Web Host Metadata
RFC 6415

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Internet Engineering Task Force (IETF)              E. Hammer-Lahav, Ed.
Request for Comments: 6415                                       B. Cook
Category: Standards Track                                   October 2011
ISSN: 2070-1721

                           Web Host Metadata

Abstract

   This specification describes a method for locating host metadata as
   well as information about individual resources controlled by the
   host.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6415.

Copyright Notice

   Copyright (c) 2011 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Hammer-Lahav & Cook          Standards Track                    [Page 1]
RFC 6415                        host-meta                   October 2011

Table of Contents

   1. Introduction ....................................................2
      1.1. Example ....................................................3
           1.1.1. Processing Resource-Specific Information ............4
      1.2. Notational Conventions .....................................5
   2. Obtaining host-meta Documents ...................................6
   3. The host-meta Document ..........................................6
      3.1. XML Document Format ........................................7
           3.1.1. The "Link" Element ..................................7
   4. Processing host-meta Documents ..................................8
      4.1. Host-Wide Information ......................................9
      4.2. Resource-Specific Information ..............................9
   5. Security Considerations ........................................10
   6. IANA Considerations ............................................11
      6.1. The "host-meta" Well-Known URI ............................11
      6.2. The "host-meta.json" Well-Known URI .......................11
      6.3. The "lrdd" Relation Type ..................................11
   Appendix A. JRD Document Format ...................................12
   Appendix B. Acknowledgments .......................................15
   Normative References ..............................................15

1.  Introduction

   Web-based protocols often require the discovery of host policy or
   metadata, where "host" is not a single resource but the entity
   controlling the collection of resources identified by Uniform
   Resource Identifiers (URIs) with a common URI host [RFC3986], which
   can be served by one or more servers.

   While web protocols have a wide range of metadata needs, they often
   use metadata that is concise, has simple syntax requirements, and can
   benefit from storing their metadata in a common location used by
   other related protocols.

   Because there is no URI or representation available to describe a
   host, many of the methods used for associating per-resource metadata
   (such as HTTP headers) are not available.  This often leads to the
   overloading of the root HTTP resource (e.g., 'http://example.com/')
   with host metadata that is not specific or relevant to the root
   resource itself.

   This document defines a lightweight metadata document format for
   describing hosts (thus the name "host-meta"), intended for use by
   web-based protocols.  This document also registers the well-known URI
   suffix "host-meta" in the Well-Known URI Registry established by
   [RFC5785].

Hammer-Lahav & Cook          Standards Track                    [Page 2]
RFC 6415                        host-meta                   October 2011

   In addition, there are times when a host-wide scope for policy or
   metadata is too coarse-grained. host-meta provides two mechanisms for
   providing resource-specific information:

   o  Link Templates - links using a URI template instead of a fixed
      target URI, providing a way to define generic rules for generating