Portfolio ↗

Terminology

2185 terms, tools, patterns and metrics an architect is expected to use precisely. Each one gets a short explanation of what it is, and — where it matters — what it is commonly confused with. Search filters as you type; the column headers sort.

All areas2185 Architecture Fundamentals77 Distributed Systems107 Data Architecture110 Cloud Architecture89 Networking88 API & Integration Architecture82 Reliability & Resilience75 Observability70 Performance & Capacity Engineering72 Security Architecture81 Cost Architecture & FinOps66 Business Architecture67 Architecture Communication67 Enterprise Architecture66 Legacy Modernization66 AI-Era Architecture69 Software Architecture & Engineering71 Architecture Patterns71 Architecture Decision-Making63 The Architect's Meta-Skills61 Delivery & Release Engineering66 Platform Engineering & Developer Experience70 Testing & Quality Architecture66 Data Platform Architecture64 Streaming & Real-Time Data69 Data Governance & Semantics69 Frontend & Experience Architecture66 Edge, Mobile & IoT68 Regulatory & Data Protection Architecture65 Assurance, Audit & Model Risk64
Kind Any concept785 practice729 pattern362 metric125 case-study77 tool62 protocol45

66 terms shown.

Term Kind Topic What it is
Airbnb's Service-Oriented Migration case-study Legacy Modernization Airbnb decomposed a large Rails monolith by first extracting a unified data-access layer, so that services were built on owned data rather than on shared database tables.
Airbnb: Monorail to Service-Oriented Architecture Airbnb SOA Migration case-study Application Decomposition Airbnb decomposed a large Rails monolith into services, and the difficult part was data ownership rather than code extraction.
Anti-Corruption Layer ACL pattern Legacy Modernization A translation layer that converts a legacy or external system's model into your own, so its concepts do not leak into your domain.
Anti-Corruption Layer in Integration pattern Legacy Integration Patterns A translation boundary that keeps a legacy system's model, vocabulary and quirks from leaking into a new system that must integrate with it.
Application Decomposition practice Application Decomposition Breaking a large application into parts — where finding the seam matters more than the extraction technique.
Archive-and-Shutdown Data-Preserving Decommission, Retire With Retention, Cold Archive Retirement pattern Decommissioning Retiring an application by exporting its data to durable archival storage in a readable format and shutting the application down - separating the obligation to keep data from the obligation to keep software running.
Business-Cycle Observation Window Full-Cycle Shutdown Soak, Longest-Period Consumer Watch practice Decommissioning Setting the period over which you watch for remaining consumers from the system's longest business cycle rather than from a round number of days, because a 30-day watch cannot see an annual job.
Characterisation Test Golden Master Test, Approval Test, Behaviour Snapshot practice Application Decomposition A test that records what a system currently does - bugs included - rather than what it should do, providing the safety net that makes changing an untested legacy system possible at all.
Coexistence Period concept Coexistence Patterns The interval during which old and new systems both operate and must be kept consistent, which is longer, more expensive and riskier than most plans assume.
Cutover Planning practice Cutover Planning The plan for the moment of switching — including the decision points, the rollback, and the rehearsal that makes it survivable.
Cutover Runbook practice Cutover Planning The step-by-step plan for a migration event, including verification points, decision criteria and the rollback path, rehearsed before it is used.
Data Migration Strategies practice Data Migration Strategies Moving data between systems with different models — where the difficulty is meaning and quality rather than transfer.
Database Migration practice Database Migration Moving data from one store to another while the system keeps running — where verification and reversibility matter more than the copy itself.
Database Migration Strategy practice Database Migration The approach for moving data to a new store, which is usually the longest pole and the highest risk in any modernisation.
Decommissioning practice Decommissioning Actually switching off and removing a replaced system, which is where the savings in every modernisation business case live.
Decommissioning Discipline practice Decommissioning The work of actually switching a legacy system off, which is where migration savings are realised and which is routinely left undone.
Decomposition by Capability practice Application Decomposition Breaking a monolithic system into parts along business capability lines rather than technical layers, so that each part changes for one reason.
Disposition Decision practice The Six Rs Choosing one of the standard migration treatments for each application, on the basis of its value, condition and the constraint that is actually binding.
Dual Write pattern Data Migration Strategies Writing the same change to both the old and new stores during a migration, and the reconciliation that makes it trustworthy.
eBay's Architectural Generations case-study Legacy Modernization eBay rewrote its core platform several times across its first decade, each time because the previous generation had hit a limit that could not be tuned away.
Expand-Contract Migration Parallel Change, Add-Migrate-Remove, N-1 Compatibility pattern Zero-Downtime Migration Making a breaking change as a sequence of individually reversible steps - add the new alongside the old, migrate readers and writers across, then remove the old - so that at no point is a rollback destructive.
Explained-Difference Criterion Shadow Exit Criterion, Zero Unexplained Differences practice Parallel Run Ending a shadow or parallel run when every observed difference has been explained, rather than when differences reach zero - because zero is unachievable and unexplained differences are by definition the dange…
Feature Parity Trap concept Rebuild vs Re-architect The expectation that a replacement system must match every behaviour of the old one before it can be adopted, which is what makes rewrites never finish.
Greenfield Velocity Illusion Rewrite Head Start, Front-Loaded Rewrite Progress concept Rebuild vs Re-architect The early speed advantage a from-scratch rebuild shows because it is running with all the real constraints switched off, which makes its estimate systematically wrong in the same direction every time.
Legacy Assessment practice Legacy Assessment Establishing what a legacy system actually does, what depends on it, and what it costs, before deciding what to do with it.
Legacy Headroom Budget Legacy Capacity Allocation, Integration Throughput Quota practice Legacy Integration Patterns The measured spare throughput of a legacy system after retry amplification, batch overlap and organic growth are deducted, allocated to new consumers as enforced quotas rather than published as available capacity.
Legacy System Assessment practice Legacy Assessment A structured evaluation of a system's business value, technical condition and risk, used to decide what to do with it rather than to describe it.
Legacy Wrapping pattern Legacy Integration Patterns Placing a modern interface in front of a legacy system so that consumers integrate with the wrapper rather than with the legacy system directly.
Lift and Shift pattern Rehosting Moving an application to new infrastructure with minimal change, trading optimisation for speed and low migration risk.
Mainframe Modernisation practice Mainframe Modernization Replacing or reducing dependence on a core system that is reliable, undocumented, and central to the business.
Mainframe Offload pattern Mainframe Modernization Moving read traffic and selected processing off a mainframe onto modern platforms, reducing cost and unblocking new development without replacing the core.
Managed Service Substitution pattern Replatforming Replacing a self-managed component with a managed equivalent during migration, without changing the application's architecture.
Managed Service Upgrade Calendar Provider Support Lifecycle Exposure, Vendor Upgrade Clock concept Replatforming The obligation, transferred to the provider at replatform time, to upgrade before a published end-of-standard-support date, which converts an indefinitely deferrable version upgrade into a dated one the team d…
Migration Risk practice Migration Risk The specific risks migrations carry, and the controls that reduce each — with reversibility as the master control.
Migration Risk Register practice Migration Risk A maintained record of what could go wrong in a migration, with likelihood, impact, owner and mitigation, reviewed as the programme progresses.
Modernisation Business Case practice Modernisation Business Case Justifying modernisation work, where the benefits are diffuse, the costs are concrete, and "it is old" persuades nobody.
Modernisation Value Case practice Modernisation Business Case The argument that funds a modernisation programme, built on quantified business consequence rather than on technical obsolescence.
Move Group Migration Affinity Group, Move Wave Affinity Set practice Rehosting The set of workloads that must cross to the new infrastructure in the same wave because the round trips between them sit on a user-facing critical path, derived from observed network flows rather than from the…
Offload Freshness Contract As-At Read Contract, Published Staleness Budget pattern Mainframe Modernization An explicit published staleness budget for a read copy that serves traffic taken off a core system, enforced by the copy itself, so that silently stale answers become visible failures rather than wrong decisions.
Ownership-First Decomposition Assign Owners Before Splitting, Logical Before Physical practice Database Migration Assigning each table a single owning team before splitting any code or data, because the ownership step costs nothing, removes the worst of the coupling immediately, and makes every subsequent step tractable.
Parallel Run practice Parallel Run Operating the old and new systems simultaneously on the same inputs and comparing outputs, to build evidence that the replacement is correct before relying on it.
Point of No Return Rollback Horizon, Commit Point practice Cutover Planning The step in a migration after which rollback would lose data or state - identified in advance, with a named authoriser and a stated recovery plan beyond it.
Progressive Shutdown Graceful Decommissioning, Staged Retirement practice Decommissioning Retiring a system through reversible stages - read-only, then blocked, then stopped, then removed - so each stage surfaces remaining consumers safely instead of breaking them.
Re-architect vs Rebuild concept Legacy Modernization Restructuring an existing system incrementally versus writing a replacement from scratch — and the strong evidence that incremental wins.
Read-First Extraction Reads Before Writes, Reversible Extraction Order pattern Strangler Fig Extracting a service's read path before its write path, because a wrong read migration is a flag flip while a wrong write migration is a data reconciliation exercise.
Rearchitecture Threshold concept Refactoring & Re-architecting The conditions under which rebuilding a system is justified, given that it is the most expensive treatment and is chosen far more often than it is warranted.
Refactor and Re-architect practice Refactoring & Re-architecting Changing the application's structure — the most expensive migration strategy, justified only where the structure itself is the constraint.
Reference Data Drift Code List Divergence, Static Data Staleness concept Data Migration Strategies The divergence between a source system's lookup tables and the copy taken at the start of a long migration, which turns into silent transaction rejections in the new system months later.
Rehost Lift and Shift practice Rehosting Moving a workload to new infrastructure with no change to the application — fastest, cheapest to execute, and the source of the bill that discredits migrations.
Replatform practice Replatforming Moving a workload with targeted changes that capture most of the platform's benefit without redesigning the application.
Repurchase Displacement Cost Buy-Instead-Of-Build Migration Load, SaaS Substitution Overhead concept The Six Rs The data migration, process change, integration rebuild and customisation retirement that replacing a bespoke application with a purchased product creates, none of which appears in the licence comparison that …
Retire-First Portfolio Bias Cheapest Sufficient Option, Retire and Retain Default practice The Six Rs Assigning every application the cheapest modernisation option that satisfies the business driver, with a written justification required for anything more - which resolves most portfolios into retire and retain…
Reverse Replication Cutover Backflow Replication, Bidirectional Cutover Window, Rollback Stream pattern Coexistence Patterns Keeping a replication stream flowing from the new store back to the old one after writes have moved, so that rolling back stays a routing change instead of a restore from backup.
Shadow Comparison pattern Parallel Run Running a new implementation alongside the old on real traffic, comparing outputs without the new system affecting users.
Six Rs Decision Migration Disposition practice The Six Rs Classifying each application into rehost, replatform, refactor, repurchase, retire or retain, based on value and effort rather than on preference.
Six Rs of Migration 6 Rs, Migration Strategies concept Legacy Modernization The standard menu of options for each application in a migration — rehost, replatform, refactor, repurchase, retire, retain.
Southwest 2022: Legacy Software Meeting Its Design Limits Southwest Airlines Meltdown case-study Modernisation Business Case A crew scheduling system that worked adequately for routine disruption could not cope with a large-scale one, and the airline cancelled roughly 16,700 flights.
Strangler Facade pattern Strangler Fig The routing layer in front of a legacy system that decides, per capability, whether a request goes to the old implementation or the new one.
Strangler Fig Execution pattern Strangler Fig Incrementally replacing a legacy system by routing slices of functionality to new implementations behind a facade, until nothing routes to the original.
Traffic Shadowing Dark Traffic, Mirroring, Shadow Testing pattern Parallel Run Sending a copy of real production traffic to a new implementation while the existing one continues to serve users, comparing results without exposing anyone to the new system's mistakes.