A Trivial Convention for using HTTP in URN Resolution
RFC 2169

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Network Working Group                                       R. Daniel
Request for Comments: 2169             Los Alamos National Laboratory
Category: Experimental                                      June 1997

         A Trivial Convention for using HTTP in URN Resolution

Status of this Memo
===================

   This memo defines an Experimental Protocol for the Internet
   community.  This memo does not specify an Internet standard of any
   kind.  Discussion and suggestions for improvement are requested.
   Distribution of this memo is unlimited.

Abstract:
=========

   The Uniform Resource Names Working Group (URN-WG) was formed to
   specify persistent, location-independent names for network accessible
   resources, as well as resolution mechanisms to retrieve the resources
   given such a name. At this time the URN-WG is considering one
   particular resolution mechanism, the NAPTR proposal [1]. That
   proposal specifies how a client may find a "resolver" for a URN. A
   resolver is a database that can provide information about the
   resource identified by a URN, such as the resource's location, a
   bibliographic description, or even the resource itself. The protocol
   used for the client to communicate with the resolver is not specified
   in the NAPTR proposal.  Instead, the NAPTR resource record provides a
   field that indicates the "resolution protocol" and "resolution
   service requests" offered by the resolver.

   This document specifies the "THTTP" resolution protocol - a trivial
   convention for encoding resolution service requests and responses as
   HTTP 1.0 or 1.1 requests and responses.  The primary goal of THTTP is
   to be simple to implement so that existing HTTP servers may easily
   add support for URN resolution. We expect that the databases used by
   early resolvers will be useful when more sophisticated resolution
   protocols are developed later.

1.0  Introduction:
==================

   The NAPTR specification[1] defined a new DNS resource record which
   may be used to discover resolvers for Uniform Resource Identifiers.
   That resource record provides the "services" field to specify the
   "resolution protocol" spoken by the resolver, as well as the
   "resolution services" it offers. Resolution protocols mentioned in

Daniel                        Experimental                      [Page 1]
RFC 2169                 HTTP in URN Resolution                June 1997

   that specification are Z3950, THTTP, RCDS, HDL, and RWHOIS. (That
   list is expected to grow over time). The NAPTR specification also
   lists a variety of resolution services, such as N2L (given a URN,
   return a URL); N2R (Given a URN, return the named resource), etc.

   This document specifies the "THTTP" (Trivial HTTP) resolution
   protocol.  THTTP is a simple convention for encoding resolution
   service requests and responses as HTTP 1.0 or 1.1 requests and
   responses. The primary goal of THTTP is to have a URN resolution
   protocol that can easily be added to existing HTTP daemons. Other
   resolution protocols are expected to arise over time, so this
   document serves a secondary purpose of illustrating the information
   that needs to be specified for a URN resolution protocol. One of the
   resolution protocols we expect to be developed is an extension of
   HTTP with new methods for the resolution services. Therefore, we use
   "THTTP" as the identifier for this protocol to leave "HTTP" for later
   developments.

   The reader is assumed to be familiar with the HTTP/1.0 [2] and 1.1
   [3] specifications. Implementors of this specification should be
   familiar with CGI scripts, or server-specific interfaces, for
   database lookups.

2.0 General Approach:
=====================

   The general approach used to encode resolution service requests in
   THTTP is quite simple:

       GET /uri-res/<service>?<uri>  HTTP/1.0

   For example, if we have the URN "urn:foo:12345-54321" and want a URL,
   we would send the request:

       GET /uri-res/N2L?urn:foo:12345-54321 HTTP/1.0

   The request could also be encoded as an HTTP 1.1 request. This would
   look like:

       GET /uri-res/N2L?urn:foo:12345-54321 HTTP/1.1
       Host: <whatever host we are sending the request to>

   Responses from the HTTP server follow standard HTTP practice. Status
   codes, such as 200 (OK) or 404 (Not Found) shall be returned.  The
   normal rules for determining cachability, negotiating formats, etc.
   apply.

Daniel                        Experimental                      [Page 2]
RFC 2169                 HTTP in URN Resolution                June 1997

   Handling these requests on the server side is easy to implement using
   CGI or other, server-specific, extension mechanisms.  CGI scripts
   will see the incoming URI in the QUERY_STRING environment variable.
   Any %encoded characters in the URN will remain in their %encoded
   state in that string. The script can take the URN, look it up in a