[Docs] [txt|pdf] [Tracker] [Email] [Diff1] [Diff2] [Nits]

Versions: 00 01 02 03 04 05 06 07 08

Network Working Group                                     P. Saint-Andre
Internet-Draft                                Jabber Software Foundation
Expires: June 9, 2005                                   December 9, 2004

     A Uniform Resource Identifier (URI) Scheme for the Extensible
                 Messaging and Presence Protocol (XMPP)
                      draft-saintandre-xmpp-uri-08

Status of this Memo

   This document is an Internet-Draft and is subject to all provisions
   of section 3 of RFC 3667.  By submitting this Internet-Draft, each
   author represents that any applicable patent or other IPR claims of
   which he or she is aware have been or will be disclosed, and any of
   which he or she become aware will be disclosed, in accordance with
   RFC 3668.

   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."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt.

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.

   This Internet-Draft will expire on June 9, 2005.

Copyright Notice

   Copyright (C) The Internet Society (2004).

Abstract

   This document defines a Uniform Resource Identifier (URI) scheme for
   use in identifying or interacting with entities that can communicate
   via the Extensible Messaging and Presence Protocol (XMPP).




Saint-Andre               Expires June 9, 2005                  [Page 1]


Internet-Draft                  XMPP-URI                   December 2004

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1   Terminology  . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Description of xmpp: URI Scheme  . . . . . . . . . . . . . . .  3
     2.1   Rationale  . . . . . . . . . . . . . . . . . . . . . . . .  3
     2.2   Form . . . . . . . . . . . . . . . . . . . . . . . . . . .  4
     2.3   Authority Component  . . . . . . . . . . . . . . . . . . .  5
     2.4   Path Component . . . . . . . . . . . . . . . . . . . . . .  6
     2.5   Query Component  . . . . . . . . . . . . . . . . . . . . .  6
     2.6   Fragment Identifier Component  . . . . . . . . . . . . . .  8
     2.7   Generation of XMPP URIs  . . . . . . . . . . . . . . . . .  8
     2.8   Processing of XMPP URIs  . . . . . . . . . . . . . . . . . 11
     2.9   Internationalization . . . . . . . . . . . . . . . . . . . 14
   3.  IANA Registration of xmpp: URI Scheme  . . . . . . . . . . . . 14
     3.1   URI scheme name  . . . . . . . . . . . . . . . . . . . . . 14
     3.2   URI scheme syntax  . . . . . . . . . . . . . . . . . . . . 14
     3.3   Character encoding considerations  . . . . . . . . . . . . 15
     3.4   Intended usage . . . . . . . . . . . . . . . . . . . . . . 15
     3.5   Applications and/or protocols which use this URL
           scheme name  . . . . . . . . . . . . . . . . . . . . . . . 15
     3.6   Security considerations  . . . . . . . . . . . . . . . . . 15
     3.7   Relevant publications  . . . . . . . . . . . . . . . . . . 16
     3.8   Person and email address to contact for further
           information  . . . . . . . . . . . . . . . . . . . . . . . 16
     3.9   Author/change controller . . . . . . . . . . . . . . . . . 16
   4.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 16
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . . 16
   6.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 16
   6.1   Normative References . . . . . . . . . . . . . . . . . . . . 16
   6.2   Informative References . . . . . . . . . . . . . . . . . . . 17
       Author's Address . . . . . . . . . . . . . . . . . . . . . . . 19
       Intellectual Property and Copyright Statements . . . . . . . . 20









Saint-Andre               Expires June 9, 2005                  [Page 2]


Internet-Draft                  XMPP-URI                   December 2004

1.  Introduction

   The Extensible Messaging and Presence Protocol (XMPP) is a streaming
   XML technology that enables any two entities on a network to exchange
   well-defined but extensible XML elements (called "XML stanzas") in
   close to real time.  [XMPP-CORE] specifies that on an XMPP network
   itself, the address of an XMPP entity MUST NOT be prepended with a
   Uniform Resource Identifier (URI) scheme (as defined in [URI]).
   However, many applications external to an XMPP network may need to
   identify XMPP entities as full URIs; examples include databases that
   need to store XMPP addresses and non-native user agents (e.g., web
   browsers and calendaring applications) that provide interfaces to
   XMPP services.  In order to address the needs of such applications,
   this memo defines an xmpp: URI scheme that conforms to both the
   requirements in [URL-REG] and the recommendations in [URL-GUIDE].

1.1  Terminology

   This document inherits terminology described in [URI] and
   [XMPP-CORE].

   The capitalized key words "MUST", "MUST NOT", "REQUIRED", "SHALL",
   "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED",  "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in RFC
   2119 [TERMS].

2.  Description of xmpp: URI Scheme

2.1  Rationale

   Many types of application can be built using XMPP.  As specified in
   [XMPP-IM], instant messaging and presence applications of XMPP MUST
   handle the im: and pres: URI schemes specified by [CPIM] and [CPP].
   However, it is appropriate to define an XMPP-specific URI scheme for
   other applications of XMPP (such as network management, workflow
   applications, generic publish-subscribe, remote procedure calls,
   content syndication, gaming, and middleware) since these applications
   do not necessarily implement instant messaging and presence
   semantics.  Therefore, this document defines a generic URI scheme
   that will enable applications to address as a URI any entity that can
   communicate via XMPP.

   The xmpp: URI scheme is provided mainly for use by non-native
   interfaces and applications, and primarily for the purpose of
   identification rather than interaction (on the latter distinction,
   see Section 1.2.2 of [URI]).  In order to ensure interoperability on
   XMPP networks, when data is routed to an XMPP entity (e.g., when an
   XMPP address is contained in the 'to' or 'from' attribute of an XML


Saint-Andre               Expires June 9, 2005                  [Page 3]


Internet-Draft                  XMPP-URI                   December 2004

   stanza) or an XMPP entity is otherwise identified in standard XMPP
   protocol elements, the entity MUST be addressed as
   <[node@]domain[/resource]> (i.e., without a URI scheme), where the
   "node identifier", "domain identifier", and "resource identifier"
   portions of an XMPP address conform to the definitions provided in
   Section 3 of [XMPP-CORE].

   (Note: For historical reasons, the term "resource identifier" is used
   in XMPP to refer to the optional portion of an XMPP address that
   follows the domain identifier and the "/" separator character (for
   details, refer to Section 3.4 of [XMPP-CORE]); this use of the term
   "resource identifier" is not to be confused with the meanings of
   "resource" and "identifier" provided in Section 1.1 of [URI].)

2.2  Form

   As described in [XMPP-CORE], an XMPP address (also known as a "JID")
   used natively on an XMPP network is a string of Unicode characters
   that (1) conforms to a certain set of [STRINGPREP] profiles and
   [IDNA] restrictions, (2) follows a certain set of syntax rules, and
   (3) is encoded as [UTF-8].  The form of such an address can be
   represented using Augmented Backus-Naur Form ([ABNF]) as:

      [ node "@" ] domain [ "/" resource ]

   The "node" and "resource" rules rely on distinct profiles of
   [STRINGPREP] and the "domain" rule relies on the concept of an
   internationalized domain name as described in [IDNA].  However,
   because a URI is allowed to contain [US-ASCII] characters only and
   certain characters are reserved in URIs (the "reserved" rule defined
   in [URI]), an XMPP address must be properly handled when transformed
   into an XMPP URI (see Section 2.7 of this memo) and the ABNF syntax
   needs to be adjusted in order to accurately capture the form of an
   XMPP URI as opposed to a native XMPP address.  Furthermore, it is
   desirable to take advantage of more advanced aspects of URI syntax
   and semantics in XMPP URIs, such as authority components, query
   components, and fragment identifier components.  Therefore, using the
   "fragment", "host", "pct-encoded", "query", "sub-delims", and
   "unreserved" rules defined in [URI], the ABNF syntax for an XMPP URI
   is defined as follows:






Saint-Andre               Expires June 9, 2005                  [Page 4]


Internet-Draft                  XMPP-URI                   December 2004

      xmppuri   = "xmpp:" hier-xmpp [ "?" querycomp ] [ "#" fragment ]
      hier-xmpp = authpath / path-xmpp
      authpath  = "//" auth-xmpp [ "/" path-xmpp ]
      auth-xmpp = nodeid "@" host
      path-xmpp = [ nodeid "@" ] host [ "/" resid ]
      nodeid    = *( unreserved / pct-encoded / nodeallow )
      nodeallow = "!" / "$" / "%" / "(" / ")" / "*" / "+" / ","
                  / ";" / "=" / "^" / "`" / "{" / "|" / "}"
      resid     = *( unreserved / pct-encoded / sub-delims )
      querycomp = querytype [ *pair ]
      querytype = *( ALPHA / DIGIT / '-' / '_' / '.' / ':' )
      pair      = "&" key "=" value
      key       = *unreserved
      value     = *( unreserved / pct-encoded )

   (Note: It would have been desirable to re-use the "userinfo" rule
   from [URI]; however, this was not possible since the "userinfo" rule
   allows characters that conform to the "sub-delims" rule, but the "&"
   and "'" characters (which are allowed by the "sub-delims" rule) are
   disallowed in XMPP node identifiers by the Nodeprep profile of
   [STRINGPREP] as specified in Appendix A of [XMPP-CORE].  Furthermore,
   there is no need to refer to punycode in the URI syntax itself, since
   any punycode representation would occur only inside an XMPP
   application in order to represent internationalized domain names.)

   The following is an example of a basic XMPP URI used for purposes of
   identifying a node associated with an XMPP server (an IM user is one
   type of such a node, but by no means the only type):

      xmpp:juliet@example.com

   Further descriptions of the various components of an XMPP URI are
   provided in the following sections.

2.3  Authority Component

   As explained in Section 2.8 of this memo, in the absence of an
   authority component the processing application would authenticate as
   a configured user at a configured XMPP server.  The presence of an
   authority component (always preceded by "//") signals the processing
   application to authenticate as the node@domain specified in the
   authority component, rather than as a configured node@domain.  Thus,
   the following XMPP URI indicates to authenticate as
   "guest@example.com":

      xmpp://guest@example.com

   Note well that this is quite different from the following XMPP URI,


Saint-Andre               Expires June 9, 2005                  [Page 5]


Internet-Draft                  XMPP-URI                   December 2004

   which identifies a node "guest@example.com" but does not signal the
   processing application to authenticate as that node:

      xmpp:guest@example.com

   Similarly, using a possible query component of "?message" to trigger
   an interface for sending a message, the following XMPP URI signals
   the processing application to authenticate as "guest@example.com" and
   send a message to "support@example.com":

      xmpp://guest@example.com/support@example.com?message

   By contrast, the following XMPP URI signals the processing
   application to authenticate as its configured default account and
   send a message to "support@example.com":

      xmpp:support@example.com?message

   (Note: It is unlikely that the authority component will be included
   in most XMPP URIs; however, the scheme allows for inclusion of the
   authority component if appropriate.)

2.4  Path Component

   The path component of an XMPP URI identifies an XMPP address or
   specifies the XMPP address to which an XML stanza shall be directed
   at the end of URI processing.

   For example, the following XMPP URI identifies a node associated with
   an XMPP server:

      xmpp:juliet@example.com

   The following XMPP URI identifies a node associated with an XMPP
   server along with a particular XMPP resource identifier associated
   with that node:

      xmpp:juliet@example.com/balcony

   Inclusion of a node is optional in XMPP addresses, so that the
   following XMPP URI simply identifies an XMPP server:

      xmpp:example.com

2.5  Query Component

   There are many potential use cases for encapsulating information in


Saint-Andre               Expires June 9, 2005                  [Page 6]


Internet-Draft                  XMPP-URI                   December 2004

   the query component of an XMPP URI; examples include but are not
   limited to:

   o  Sending an XMPP message stanza.
   o  Adding a roster item.
   o  Sending a presence subscription.
   o  Probing for current presence information.
   o  Joining an XMPP-based text chat room (see [JEP-0045]).
   o  Registering with another entity (see [JEP-0077]).
   o  Triggering a remote procedure call (see [JEP-0009]).
   o  Providing a SOAP interface (see [JEP-0072]).
   o  Discovering the identity or capabilities of another entity (see
      [JEP-0030]).
   o  Interacting with publish-subscribe channels (see [JEP-0060]).

   Many of these potential use cases are application-specific, and the
   full range of such applications cannot be foreseen in advance given
   the continued expansion in XMPP development; however, there is
   agreement within the Jabber/XMPP developer community that all of the
   uses envisioned to date can be encapsulated via a "query type",
   optionally supplemented by one or more "key-value" pairs (this is
   similar to the "application/x-www-form-urlencoded" MIME type
   described in [HTML]).

   As an example, an XMPP URI intended to launch an interface for
   sending a message to the XMPP entity "juliet@example.com" might be
   represented as follows:

      xmpp:juliet@example.com?message

   Similarly, an XMPP URI intended to launch an interface for sending a
   message to the XMPP entity "juliet@example.com" with a particular
   subject might be represented as follows:

      xmpp:juliet@example.com?message&subject=Hello%20World

   If included, the query component MUST first be encoded as a [UTF-8]
   string; any [UTF-8] encoded octets MUST then be converted into
   US-ASCII characters, making sure to represent any reserved character
   (i.e., any character that conforms to the "reserved" rule defined in
   [URI]) and any character that is outside the range of the US-ASCII
   coded character set as a percent-encoded octet (see Section 2.1 of
   [URI]).

   If the processing application does not understand query components,
   it MUST ignore the query component and treat the URI as consisting
   of, for example, <xmpp:juliet@example.com> rather than
   <xmpp:juliet@example.com?query>.  If the processing application does


Saint-Andre               Expires June 9, 2005                  [Page 7]


Internet-Draft                  XMPP-URI                   December 2004

   not understand a particular key within the query component, it MUST
   ignore that key and its associated value.

   In pursuit of interoperability, it may be valuable to maintain a
   registry of query types and perhaps even of keys for use in the query
   component portion of XMPP URIs.  Given that such values will most
   likely be specific to particular applications of XMPP rather than
   core to XMPP itself, it seems reasonable that such a registry, if
   created, would be maintained by the Jabber Registrar function of the
   Jabber Software Foundation as described in [JEP-0053], rather than by
   the IANA.  A proposal for creating such a registry is described in
   [JEP-0147].

2.6  Fragment Identifier Component

   As stated in Section 3.5 of [URI], "The fragment identifier component
   of a URI allows indirect identification of a secondary resource by
   reference to a primary resource and additional identifying
   information."  Because the resource identified by an XMPP URI does
   not make available any media type (see [MIME]) and therefore (in the
   terminology of [URI]) no representation exists at an XMPP resource,
   the semantics of the fragment identifier component in XMPP URIs are
   to be "considered unknown and, effectively, unconstrained" (ibid.).
   Particular XMPP applications MAY make use of the fragment identifier
   component for their own purposes.  However, if a processing
   application does not understand fragment identifier components or the
   syntax of a particular fragment identifier component included in an
   XMPP URI, it MUST ignore the fragment identifier component.

   If included, the fragment identifier component MUST first be encoded
   as a [UTF-8] string; any [UTF-8] encoded octets MUST then be
   converted into US-ASCII characters, making sure to represent any
   reserved character (i.e., any character that conforms to the
   "reserved" rule defined in [URI]) and any character that is outside
   the range of the US-ASCII coded character set as a percent-encoded
   octet (see Section 2.1 of [URI]).

2.7  Generation of XMPP URIs

2.7.1  URI Generation Method

   When generating a conformant XMPP URI from an XMPP address, it is
   necessary to use consistent methods for transforming (1) an XMPP
   "node identifier" into a string of US-ASCII characters that conforms
   to the "nodeid" rule, (2) an XMPP "domain identifier" into a string
   of US-ASCII characters that conforms to the "host" rule, and (3) an
   XMPP "resource identifier" into a string of US-ASCII characters that
   conforms to the "resid" rule; such methods are described below.


Saint-Andre               Expires June 9, 2005                  [Page 8]


Internet-Draft                  XMPP-URI                   December 2004

   Naturally, if the XMPP address exists in a non-UTF-8 form (e.g.,
   having been written on a piece of paper or having been represented
   internally in a computer program as UTF-16), it MUST first be
   converted to [UTF-8] before the XMPP URI is generated.

   In order to transform an XMPP "node identifier" into a string of
   US-ASCII characters that conforms to the "nodeid" rule, the node
   identifier MUST first be constructed in accordance with the rules
   specified in [XMPP-CORE], including application of the Nodeprep
   profile of [STRINGPREP] (see Appendix A of [XMPP-CORE]) and encoding
   as a [UTF-8] string; any [UTF-8] encoded octets of the XMPP "node
   identifier" MUST then be converted into US-ASCII characters, making
   sure to represent any reserved character (i.e., any character that
   conforms to the "reserved" rule defined in [URI]) and any character
   that is outside the range of the US-ASCII coded character set as a
   percent-encoded octet (see Section 2.1 of [URI]).

   In order to transform an XMPP "domain identifier" into a string of
   US-ASCII characters that conforms to the "host" rule, the domain
   identifier  MUST first be constructed in accordance with the rules
   specified in [XMPP-CORE], including application of the [NAMEPREP]
   profile of [STRINGPREP] and encoding as a [UTF-8] string; any [UTF-8]
   encoded octets of the XMPP "domain identifier" MUST then be converted
   into US-ASCII characters, making sure to represent any reserved
   character (i.e., any character that conforms to the "reserved" rule
   defined in [URI]) and any character that is outside the range of the
   US-ASCII coded character set as a percent-encoded octet (see Section
   2.1 of [URI]).

   In order to transform an XMPP "resource identifier" into a string of
   US-ASCII characters that conforms to the "resid" rule, the resource
   identifier MUST first be constructed in accordance with the rules
   specified in [XMPP-CORE], including application of the Resourceprep
   profile of [STRINGPREP] (see Appendix B of [XMPP-CORE]) and encoding
   as a [UTF-8] string; any [UTF-8] encoded octets of the XMPP "resource
   identifier" MUST then be converted into US-ASCII characters, making
   sure to represent any reserved character (i.e., any character that
   conforms to the "reserved" rule defined in [URI]) and any character
   that is outside the range of the US-ASCII coded character set as a
   percent-encoded octet (see Section 2.1 of [URI]).

   In order to form an XMPP URI from the foregoing components, the
   generating application MUST concatenate:

   1.  the "xmpp:" scheme
   2.  optionally (if an authority component is to be included), the
       characters "//", an authority component of the form node@domain,
       and the character "/"


Saint-Andre               Expires June 9, 2005                  [Page 9]


Internet-Draft                  XMPP-URI                   December 2004

   3.  optionally (if the XMPP address contained an XMPP "node
       identifier"), a string of US-ASCII characters that conforms to
       the "nodeid" rule, followed by the "@" character
   4.  a string of US-ASCII characters that conforms to the "host" rule
   5.  optionally (if the XMPP address contained an XMPP "resource
       identifier"), the character "/" and a string of US-ASCII
       characters that conforms to the "resid" rule
   6.  optionally (if a query component is to be included), the "?"
       character and query component
   7.  optionally (if a fragment identifier component is to be
       included), the "#" character and fragment identifier component

2.7.2  URI Generation Example

   Consider the following XMPP address:

         <ji&#x159;i@&#x10D;echy.example/v Praze>

   (Note: The string "&#x159;" stands for the Unicode character LATIN
   SMALL LETTER R WITH CARON and the string "&#x10D;" stands for the
   Unicode character LATIN SMALL LETTER C WITH CARON, following the "XML
   Notation" used in [IRI] to represent characters that cannot be
   rendered in ASCII-only  documents.  The '<' and '>' characters are
   not part of the address itself, but are provided to set off the
   address for legibility.  For those who do not read Czech, this
   example could be Anglicized as "george@czech-lands.example/In
   Prague".)

   In accordance with the process specified above, the generating
   application would do the following to generate a valid XMPP URI from
   this address:

   1.  First ensure that the XMPP address conforms to the rules
       specified in [XMPP-CORE], including application of the relevant
       [STRINGPREP] profiles and encoding as a [UTF-8] string.
   2.  Split the address into an XMPP "node identifier" ("ji&#x159;i"),
       XMPP "domain identifier" ("&#x10D;echy.example"), and XMPP
       "resource identifier" ("v Praze").
   3.  Transform the XMPP "node identifier" into a string of US-ASCII
       characters that conforms to the "nodeid" rule by converting the
       [UTF-8] string to US-ASCII, including conversion of the LATIN
       SMALL LETTER R WITH CARON character to its percent-encoded
       representation "%C5%99"; the result is the string "ji%C5%99i".
   4.  Transform the XMPP "domain identifier" into a string of US-ASCII
       characters that conforms to the "host" rule by converting the
       [UTF-8] string to US-ASCII, including conversion of the LATIN
       SMALL LETTER C WITH CARON character to its percent-encoded
       representation "%C4%8C"; the result is the string


Saint-Andre               Expires June 9, 2005                 [Page 10]


Internet-Draft                  XMPP-URI                   December 2004

       "%C4%8Cechy.example".
   5.  Transform the XMPP "resource identifier" into a string of
       US-ASCII characters that conforms to the "resid" rule by
       converting the [UTF-8] string to US-ASCII, including conversion
       of the " " (SP) character to its percent-encoded representation
       "%20"; the result is the string "v%20Praze".
   6.  Concatenate the following:
       1.  the "xmpp:" scheme
       2.  a URI "authority component" if included (not shown in this
           example)
       3.  the string of US-ASCII characters that conforms to the
           "nodeid" rule, followed by the "@" character
       4.  the string of US-ASCII characters that conforms to the "host"
           rule
       5.  the "/" character followed by the string of US-ASCII
           characters that conforms to the "resid" rule
       6.  the "?" character followed by a URI "query component" if
           appropriate to the application (not shown in this example)
       7.  the "#" character followed by a URI "fragment identifier
           component" if appropriate to the application (not shown in
           this example)

   The result is this XMPP URI:

       <xmpp:ji%C5%99i@%C4%8Cechy.example/v%20Praze>

2.8  Processing of XMPP URIs

2.8.1  URI Processing Method

   As with the generation of an XMPP URI from an XMPP address, so also
   with the processing of an XMPP URI (including the extraction of an
   XMPP address therefrom): it is necessary to use consistent methods;
   such methods are described below.

   In order to decompose an XMPP URI, a processing application MUST
   separate:

   1.  the "xmpp:" scheme
   2.  optionally (if the XMPP URI contains an authority component), the
       authority component (the string of US-ASCII characters between
       the "//" characters and the first "/" character or the end of the
       URI)
   3.  optionally a string of US-ASCII characters that conforms to the
       "nodeid" rule (if any), using the "@" character as a separator
   4.  a string of US-ASCII characters that conforms to the "host" rule


Saint-Andre               Expires June 9, 2005                 [Page 11]


Internet-Draft                  XMPP-URI                   December 2004

   5.  optionally a string of US-ASCII characters that conforms to the
       "resid" rule (if any), using the "/" character as a separator
   6.  optionally the query component (if any), using the "?" character
       as a separator
   7.  optionally the fragment identifier component (if any), using the
       "#" character as a separator

   In order to reconstruct the XMPP address from the foregoing
   components, the processing application MUST:

   o  Transform the string of US-ASCII characters that conforms to the
      "nodeid" rule into an XMPP "node identifier" by converting each
      sequence of percent-encoded octets into the appropriate sequence
      of reserved or non-US-ASCII octets by (1) decoding percent-encoded
      octets into actual octets, (2) interpreting the octets as [UTF-8],
      and (3) applying the Nodeprep profile of [STRINGPREP] as specified
      in Appendix A of [XMPP-CORE].
   o  Transform the string of US-ASCII characters that conforms to the
      "host" rule into an XMPP "domain identifier" by converting each
      sequence of percent-encoded octets into the appropriate sequence
      of reserved or non-US-ASCII octets by (1) decoding percent-encoded
      octets into actual octets, (2) interpreting the octets as [UTF-8],
      and (3)  applying the [NAMEPREP] profile of [STRINGPREP].
   o  Transform the string of US-ASCII characters that conforms to the
      "resid" rule into an XMPP "resource identifier" by converting each
      sequence of percent-encoded octets into the appropriate sequence
      of reserved or non-US-ASCII octets by (1) decoding percent-encoded
      octets into actual octets, (2) interpreting the octets as [UTF-8],
      and (3) applying the Resourceprep profile of [STRINGPREP] as
      specified in Appendix B of [XMPP-CORE].
   o  Concatenate the following (ensuring that the resulting string is
      encoded as [UTF-8]):
      1.  the XMPP "node identifier" and the "@" character (if a string
          of US-ASCII characters that conforms to the "nodeid" rule was
          included)
      2.  the XMPP "domain identifier"
      3.  the "/" character and XMPP "resource identifier" (if a string
          of US-ASCII characters that conforms to the "resid" rule was
          included)

   At this point, the processing application would either (1) complete
   further XMPP handling itself or (2) invoke a helper application to
   complete XMPP handling; such XMPP handling would most likely consist
   of the following steps:

   1.  Authenticating either as the user specified in the authority
       component or as the configured user at the configured XMPP server
       if not already so authenticated.


Saint-Andre               Expires June 9, 2005                 [Page 12]


Internet-Draft                  XMPP-URI                   December 2004

   2.  Optionally determining the nature of the intended recipient
       (e.g., via [JEP-0030]).
   3.  Optionally presenting an appropriate interface to a user based on
       the nature of the intended recipient and/or the contents of the
       query component.
   4.  Generating an XMPP stanza that translates any user or application
       inputs into their corresponding XMPP equivalents.
   5.  Sending the XMPP stanza via the authenticated server connection
       for delivery to the intended recipient.

   Note: It may help implementors to note that the first two steps of
   the "further XMPP handling" are similar to HTTP authentication
   ([HTTP-AUTH]), while the next three steps are similar to the handling
   of mailto: URIs ([MAILTO]).

2.8.2  URI Processing Example

   Consider the XMPP URI that resulted from the previous example:

         <xmpp:ji%C5%99i@%C4%8Cechy.example/v%20Praze>

   In accordance with the process specified above, the processing
   application would do the following to extract the XMPP address from
   this XMPP URI:

   1.  Split the URI into a string of US-ASCII characters that conforms
       to the "nodeid" rule ("ji%C5%99i"), a string of US-ASCII
       characters that conforms to the "host" rule
       ("%C4%8Cechy.example"), and a string of US-ASCII characters that
       conforms to the "resid" rule ("v%20Praze").
   2.  Transform the string of US-ASCII characters that conforms to the
       "nodeid" rule into an XMPP "node identifier" by converting the
       percent-encoded representation "%C5%99" to its equivalent [UTF-8]
       character (LATIN SMALL LETTER R WITH CARON), making sure that the
       entire string is encoded as [UTF-8]; the result is an XMPP "node
       identifier" of "ji&#x159;i".
   3.  Transform the string of US-ASCII characters that conforms to the
       "host" rule into an XMPP "domain identifier" by converting the
       US-ASCII string to [UTF-8] and converting the percent-encoded
       representation "%C4%8C" to its equivalent [UTF-8] character
       (LATIN SMALL LETTER C WITH CARON), making sure that the entire
       string is encoded as [UTF-8]; the result is an XMPP "domain
       identifier" of "&#x10D;echy.example" (encoded as a [UTF-8]
       string).
   4.  Transform the string of US-ASCII characters that conforms to the
       "resid" rule into an XMPP "resource identifier" by converting the
       percent-encoded representation "%20" to its equivalent [UTF-8]
       character (SP), making sure that the entire string is encoded as


Saint-Andre               Expires June 9, 2005                 [Page 13]


Internet-Draft                  XMPP-URI                   December 2004

       [UTF-8]; the result is an XMPP "resource identifier" of "v
       Praze".
   5.  Concatenate the following (ensuring that the resulting string is
       encoded as [UTF-8]):
       1.  the XMPP "node identifier" and the "@" character
       2.  the XMPP "domain identifier"
       3.  the "/" character and the XMPP "resource identifier"

   The result is this XMPP address:

       <ji&#x159;i@&#x10D;echy.example/v Praze>

2.9  Internationalization

   Because XMPP addresses are [UTF-8] strings and because the
   non-US-ASCII octets in XMPP addresses can be easily converted to
   percent-encoded octets, XMPP addresses are designed to work well with
   Internationalized Resource Identifiers ([IRI]).  In particular, with
   the exception of stringprep verification and the conversion of
   syntax-relevant US-ASCII characters (e.g., "?"), an XMPP IRI can be
   constructed directly by prepending "xmpp:" to an XMPP address.

3.  IANA Registration of xmpp: URI Scheme

   This section provides the information required to register the xmpp:
   URI scheme.

3.1  URI scheme name

   xmpp

3.2  URI scheme syntax

   The syntax for an xmpp: URI is defined below using Augmented
   Backus-Naur Form as specified by [ABNF].  The "fragment", "host",
   "pct-encoded", "query", "sub-delims", and "unreserved" rules are
   defined in [URI].







Saint-Andre               Expires June 9, 2005                 [Page 14]


Internet-Draft                  XMPP-URI                   December 2004

      xmppuri   = "xmpp:" hier-xmpp [ "?" querycomp ] [ "#" fragment ]
      hier-xmpp = authpath / path-xmpp
      authpath  = "//" auth-xmpp [ "/" path-xmpp ]
      auth-xmpp = nodeid "@" host
      path-xmpp = [ nodeid "@" ] host [ "/" resid ]
      nodeid    = *( unreserved / pct-encoded / nodeallow )
      nodeallow = "!" / "$" / "%" / "(" / ")" / "*" / "+" / ","
                  / ";" / "=" / "^" / "`" / "{" / "|" / "}"
      resid     = *( unreserved / pct-encoded / sub-delims )
      querycomp = querytype [ *pair ]
      querytype = *( ALPHA / DIGIT / '-' / '_' / '.' / ':' )
      pair      = "&" key "=" value
      key       = *unreserved
      value     = *( unreserved / pct-encoded )

3.3  Character encoding considerations

   Prior to any conversion into a URI and in accordance with
   [XMPP-CORE], an Extensible Messaging and Presence Protocol (XMPP)
   address MUST be represented as [UTF-8] by the generating application
   (e.g., by transforming an application's internal representation of
   the address as a UTF-16 string into a UTF-8 string).  The UTF-8
   string MUST then be converted into a US-ASCII string in order to be
   included in a URI; as part of this conversion, non-US-ASCII octets
   MUST be percent-encoded as described in Section 2.1 of [URI].

3.4  Intended usage

   The xmpp: URI identifies entities that natively communicate using the
   Extensible Messaging and Presence Protocol (XMPP), and is mainly used
   for identification rather than processing.  However, an application
   that processes an xmpp: URI SHOULD reconstruct the encapsulated XMPP
   address, authenticate with the appropriate XMPP server, and send an
   appropriate XMPP "stanza" (XML fragment) to the XMPP address.  There
   is no MIME type associated with this URI.

3.5  Applications and/or protocols which use this URL scheme name

   The xmpp: URI is intended to be used by interfaces to an XMPP network
   from non-native user agents such as web browsers, as well as by
   non-native applications that need to identify XMPP entities as full
   URIs.

3.6  Security considerations

   See Security Considerations (Section 5) of XXXX.


Saint-Andre               Expires June 9, 2005                 [Page 15]


Internet-Draft                  XMPP-URI                   December 2004

3.7  Relevant publications

   [XMPP-CORE]

3.8  Person and email address to contact for further information

   Peter Saint-Andre [mailto:stpeter@jabber.org]

3.9  Author/change controller

   This scheme is registered under the IETF tree.  As such, the IETF
   maintains change control.

4.  IANA Considerations

   This document registers a URI scheme.  The registration template can
   be found in Section 3 of this document.

5.  Security Considerations

   Detailed security considerations for Uniform Resource Identifiers are
   given in [URI], and for the Extensible Messaging and Presence
   Protocol in [XMPP-CORE].  Providing an interface to XMPP services
   from non-native applications introduces new security concerns.  For
   example, the ability to interact with XMPP entities via a web browser
   may expose sensitive information to attacks that are not possible or
   that are unlikely on a native XMPP network.  Due care must be taken
   in deciding what information is appropriate for representation in
   XMPP URIs.  Care must also be taken in exposing XMPP addresses in the
   authority and path components of XMPP URIs that are publicly
   accessible.

6.  References

6.1  Normative References

   [ABNF]     Crocker, D. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", RFC 2234, November 1997.

   [TERMS]    Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [URI]      Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax",
              draft-fielding-uri-rfc2396bis-07 (work in progress),
              September 2004.

   [URL-GUIDE]


Saint-Andre               Expires June 9, 2005                 [Page 16]


Internet-Draft                  XMPP-URI                   December 2004

              Masinter, L., Alvestrand, H., Zigmond, D. and R. Petke,
              "Guidelines for new URL Schemes", RFC 2718, November 1999.

   [URL-REG]  Petke, R. and I. King, "Registration Procedures for URL
              Scheme Names", BCP 35, RFC 2717, November 1999.

   [UTF-8]    Yergeau, F., "UTF-8, a transformation format of ISO
              10646", STD 63, RFC 3629, November 2003.

   [XMPP-CORE]
              Saint-Andre, P., "Extensible Messaging and Presence
              Protocol (XMPP): Core", RFC 3920, October 2004.

   [XMPP-IM]  Saint-Andre, P., "Extensible Messaging and Presence
              Protocol (XMPP): Instant Messaging and Presence", RFC
              3921, October 2004.

6.2  Informative References

   [CPIM]     Peterson, J., "Common Profile for Instant Messaging
              (CPIM)", RFC 3860, August 2004.

   [CPP]      Peterson, J., "Common Profile for Presence (CPP)", RFC
              3859, August 2004.

   [HTML]     Raggett, D., "HTML 4.0 Specification", W3C REC
              REC-html40-19980424, April 1998.

   [HTTP-AUTH]
              Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S.,
              Leach, P., Luotonen, A. and L. Stewart, "HTTP
              Authentication: Basic and Digest Access Authentication",
              RFC 2617, June 1999.

   [IDNA]     Faltstrom, P., Hoffman, P. and A. Costello,
              "Internationalizing Domain Names in Applications (IDNA)",
              RFC 3490, March 2003.

   [IMP-MODEL]
              Day, M., Rosenberg, J. and H. Sugano, "A Model for
              Presence and Instant Messaging", RFC 2778, February 2000.

   [IMP-REQS]
              Day, M., Aggarwal, S. and J. Vincent, "Instant Messaging /
              Presence Protocol Requirements", RFC 2779, February 2000.

   [IRI]      Duerst, M. and M. Suignard, "Internationalized Resource
              Identifiers (IRIs)", draft-duerst-iri-11 (work in


Saint-Andre               Expires June 9, 2005                 [Page 17]


Internet-Draft                  XMPP-URI                   December 2004

              progress), December 2004.

   [JEP-0009]
              Adams, D., "Jabber-RPC", JSF JEP 0009, December 2002.

   [JEP-0030]
              Hildebrand, J., Millard, P., Eatmon, R. and P.
              Saint-Andre, "Service Discovery", JSF JEP 0030, July 2004.

   [JEP-0045]
              Saint-Andre, P., "Multi-User Chat", JSF JEP 0045, October
              2004.

   [JEP-0053]
              Saint-Andre, P., "Jabber Registrar", JSF JEP 0053, May
              2004.

   [JEP-0060]
              Millard, P., "Publish-Subscribe", JSF JEP 0060, July 2004.

   [JEP-0072]
              Forno, F., "SOAP Over XMPP", JSF JEP 0072, May 2004.

   [JEP-0077]
              Saint-Andre, P., "In-Band Registration", JSF JEP 0077,
              August 2004.

   [JEP-0147]
              Saint-Andre, P., "XMPP URI Query Components", JSF JEP
              0147, November 2004.

   [MAILTO]   Hoffman, P., Masinter, L. and J. Zawinski, "The mailto URL
              scheme", RFC 2368, July 1998.

   [MIME]     Freed, N. and N. Borenstein, "Multipurpose Internet Mail
              Extensions (MIME) Part Two: Media Types", RFC 2046,
              November 1996.

   [NAMEPREP]
              Hoffman, P. and M. Blanchet, "Nameprep: A Stringprep
              Profile for Internationalized Domain Names (IDN)", RFC
              3491, March 2003.

   [STRINGPREP]
              Hoffman, P. and M. Blanchet, "Preparation of
              Internationalized Strings ("STRINGPREP")", RFC 3454,
              December 2002.


Saint-Andre               Expires June 9, 2005                 [Page 18]


Internet-Draft                  XMPP-URI                   December 2004

   [US-ASCII]
              American National Standards Institute, "Coded Character
              Set - 7-bit American Standard Code for Information
              Interchange", ANSI X3.4, 1986.

Author's Address

   Peter Saint-Andre
   Jabber Software Foundation

   EMail: stpeter@jabber.org




















Saint-Andre               Expires June 9, 2005                 [Page 19]


Internet-Draft                  XMPP-URI                   December 2004

Intellectual Property Statement

   The IETF takes no position regarding the validity or scope of any
   Intellectual Property Rights or other rights that might be claimed to
   pertain to the implementation or use of the technology described in
   this document or the extent to which any license under such rights
   might or might not be available; nor does it represent that it has
   made any independent effort to identify any such rights.  Information
   on the procedures with respect to rights in RFC documents can be
   found in BCP 78 and BCP 79.

   Copies of IPR disclosures made to the IETF Secretariat and any
   assurances of licenses to be made available, or the result of an
   attempt made to obtain a general license or permission for the use of
   such proprietary rights by implementers or users of this
   specification can be obtained from the IETF on-line IPR repository at
   http://www.ietf.org/ipr.

   The IETF invites any interested party to bring to its attention any
   copyrights, patents or patent applications, or other proprietary
   rights that may cover technology that may be required to implement
   this standard.  Please address the information to the IETF at
   ietf-ipr@ietf.org.

Disclaimer of Validity

   This document and the information contained herein are provided on an
   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
   OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
   ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
   INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
   INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
   WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Copyright Statement

   Copyright (C) The Internet Society (2004).  This document is subject
   to the rights, licenses and restrictions contained in BCP 78, and
   except as set forth therein, the authors retain all their rights.

Acknowledgment

   Funding for the RFC Editor function is currently provided by the
   Internet Society.


Saint-Andre               Expires June 9, 2005                 [Page 20]


Html markup produced by rfcmarkup 1.129c, available from https://tools.ietf.org/tools/rfcmarkup/