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Ameen Abozaid
Englishالعربية
ARC-034

Architecture deliverables

  • 6 Lessons
  • 4 h practice (estimate)
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On this page 9 topics

Overview

Topics

  • HLD
  • LLD
  • ADRs
  • interface contracts
  • deployment diagrams

Learn first

4 h of practice (estimate)

Learning outcomes

  1. Write a high-level design (HLD) that reviewers can approve and a low-level design (LLD) that teams can build from.
  2. Write ADRs for significant decisions.
  3. Specify interface contracts precisely enough for parallel delivery.
  4. Produce deployment diagrams that operations teams can use.

Lessons

  1. 01Deliverables and their readers
  2. 02The high-level design
  3. 03The low-level design
  4. 04Interface contracts and deployment diagrams
  5. 05Demo: writing Larkspur's HLD section by section
  6. 06Demo: turning an HLD component into an LLD a team can build

Lab and exercises

Lab

ARC-034-LAB1 · Larkspur HLD and LLD

Outcomes: 1–4 · Time: ~4 h

  1. Write the platform HLD: scope, constraints, context and container views, quality attribute targets, risks, and open questions.
  2. Write ADRs for the five biggest decisions, each with context, options, decision, and consequences.
  3. Write the LLD for order fulfillment: state model, sequence flows, failure cases, and non-functional specifics.
  4. Write interface contracts for the ERP order posting and the payment provider, with schemas, error codes, and versioning.
  5. Draw the deployment diagram with zones, environments, and the link to on-premises ERP.
  6. Hand the LLD to a role-played delivery lead and resolve every clarification asked.

Acceptance: a role-played delivery lead can estimate from the LLD without asking for clarifications on scope.

Exercises (case-based; six exercises)

IDOutcomeTask
ARC-034-EX011A 60-page Larkspur HLD contains table definitions and Spring configuration, and the board has not read it. Write a review note listing what to move out and what to keep.
ARC-034-EX021Take the LLD for "click and collect orders" and list ten failure and edge cases it must cover.
ARC-034-EX032Write an ADR for "use event notifications from the platform to ERP instead of nightly batch", with at least two rejected options.
ARC-034-EX042A team wrote its ADR three months after the decision. Explain the risks and set a rule for when ADRs are written.
ARC-034-EX053Write the contract for "post order to ERP": fields, required/optional, errors, idempotency, version policy, owner.
ARC-034-EX064Draw a deployment diagram for the Larkspur platform in two environments and list five facts operations needs that a logical diagram omits.
Show solutions
  • EX01 Keep purpose, context, decisions, quality targets, risks; move schemas and configuration to the LLD or repositories; link rather than embed; one-page summary on top.
  • EX02 Examples: stock changes between order and pick; store closed at pickup time; customer misses the pickup window; duplicate order submission; payment captured but ERP unreachable; partial pickup; ID check fails; item damaged at the store; carrier or store system timeout; refund after expiry.
  • EX03 Context: ERP outages blocked nightly batch and orders arrived late; options: nightly batch, event notifications, direct synchronous calls; decision: events with ERP adapter; consequences: needs replay, ordering rules, and monitoring.
  • EX04 Reasons are forgotten and the record is rewritten to look rational; rule: draft the ADR when the options are compared, mark it proposed, and accept it at decision time.
  • EX05 Operation POST orders with orderId and idempotency key required; lines, totals, tax required; errors for validation (400), duplicate (409 with original id), unavailable (503); versioned in the path or schema version header; owner named on both sides.
  • EX06 Zones, networks and ports, hostnames or services, failover and replica placement, backup targets, secrets location, and environment differences.

All four outcomes are also covered by the lab acceptance and the quiz.

Workplace evidence: an HLD or LLD you wrote that a team delivered from.

Quiz

Outcomes: O1 HLD and LLD · O2 ADRs · O3 interface contracts · O4 deployment diagrams.

A self-check for you: nothing is graded, saved or sent anywhere. Choose an answer, then check it. You can try again as often as you like.

  1. 1The primary reader of an HLD is:O1
  2. 2Which content belongs in an LLD rather than an HLD?O1
  3. 3A team estimates from an LLD and keeps asking what is in scope. The LLD most likely lacks:O1
  4. 4An ADR should be written:O2
  5. 5Which element is essential in an ADR?O2
  6. 6A contract precise enough for parallel delivery states:O3
  7. 7Why publish a contract as a machine-readable file?O3
  8. 8A deployment diagram that operations can use shows:O4
  9. 9Which is a common HLD mistake?O1
  10. 10Larkspur chose events over nightly batch for ERP posting. The ADR consequences should mention:O2

Practical part

Deliverable review against a checklist on the Larkspur lab: HLD without implementation detail, LLD with failure cases, five ADRs, two contracts, and a deployment diagram. Pass: quiz at least 8/10, at least five of six exercises correct, and a lab where the role-played delivery lead can estimate without scope clarifications.

Common mistakes

HLDs full of implementation detail; LLDs missing error and edge cases; ADRs written after the fact.

Assessment

Deliverable review against a checklist.

Workplace evidence

An HLD or LLD you wrote that a team delivered from.

Career relevance

Deliverables are how architects' decisions reach delivery teams.

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