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Road-movie architectures

Road-movie architectures

This slide deck is about one of the drivers of accidental complexity in IT, I often see: The current target architecture of a company, often embedded in big technical transformation initiatives with the goal to "get rid of the existing mess for good" and eventually result in a nice, superior, homogeneous system landscape.

While the idea sounds nice in theory, in practice these initiatives are never completed, but are being replaced by a new target architecture, piling up more and more complexity.

Hence I continue, the better approach is to accept that our system landscapes will always be heterogeneous to a certain degree and design systems that do not only work nicely with other systems of the same kind, but with all kinds of systems that are there.

Then I present a few desirable properties of such systems and some ideas how to implement them. The list is not complete by any means, but is meant as a starting point for further discussion.

As always, the voice track is missing (but I hope a recording of this talk will be published soon). Still, I hope it gives you a few ideas to ponder and maybe even some new ideas that you want to share with the community.

Uwe Friedrichsen

November 01, 2022

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  1. Current target architecture • Many companies have a target architecture

    • Either implicit or explicit • Default for all new development projects • Usually strongly influenced by current fashions • Usually targets an ideal “end state” • Will unfold full benefits after entire conversion of IT landscape • Often accompanied by big transformation initiatives
  2. Reality check • Target architectures change over time • Transformation

    initiatives are never completed • IT landscapes never become fully homogeneous • Promised benefits of ideal “end state” never fully unfold • Deviations from the target architecture are the norm • The Pareto principle (80/20 rule) strikes surprisingly often • Silent deviations often go undetected for a long time
  3. The complexity trap • Aiming for an ideal “end state”

    increases complexity • Layers of incomplete implementations add to IT landscape • Different target architectures usually do not play well with each other • IT landscape complexity grows disproportionally • Everything and everyone suffers • Understandability, reliability, maintainability, evolvability, … • Growing headaches for the people involved
  4. “We know our current landscape is a mess. But with

    this new initiative, we will clean it up for good.”
  5. Or the new fashion appears to be so much better

    that we push for a new target architecture
  6. We need to accept that eventually reaching an “end state”

    when the whole IT landscape homogeneously conforms to a given target architecture is an illusion
  7. We need to take the diversity of our IT system

    landscape into account when designing solutions
  8. We need to design our solutions in a way they

    become "good citizens" of a heterogeneous system landscape
  9. Desirable solution properties • Collaborative and inclusive • Simple to

    interact with (from the perspective of other systems) • Traveling light • Simple to be removed (from the IT system landscape) • Topical and flexible • Keeping its value, aging slowly
  10. Collaborative and inclusive • Simple to be used by other

    systems • Integration first system design Benchmark Ø The application can be used from another application in less than a day
  11. Traveling light • Simple to be removed from the IT

    system landscape • Construction for deconstruction (C4D) Benchmark Ø The application can be shut down and removed within 1 day while keeping the remaining system landscape intact
  12. Topical and flexible • Maintaining its business value over time

    • Preserving its changeability and evolvability Benchmark Ø The application can still be evolved easily after 20 years, i.e., changes do not take longer and are not riskier than a year after the application's first release
  13. Collaborative and inclusive • Minimal, well-documented APIs • Not only

    API reference but also concepts, tutorials, how-to, … • Keep need for synchronous responses low • At the functional level, not necessarily at the technical level • Offer fallback integrations that older systems can also use • Not all systems talk REST, GraphQL, Events, gRPC or alike
  14. Traveling light (1/2) • Plan the systems with its removal

    in mind • Work hard for good functional design with low coupling • Make global dependencies explicit and keep them minimal • Keep APIs minimal (and design them usage-driven) • Think in flows (behavior and data), not state and entities
  15. Traveling light (2/2) • Document well what the system does

    (but keep it concise) • Document how to shutdown and remove the system • Plan how to remove data that is used locally only • Consider stepwise shutdown • Reserve time to continually simplify your landscape
  16. Topical and flexible (1/2) • Understand the domain • Follow

    the “low coupling, high cohesion” principle inside the application/service, too • Create dependable and secure systems • Create the simplest solution possible without compromising dependability
  17. Topical and flexible (2/2) • Document your system for those

    who will follow • High-level functional structure • Architectural style • Core principles and idioms • (Non-obvious) design decisions • Avoid fashions – use boring technology instead • Manage technical debt – and throw things away!
  18. Additional considerations • Observe system obsolescence • Watch functional fitness

    and ease of evolvability • Monitor tool chain dependencies • Limit access to (out)dated systems • Makes removal simpler • Many solution options rooted in organization and processes • Money is not the constraint
  19. Summing up • Ideal “end state” of a target architecture

    is an illusion • Aiming for a homogeneous “end state” increases complexity • Accept heterogeneity in your system landscape • Take diversity into account when designing solutions • Design road movie architectures • Collaborative and inclusive • Traveling light • Topical and flexible