Architecture Technical Debt: The Curse of Agile?

Architecture Technical Debt: The Curse of Agile?

Nowhere is the poor architect?s quest for respect more difficult than on Agile development teams. Even when Agilists admit the need for architecture, they begrudgingly call for the bare minimum necessary to get the job done ? what they often call the minimum viable architecture. The last thing they want are ivory tower architects, churning out reams of design artifacts for elaborate software castles in the sky, when the poor Agile team simply wants to get working software out the door quickly.

My counterpart in Agile Architecture punditry, Charlie Bess of HP, said as much in his recent column for CIO Magazine ominously entitled Is there a need for agile architecture? His conclusion: create only an architecture that is ?good enough – don?t let the perfect architecture stand in the way of one that is good enough for today.?

Bess isn?t alone in this conclusion (in fact, he based it on conversations with many Agilists). But any developer who?s been around the block a few times will recognize the ?good enough? mantra as a call to incur technical debt ? which may or may not be a good thing, depending upon your perspective. Let?s dive into the details and see if we?re asking for trouble here, and if so, how do we get out of it.

Technical debt refers to making short-term software design compromises in the current iteration for the sake of expedience or cost savings, even though somebody will have to fix the resulting code sometime in the future. However, there?s actually two kinds of technical debt (or perhaps real vs. fake technical debt, depending on who?s talking). The ?fake? or ?type 1? technical debt essentially refers to sloppy design and bad coding. Yes, in many cases bad code is cheaper and faster to produce than good code, and yes, somebody will probably have to clean up the mess later. But generally speaking, the cost of cleaning up bad code outweighs any short-term benefits of slinging it in the first place ? so this sloppy type of technical debt is almost always frowned upon.

In contrast, type 2 (or ?real?) technical debt refers to intentionally designed shortcuts that lead to working code short-term, but will require refactoring in a future iteration. The early code isn?t sloppy as in type 1, but rather has an intentional lack of functionality or an intentional design simplification in order to achieve the goals of the current iteration in such a way that facilitates future refactoring. The key point here is that well-planned type 2 technical debt is a good thing, and in fact, is an essential part of proper Agile software design.

The core technical debt challenges for Agile teams, therefore, are making sure (a) any technical debt is type 2 (no excuses for bad code!) and (b) that the technical debt incurred is well-planned. So, what does it mean for technical debt to be well-planned? Let?s take a look at the origin of the ?debt? metaphor. Sometimes borrowing money is a good thing. If you want to buy a house, taking out a 30-year mortgage at 4% is likely a good idea. Your monthly payments should be manageable, your interest may be tax deductible, and if you?re lucky, the house will go up in value. Such debt is well-planned. Let?s say instead your loser of a brother buys a house, but borrows the money from a loan shark at 10% per week. The penalty for late payment? Broken legs. We can all agree your brother didn?t plan his debt very well.

Just so with technical debt. Over time the issues that result from code shortcuts start to compound, just as interest does ? and the refactoring effort required to address those issues is always more than it would have taken to create the code ?right? in the first place. But I put ?right? in quotes because the notion that you can fully and completely gather and understand the requirements for a software project before you begin coding, and thus code it ?right? the first time is the fallacy of the waterfall approach that Agile was invented to solve. In other words, we don?t want to make the mistake of assuming the code can be complete and shortcut-free in early iterations, so we must plan carefully for technical debt in order to deliver better software overall ? a fundamental Agile principle.

So, where does this discussion leave Bess?s exhortation that you should only create architecture that is just good enough? The problem: ?just good enough? architecture is sloppy architecture. It?s inherently and intentionally short-sighted, which means that we?re avoiding any planning of architectural debt because we erroneously think that makes us ?Agile.? But in reality, the planning part of ?well-planned technical debt? is a part of your architecture that goes beyond ?just good enough,? and leaving it out actually makes us less Agile.

Bloomberg Agile Architecture? (BAA) has a straightforward answer to this problem, as core Agile Architecture activities happen at the ?meta? level, above the software architecture level. By meta we mean the concept applied to itself, like processes for creating processes, methodologies for creating methodologies, and in this case, an architecture for creating architectures ? what we call a meta-architecture. When we work at the meta level, we?re not thinking about the things themselves ? we?re thinking about how those things change. The fundamental reason to work at the meta level is to deal with change directly as part of the architecture.

In order to adequately plan for architecture technical debt on an Agile development project, then, we must create a meta-architecture that outlines the various phases our architecture must go through as we work our way through the various iterations of our project. The first iteration?s architecture can thus be ?just enough? for that iteration, but doesn?t stand alone as the architecture for the entire project, as the meta-architecture provides sufficient design parameters for iterative improvements to the architecture.

However, it?s easier said than done to get this meta-architecture right. In fact, there are two primary pitfalls here that Agilists are likely to fall into. First, they may incorrectly assume the meta-architecture is really just a part of the architecture and thus conclude that any effort put into the meta-architecture should be avoided, as it would be more than ?just enough? and would thus constitute an example of overdesign. The second pitfall is to assume the activities that go into creating the meta-architecture are similar to the activities that go into creating the architecture, thus confusing the two ? which can lead to architecture masquerading as meta-architecture, which would actually be an instance of overdesign in reality.

In fact, working at the meta-architecture level represents a different set of tasks and challenges from software architecture, and the best choice for who should create the meta-architecture might be different people from the architects responsible for the architecture. These ?meta-architects? must focus on how the stakeholders will require the software to change over time, and how to best support that change by evolving the architecture that drives the design of the software (learn to be a meta-architect in my BAA Certification course).

Such considerations, in fact, go beyond software architecture altogether, and are closer to Enterprise Architecture. In essence, when I talk about Bloomberg Agile Architecture, I?m actually talking about meta-architecture, as the point to BAA is to architect for business agility. Building software following Agile methods isn’t enough. You must also implement architecture that is inherently Agile, and for that, you need meta-architecture.


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