IRItoURI

IRItoURI refers to the process of converting an Internationalized Resource Identifier (IRI) into a Uniform Resource Identifier (URI). IRIs extend URIs to allow non‑ASCII characters, while URIs are restricted to the US-ASCII character set. The translation is defined by standards that govern how non‑ASCII characters should be represented in a URI form, preserving the original resource while making it usable in systems that require ASCII.

The typical mapping involves two steps. First, the host component of the IRI is converted to ASCII using IDNA (Internationalized Domain Names in Applications), which yields an ASCII domain name encoded with Punycode. Second, non‑ASCII characters in the path, query, and fragment are encoded by converting each character to UTF-8 and then percent‑encoding every resulting octet. Unreserved characters may remain unescaped, while other characters that serve syntactic purposes in a URI are encoded as needed to avoid ambiguity.

This conversion enables IRIs to be used in environments and protocols that expect URIs, such as certain web servers, caches, and links. Many programming languages provide libraries or functions to perform IRItoURI conversions, handling IDNA processing and percent‑encoding according to the relevant RFCs (notably RFC 3987 and RFC 3986).

Example: an IRI such as http://例子.测试/路径?查询=测试 would be converted to a URI like http://xn--fsq.xn--0zwm56d/%E8%B7%AF%E5%BE%84?%E6%9F%A5%E8%AF%95=%E6%B5%8B%E8%AF%95. See also IRI, URI, IDNA, percent-encoding.