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Network Working Group                                        M. MeallingRequest for Comments: 3368                                VeriSign, Inc.Category: Standards Track                                    August 2002The 'go' URI Scheme for the Common Name Resolution ProtocolStatus of this Memo   This document specifies an Internet standards track protocol for the   Internet community, and requests discussion and suggestions for   improvements.  Please refer to the current edition of the "Internet   Official Protocol Standards" (STD 1) for the standardization state   and status of this protocol.  Distribution of this memo is unlimited.Copyright Notice   Copyright (C) The Internet Society (2002).  All Rights Reserved.Abstract   This document defines a URI scheme, 'go:' to be used with the Common   Name Resolution Protocol.  Specifically it lays out the syntactic   components and how those components are used by URI Resolution to   find the available transports for a CNRP service.  Care should be   taken with several of the URI components because, while they may look   like components found in other URI schemes, they often do not act   like them.  The "go" scheme has more in common with the location   independent "news" scheme than any other URI scheme.Mealling                    Standards Track                     [Page 1]

RFC 3368                CNRP URI Specification               August 2002Table of Contents1.    Goals  . . . . . . . . . . . . . . . . . . . . . . . . . . .22.    Terminology  . . . . . . . . . . . . . . . . . . . . . . . .23.    Syntax Rules . . . . . . . . . . . . . . . . . . . . . . . .33.1   General Syntax . . . . . . . . . . . . . . . . . . . . . . .33.2   ABNF Grammar . . . . . . . . . . . . . . . . . . . . . . . .33.3   Special Cases and Default Values . . . . . . . . . . . . . .43.3.1 If There is Only a Server  . . . . . . . . . . . . . . . . .43.3.2 If Server is Empty Then server=localhost . . . . . . . . . .43.3.3 Default Port . . . . . . . . . . . . . . . . . . . . . . . .43.4   Encoding Rules . . . . . . . . . . . . . . . . . . . . . . .44.    Transport Independence . . . . . . . . . . . . . . . . . . .45.    Examples . . . . . . . . . . . . . . . . . . . . . . . . . .46.    Security Considerations  . . . . . . . . . . . . . . . . . .57.    IANA Considerations  . . . . . . . . . . . . . . . . . . . .5         References . . . . . . . . . . . . . . . . . . . . . . . . .6A.    Registration Template  . . . . . . . . . . . . . . . . . . .7         Author's Address . . . . . . . . . . . . . . . . . . . . . .7         Full Copyright Statement . . . . . . . . . . . . . . . . . .81. Goals   The two goals of the CNRP [3] URI [1] are to identify both a specific   common-name record at a specific server and to identify a possibly   dynamic query or entry point into the query process.  Since CNRP   requires that the ID be a core query term, these two cases can be   generalized down to simply specifying a query that contains only the   ID of the item.   On first glance it would seem a simple enough exercise to   canonicalize the XML encoded query and then insert it into the query   portion of the URL.  The problem here is that, due to the encoding   rules, any remotely complex query will quickly blow out the URI   length limitations.  The suggested solution is to provide a   simplified query syntax that is a subset of what is available via the   XML.2. Terminology   The 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 inRFC 2119 [4].Mealling                    Standards Track                     [Page 2]

RFC 3368                CNRP URI Specification               August 20023. Syntax Rules3.1 General Syntax   The CNRP URI comes in two forms.  The first form is for talking to a   specific server.  The second form is for expressing a query that is   meant to be sent to several different CNRP services.  The following   two examples are for pedagogical purposes only.  The complete ABNF   grammar inSection 3.2 is the only authoritative syntax definition.   go://[<host>]?[<common-name>]*[;<attribute>=[<type>,]<value>]   and   go:<common-name>*[;<attribute>=[<type>,]<value>]3.2 ABNF Grammar   The full ABNF [2] (certain values are included by reference fromRFC2396 [1]):   cnrp-uri      = "go:" (form1 / form2)   form1         = "//" [server] ["?" ((common-name *avpair) / id-req) ]   form2         = common-name *avpair   id-req        = "id=" value   avpair        = ";" attribute "=" [ type "," ] value   server        = // as specified inRFC2396   common-name     = *(unreserved | escaped)   attribute       = *(unreserved | escaped)   value           = *(unreserved | escaped)   type            = *(unreserved | escaped)   unreserved      = // as specified inRFC2396   escaped       = "%" hex hex   hex           = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" |                   "8" | "9" | "A" | "B" | "C" | "D" | "E" | "F" |                   "a" | "b" | "c" | "d" | "e" | "f"Mealling                    Standards Track                     [Page 3]

RFC 3368                CNRP URI Specification               August 20023.3 Special Cases and Default Values3.3.1 If There is Only a Server   In the case where the CNRP URI contains only the server production   then the URI identifies a given CNRP server, not any particular query   that is to be done.  A client can assume that this server will at   least answer the 'servicequery' request.3.3.2 If Server is Empty Then server=localhost   If the 'server' element has no value then its value MUST be assumed   to be "localhost".3.3.3 Default Port   CNRP's well known HTTP transport port is 1096.  If the port value   portion of the server production is not specified then port 1096   SHOULD be used if the client has no prior knowledge about other ports   or transports that the service may support.3.4 Encoding Rules   The common-name, query parameters, and parameter values must be   encoded using the UTF-8 encoding scheme [5], and any octet that is   not one of the permitted characters per the above grammar MUST   instead be represented by a "%" followed by two characters from the   <hex> character set above.  The two characters give the hexadecimal   representation of that octet.4. Transport Independence   As stated in the CNRP protocol specification [3], CNRP is allowed to   be expressed over multiple transport protocols with HTTP being   mandatory to implement.  In the case where a client attempts to   resolve a CNRP URI and it knows nothing about the service being   referenced in that URI, then it SHOULD use HTTP on the CNRP default   port (1096).5. Examples   go:Mercedes%20Benz      This example shows a general query for the common-name "Mercedes      Benz".  The intent is that the query should be packaged with any      client provided defaults and sent to the one or more services that      the client has configured to ask.Mealling                    Standards Track                     [Page 4]

RFC 3368                CNRP URI Specification               August 2002   go://?Mercedes%20Benz      This example shows a general query for the common-name "Mercedes      Benz" that is sent to the server running on the 'localhost'.   go://cnrp.foo.com?Mercedes%20Benz;geography=US-ga      This example shows a query for the common-name "Mercedes Benz" in      the geographic area "US-ga" which should be sent to the server      found at cnrp.foo.com.   go://cnrp.foo.org?Martin%20J.%20D%C3%BCrst      This example includes a UTF-8 character encoded using hex      escaping.  The value encoded is a u-umlaut (a 'u' with two dots      over it).  This simple query is sent to a server found at      cnrp.foo.org with no parameters.   go://cnrp.foo.com?id=5432345      Here only an id is given which means that his example points      directly at a particular common-name record on a particular      server.  This example would probably be found in a link on a web      page of some type.6. Security Considerations   In addition to the security considerations inherent in CNRP itself   (see the Security Considerations section ofRFC 3367 [3]), the URI   mechanism can also be used to retrieve a URI identifying some other   site by including just the ID and not the common-name being linked   to.  I.e., the user may think he/she is being shown the URI currently   mapped to the "BMW" common-name but in the case where only the ID is   used the actual common-name is not part of the URI, thus making it   possible to use a CNRP URI without knowing which common-name it is   referring to.7. IANA Considerations   The IANA is asked to register the URL registration template found inAppendix A in accordance withRFC 2717 [6].Mealling                    Standards Track                     [Page 5]

RFC 3368                CNRP URI Specification               August 2002References   [1]  Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform Resource        Identifiers (URI): Generic Syntax",RFC 2396, August 1998.   [2]  Crocker, D., "Augmented BNF for Syntax Specifications: ABNF",RFC 2234, November 1997.   [3]  Popp, N., Mealling, M. and M. Moseley, "Common Name Resolution        Protocol (CNRP)",RFC 3367, August 2002.   [4]  Bradner, S., "Key words for use in RFCs to Indicate Requirement        Levels",BCP 14,RFC 2119, March 1997.   [5]  The Unicode Consortium, "The Unicode Standard, Version 2.0:Appendix A.2", ISBN 0-201-48345-9, January 1988.   [6]  Petke, R. and I. King, "Registration Procedures for URL Scheme        Names",BCP 35,RFC 2717, November 1999.Mealling                    Standards Track                     [Page 6]

RFC 3368                CNRP URI Specification               August 2002Appendix A. Registration Template   URL scheme name: go   URL scheme syntax:Section 3.2   Character encoding considerations:Section 3.4   Intended usage:Section 1   Applications and/or protocols which use this scheme: [3]   Interoperability considerations: None not specified in [3]   Security considerations:Section 6   Relevant publications: [3]   Contact: CNRP Working Group   Author/Change Controller: IESGAuthor's Address   Michael Mealling   VeriSign, Inc.   21345 Ridgetop Circle   Dulles, VA  20170   US   Phone: (703) 742-0400   EMail: michael@verisignlabs.comMealling                    Standards Track                     [Page 7]

RFC 3368                CNRP URI Specification               August 2002Full Copyright Statement   Copyright (C) The Internet Society (2002).  All Rights Reserved.   This document and translations of it may be copied and furnished to   others, and derivative works that comment on or otherwise explain it   or assist in its implementation may be prepared, copied, published   and distributed, in whole or in part, without restriction of any   kind, provided that the above copyright notice and this paragraph are   included on all such copies and derivative works.  However, this   document itself may not be modified in any way, such as by removing   the copyright notice or references to the Internet Society or other   Internet organizations, except as needed for the purpose of   developing Internet standards in which case the procedures for   copyrights defined in the Internet Standards process must be   followed, or as required to translate it into languages other than   English.   The limited permissions granted above are perpetual and will not be   revoked by the Internet Society or its successors or assigns.   This document and the information contained herein is provided on an   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING   TASK FORCE DISCLAIMS 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.Acknowledgement   Funding for the RFC Editor function is currently provided by the   Internet Society.Mealling                    Standards Track                     [Page 8]