Xulq

Xulq is an open standard that combines a data interchange format with a declarative query language, intended for use across distributed systems including microservices, edge devices, and cloud platforms. It aims to provide compact encoding, self-describing schemas, and deterministic semantics to facilitate offline operation, streaming, and schema evolution without breaking compatibility.

The data model of Xulq is a typed, graph-friendly structure consisting of primitives, maps, lists, and references. Data is serialized in a compact binary or text form, selectable by the encoder at runtime. Schemas describe allowed fields, types, and constraints, enabling validation and self-documentation. Extensions allow metadata, versioning, and provenance to be attached to data items while preserving interoperability.

Xulq includes XQL, a query language that supports filtering, projection, joins across datasets, and lightweight aggregations. XQL queries can be embedded in data streams or executed on demand by services equipped with an Xulq runtime. The language emphasizes declarative semantics and predictable performance, with execution plans that can be cached or pushed to edge nodes.

Development of Xulq began in the mid-2010s under the Xulq Foundation, with input from academia and industry contributors. The specification is maintained as an open standard with community-driven proposals for extensions and interoperability profiles.

Adoption has been limited to niche domains requiring strict schema evolution and offline capabilities, such as edge analytics and IoT platforms. Critics note the added complexity relative to JSON or Protobuf in simple use cases, and emphasize the need for mature tooling and runtime support.