as well. Even when these nightmarishly large missions are eventually done – they end up being something of a Pyrrhic victory.

So, what to do?

Well, beyond financing a certain amount of directed and scoped research and development to get a better handle on that beast, let me suggest this:

Enter the “Lean Startup”

If you haven’t heard about it yet, and regardless of whether you’re actually working at a startup (I’d say that it is even more important for large organization), you need to check out the Lean Startup.

While I won’t be able to do justice to it here, let me use this admittedly gross oversimplification:

You are mistaken about the predicted business value.


So what you need to do is to start applying the scientific method – a series of experiments in which you are looking for proof to validate your hypothesis about the predicted value, where the outcome of one experiment is used to formulate another hypothesis to be tested in the next experiment.

Let me say this differently – until you are as rigorous in evaluating the predicted value of a given initiative as you are in estimating its cost, with that rigor increasing with the size of the initiative, you have no business starting to work on it.

And this is what’s missing from most of the software development world.

Portfolio management

I don’t really care what you call it, but the portfolio of potential investments and the risk analysis around them needs to be handled properly.

Based on the language I’ve chosen, you can see parallels to the world of finance. Now, before your mind starts going to the news of all the shady crap that’s been going on in the world of finance, understand that there are both positive and negative outliers in every domain.

That being said, I won’t point you to books on finance (at least, not for starters).

I suggest reading Manage your project portfolio, by Johanna Rothman (one of my favorite people in the world). She also has a couple of blogs, and that can help you get started.

This has already gotten quite long, so I’ll skip a bit and talk about what you should do if you’re “just” a developer being asked to give an estimate.

How to give a good fine-grained estimate

Here’s the format to use:

This will take a team of N between T1 and T2 and I am P% confident in that range, with the following assumptions (1, 2, 3), and most importantly, that the team does not work on anything else during that period of time.

Let me repeat that important bit again:

Assuming the team does not work on anything else.

Most of the kinds of people who ask for estimates aren’t going to like that kind of answer. You may get some pushback, “don’t be clever – can this be done by the end of the year, or not?”. In other words, they’re asking you for a commitment – not an estimate. This is common with certain types of dysfunctional organizations – the project management people are only measured on adherence to schedule, not on whether the system solves the right problem. You, the developer, want to make sure you’re solving the right problem – you want to be Agile. But that’s not the point.

Let me repeat – Agile is not the point.

If the organization around you is dysfunctional, be smart – don’t try to be right. Solving the right business problem is the right thing to do, but often it’s not smart thing to do. If you don’t like having to deal with this kind of organizational politics, you had better find yourself a different organization – otherwise, you had better be smart.

How to receive good estimates

Assuming you’re a team lead, project manager, product owner, or something similar, here’s how to respond when someone gives you an estimate in the above format.

  1. If P is subjectively high enough and T2 is subjectively low enough, give them the green light.
  2. If P isn’t high enough, or the range of T1 to T2 is too broad:

    1. If you have previously given them time to do research (RT), double the value of RT.
    2. Make sure they are only doing research during this time (no other development).
    3. The purpose of the research is to increase P, or decrease the range of T1-T2
    4. When receiving the new estimate, go back to the beginning.

To be clear, “research” does not mean navel-gazing. It can and often will involve writing a bunch of code as well as on figuring out what the requirements should have been in the first place.

“But Udi, won’t this end up wasting time that could be better used on actually building the system?”


In reality, this will end up paying back all the time that should have been spent up-stream on portfolio management and requirements analysis activities.

Which brings me to…

Working software over comprehensive documentation

Sometimes, writing high-quality working software is the last thing you want to do.
Specifically, the earlier you are in the project, the less likely that you should be focusing on code.

Often, the most cost-effective thing to do is some rapid-prototyping like creating UI mock-ups to verify what the system should really do.

This really deserves a blog post of its own (with thanks to Geert for finding the link), but suffice it to say that this is a skill-set all its own that should exist in every software development organization.

On other word on small startups – I often hear from people who are doing their own startup that want to do DDD, CQRS, SOA, and a bunch of other three-letter-acronyms they picked up on various blogs and books, because this time it’s up to them; this time they’re going to do it right.

No, no, no – stop that. Go read the Lean Startup. Then do it. And if you’re extremely lucky, you will be so successful that in a couple of years you will be in the position to rewrite the system – the only difference is that now you’ll REALLY know what the system is supposed to be.

In closing

OK – so that’s well over 1500 words I’ve spilled on the topic.

While the hashtag #NoEstimates makes a great soundbite, estimates are an important part of the information that needs to flow around the organization to help quantify and mitigate risk. Too often there are various organizational dysfunctions tangled up in the same areas as estimates which, I suppose, could give the impression that the estimates are to blame.

While I wish I could tell you that all you need to do is find an organization that doesn’t have any of these dysfunctions and all will be well for you, unfortunately there aren’t any organizations without them. Just like all families are dysfunctional in one way or another, so too are organizations. This is simply because each of us human beings is somewhat dysfunctional.

Well functioning organizations are made up of highly aware individuals – people who have become able to see and mitigate some of their personal issues, and thus can be patient as the people around them similarly work through their issues. Together, these individuals continuously create and adapt their working processes and systems to compensate for the various dysfunctions in the group.

Under these iteratively growing conditions of mutual trust, various kinds of estimates are performed at different levels and times and are just a normal part of communication and decision-making.

Please, don’t throw out the baby with the bath-water.

Thoughts on a career in software development

Friday, December 27th, 2013

helping_handFor much of the history of computers, programmers really only had one path to take – upward into management.

While you could go from Junior Programmer to Senior Programmer, sooner or later you were faced with the choice of becoming a Team Lead or having your career stagnate.

The primary difficult with becoming a team lead is that the skills that made you an excellent Senior Programmer didn’t really carry over to leading a team.

On leading teams

Much ink has been spilled (and keyboards been pounded) on this topic, so I’ll just give the common solution that is proposed to this issue – having a parallel technical career track to the traditional management track.

After being a senior programmer, developers can grow into architects and upwards. IBM, for example, has the title “Fellow” reserved for this ultimate level.

An IBM Fellow is an appointed position at IBM made by IBM’s CEO. Typically only 4 to 9 IBM Fellows are appointed each year in May or June. It is the highest honor a scientist, engineer, or programmer at IBM can achieve. —Wikipedia

All that’s well and good, but I have a feeling that something is still missing.

Why does it have to be either/or?

What if we allowed, nay – encouraged, developers to try both types of roles as they advance in their career?

After your first year as a senior programmer, you are then assigned to be a mentor to a junior programmer. You don’t assign them work, but take responsibility for some of their professional development. During this time, you also start learning what it takes to be a good team lead and developing your soft skills – yourself being mentored by a more senior team lead (probably not a good idea for it to be the team lead on the project you’re working on). From there, you take on a team lead role on a small-ish project leading 2-3 other developers.

During your time as a team lead, architects in the company work with you to deepen your technical knowledge of larger system concerns – grooming you for your next role: an architect. Your experience as a team lead gives you new found appreciation for managing technical risk.

Later, as an architect with developed soft-skills, you are now much more capable of getting teams to adopt your ideas and to want to do “the right thing”, rather than just deliver the project any way they know how. Even as you develop your expertise in various technological areas, the organization has an eye on bringing you back to being a team lead, this time on a larger project.

In praise of the zigzag

I think this has actually been happening more than just a little in our industry, although I believe it usually happens as people move from one company to another.

Is it possible that the limitations of the structures in their previous companies contributed to their choice to move to another company? Well, I wouldn’t discount it.

I don’t think companies should pigeonhole developers – either you’re an X or a Y.

Human beings thrive on variety and occasionally stretching out of their comfort zone.

I believe this model optimizes for people’s personal growth and can be tuned quite easily.

I think this is also very much in alignment with the Software Craftsmanship movement and can make it easier for companies to develop and hold on to the talent they’ve been lucky enough to hire in the first place.

In closing

While I believe this model is workable for a lot of the software industry, both for consulting companies and internal development organization, it’s clearly not going to be applicable for small startups. That being said, if the startup is successful and starts growing, it might not be such a bad idea to lay the groundwork for the team early on.

I don’t claim that this is the “best model” out there, and I haven’t tried it myself (yet), but I do believe that it has potential and would love to (re)spark the conversation about processes and structure that has seemed to die down under the Agile maxim of “Individuals and interactions over processes and tools” (though I believe that Agile as a whole *has* gotten us pointed in a better direction than where the industry was before).

What are your thoughts?

Write a comment or, even better, write something on your blog and spread the word!

The right methodology for your project

Sunday, August 4th, 2013

certified_agileIn this day and age where “Agile” is kind of the default in many organizations, I thought I’d point this out:

I’m on record that every project needs its own methodology; further, that for most projects, the beginning, middle, and end are different enough to need their own; further, that every team ought to reexamine, alter and experiment every month.
Alistair Cockburn – one of the authors of the Agile Manifesto1, 2

Allow me to say that again:

Every project needs its own methodology

And that that methodology should not be statically adhered to – instead you should expect to adjust that methodology monthly, to the level that an external observer seeing the middle of your project would identify that you are, in fact, using a different methodology than the one you were using at the beginning of the project. And the same would go for the end of the project.

And if you don’t know Alistair yet, let me tell you – he really knows what he’s talking about.

Read more of Alistair’s work.

Service-Oriented API implementations

Monday, December 10th, 2012

gearsIt’s quite common for our systems to need to expose an API for external parties to call that isn’t exactly aligned with our service boundaries – at least, when you follow the “vertical services” model rather than the “layered services” approach. I’ve blogged many times about the problems with layering, so I won’t go into that now beyond to say that you really, REALLY, should avoid it.

A short intro to SOA, done right

In the “vertical services” approach I espouse, you often see components from multiple services deployed to any given endpoint. While these services usually don’t need to communicate with each other at all, occasionally you’ll see them leaving “breadcrumbs” behind for each other – things like UserId or OrderId in the session. What’s especially important is that these IDs are accessible even before the entity is finalized – this enables each service to collect its own data without needing any other service to know about that data.

In an ecommerce environment, we would see one service owning money, another the product catalog (excluding prices, those would be owned by the previous service), another service owning the customers’ payment info (credit cards, etc), and yet another owning shipping addresses – all of these separate from the one that owns the shopping cart. Let’s call these Finance, Catalog, Payment, Shipping, and finally Shopping – just so that we have something to reference later.


While we can do all sorts of cool browser composition with the UI in our own system, enabling each service to collect and display its own information, if we want to expose an API for clients to call, we wouldn’t want to force those clients to have to make a separate call to each service in order to make a purchase. Instead, we’d want something that looks like:

MakePurchase(Guid orderId, Dictionary cart, CreditCardInfo cc, Address shippingAddress)

In case you were wondering, the service which owns the definition of this API is different from all of the above services – it is a service that is primarily technical in nature and is responsible for things like integration and data transformations. I call this service IT/Ops.

Getting the data from the API to the services

So, we don’t want any of our business-centric services to know about anybody else’s data structures, so that leaves it to IT/Ops to pass the data to them. The thing is that we still want to do that in the most loosely-coupled way possible – with messaging being a good candidate for that.

So, what we’ll do is have IT/Ops send a message containing the data to the other services, but with a slight twist.

Here’s what the code would look like with NServiceBus:

Bus.SendLocal(new Order { Id = orderId, Cart = cart, 
                          CreditCard = cc, ShippingAddress = shippingAddress });

Why the SendLocal?

So that the components from the other services can all run together with IT/Ops in the same process giving a nice tight deployment model.


If you’re using a transport like RabbitMQ that is set up as a remote broker, the overhead of going back through the broker might not be worth the improved reliability you’d get by going through messaging. In that case, you might want to consider the Domain Events approach. This would give you a similar level of decoupling but then IT/Ops would need to set up an surrounding transaction, well, that is if you want all the services processing to succeed/fail as one unit. If you don’t, you’d probably be better off just sending messages from IT/Ops to endpoints that host each of the components of the other services.

End Update

Before we get to the services, let me show you the Order class – specifically, the interfaces it implements:

public class Order : ShoppingOrder, PaymentsOrder, ShippingOrder
    public Guid OrderId { get; set; }
    public Dictionary<Guid, int> Cart { get; set; }
    public CreditCardInfo CreditCard { get; set; }
    public Address ShippingAddress { get; set; }

public interface ShoppingOrder
    Guid OrderId { get; set; }
    Dictionary<Guid, int> Cart { get; set; }

public interface PaymentsOrder
    Guid OrderId { get; set; }
    CreditCardInfo CreditCard { get; set; }

public interface ShippingOrder
    Guid OrderId { get; set; }
    Address ShippingAddress { get; set; }

Each of the above interfaces represents the data that each service cares about. Therefore, each service will provide an assembly that handles that message/data and persists it to its database, like this:

public class ShoppingAPIHandler : IHandleMessages<ShoppingOrder>
    public void Handle(ShoppingOrder message)
        //persist to shopping service db

public class PaymentsAPIHandler : IHandleMessages<PaymentsOrder>
    public void Handle(PaymentsOrder message)
        //persist to payment service db

public class ShippingAPIHandler : IHandleMessages<ShippingOrder>
    public void Handle(ShippingOrder message)
        //persist to shipping service db

Since the Order object being sent is a polymorphic match for all of these interfaces, NServiceBus knows to invoke all of these handlers. By the way, if you care about the order of invocation, then you can control that as well (but I won’t get into that here).

Also, since all of these handler assemblies are deployed to the same endpoint, and the Order object is sent just once, this means that all the handlers will be invoked in a single transaction on a single thread – either all of them succeeding, or all failing. Since they’re all connected on the same Order Id, referential integrity can be preserved as well.

Wrapping up

When you are building a system on SOA principles, you’ll often find that you need a service like IT/Ops to handle data transformation and other broker-centric tasks. While much of SOA is based on the Bus Architectural Style – meaning primarily publish/subscribe interaction between services – that doesn’t mean that your business-centric services cannot have their components deployed in the same process.

I’d go so far as to say that if you aren’t deploying components from multiple services in process with each other at least some of the time then it’s quite likely that your service boundaries are probably incorrect.

Anyway, I hope you found this post interesting. Shout out to Slawek who gave me the idea for this post.

By the way, if you’d like to learn more about these kinds of patterns, the next batch of courses is open for registration – but the early bird prices are almost over, so you’d better hurry.

Register for   Denver CO, USA,     Bad Ems, Germany,     Perth, Australia.

Leveraging irrationality towards success

Thursday, September 27th, 2012

irrationalWe’ve all seen good ideas emerge in the software space – from objects, to components, to services, to domain models, and the *DD approaches. Yet, in most organizations, it is very hard for these ideas to get traction.

I’ve heard from countless developers and architects over the years about their frustration in getting everybody else to go along with them. “Can’t they see how much better [new approach] is over what we’re doing now?!” they ask, believing that things could and actually would be evaluated on their merits, especially in a rational field like IT.

The usual explanation I give has a couple of parts.

Conway’s Law

In 1968 Melvin Conway penned what later became known as Conway’s Law which stated:

“organizations which design systems … are constrained to produce designs which are copies of the communication structures of these organizations.”

An important corollary of that law is that if you wish to have a significant impact on the design of a system, you would need to have a similarly significant impact on the communication structure of the organization making that system.

The main problem is that the people that tend to be pushing for DDD, IoC, CQRS, SOA, etc are usually not as strong when it comes to the soft skills that are so necessary for bringing about organizational change. The thing is that, at a minimum, these types of changes take 3 to 5 years so it really takes a long-term commitment, both from the individual and the organization.

On the rationality of people in IT

First of all, people are a whole lot less rational than they’d like to believe – or that they’d like other people to notice. In fact, people will go to great lengths to maintain the appearance of consistency and rationality, even at the cost of harm to themselves. How’s that for irrational?

Don’t take my word for it – there’s a great book on the topic: Predictably Irrational: The Hidden Forces That Shape Our Decisions. The somewhat scary thing about it is that not only are we irrational beings, but that that irrationality can be predicted and, yes, even manipulated.

Once you can understand that the people you’re trying to convince aren’t Vulcan, you have a much better chance of being effective. I’d say that, for myself, understanding my own modes of irrationality increased my effectiveness as well, and made me quite a bit happier in life too.

Why you need to bring in a consultant

This isn’t me hawking my wares – believe me, I’m busy enough as it is, but let me know when this starts to sound familiar to you.

There’s a problem in your organization – could be that you’re not delivering software fast enough, high enough quality, whatever. Suffice it to say that Management isn’t happy. You’ve been living this pain for a while and know exactly what the source of the problem is (more often than not, management has at least a hand if not a whole arm in it). You come up with some recommendations, bring them to the higher-ups, but ultimately are ignored, dismissed, or don’t even get into the room.

Some time later, management brings in a Consultant (that’s right, with a capital ‘C’) who is there to figure out what’s wrong and come up with recommendations. In some cases, especially in larger organizations, they bring in a whole bunch of them from a brand name like McKinsey or Ernst & Young.

If these guys are smart, they listen to you, ultimately presenting your analysis and recommendations to management. Of course, those higher-ups are in awe of how quickly these guys were able to understand the inner workings of their organization. That awe lends instant credibility to their recommendations which are then adopted and given powerful political backing.

And you’re sitting there thinking, “but… but… but that’s what I was saying!!”.

It’s not the message – it’s the messenger.

Let me put it another way, explained from the perspective of management – we’re having problems, you work here, ergo you’re part of the problem. Also, you don’t make that much money (compared to management), so how smart could you be? Those brand-name consultants, well, they cost a LOT, so they MUST be good (good enough to know not to work here too).

Therefore the more the consultant costs, the more likely management is to listen, which ultimately creates the conditions for success, which makes the change happen, which proves to management that they were right to bring in an expensive consultant. A vicious (or virtuous) cycle – depending on how you look at it.

Now, it doesn’t always work this way, but it does often enough to perpetuate management’s world view.

In Closing

I do hope your organization and its leaders aren’t trapped in this kind of dysfunction, but if they are, know that you’re not alone and that you can get help – either via consulting or in some books:

Some good books include Made to Stick: Why Some Ideas Survive and Others Die and the grandfather of the field: How to Win Friends & Influence People. There are countless others and there isn’t any right place to start – the most important thing to do is to start.

It’s been over 40 years since Melvin Conway’s observation and, as an industry, we’re still relearning these things – usually through the school of hard knocks. But there is an upside here – I’m pretty sure that, knowing these patterns, you could pick up on some signals during the interviewing process and find a company that’s outgrown many of these issues – one that would be able to have more meritocratic discussions on technical choices.

In the worst case, you could become a consultant and make a living off of all this irrationality :-)

UI Composition Techniques for Correct Service Boundires

Saturday, June 23rd, 2012

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

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


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

The traditional way

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

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

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

What to do?

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

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

This raises other questions, of course.

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

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

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

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

Some words on CQRS

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

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

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

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

In closing

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

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

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

Thanks a bunch.

NServiceBus 3.2 Released

Wednesday, May 23rd, 2012

Following on the official announcement, I wanted to talk a bit about this new release – specifically the modeling tools we’ve integrated with NServiceBus.

Drag & Drop? Code-Gen?! Run Away!!

You see, I’ve always been very opposed to draggy-droppy development environments. Also, I’ve had pretty bad experiences with code generation – usually taking the stance that if there was something repetitive that was being handled by code-gen, it would have been better to design the system in such a way that it wouldn’t require anything repetitive.

And yet, here I am, telling you that I think that the draggy-droppy code-gen that we’ve introduced with ServiceMatrix make NServiceBus that much better – not only does it shorten and flatten the learning curve for those looking at NServiceBus for the first time, but it also really improves the productivity of those already experienced with it.

I almost can’t believe I’m saying this, but it is the future.

The current state of things

That being said, it currently is still very much a v1 release – more of an accelerator for setting a new system up quickly than something integrated in the full system life-cycle.

Update:We’ve now get everything updated for VS2012 and would love your feedback. Check out ServiceMatrix.

Here are some things that are on the roadmap for the future:

  1. Making large solutions easier to navigate by integrating a kind of “pivoting view” that shows different dimensions of the solution and the relationships between them instead of the current single-dimensional tree view.Done
  2. Round-tripping – changes to code sync-ing back to the model. Renaming a message or a handler should work whether you go model-first or code-first.
  3. Audit visualizations – taking the results of the previous run from our audit log and making it easy to see who sent which messages to whom, rewinding, fast-forwarding, and replaying the audit log to debug that last execution

I’ll be honest with you – building this stuff is expensive. If we hadn’t gone down the path of commercializing NServiceBus, there was no way we could have gotten this far, let alone have a chance to do all the other things we’re planning.

On Licensing

We’ve made our fair share of mistakes along the way, particularly around licensing.
We’re a bunch of engineers – what did we know about sales?

But we’re learning and are working to get better at it – like introducing a new license calculator.

So, I’d like to take this opportunity to thank the NServiceBus community at large for sticking by us as we make these transitions, our paying customers for voting with their hearts and their wallets for the continued existence of NServiceBus, and the open-source committers who continue to contribute both with their time and their genius.

We couldn’t have done it without you and we really appreciate your support.

Go on then, give it a download, and let us know what you think. There is some nice “getting started” documentation that will take you, step by step, from a blank Visual Studio to a running ASP MVC integrated publish/subscribe solution.

NServiceBus Saga Tips

Monday, February 27th, 2012

As NServiceBus comes closer to it’s official 3.0 release, I thought I’d share some small tips.

This one’s about sagas.

When you have a time-bound process that you are using a saga to manage, often you’ll request a timeout passing in the specific amount of time to wait like so:

RequestUtcTimeout(TimeSpan.FromHours(2), someState);

In order to make the timeout period configurable, don’t have your saga code call out to some configuration infrastructure directly. Instead, declare the timeout period as a property on your saga – say, TimeToWait, and then define the value that should be injected into that property with some custom initialization like so:

    public class MySagaConfig : IWantCustomInitialization        
        public void Init()
                .ConfigureProperty<MySaga>(s => s.TimeToWait, TimeSpan.FromHours(2));

Finally, instead of hard coding the TimeSpan in code, you can get the value from a config file or a database or wherever. This can enable you to take your time-bound long-running processes and make them data-driven as well.

Keep in mind, though, how changes to this data may influence processes already in-flight. Do you want the changes to affect them or not? How would your answer change for sagas which took weeks or months to complete rather than those finishing in a day or less? What about sagas that (potentially) never end?

Food for thought.

Enterprise, SaaS, and Platforms

Sunday, June 19th, 2011

mission_impossibleSo it’s been about a year and a half since my promise to follow up on my Non-Functional Architectural Woes post. Just to give you a short summary, in that post I talked about the fact that many of today’s “best practices” for software design (like layering, ORMs, and web services) don’t actually provide the promised flexibility when requirements end up changing.

Since that post I’ve blogged about many techniques and approaches to identify better boundaries (like with SOA and DDD) and I’m seeing more and more developers starting to apply them.

This post will be slightly different.

You see, occasionally we technical people will get requirements that can’t easily be broken down by functional boundaries. Sometimes the business calls this a “platform” – here’s an example:

“We want a flexible, customizable workflow-driven platform that allows end-users to add their own columns to any screen able to support massive datasets for large enterprise customers that will also be intuitive and easy to use for our SaaS push to small and medium-sized businesses (SMBs) – oh, and then it needs to be multi-tenant too. Did I mention that we promised this would be ready for our most important client by the end of the year?”

There is only one reasonable answer to the above:

“I know you want it but, I’m very sorry, you can’t have that. It isn’t possible to do that with one system.”

It’s really rare for a technical person to say something like that. The simple reason is that in software, we believe that almost everything is fundamentally possible – given enough time/money/resources. So, when someone in business comes to us with the requirements above, we say “It’s *possible*”, loosely translated to “We can’t prove that that’s impossible”.

There are many reasons why you can’t be SaaS and Enterprise at the same time – not all of them dealing with software. The marketing, sales, and support stories of each of those markets is VERY different. In the enterprise you’re usually working with professional services people that customize the generic product – which then becomes a backwards-compatibility requirement for new development. This will hinder the development team’s ability to roll out the new shiny features needed to remain competitive in the SaaS space.

In the cases where I’ve been brought in to help clients with these kinds of systems, I try to work my way up to the person in management who is in charge of the project/product – often the CEO. Then, in the nicest way possible, I explain that really the only way to have your cake and eat it too is to create 2 companies – each one focused on its own space – Saas and Enterprise; each one with its own development team, feature set, release schedule, etc.

There’s a reason that there’s an SAP *and* a Salesforce – it’s because no one can be all things to all people. It’s hard enough to become a market leader in just one space. Trying to do both is VERY expensive, and increases the chance of the project failing from the average 60-70% in the industry to probably about 99.9%.

Hope that will save you some grief.

Cautiously Merging IL

Sunday, August 1st, 2010

Caution, Merge AheadAs Dru mentioned on his blog, while having dinner in Kansas City, I described why NServiceBus makes use of IL Merge and some of the challenges we were facing with version management as a result. While I do think that we’ve managed to find the right balance, I must say that it wasn’t easy and I urge other developers use caution when employing it.

Mistakes Made

In the previous version of NServiceBus (1.9) we over aggresively merged 3rd party libraries like Castle into the NServiceBus binaries. That in itself, wasn’t the big problem. The problem was that we didn’t know about internalizing the libraries we merged.

This resulted in all the 3rd party types being exposed when a developer used NServiceBus. For those who happened to use the same version of those libraries as that which was merged, it wasn’t a problem. Unfortunately, developers who used libraries like Castle tended to be very particular about which version they used – which resulted in version conflicts, also known as “versioning hell”.

Internalization Challenges

As we moved to NServiceBus 2.0, we were a lot more careful about which libraries were merged and made sure to internalize them as much as possible. Yes, you read that right, “as much as possible”. You can’t always internalize all the types of a given library.

For example, NServiceBus internally uses NHibernate to persist the state of long-running processes (called sagas) and we want this implementation detail to not conflict with anything that developers want to do on top of NServiceBus. The only thing is that for NHibernate to work, it needs certain types to be exposed to the configuration environment, specifically all the types in the NHibernate.Cfg.MappingSchema namespace.

Extensibility Challenges

Once you take on an external dependency, you want to configure it to “just work” so that developers that aren’t familiar with it don’t have to learn yet another library to use your framework. So far, we’ve been able to do that quite successfully with NServiceBus. The challenge comes when developers want to customize the behavior of those 3rd party libraries, wanting to call into their APIs.

You see, once you internalize those libraries and their types, developers can’t access them. This leads to all sorts of tricky extensibility problems especially for different kinds of developers. Some are happy enough to configure things from the outside using XML – like using hbm.xml files to describe how their sagas get persisted, while others really want to use Fluent NHibernate, which is fully internalized.

Finding a Balance

What we’ve currently got for NServiceBus to try to keep everyone happy is a progressive exposure model. From the developer who’s downloading NServiceBus for the first time and wants everything to just work without changing anything, our API unfolds in multiple dimensions to allow for the highest level of extensibility and pluggability. That being said, the Fluent NHibernate issue mentioned above isn’t solvable at just an API level.

In order to address the class of developer that wants full control, we’ve got a “core only” build that doesn’t merge any assemblies into it. This class of developer usually doesn’t have a problem with referencing some more assemblies as long as they retain full control of the behaviors they want.

It ain’t easy keeping everybody happy, or, at least, not unhappy.

In Closing

I would agree that more OSS frameworks should merge and internalize 3rd party libraries that don’t need to be exposed to developers – it shortens the learning curve and increases adoption. But walk this path cautiously, it’s hard striking a balance that will work all users of your framework and it takes quite some time to get it right.

And one last thing, please, PLEASE, take care of maintaining binary compatibility from one version to the next. I know it’s a pain – we’ve been doing it with NServiceBus for the past 3 years, but your users will thank you for it.


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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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“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.
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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.

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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.
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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.”

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“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.”

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“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.”

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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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Guest Authored Books
Chapter: Introduction to SOA    Article: The Enterprise Service Bus and Your SOA

97 Things Every Software Architect Should Know

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