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<pre>Network Working Group M. Mealling
Request for Comments: 3368 VeriSign, Inc.
Category: Standards Track August 2002
<span class="h1">The 'go' URI Scheme for the Common Name Resolution Protocol</span>
Status 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.
<span class="grey">Mealling Standards Track [Page 1]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-2" ></span>
<span class="grey"><a href="./rfc3368">RFC 3368</a> CNRP URI Specification August 2002</span>
Table of Contents
<a href="#section-1">1</a>. Goals . . . . . . . . . . . . . . . . . . . . . . . . . . . <a href="#page-2">2</a>
<a href="#section-2">2</a>. Terminology . . . . . . . . . . . . . . . . . . . . . . . . <a href="#page-2">2</a>
<a href="#section-3">3</a>. Syntax Rules . . . . . . . . . . . . . . . . . . . . . . . . <a href="#page-3">3</a>
<a href="#section-3.1">3.1</a> General Syntax . . . . . . . . . . . . . . . . . . . . . . . <a href="#page-3">3</a>
<a href="#section-3.2">3.2</a> ABNF Grammar . . . . . . . . . . . . . . . . . . . . . . . . <a href="#page-3">3</a>
<a href="#section-3.3">3.3</a> Special Cases and Default Values . . . . . . . . . . . . . . <a href="#page-4">4</a>
<a href="#section-3.3.1">3.3.1</a> If There is Only a Server . . . . . . . . . . . . . . . . . <a href="#page-4">4</a>
<a href="#section-3.3.2">3.3.2</a> If Server is Empty Then server=localhost . . . . . . . . . . <a href="#page-4">4</a>
<a href="#section-3.3.3">3.3.3</a> Default Port . . . . . . . . . . . . . . . . . . . . . . . . <a href="#page-4">4</a>
<a href="#section-3.4">3.4</a> Encoding Rules . . . . . . . . . . . . . . . . . . . . . . . <a href="#page-4">4</a>
<a href="#section-4">4</a>. Transport Independence . . . . . . . . . . . . . . . . . . . <a href="#page-4">4</a>
<a href="#section-5">5</a>. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . <a href="#page-4">4</a>
<a href="#section-6">6</a>. Security Considerations . . . . . . . . . . . . . . . . . . <a href="#page-5">5</a>
<a href="#section-7">7</a>. IANA Considerations . . . . . . . . . . . . . . . . . . . . <a href="#page-5">5</a>
References . . . . . . . . . . . . . . . . . . . . . . . . . <a href="#page-6">6</a>
<a href="#appendix-A">A</a>. Registration Template . . . . . . . . . . . . . . . . . . . <a href="#page-7">7</a>
Author's Address . . . . . . . . . . . . . . . . . . . . . . <a href="#page-7">7</a>
Full Copyright Statement . . . . . . . . . . . . . . . . . . <a href="#page-8">8</a>
<span class="h2"><a class="selflink" id="section-1" href="#section-1">1</a>. Goals</span>
The two goals of the CNRP [<a href="#ref-3" title=""Common Name Resolution Protocol (CNRP)"">3</a>] URI [<a href="#ref-1" title=""Uniform Resource Identifiers (URI): Generic Syntax"">1</a>] 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.
<span class="h2"><a class="selflink" id="section-2" href="#section-2">2</a>. Terminology</span>
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 in <a href="./rfc2119">RFC 2119</a> [<a href="#ref-4" title=""Key words for use in RFCs to Indicate Requirement Levels"">4</a>].
<span class="grey">Mealling Standards Track [Page 2]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-3" ></span>
<span class="grey"><a href="./rfc3368">RFC 3368</a> CNRP URI Specification August 2002</span>
<span class="h2"><a class="selflink" id="section-3" href="#section-3">3</a>. Syntax Rules</span>
<span class="h3"><a class="selflink" id="section-3.1" href="#section-3.1">3.1</a> General Syntax</span>
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 in <a href="#section-3.2">Section 3.2</a> is the only authoritative syntax definition.
go://[<host>]?[<common-name>]*[;<attribute>=[<type>,]<value>]
and
go:<common-name>*[;<attribute>=[<type>,]<value>]
<span class="h3"><a class="selflink" id="section-3.2" href="#section-3.2">3.2</a> ABNF Grammar</span>
The full ABNF [<a href="#ref-2" title=""Augmented BNF for Syntax Specifications: ABNF"">2</a>] (certain values are included by reference from <a href="./rfc2396">RFC</a>
<a href="./rfc2396">2396</a> [<a href="#ref-1" title=""Uniform Resource Identifiers (URI): Generic Syntax"">1</a>]):
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 in <a href="./rfc2396">RFC2396</a>
common-name = *(unreserved | escaped)
attribute = *(unreserved | escaped)
value = *(unreserved | escaped)
type = *(unreserved | escaped)
unreserved = // as specified in <a href="./rfc2396">RFC2396</a>
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"
<span class="grey">Mealling Standards Track [Page 3]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-4" ></span>
<span class="grey"><a href="./rfc3368">RFC 3368</a> CNRP URI Specification August 2002</span>
<span class="h3"><a class="selflink" id="section-3.3" href="#section-3.3">3.3</a> Special Cases and Default Values</span>
<span class="h4"><a class="selflink" id="section-3.3.1" href="#section-3.3.1">3.3.1</a> If There is Only a Server</span>
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.
<span class="h4"><a class="selflink" id="section-3.3.2" href="#section-3.3.2">3.3.2</a> If Server is Empty Then server=localhost</span>
If the 'server' element has no value then its value MUST be assumed
to be "localhost".
<span class="h4"><a class="selflink" id="section-3.3.3" href="#section-3.3.3">3.3.3</a> Default Port</span>
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.
<span class="h3"><a class="selflink" id="section-3.4" href="#section-3.4">3.4</a> Encoding Rules</span>
The common-name, query parameters, and parameter values must be
encoded using the UTF-8 encoding scheme [<a href="#ref-5" title="">5</a>], 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.
<span class="h2"><a class="selflink" id="section-4" href="#section-4">4</a>. Transport Independence</span>
As stated in the CNRP protocol specification [<a href="#ref-3" title=""Common Name Resolution Protocol (CNRP)"">3</a>], 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).
<span class="h2"><a class="selflink" id="section-5" href="#section-5">5</a>. Examples</span>
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.
<span class="grey">Mealling Standards Track [Page 4]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-5" ></span>
<span class="grey"><a href="./rfc3368">RFC 3368</a> CNRP URI Specification August 2002</span>
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.
<span class="h2"><a class="selflink" id="section-6" href="#section-6">6</a>. Security Considerations</span>
In addition to the security considerations inherent in CNRP itself
(see the Security Considerations section of <a href="./rfc3367">RFC 3367</a> [<a href="#ref-3" title=""Common Name Resolution Protocol (CNRP)"">3</a>]), 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.
<span class="h2"><a class="selflink" id="section-7" href="#section-7">7</a>. IANA Considerations</span>
The IANA is asked to register the URL registration template found in
<a href="#appendix-A">Appendix A</a> in accordance with <a href="./rfc2717">RFC 2717</a> [<a href="#ref-6" title=""Registration Procedures for URL Scheme Names"">6</a>].
<span class="grey">Mealling Standards Track [Page 5]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-6" ></span>
<span class="grey"><a href="./rfc3368">RFC 3368</a> CNRP URI Specification August 2002</span>
References
[<a id="ref-1">1</a>] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform Resource
Identifiers (URI): Generic Syntax", <a href="./rfc2396">RFC 2396</a>, August 1998.
[<a id="ref-2">2</a>] Crocker, D., "Augmented BNF for Syntax Specifications: ABNF",
<a href="./rfc2234">RFC 2234</a>, November 1997.
[<a id="ref-3">3</a>] Popp, N., Mealling, M. and M. Moseley, "Common Name Resolution
Protocol (CNRP)", <a href="./rfc3367">RFC 3367</a>, August 2002.
[<a id="ref-4">4</a>] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", <a href="https://www.rfc-editor.org/bcp/bcp14">BCP 14</a>, <a href="./rfc2119">RFC 2119</a>, March 1997.
[<a id="ref-5">5</a>] The Unicode Consortium, "The Unicode Standard, Version 2.0:
<a href="#appendix-A.2">Appendix A.2</a>", ISBN 0-201-48345-9, January 1988.
[<a id="ref-6">6</a>] Petke, R. and I. King, "Registration Procedures for URL Scheme
Names", <a href="https://www.rfc-editor.org/bcp/bcp35">BCP 35</a>, <a href="./rfc2717">RFC 2717</a>, November 1999.
<span class="grey">Mealling Standards Track [Page 6]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-7" ></span>
<span class="grey"><a href="./rfc3368">RFC 3368</a> CNRP URI Specification August 2002</span>
<span class="h2"><a class="selflink" id="appendix-A" href="#appendix-A">Appendix A</a>. Registration Template</span>
URL scheme name: go
URL scheme syntax: <a href="#section-3.2">Section 3.2</a>
Character encoding considerations: <a href="#section-3.4">Section 3.4</a>
Intended usage: <a href="#section-1">Section 1</a>
Applications and/or protocols which use this scheme: [<a href="#ref-3" title=""Common Name Resolution Protocol (CNRP)"">3</a>]
Interoperability considerations: None not specified in [<a href="#ref-3" title=""Common Name Resolution Protocol (CNRP)"">3</a>]
Security considerations: <a href="#section-6">Section 6</a>
Relevant publications: [<a href="#ref-3" title=""Common Name Resolution Protocol (CNRP)"">3</a>]
Contact: CNRP Working Group
Author/Change Controller: IESG
Author's Address
Michael Mealling
VeriSign, Inc.
21345 Ridgetop Circle
Dulles, VA 20170
US
Phone: (703) 742-0400
EMail: michael@verisignlabs.com
<span class="grey">Mealling Standards Track [Page 7]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-8" ></span>
<span class="grey"><a href="./rfc3368">RFC 3368</a> CNRP URI Specification August 2002</span>
Full 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]
</pre>
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