So here are some of the things that surfaced at the Forum, and my narrow, unworldly opinion on each (i.e. I’m just trying to fill that hollow feeling).

When we talk about architecture, we need to define what we mean by architecture?

In my talk it was a very simple view of architecture which, thinking back, I should have disclosed very early.  I am now applying from Kent Beck who talks about mutually beneficial relationships.   So I think of architecture as the mutually beneficial relationship between two or more things.  So what is a thing?  It could be  lines code in a method, methods in a class, classes in namespace, namespaces in code base, binaries in an application server, application servers in a cluster, … see where I am going?  Architecture is about creating beneficial relationships, and the 5 things I discussed are based on this view.  If you don’t know anything about the things, then you cannot create beneficial relationships.  From an agile perspective, the beneficial relationship that you create should only be beneficial based on your knowledge right now.  Tomorrow your knowledge changes, so the relationship may not be as beneficial as yesterday.  Time to change.

Building infrastructural architecture independently of functional requirements…

I am not convinced of the benefit of this approach.  In my limited experience, every business need defines the constraints or needs of the infrastructural architecture.  I find it hard to find the point of departure, yet there is a school of thought that suggests that function is orthogonal to the architecture.  Perhaps I just don’t understand this.  However from an agile perspective, I want to release early and there are many constraints on infrastructure from the business (for example, administrative processes like procurement of hardware).  I like to understand what these are early on, reach agreement on what we can release at the earliest and design accordingly.  Perhaps the first release is on lightweight infrastructure and that means we “limit” scalability.  So, I don’t design for beyond what I know is real.

Model Driven Architecture …

My view is more philosophical and abstract.  What is a model?  For me, a model is something intangible.  It is a way we understand something.  But we represent our models in many ways.  Through words in written or spoken conversation, in unstructured pictures, in structured notation like UML, even code is a representation of a model.

What do we mean by driven? I view it as a something that takes an input that produces an output.  In this case, we take an input, the model, and produce an output, an architecture.  So, I take an understanding of problem and use that to derive an architecture.  So, that’s nothing new here.  However, I don’t like to confuse driving out an architecture from a representation of the model.  That’s different.  Now we are going beyond thought processes  into mechanical processes.  Then the challenge is about how to apply the feedback to the representation of the model – and that is what will make you agile.  Too much for my small brain.

Plumbing …

Yup, we do too much hand crafted plumbing!  It’s something that we have been working on for a long, long time.  I think convention over configuration, dependency inversion, meta-programming are all attempts at addressing this problem.  Some early success that I have experienced is on taking a polyglot approach. I am not talking about mixing general purpose languages on one runtime only.  I am also including domain specific languages. I’ve had some early success where using DSL to describe functional intentions and then generating a large portion of the plumbing.  Where I’ve suffered is when I mix concepts from different domains.  There is the domain of plumbing and the domain of the business.  Whenever I’ve mixed the two, it pains later rather than sooner.  Right now, the only way I’ve had some success is with aspect orientation and meta-programming.

@StatelessSessionBean …

Chris Naidoo is right.  That thing called J2EE and subsequent versions is just horribly broken.  It’s broken encapsulation and a whole lot more.  The fact that we now must use an annotation and not implement an interface is immaterial.  Both result in the same pain – mixed concepts (see plumbing above).  Annotations should be specific to the business such as @RecalculateCostsOnRerouteOfCargo can be used as an interception point for injecting a rule on a class or method.

I would go even further and say that the POJO JavaBean specification is also broken.  Why on earth must I have a no-argument constructor and accessors and mutators.

Last thoughts …

I may have missed some of the other discussions but these are the ones that I woke up with this morning. In general, my observation is that we need to be very concrete very early if we want to be agile, even in architecture.

Technical debt is one of those metaphors that have been extended so far, that it is believed by many to be something tangible.  Let’s get real here:  Technical debt does not exist.  It is just a metaphor for us to realise that our code base may cost us more money than it should, and that is a future view.  Sometimes our metaphors become euphemisms, and then it is dangerous.  When it comes to technical debt, the less I think of code problems as debt the more I am able to face the problems head on.

Ironically, I did a talk recently on dealing with technical debt.  My fundamental position is simple.  Either your code base has things that exist as a result of broken principles or it does not.  The more principles you break, the more potential problems you have in your code. It is not a problem right now, but it may be a problem in the future.  This future can be a minute away when I run my next test or a year away.  If the future is infinitely far away, then it is not a problem at all.

My first prize is to not break principles, so I don’t create potential problems.  My second prize is to deal with real problems and just leave the potential problems for the future.

(Warning: I’m drifting into my enlightenment self-reflection, so feel free to stop reading now.)

If I am part of the exploration that is looking for a solution (living in the moment and not outside it as an observer), then I should be aware of principles that I am breaking and I should change course immediately.  If I am part of the exploration that is dealing with the potential problem that is now a real problem, than I need to understand the principle that was broken and fix the problem by restoring the principle.  Restoring the principle could mean going on a search for the right solution to the original problem, not just trying to fix the problem that is a result of breaking a principle.  This problem that broke the principle may just be the wrong solution that we thought was the right solution because we ignored our principles in the first place.

Hmmm, that’s an interesting thought.  Karen Greaves asked me if a re-write can be justified and I mumbled something about technology, etc.  What tripe!  Now I think I’ve just reflected on when a rewrite is justified.  When refactoring will not fix the broken principle, then the right solution was never discovered in the first instance.  That is also what I mean when I say that clean code is necessary by not sufficient.  At factor10, we call this a radical makeover.  Radical makeovers are a viable way of getting rid of real problems, and restoring principles.

Heck!  This blog post is less about technical debt metaphors than I thought.  Oh well, the ride on this journey never stops.

By the way, a huge thank you to Steve for helping me realise that all problems come from breaking principles, in code and in life.

But, I think I am equally excited at the possibility of seeing some familiar faces again in Johannesburg.

Oh yeah, I´ll tell you something
I think you'll understand
When I say that something
I wanna hold your hand
I wanna hold your hand
I wanna hold your hand

So what made me think about this?  That frustrating construction of the new M5/N1 interchange in Cape Town!!  When you’re sitting in traffic, you can’t do anything but look and think.  And I’ve seen this scaffolding get taller and taller and wider and wider and longer and longer and more and more people appear on it each day.

Sourced from http://www.capetown.gov.za

I know that one day, they will remove the scaffolding and the concrete will just hang there in mid air on those massive pillars and walls that they’re busy building, and I won’t be sitting in traffic any longer, and it will all just work.

What a shame that software is not like that !!  So many people get turned on by scaffolding.  And The Beatles sang on …

And when I touch you i feel happy, inside
It's such a feeling
That my love
I can't hide
I can't hide
I can't hide

And just like the M5 construction, so much scaffolding gets built, and so many people climb on.  But then, they don’t climb down.  And they don’t tear down the scaffolding.  And it just stays there mashed in with the concrete bits.  And then they ask people to use it.  And it takes strain and then it’s a performance problem, or a load problem, or it just crashes down.

I do use scaffolding, but most of the time it’s in a spike and more often it’s in a test, just to get me over my point of fear.  Deploying software with scaffolding is just dangerous and negligent.  I really don’t want to drive my car over the M5 interchange while those thin steel pipes are holding up the concrete slabs.

But above all of that, the most important scaffolding is social scaffolding.  It’s better to provide human scaffolding to support each other on a team that is focused on delivering quality software.  It’s worse to plug in weak struts in the code base that will just collapse when the next developer builds on top of it.  Very un-ubuntu!

So, the Beatles song still holds true, but only for social scaffolding.

Yeah you, got that something
I think you'll understand
When I say that something
I wanna hold your hand
I wanna hold your hand
I wanna hold your hand
I wanna hold your ha-a-a-a-a-a-and

It helps me conquer and divide.

That’s not a bad thing.  What I find really painful is casting the design in concrete.  When your design is cast, then your mental state is already cast in concrete too.  And that means that it is a lot harder to do the right things.  So, more gets added to the concrete slab and it’s real hard work to break anything off.  When I have a BIG DUF, I often look at how to reduce it, rather than increase it.

I don’t think it’s wrong to have a  BIGDUF, it’s worse if you have a BIGDIC (BIG Design in Concrete).  That concrete block will hurt you later … a lot.

In other words, the size of a BIGDIC does not matter, it’s the rigidity that’s the problem (– That’s so lame, I could not resist!)

The entire world lives on trust. Every aspect in life moves with trust.

The more I think about situations in life that will prove this statement false, the more it seems to hold true.  Even in design it holds true.  Your most fundamental architectural decisions are based on trust and the implementations of that architecture work because of trust.

It’s true for code too.  If you don’t trust the code on which you build or depend, then you might as well write everything yourself, and give up your place on your team.

I was thinking about the AOP with DDD tutorial that I will be giving at OOPSLA this year, and this trust thing came up.  Here again, aspects and the classes into which they get woven, need a trust relationship.  It may seem like a stretch to make that statement, but I think it holds true again.

So, how do you gain trust?  I am not sure, but I think you have give up something first.  Maybe you need to show your vulnerability first, then it becomes easier to let someone into your space.  Then, perhaps, they will let you in to their space too.  When ego walls are erected, then trust finds it hard to grow.  By ego, I don’t mean arrogance, I mean awareness of your self that you hide from others for fear.  Perhaps, it is only when you show your true interface, that the other will worry less about hidden agendas.

In code, trust lies in interfaces and types, not in implementations.  It’s really about trusting the implementation that makes types worthy.  When you trust the type and send it a message and it behaves as expected, then you trust it.  If you request something of an abstract type and the message was received by an instance of a subclass, then you expect the subclass to behave like the abstract type.  You don’t hope that it does behave consistently, you trust that it does!

Trust is tied in with ubuntu too.  You can’t be part of a community nor allow yourself to be defined and shaped by the people around you, if you can’t trust them.  I think ubuntu coding needs trust as one of it’s values.  It’s already a value in XP, and Scrum, and families.  It needs to be in teams, and organisations, and communities and nations too.

With such isolation of parts, it was convenient to not worry about what happened elsewhere when something was thrown to this gadget for processing.  And we started wondering about scalability things and decided that asynchronous was the way to go … disconnected, stateless, etc, all good, well-intentioned things and useful things.

Then the pattern became a product.  And on top of this product we had more products like business process orchestrators or workflow managers.  And below this product we had applications and databases and ftp locations and all sorts of things that catered for every imaginable protocol.  And around all of this we had some enterprise-ish sort of management thing to keep on eye on everything that was happening inside this very busy product.

Then, services moved from applications to the ESB product.  After all, it’s a service and that’s an enterprise service bus, right?  And when the services where moved over to their new home, all the dependencies had to come along too.  And then we started arguing about getting granularity right in the ESB.  I used to just think that the ESB had a proxy of sorts to the service that still was at the application.  Maybe I got it all wrong.

Now this ESB is starting to feel like an Application Server with a messaging gadget, workflow gadget, transformers, routers, protocol handlers.  And some ESB’s have a web server too, since they have browser based management consoles.

Some people also like the idea of a rules engine for their complex domain rules and embedded those in their applications.  Hold on, those content based routers in the ESB also used a rules engine.  Ok, let’s move our rules over to the ESB too.  Cool, my ESB is also a rules engine.

Now, I see people writing the most hellish XML that is meant to do everything from configure routing, define transformations, execute code, persist messages, fire off sets of rules and more.  It reminds me so much of those weird and wonderful stored procedures and cascading triggers that we wrote.  The other day I got a laugh out of a friend when I told him that ESB’s are now DB servers and everyone writes sprocs in XML.

And we tried to do everything in the database server – rules, custom types, defaults, constraints, sprocs, triggers, batch jobs … even jump into a shell and execute something else.  It did not work out very well then.

If I was an ESB, I’d be very confused.  I started life as a pattern with a reasonable implementation using messaging and transformation and routing.  Now all of this.  In fact, I’d be more stressed than confused.

Then again, maybe the ESB is not confused, and maybe the people that use the ESB that are confused.  In fact, if I was one of those people, I’d be stressed too.

The one thing I can tell you is that the course is a very immersive experience.  I really hate lecturing but I enjoy probing conversations and that’s how I give the course. I don’t have answers to the practical work and concerns are addressed as we go along.  As a result, the day takes unexpected turns and routes.  But in the end I get you to the right destination.  Come along; you will leave exhausted, but inspired!

Take the Fast Track to Domain Driven Design

about the course /  course contents / should you attend? / register for the course

factor10 has expanded its services in South Africa to include our advanced and
expert level courses aimed for the software professional.  On September 8-9, 2009,
we will be offering a fast track to DDD for Architects at the BMW Pavilion in
Cape Town.

Who should attend?

This course is for software professionals that want to take the right steps towards
advanced and expert levels in their careers.  Register for this course if you want to …

• learn more than just another syntax and set of tools
• write software for large, long living systems
• increase the quality and maintainability of your design
• design high quality models and use code to represent those models effectively
• develop applications with a good APIs
• add a design edge to your skill set

Why should you learn DDD?

More and more developers and architects realise that learning every detail of a new
API just isn’t the way to deliver the best business value. It’s such a tough balancing
act; focus on the solving the business problem and focus on building working software
with your frameworks.

One way of taking a big leap in the right direction is to learn and apply domain driven
design. It is definitely not abstract and fluffy; it deals a lot with the code also. DDD
leads us to focus on understanding and to communicate that understanding very well;
in language, in design and in code. You will shift your focus away from designing for a
technology, and you will learn to design for the business domain; to the core of the
problems and solutions. Those are the most interesting parts and what your users
and customers really care about.

about the course /  course contents / should you attend? / register for the course

What were they actually doing? They were mapping the client’s domain to the reference architecture domain and thereby identified reference architecture services that supported the client’s needs.  This most probably works for some people.   But I feel uncomfortable with it because…

• It means translating from one domain to another and back again.  It’s like having one massive bounded context around the reference architecture with a gigantic set of adaptors and transformers.
• There is a very real possibility of semantic impedance on the boundary of the two domains.
• There is likely to be two domain vocabularies or one large polluted vocabulary with synonyms, etc.

There are other reasons but these few are just old problems and habits coming back again.  Things that we accepted as dangerous and limits success in creating good software.

So, are reference architectures bad? Yes and no.  Maybe you should consider adopting its domain vocabulary as a first step.  A reference architecture with a rich metamodel is more likely to be more valuable than one without a metamodel.

And the moment you start thinking at a meta level, then you’re moving into a higher level of abstraction.  In this higher level, you will have a greater opportunity to describe your intentions agnostic of the reference architecture and the vendor’s technology stack.

The way I see it, services are defined at a meta level.  They describe your intentions and are independent of a reference architecture.  However, if you chose a reference architecture up front, then describe your intentions in the vocabulary of the reference architecture.

Does this make sense?  Because I’m just hypothesising here.