Middleware and integration engineering

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. Apply the declared decoder and extension-field policy

   Decode only a supported message envelope and apply its declared extension-field policy before downstream work.

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2. Preserve machine-readable failure identity through two services

   Preserve the public machine-readable failure identity across service hops without exporting private details.

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3. Preserve entity revision order across a partitioned stream

   Choose partition ownership that preserves each entity’s revision order across the delivered stream.

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4. Extend visibility only for the delivery lease still owned

   Extend visibility only for the delivery lease currently owned, rejecting a replaced consumer’s token.

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5. Apply a rate bucket to the real caller rather than a forged header

   Apply rate policy to the actual authenticated caller rather than a caller-supplied identity header.

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6. Reject an oversized request before copying it through the chain

   Reject an oversized request before copying its body through the middleware chain.

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7. Hold an out-of-order revision until its predecessor is accepted

   Hold a bounded out-of-order revision until its required predecessor has actually been accepted.

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8. Trust forwarded caller fields only from the configured ingress

   Trust forwarded caller fields only when the actual peer is the configured ingress authority.

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9. Wrap downstream failure without swallowing owned cancellation

   Wrap a downstream failure without swallowing cancellation that still belongs to the caller.

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10. Bound acquired deliveries before they overload worker memory

    Limit acquired deliveries according to downstream capacity instead of growing an unbounded worker backlog.

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11. Retry only a route whose operation contract permits replay

    Retry only routes whose effect contract permits replay and reconcile uncertain non-repeatable effects.

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12. Build a replay-safe versioned transport adapter

    Execute the versioned transport adapter against durable identity, projection and cursor boundaries.

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13. Reject a changed command borrowing an accepted operation key

    Reject a changed command reusing an accepted scoped operation identity rather than applying it as new work.

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14. Retire sent intents without forgetting still-legal replays

    Retire publication intents only while retaining the acceptance evidence required by still-legal replays.

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15. Keep operation acceptance for every still-permitted retry

    Keep operation acceptance for the entire promised retry horizon instead of expiring its effect identity early.

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16. Expire unused capacity without releasing fulfilled ownership

    Expire only tentative capacity and preserve ownership already transferred to a fulfilled order.

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17. Restore the caller context after an interleaved asynchronous child

    Restore the caller’s logical context after nested work instead of retaining another operation’s context.

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18. Propagate approved bounded context without exporting caller secrets

    Propagate only allowlisted bounded context fields and exclude caller secrets from diagnostic transport.

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19. Alert on poison growth without confusing it with transient retries

    Alert on quarantine growth independently of transient retry backlog and preserve identity for a verified redrive.

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20. Measure overlapping attempts without inflating logical operation time

    Measure logical elapsed latency separately from aggregate and overlapping attempt work.

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