HTTP/1.1 200 OK Date: Tue, 09 Apr 2002 10:03:26 GMT Server: Apache/1.3.20 (Unix) Last-Modified: Mon, 15 Jul 1996 22:22:00 GMT ETag: "361e88-118b-31eac488" Accept-Ranges: bytes Content-Length: 4491 Connection: close Content-Type: text/plain Internet-Draft draft-masinter-url-data-01.txt July 12, 1996 Expires in 6 months "Data: URL scheme" Status of This Memo This document is an Internet-Draft. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet- Drafts as reference material or to cite them other than as ``work in progress.'' To learn the current status of any Internet-Draft, please check the ``1id-abstracts.txt'' listing contained in the Internet- Drafts Shadow Directories on ftp.is.co.za (Africa), nic.nordu.net (Europe), munnari.oz.au (Pacific Rim), ds.internic.net (US East Coast), or ftp.isi.edu (US West Coast). Abstract A new URL scheme, "data:", is defined. It allows inclusion of small data items as "immediate" data, as if it had been included externally. Description Some applications that use URLs also have a need to embed (small) media type data directly inline. This document defines a new URL scheme that would work like 'immediate addressing'. The URLs are of the form: data:[][;base64], The is an Internet media type specification (with optional parameters, etc.) The appearance of ";base64" means that the value is encoded as base64. Without ";base64", the value (as a sequence of octets) is represented directly; octets outside of the range representable by safe URL characters should be encoded using the standard %xx hex encoding of URLs. If is omitted, it defaults to text/plain;charset=US-ASCII. As a shorthand, "text/plain" can be omitted but the charset parameter supplied. The "data:" URL scheme is only useful for very short values. Note that some applications that use URLs may impose a length limit; for example, URLs embedded within anchors in HTML have a length limit determined by the HTML DTD. Examples A data: URL might be used for arbitrary types of data. data:,A%20brief%20note encodes the text/plain string "A brief note", which might be useful in a footnote link. The HTML fragment: Larry could be used for a small inline image in a HTML document. (The embedded image is probably near the limit of utility. For anything else larger, data URLs are likely to be inappropriate.) Some applications may use the "data:" URL scheme in order to provide setup parameters for other kinds of networking applications. For example, one might create a media type application/vnd.xxx-query whose content consists of a query string and a database identifier for the "xxx" vendor's databases. A URL of the form: data:application/vnd.xxx-query,select_vcount,fcol_from_fieldtable/local could then be used in a local application to launch the "helper" for application/vnd.xxx-query and give it the immediate data included. History This idea was originally proposed August 1995. Some versions of the data URL scheme have been used in the definition of VRML, and a version has appeared as part of a proposal for embedded data in HTML. Various changes have been made, based on requests, to elide the media type, pack the indication of the base64 encoding more tightly, and eliminate "quoted printable" as an encoding since it would not easily yield valid URLs without additional %xx encoding, which itself is sufficient. Security Immediate data URLs introduce no new security considerations. References [RFC1738] RFC 1738. Uniform Resource Locators (URL). T. Berners-Lee, L. Masinter & M. McCahill. December 1994. [RFC1808] RFC 1808. Relative Uniform Resource Locators. R. Fielding. June 1995. Author contact information: Larry Masinter Xerox Palo Alto Research Center 3333 Coyote Hill Road Palo Alto, CA 94304 masinter@parc.xerox.com