Software architecture under change

The course, in order

Open a unit in the map to inspect its activities. Reading, guided completion, independent work and review remain distinct evidence.

1. Reject a stale entity transition at the fact owner

   Reject a stale entity transition at the authoritative fact owner before publishing derived views.

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2. Choose reads from the promised freshness scope

   Select a read path that satisfies the caller’s promised freshness scope rather than choosing by convenience.

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3. Give inventory one writer and a separate derived read path

   Give inventory changes one authoritative writer and keep derived read ownership separate.

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4. Publish a versioned domain fact without exposing its storage layout

   Publish a versioned domain fact whose public contract does not expose private storage representation.

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5. Move policy ownership while keeping a legacy transport adapter compatible

   Move domain policy ownership while retaining a compatible legacy transport boundary.

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6. Turn a quality claim into a measurable workload scenario

   Turn a qualitative requirement into a measurable workload, response and acceptance scenario.

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7. A decision record includes the rejected alternatives

   Record the chosen decision, rejected alternatives and consequences rather than preserving only the conclusion.

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8. Compensate an owned reservation without releasing another operation’s stock

   Compensate only the reservation still owned by the failed operation, retaining another accepted owner’s stock.

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9. Invert a storage dependency without moving domain policy into the adapter

   Invert a storage dependency without transferring domain policy into its implementation adapter.

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10. Give a renderer only the data and operations its task requires

    Give a renderer only the data and capabilities required by its current task.

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11. Keep publication intent and consumer acceptance with their own effects

    Keep publication intent and consumer acceptance in the durable boundary that owns their respective effects.

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12. Admit only work that fits both capacity and time

    Admit work only when both its capacity demand and deadline fit the declared budget.

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13. Reserve capacity for a lost node without exceeding the shared database pool

    Reserve capacity for a failed node without exceeding the database pool shared by surviving nodes.

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14. Contain a failing notification dependency within its reserved pool

    Contain a failing notification dependency within its reserved pool so unrelated work remains admissible.

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15. Move one live route without creating two writers

    Move a live route through one authoritative writer rather than temporarily creating two competing owners.

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16. Withdraw admission and verify a drain before releasing a measured bottleneck

    Withdraw new admission and verify the measured drain before releasing a bottleneck resource.

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17. Enforce a transitive policy boundary while reviewing a plausible module graph

    Enforce the transitive dependency policy instead of checking only the immediate module edges.

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18. Retire an old data representation only after compatible readers and references

    Retire an old representation only after compatible consumers and retained references no longer require it.

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19. Restore a failed authority before rebuilding its derived consumers

    Restore authoritative facts before rebuilding consumers whose state is derived from them.

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20. Resolve competing quality requirements with an explicit cost model

    Compare competing quality requirements with an explicit workload and cost model.

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