An open standard for sharing content across independent xanalogical systems — the docuverse first envisioned as Xanadu.
XCP is a minimal protocol that enables any xanalogical system (transclusion-by-reference, verifiable content — the class of systems pioneered by Xanadu) to reference, retrieve, and verify content on any other system — regardless of internal architecture.
It builds on the concepts and open-source release of Udanax Gold and the vision of Project Xanadu by Ted Nelson.
The name is provisional and open to community discussion. ("Xanalogical" — Nelson's own term for the general class — describes the systems XCP interconnects; "Xanadu" remains the proper noun for Ted Nelson's specific project.)
The xanalogical docuverse — first envisioned as Project Xanadu — is a connected literature where every quotation maintains its bond to the original. That vision requires interoperability — content on one implementation must be referenceable from any other.
XCP provides that interop layer without requiring implementations to share:
- Data structures (enfilades, CRDTs, etc.)
- Wire protocols (FeBe, WebSocket, etc.)
- Programming languages (C++, Smalltalk, Rust, Python, etc.)
- Transaction models
An implementation conforms to XCP v1 by providing two HTTP endpoints:
GET /.well-known/xanadu-server.json— tells the world who you areGET /api/public/work/{id}— serves content with BLAKE3 hash verification
That's it. Any system that serves those two endpoints can join the docuverse.
| Implementation | Language | Status |
|---|---|---|
| Xudanu | Rust | Conformant (v1) |
| Udanax Gold | C++ | Pending (needs REST adapter) |
| Udanax Green | Smalltalk | Pending |
| Your implementation | Any | Add yours |
The full specification is in spec.md.
XCP is not affiliated with, endorsed by, or sponsored by Ted Nelson, Project Xanadu, the Xanadu Operating Company, Autodesk Inc., or the Udanax development team. It is an independent community effort to enable interoperability between systems inspired by Ted Nelson's vision.
The protocol name "XCP" and this specification are licensed under Apache 2.0. Anyone may implement the protocol for any purpose.
This is a draft specification seeking community input. Issues and pull requests are welcome.
Priority areas for feedback:
- Tumbler format compatibility with Gold/Green
- Hash algorithm (BLAKE3 vs alternatives)
- Authentication for private content
- Trail sharing format
Apache 2.0 — see LICENSE.