xsID

xsID is a term used in software engineering to describe a cross-system identifier, a value designed to uniquely identify an entity across multiple services, databases, and domains. The concept aims to support reference consistency and interoperability by decoupling an external identity from any single internal primary key.

There is no single universal standard named xsID; instead, various projects and vendors use xsID to denote their own cross-system identifier schemes. In practice, xsID implementations emphasize portability and stability across system boundaries, enabling references to persist even as internal data models evolve.

Common design characteristics include a namespace component to avoid collisions, a locally assigned identifier, and an integrity or authenticity layer such as signing or hashing to prevent tampering. Formats vary but typical patterns include namespace:localId or urn-like strings, with some implementations using URL-safe tokens for easy embedding in APIs and logs.

Usage scenarios for xsID include cross-system references in distributed architectures, federated identity and authorization, event logging and auditing, and durable links in data pipelines. Advantages of xsID concepts include reduced coupling to internal schemas, improved ability to merge data from diverse sources, and more stable references for long‑lived data.

Challenges and considerations involve privacy and exposure risks, key management for any signing or hashing, revocation and versioning of identifiers, and governance of naming namespaces. Effective implementations require clear naming discipline, namespace governance, and compatibility with existing identifier schemes such as UUIDs and URNs, along with attention to security and lifecycle management.

Related topics include UUID, URN, URL, JWT, and general identity management in distributed systems.