Layerbacked

Layerbacked is a software design approach in which a data-access or storage system is built as a stack of layered backends that collectively provide a single unified interface. Each layer exposes a narrow, well-defined contract and can implement functions such as caching, persistence, indexing, or data transformation. The layers are arranged so that higher layers depend on lower ones while remaining independently replaceable.

Common arrangement includes an in-memory cache layer, a local durable storage layer, and one or more remote or distributed backends. An orchestration layer coordinates requests, routes reads to the most appropriate layer, and ensures consistency policies between layers. Implementations often support pluggable backends and configurable fallbacks.

Data flow: a read might check the cache, then the local store, then a remote service; a write may be propagated through the chain with caching or event-driven invalidation. Consistency models vary, from eventual to strong, depending on the layering and coordination between backends.

Advantages include modularity, easier experimentation with different storage technologies, improved performance via caching, and resilience through layering. Drawbacks include added complexity, potential latency due to multiple lookups, and the need for careful cache-coherence and failure handling.

Layerbacked concepts appear in distributed databases, content delivery networks, and offline-first applications where different storage tiers and services must interoperate under a unified interface. The term Layerbacked is used in some design discussions to describe this layering approach, though specific implementations differ across projects.

Relation to other concepts: it relates to layered architecture, tiered storage, and cache-aside patterns, but emphasizes end-to-end orchestration of multiple backends as a single logical repository.