I-name
I-names are one form of an XRI – an OASIS standard for abstract identifiers designed for sharing resources and data across domains and applications. I-names are human-friendly XRIs intended to be as easy as possible for people to remember and use. For example, a personal i-name could be as simple as "=Mary" or "=Mary.Jones". An organizational i-name can be a simple as "@Acme" or "@Acme.Corporation".
One problem XRIs are designed to solve is persistent addressing – how to maintain an address that does not need to change no matter how often the contact data for a person or organization changes. XRIs accomplish this by adding a new layer of abstract addressing over the existing IP numbering and DNS naming layers used on the Internet today. Such an abstraction layer is not new — URNs (Uniform Resource Names) and other persistent identifier architectures do the same thing. What's unique about the XRI layer is that it offers a uniform syntax and resolution protocol for two types of abstract identifiers that mirror the two layers below it (DNS domain names and Internet IP numbers). These are:
- I-names – human-friendly identifiers that resemble domain names but are even simpler and easier to use. Though typically long-lived, i-names may, like domain names, be transferred or reassigned to another resource by their owner. For example, a company that changes its corporate name could sell its old i-name to another company, while both companies could retain their original i-number. However what most differentiates i-names from domain names is that they have paired (synonymous)...
- I-numbers – machine-friendly identifiers (similar to IP addresses) that are registered to a resource (person, organization, application, file, digital object, etc.) and never reassigned. This means an i-number can always be used to address a network representation of the resource as long it remains available somewhere on the network. I-numbers, like IP addresses, are designed to be very efficient for network routers to process and resolve.
XRI syntax also allows i-names and i-numbers to be combined within the same XRI. So effectively the XRI layer supports paired i-name/i-number synonyms for resources – one that reflects real-world semantics and can change over time, and one that reflects the persistent identity of a resource no matter how often its attributes (including its i-names) may change. And the same HTTP-based XRI resolution protocol can be used to resolve either an i-name or an i-number (or any combination of the two in the same XRI).
XRIs are backwards compatible with the DNS and IP addressing systems, so it is possible for domain names and IP addresses to used as i-names (or, in rare cases, as i-numbers). Like DNS names, XRIs can also be delegated, i.e., nested multiple levels deep, just like the directory names on a local computer file system. For example, a company can register a top-level (global) i-name for itself and then assign second- or lower-level (community) i-names to its divisions, employees, etc.
I-names are called universal private addresses because they can be resolved using the XRI protocol into any other type of contact data for the identity they represent (or any other type of data under the control of this identity – see XDI). Privacy is protected because the identity owner controls this resolution. For example, the registrant of "=Mary.Jones" would never receive spam from this i-name because it is not an email address. To resolve "=Mary.Jones" into an email address would first require Mary's permission, and such requests can be verified by i-brokers to make sure they are legimate.
In addition to "=names" for people and "@names" for organizations, the third major type of i-names is "+names" for generic concepts. This is the XRI equivalent of a generic noun in the English language, for example, "+flowers", "+phone.number", or "+table.of.contents". +names are extremely useful in data sharing because they can be used as XRI cross-reference to specify the precise type of data to be shared. For example, "=Mary.Jones/(+phone.number)/(+daytime)" and "@Acme/(+phone.number)/(+daytime)" can be used to request Mary's and Acme's daytime phone numbers, respectively.
Although typically long-lived, i-names may, like domain names, be transferred or reassigned to another owner. For example, a company that changes its corporate identity could sell its former i-name to another company. Because a person's or organization's underlying identity does not change when their i-name changes, however, the best practice for persistent linking is to use an i-name "synonym" called an i-number. I-numbers are the second form of XRIs: persistent, machine-friendly identifiers (similar to an IP addresses) that are assigned once to a resource and never reassigned. The i-number that is coupled with an i-name enables a person or organization to maintain a long-term privacy-protected Internet identity that will not break even if their i-name (or any other contact data) changes.