Shared Library

A Shared Library is a versioned code package consumed by multiple applications or services. It is useful for stable, low-variability concerns such as protocol clients, data types, validation helpers, telemetry instrumentation, or security primitives.

Unlike a shared service, a shared library runs inside each consuming process. This avoids a network dependency but couples consumers to package versions, runtime compatibility, and release practices.

Use it when

• The capability is deterministic and does not need centralized state.
• Local execution is important for latency or availability.
• Consumers can upgrade independently.

Be cautious when

• Business rules change frequently across teams.
• Consumers need different behavior.
• A library would expose internal domain models.
• Coordinated upgrades would become mandatory.