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Shared Kernel Pattern

Shared Kernel Pattern governs shared model subset, shaping system behavior under specific failure modes and workloads.

architecture

Definition

Shared Kernel Pattern is a design property concerning shared model subset. It defines how the system behaves under specific conditions — what guarantees hold, what trade-offs apply, and how the mechanism interacts with related techniques. The property is only meaningful when its preconditions are met; outside those conditions it provides no benefit and may add cost.

Context and scope

Apply Shared Kernel Pattern when designing systems where shared model subset matters. It is most useful under partial failure, high load, or correctness requirements. Pair it with observability to verify the claimed behavior in production. Do not assume the property holds without testing the specific configuration and workload.

Common misconceptions

  • Shared Kernel Pattern eliminates all problems in its domain — it only bounds or shapes specific failure modes, not all pathologies.
  • Shared Kernel Pattern is free once you adopt the right tool — the property depends on configuration, workload, and failure pattern, not the product label alone.

Anti-patterns

  • Enabling Shared Kernel Pattern without measuring its cost in latency, availability, or operational complexity under production-like conditions.
  • Assuming Shared Kernel Pattern composes safely with other guarantees — combining mechanisms can introduce new failure modes or negate benefits.

Related concepts

Authoritative source

https://martinfowler.com/architecture/

What it is

Shared Kernel Pattern is a design property concerning shared model subset. It defines how the system behaves under specific conditions — what guarantees hold, what trade-offs apply, and how the mechanism interacts with related techniques. The property is only meaningful when its preconditions are met; outside those conditions it provides no benefit and may add cost.

When to use

Apply Shared Kernel Pattern when designing systems where shared model subset matters. It is most useful under partial failure, high load, or correctness requirements. Pair it with observability to verify the claimed behavior in production. Do not assume the property holds without testing the specific configuration and workload.

Common misconceptions

  • Shared Kernel Pattern eliminates all problems in its domain — it only bounds or shapes specific failure modes, not all pathologies.
  • Shared Kernel Pattern is free once you adopt the right tool — the property depends on configuration, workload, and failure pattern, not the product label alone.

Anti-patterns to avoid

  • Enabling Shared Kernel Pattern without measuring its cost in latency, availability, or operational complexity under production-like conditions.
  • Assuming Shared Kernel Pattern composes safely with other guarantees — combining mechanisms can introduce new failure modes or negate benefits.
  • Bounded Context (bounded-context)
  • Domain-Driven Design (domain-driven-design)