Term Kind Topic What it is
Ambassador Pattern pattern Sidecar & Ambassador A helper process that handles outbound network communication on behalf of an application, adding retries, routing, security and telemetry without changing it.
Anti-Corruption Layer ACL pattern Anti-Corruption Layer A translation boundary that keeps another system's model — usually a legacy or vendor one — from leaking into your domain.
API Gateway pattern API Gateway A single entry point that handles cross-cutting edge concerns — routing, authentication, rate limiting, TLS — so backend services do not each implement them.
Approximate-Then-Commit Stale Selection Exact Commitment, Two-Phase Precision pattern Materialized Views Selecting candidates from a deliberately stale projection and committing with a conditional write against the authoritative record - which buys cheap selection without sacrificing correctness at the moment it …
Architecture Sinkhole concept Layered Architecture A request that passes through every layer of a layered architecture without any layer adding logic, indicating that the layering is pure overhead for that path.
AWS: Shuffle Sharding Shuffle Sharding, Virtual Sharding case-study Cell-Based Architecture Assigning each customer a random subset of workers rather than a fixed shard, so that one abusive tenant affects almost nobody else.
Backend for Frontend BFF pattern Backend for Frontend A dedicated backend per client experience, owned by the team that owns that client, so each surface gets exactly the payload it needs.
Backend for Frontend BFF pattern Architecture Patterns A separate, narrow backend per client experience, which aggregates and reshapes downstream services for exactly that client's needs.
Broker and Mediator Topology pattern Event-Driven Architecture Two ways of organising an event-driven system — components reacting independently to a shared channel, or a central component coordinating a defined sequence.
Cell Cellular Architecture, Bulkhead Cell, Independent Stack pattern Cell-Based Architecture A complete, independent instance of a system serving a subset of customers, sharing no state with other cells - so that almost every class of failure is bounded to one cell's population rather than the whole u…
Cell Router Cell Mapping Layer, Partition Front Door pattern Cell-Based Architecture The thin shared component that maps a customer to their cell - the one part of a cell-based architecture that is not isolated, and therefore the part that must be simplest.
Cell-Based Architecture Cellular Architecture, Shuffle Sharding pattern Cell-Based Architecture Running many complete, independent copies of the stack, each serving a subset of users, so any failure is confined to one cell.
Choreography vs Orchestration concept Orchestration vs Choreography Whether a multi-service process is driven by a central coordinator or emerges from services reacting to each other's events.
Client-Specific Aggregation pattern Backend for Frontend A dedicated backend per client type that shapes and combines downstream data for that client's needs, owned by the client team.
Competing Consumers pattern Competing Consumers Multiple instances reading from the same queue, each taking different messages, so throughput scales by adding consumers.
Consumer Liveness Gap Zombie Consumer, Progress Blindness concept Competing Consumers The interval in which a queue consumer is alive by every health signal yet is making no progress, so its share of the work stalls while pool-level metrics stay normal.
Contract Event Designed Event vs Row Change, Deliberate Emission concept Outbox An event a system deliberately emits with a schema it owns and a meaning it controls, as opposed to a captured row change that exposes the producer's table structure as a public interface.
Control-Plane Push Amplification Config Fan-Out, xDS Amplification concept Service Mesh The property that one endpoint change can force a configuration push to every proxy in the fleet, making control-plane work scale with proxies multiplied by services rather than with either alone.
CQRS Command Query Responsibility Segregation pattern CQRS Separating the model that accepts writes from the model that serves reads, so each can be optimised independently — at the cost of the gap between them.
Durable Execution Workflow-as-Code, Replay-Based Workflows, Persistent Execution pattern Saga Running workflow code whose complete execution history is persisted, so a crashed process resumes by replaying that history rather than restarting - which makes process failure an implementation detail rather …
Edge Policy Ordering Gateway Filter Order, Admission Sequence practice API Gateway The sequence in which a gateway applies connection limits, authentication, quotas and validation, which decides whether a flood of unauthenticated traffic consumes your cheapest resource or your most expensive one.
Event Sourcing in Practice Event Store, Append-Only State pattern Event Sourcing Storing the sequence of changes rather than current state, the capabilities that follow, and the erasure problem that must be designed for on day one.
Event Stream Versioning pattern Event Sourcing Transforming an old event version into the current shape when it is read, allowing a stored event history to be interpreted by evolved code.
Event-Driven Architecture EDA pattern Event-Driven Architecture A style in which components communicate by publishing and reacting to facts, rather than by calling each other and waiting.
Event-Driven Architecture EDA pattern Architecture Patterns A style in which components communicate by emitting and reacting to facts about what happened, rather than by calling each other.
Fan-Out Delivery pattern Publish/Subscribe Delivering one published message to many independent subscribers, each with its own copy, position and failure handling.
Fan-out Threshold Celebrity Threshold, Hybrid Fan-out Switch practice Publish/Subscribe The membership or follower count at which a system switches from pushing to recipients to having recipients pull - and the monitoring that keeps the classification correct.
Filter Composability concept Pipes and Filters The property that makes a pipeline style work — each stage transforms input to output with no shared state, so stages can be reordered, reused and scaled independently.
Gateway Aggregation pattern API Gateway Combining several backend calls into one client-facing response at the gateway, reducing client round trips at the cost of coupling the gateway to backend structure.
Hexagonal Architecture Ports and Adapters pattern Architecture Patterns Putting the domain at the centre and letting everything external — UI, database, queues — attach through ports implemented by replaceable adapters.
Layer Enforcement Ratchet Violation Baseline, Architecture Debt Ratchet, Boundary Gate with Baseline practice Layered Architecture Gating a layering rule on a recorded baseline of existing violations that may shrink but never grow, so an architectural boundary becomes mechanical on a legacy codebase without a cleanup project first.
Layered Architecture N-Tier pattern Layered Architecture Organising a system into horizontal layers with a strict dependency direction — the default structure, valuable for its constraint rather than its shape.
Layered Architecture N-Tier pattern Architecture Patterns Organising code into horizontal layers — presentation, application, domain, data — where each layer may only call the one beneath it.
Legacy Side-Effect Inventory Trigger Inventory, Write Consequence Map practice Strangler Fig The enumerated list of triggers, stored procedures, scheduled jobs and integrations that fire as a consequence of a legacy write, which determines whether a capability can be moved incrementally at all.
Logical Shard Virtual Shard, Shard Slot pattern Sharding Patterns A unit of partitioned data that routing targets by name rather than by machine, so data can be moved between physical hosts without changing how anything is addressed.
Materialised View Pattern pattern Materialized Views Maintaining a pre-computed, query-shaped copy of data so reads are cheap, at the cost of write amplification and staleness.
Mesh Control Plane concept Service Mesh The component that configures and coordinates a service mesh's data plane proxies, distributing policy, identity and routing rules.
Model Translation Boundary pattern Anti-Corruption Layer The layer at which an external system's model is converted into your own, preventing its concepts and accidents from spreading into your domain.
Modular Monolith pattern Architecture Patterns A single deployable unit internally partitioned into modules with enforced boundaries, explicit interfaces and no shared internal state.
Outbox Relay pattern Outbox The process that reads pending messages from an outbox table and publishes them to a broker, providing at-least-once delivery with no distributed transaction.
Partition Assignment concept Competing Consumers The mapping of partitions to consumer instances that determines parallelism, ordering guarantees and what happens when the consumer set changes.
Pipes and Filters pattern Pipes and Filters Decomposing processing into independent stages connected by data channels, so each stage can be developed, tested, scaled and restarted alone.
Pipes and Filters pattern Architecture Patterns Decomposing processing into independent steps connected by channels, each transforming its input and passing it on.
Prime Video's Move Back to a Monolith Prime Video VQA Rearchitecture case-study Architecture Patterns Amazon Prime Video consolidated a serverless, distributed audio/video monitoring service into a single process and reported a 90% cost reduction — the most-cited example of microservices being the wrong tool.
Process Manager pattern Orchestration vs Choreography A component that owns the state and sequencing of a multi-step business process, deciding what happens next in response to events.
Process Ownership Gap Unowned Workflow, Orphaned Business Process concept Orchestration vs Choreography The condition in which every step of a multi-service process has an owning team but the process itself has none, so a stall produces no error, no deadline breach and no page.
Projection Rebuild Budget Read Model Rebuild Time, Rebuild Service Level Objective metric CQRS The measured wall-clock time to rebuild a read model from scratch, treated as a service level objective, because it bounds how quickly a projection defect can be corrected and therefore whether CQRS is reversi…
Publish-Subscribe Pub/Sub pattern Publish/Subscribe One publication delivered to many subscribers, with the publisher unaware of who they are — and the fan-out problem that comes with it.
Publish/Subscribe Pub/Sub pattern Architecture Patterns A messaging pattern where each published message is delivered to every interested subscriber, rather than to one competing worker.
Read Model Projection pattern CQRS A denormalised store built and maintained from write-side events specifically to serve one query shape efficiently.
Replay Determinism Projection Purity, Deterministic Fold concept Event Sourcing The property that folding an event log through a projection handler yields the same state every time it is run, which is what makes an event log rebuildable rather than merely stored.
Saga Compensation Design practice Saga Designing the undo actions for a distributed transaction, where compensation is a new business action rather than a rollback.
Saga Isolation Anomaly concept Saga The intermediate states visible to other transactions during a saga, because a saga provides atomicity and durability but not isolation.
Seam Identification practice Strangler Fig Locating the places in a legacy system where behaviour can be intercepted and redirected, which determines whether an incremental migration is feasible at all.
Selective Reliability Partial Reliability, Deadline-Aware Delivery concept Pipes and Filters Retransmitting only what is still useful and discarding what has expired - because for time-sensitive data, late delivery consumes capacity without providing value.
Semantic Coupling Meaning Drift, Invisible Event Coupling concept Publish/Subscribe Dependence on what an event or field means rather than on its shape - the coupling that survives every schema check, breaks nothing when violated, and is the hardest failure to detect in an event-driven system.
Service Mesh tool Service Mesh Moving connection-level concerns — discovery, retries, timeouts, mTLS, telemetry — out of application code and into a proxy alongside every service.
Service Mesh tool Architecture Patterns An infrastructure layer of sidecar proxies that handles service-to-service networking — mTLS, retries, timeouts, routing, telemetry — outside the application.
Shard Key Selection practice Sharding Patterns Choosing the attribute that determines a record's partition, which fixes the system's distribution, query patterns and future flexibility.
Sharding Patterns Horizontal Partitioning pattern Sharding Patterns Splitting data across independent stores by a key, and the choice of that key — which is the decision that will define the system for years.