Lainspec

Lainspec is a declarative specification language designed to describe data models and service interfaces in distributed systems. It aims to provide a language-agnostic contract that can be validated at runtime and used to generate client and server code across programming languages.

It originated from the Lainspec Initiative, a community project launched in the late 2010s to improve interoperability between APIs and data pipelines. An initial draft appeared in 2019 and several reference implementations followed in subsequent years.

Design and features: Lainspec defines modules, types, and interfaces. Its type system includes primitives, records, unions, and recursive definitions. Modules can be composed, versioned, exported, and imported, enabling reusable contracts. A built-in validator and a code-generator produce stubs for multiple languages and runtime adapters. The specification also supports deprecation markers and backward-compatibility policies.

Syntax and tooling: The syntax is human-readable, YAML-inspired, with a formal grammar for parsing. Tooling includes a compiler, a linter, and integrations for popular IDEs. There are reference implementations and a central registry for reusable modules, along with security features such as signature verification of modules.

Usage and reception: Lainspec has seen adoption in mid-sized organizations for API contracts and data-pipeline configurations. Support is pragmatic but uneven; advocates point to reduced boilerplate and cross-language consistency, while critics note the learning curve and ecosystem fragmentation.

See also: API specification languages, OpenAPI, JSON Schema, Protocol Buffers, Thrift, Interface Definition Language.