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Jan Bosch is a research center director, professor, consultant and angel investor in startups. You can contact him at jan@janbosch.com.

21 June

In the early 2000s, I was one of those people preaching the importance of careful design and analysis of a system’s architecture before starting development. The belief was that especially non-functional requirements, such as performance and robustness, are hard to ‘bolt on’ to the system once development is underway. So, the software architecture community, including me, developed all kinds of tools and techniques to structure and provide systematic means to take architecture design decisions, assess the architecture’s ability to meet the non-functional requirements, such as performance and maintainability, and ensure the alignment between requirements and the architecture.

Although these techniques were and are extremely valuable, even today, there are several challenges with this view of the world. The first is that the original viewpoint is one where we start from a stable and complete set of requirements for the system. As pointed out when we discussed the first outdated belief, requirements are far from stable and tend to evolve at about 1 percent per month for most systems. That means that requirements form a moving target and can’t be used as a stable fundament for the development of a system.

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The second challenge is the assumption that we have a greenfield context and are starting from scratch. Although new systems are built from scratch, the vast majority of the development effort is on systems that have been around for a while. With the emergence of the minimal viable product (MVP) style thinking, we can see that the greenfield period for any new system is intentionally shortened to the minimally possible period.

The third challenge with the original view is that it assumes that we only need architecture work at the beginning of the project. Once the architecture is ‘done,’ we can move on to development and testing and no further architecture work is required. Anyone who has ever worked on a real-world system realizes how wrong that assumption is.

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Finally, the traditional way of thinking is that it’s all about the architecture and not about the architects. Although the architecture establishes the guidelines, structures and boundaries for the system, it’s the architects that define these and then evolve them over time. So, the architecture is only one of the relevant artifacts that we benefit from during development. It’s also about the underlying principles, the design decisions that led to the architecture, the connection to the business drivers, and so on.

Today, it’s clear that a system’s architecture evolves continuously, eg in response to new requirements, evolving technologies or changing user behavior. The architecture isn’t a static artifact, cast in stone, but rather a continuously evolving, organic entity that responds to the needs of the various stakeholders. It tends to evolve more slowly than the system’s features and functionality and as such provides structure, but it does need to evolve.

That brings us to the outdated belief that we’re discussing here. The architecture of a new system starts small, largely undefined and not well understood and covering only the needs of the MVP. If the MVP is successful and we want to grow it, then the architecture needs to evolve to meet requirements like scalability, performance and the system’s increased functionality needs. And often it needs to build integrations with other systems, demanding interfaces where we never expected to have these in the first place.

There are three principles that I believe are critical for working successfully with software architecture. First, it’s about architects, not architecture. The architecture is the constantly evolving artifact and any architecture documentation is like a milestone along the way: accurate when created but outdated when published. Much more important are the people driving this constant evolution, the architects. They need to bridge the link between business and technology.

Second, as I already alluded to several times in this post, architecture is continuously evolving in response to a constantly evolving and changing world. Rather than trying to resist and slow down the change, we should lean into the future and proactively evolve the architecture based on the needs we can see appearing. Our research shows no correlation between the age of an architecture and the need for technical debt management. Hence, we need to start evolving the architecture from the start.

Third, most professionals don’t realize this, but architecture is the incarnation of the future business strategy. In virtually all situations, the pace at which the architecture can change and evolve is very slow. That means that the architecture design decisions made today make certain business strategies very easy to realize in one or a few years, and others prohibitively expensive. Therefore, the architecture evolution initiated today defines the range of realistic business strategies down the line. In practice, it’s not the business leaders but rather the architects who determine business strategy.

Software architecture isn’t a one-time effort where we pour the concrete for the foundation of the system to never change it again. Instead, it’s a constantly evolving artifact that happens to evolve more slowly than the features and functionality in the system. Consequently, it’s about doing just enough architecture work at the start of a new system to get the MVP in place and then growing the architecture with the system in response to the needs of the business supported by the architecture. We need to welcome change and lean into the future as not doing so will cause the system to become outdated and irrelevant. And writing off many person-years of effort and losing vast amounts of codified domain knowledge is wasteful in ways that few things are. And who wants that?