From IIW

What is XRI?

XRI (Extensible Resource Identifier) is a new open standard for digital identifiers from OASIS (home of SAML, WS-Security, WS-Federation, ebXML, XACML, and many other XML standards). XRI has been under development since 2003 by over a dozen companies and organizations including AMD, AmSoft, Boeing, Booz Allen Hamilton, Cordance, ooTao, NeuStar, NRI, PlaNetwork, Visa International, and XDI.org.

What is XRDS?

XRDS (Extensible Resource Descriptor Sequence) is the simple XML file format developed by the OASIS XRI Technical Committee for discovering the services available for a resource. XRDS is used by both XRI resolution and OpenID discovery, and works with both URLs and XRIs.

How are XRIs different from URLs?

XRI is “XML for identifiers” – a language for expressing rich, structured identifiers just like XML enables expressing rich, structured documents. XRIs are compatable with today’s Web but offer some new features most URLs do not have:

  • XRIs typically come in pairs – a human-friendly “i-name” and an unchanging “i-number”. This allows the name of a resource to change over time without breaking links (because links can use the permanent i-number).
  • XRIs are portable across domains, i.e., a user or a business can “take their XRI with them” to any site or application that uses XRIs – you don’t need to register a new username or address.
  • XRIs are “composable” – you can build XRIs from other XRIs like lego blocks (and human language). You can even build XRIs out of other identifiers (URLs, phone numbers, email addresses, etc.)
  • XRIs are fully internationalized, so they work in all languages.

What problems does XRI solve for users?

Simplicity, portability, and privacy. A personal XRI like =drummond.reed or =web*terry is the first Internet identifier designed explicitly for personal digital addressing – a persistent address for you (not your devices) that's easy to remember and type, useable for all types of services on the net, portable across all types of sites and applications, and protected from spam, phishing, and data leakage.

What problems does XRI solve for businesses?

Intelligent resource identification. From a business point of view, XRIs are to URLs what fax numbers are to ordinary phone numbers. As digital data sharing protocols like OpenID, SAML, and XDI gain adoption, a business XRI like @cordance (and the underlying i-number) will become their universal “web services number” – one that keeps working no matter how often they move, change names, reorganize, merge, etc.

What problem does XRI solve for everyone?

Universal tagging. XRI is the first digital addressing standard explicitly designed to include tags — generic identifiers like +budget, +home, +phone, or +poodle that everyone can use to describe resources in a way both people and machines can understand. And because XRIs are composable, even XRIs themselves can be tagged.

What software supports XRIs today?

XRI support is included in OpenID 2.0, specifically to use the XRDS (Extensible Resource Descriptor Sequence) service discovery format and to solve the OpenID recycling problem (having someone take over your OpenID because you lose your username or domain name). The Higgins Project uses XRI for data addressing, and XRI is the basis for the OASIS XDI data sharing protocol. There are two open source XRI resolver/server projects – OpenXRI (Java) and Barx (Ruby).

Where can I register an XRI?

XRI registries come in three types: global registries (similar to DNS top-level domains), community registries (similar to DNS delegated domains), and peer-to-peer registries. Global registries are operated by XDI.org, an international non-profit public trust organization. XDI.org hosts a list of the XDI.org Accredited I-Brokers accredited to register global i-names for a fee, just like registering a domain name. Free community i-names are available from s number of XRI community registries such as @FreeXRI and @xrid. Peer-to-peer registries can be created using the XRI server software from XRI open source projects such as OpenXRI.

Where can I go for more info?

The three best sources are:

Also feel free to contact members of the XRI community listed in the dev.xri.net directory.