Architecture Fundamentals
General material on what solution architecture is and what an architect is accountable for.
2 to work through
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intermediate
A team shows you a design with eight services. Without knowing the domain, what questions tell you whether the boundaries are right?
2 min answer -
intermediate
Instagram served 14 million users with three engineers on Django and Postgres. What does that tell you about how to choose an architecture for a new product?
2 min answer
16 terms in this topic
Abstraction
Exposing what a component does while hiding how it does it, so callers depend on the contract rather than the mechanism.
conceptArchitectural Driver
The small subset of requirements and constraints that actually shape the structure of the system.
practiceArchitecture Principle
A durable, agreed rule that constrains design decisions in advance, stated with its rationale and its implications.
conceptArchitecture Style
A named, coarse-grained way of organising a whole system, as distinct from a pattern that solves one recurring problem inside it.
conceptCohesion
The degree to which everything inside one component belongs together and changes for the same reason.
conceptConway's Law
Systems tend to mirror the communication structure of the organisation that builds them.
conceptCoupling
The degree to which one component must know about, or change alongside, another.
conceptEncapsulation
Keeping a component's state private, so it can only be changed through operations that maintain its invariants.
practiceEvolutionary Architecture
Designing for guided, incremental change rather than trying to get the structure right once, up front.
practiceFitness Function
An automated check that an architectural characteristic still holds, run continuously rather than reviewed occasionally.
case-studyInstagram's Early Scaling
Instagram reached tens of millions of users on Django and PostgreSQL with a handful of engineers, by deliberately choosing boring technology and doin…
conceptModularity
The degree to which a system is composed of parts that can be understood, changed and replaced independently.
conceptNon-Functional Requirement
A requirement about how well the system must behave rather than what it must do — latency, availability, throughput, security, cost.
practiceQuality Attribute Scenario
A structured, testable statement of a non-functional requirement: source, stimulus, environment, artefact, response, response measure.
conceptSeparation of Concerns
Organising a system so each part addresses one concern, and a change to that concern touches one part.
conceptSolution Architecture
The design of a specific system that satisfies a specific business problem under a specific set of constraints.
Neighbouring topics
Requirements to Constraints
Turning stated requirements into the constraints that actually bound a design.
No content yetFunctional vs Non-Functional
Behaviour versus quality of behaviour, and why only the second constrains structure.
No content yetArchitectural Drivers
The small subset of requirements whose change would force the structure to change.
No content yetQuality Attributes
Availability, latency, throughput, security, cost — expressed as testable scenarios.
No content yetArchitecture Principles
Durable agreed rules that rule options out, stated with rationale and implications.
No content yetCoupling
How much one component must know about, or change alongside, another.
No content yetCohesion
Whether the things inside a boundary belong together and change for the same reason.
No content yetModularity
Composing a system from parts that can be understood and replaced independently.
No content yetSeparation of Concerns
Organising so that a change to one concern touches one place.
No content yetAbstraction & Encapsulation
Hiding mechanism behind contract, and protecting invariants by owning state.
No content yetArchitecture Styles
System-level organising shapes, and how they differ from problem-level patterns.
No content yetEvolutionary Architecture
Designing for guided incremental change rather than for correctness on day one.
No content yetFitness Functions
Automated checks that an architectural characteristic still holds.
No content yetArchitecture Documentation
What to write down, at what altitude, and what nobody will ever read.
No content yetConway's Law
Systems mirroring the communication structure of the organisation that builds them.
No content yetTrade-off Fundamentals
Why every architecture is a set of purchases, and how to state what you gave up.
No content yetTechnical Constraints
Existing estate, skills, licences and platforms as inputs rather than obstacles.
No content yetArchitecture Roles
Solution, enterprise, domain and platform architecture, and where each is accountable.
No content yetReference Models
Shared conceptual frames — layering, tiers, viewpoints — and their limits.
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