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rfc:rfc4991

Network Working Group A. Newton Request for Comments: 4991 VeriSign, Inc. Category: Standards Track August 2007

     A Common Schema for Internet Registry Information Service
                         Transfer Protocols

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 IETF Trust (2007).

Abstract

 This document describes an XML Schema for use by Internet Registry
 Information Service (IRIS) application transfer protocols that share
 common characteristics.  It describes common information about the
 transfer protocol, such as version, supported extensions, and
 supported security mechanisms.

Table of Contents

 1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  2
 2.  Document Terminology . . . . . . . . . . . . . . . . . . . . .  2
 3.  Formal XML Syntax  . . . . . . . . . . . . . . . . . . . . . .  3
 4.  Version Information  . . . . . . . . . . . . . . . . . . . . .  6
 5.  Size Information . . . . . . . . . . . . . . . . . . . . . . .  7
 6.  Authentication Success Information . . . . . . . . . . . . . .  8
 7.  Authentication Failure Information . . . . . . . . . . . . . .  8
 8.  Other Information  . . . . . . . . . . . . . . . . . . . . . .  9
 9.  Internationalization Considerations  . . . . . . . . . . . . .  9
 10. IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 10
   10.1.  XML Namespace URN Registration  . . . . . . . . . . . . . 10
 11. Security Considerations  . . . . . . . . . . . . . . . . . . . 10
 12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
   12.1.  Normative References  . . . . . . . . . . . . . . . . . . 11
   12.2.  Informative References  . . . . . . . . . . . . . . . . . 11
 Appendix A.  Contributors  . . . . . . . . . . . . . . . . . . . . 12

Newton Standards Track [Page 1] RFC 4991 Common Schema for IRIS Transfer Protocols August 2007

1. Introduction

 IRIS [8] has two transfer protocols, LWZ (lightweight using
 compression) [9] and XPC (XML pipelining with chunks) [10], that
 share common negotiation mechanisms.  Both transfer protocols have a
 need for the server to provide rich status information to clients
 during protocol negotiation.  In many cases, this status information
 would be too complex to describe using simple bit fields and length-
 specified octet sequences.  This document defines an XML Schema for
 this rich status information and describes the usage of conformant
 XML for conveying this status information.
 This document defines five types of information used in the
 negotiation of protocol capabilities: version, size, authentication
 success, authentication failure, and other information.  The version
 information is used to negotiate the versions and extensions to the
 transfer protocol, the application operations protocol, and data
 models used by the application operations.  Size information is used
 to indicate request and response size capabilities and errors.
 Authentication success and failure information is used to indicate
 the outcome of an authentication action.  Other types of information
 may also be conveyed that is generally a result of an error but
 cannot be corrected through defined protocol behavior.
 As an example, upon initiation of a connection, a server may send
 version information informing the client of the data models supported
 by the server and the security mechanisms supported by the server.
 The client may then respond appropriately.  For example, the client
 may not recognize any of the data models supported by the server, and
 therefore close the connection.  On the other hand, the client may
 recognize the data models and the security mechanisms and begin the
 procedure to initialize a security mechanism with the server before
 proceeding to query data according to a recognized data model.
 Both LWZ [9] and XPC [10] provide examples of the usage of the XML
 Schema defined in this document.

2. Document 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 in RFC 2119 [6].

Newton Standards Track [Page 2] RFC 4991 Common Schema for IRIS Transfer Protocols August 2007

3. Formal XML Syntax

 The following is the XML Schema used to define transfer protocol
 status information.  See the following specifications: [2], [3], [4],
 [5].  Updates or changes to this schema require a document that
 UPDATES or OBSOLETES this document.
 <?xml version="1.0"?>
 <schema xmlns="http://www.w3.org/2001/XMLSchema"
         xmlns:iristrans="urn:ietf:params:xml:ns:iris-transport"
         targetNamespace="urn:ietf:params:xml:ns:iris-transport"
         elementFormDefault="qualified" >
 <annotation>
   <documentation>
     A schema for describing status information
     for use by multiple transfer protocols.
   </documentation>
 </annotation>
 <element name="versions">
   <complexType>
     <sequence>
       <element name="transferProtocol" maxOccurs="unbounded">
         <complexType>
           <sequence>
             <element name="application" minOccurs="0"
               maxOccurs="unbounded">
               <complexType>
                 <sequence>
                   <element name="dataModel" minOccurs="0"
                     maxOccurs="unbounded">
                     <complexType>
                       <attribute name="protocolId" type="token"
                         use="required" />
                       <attribute name="extensionIds"
                         type="normalizedString" />
                     </complexType>
                   </element>
                 </sequence>
                 <attribute name="protocolId" type="token"
                   use="required" />
                 <attribute name="extensionIds"
                   type="normalizedString" />
               </complexType>
             </element>
           </sequence>
           <attribute name="protocolId" type="token" use="required"

Newton Standards Track [Page 3] RFC 4991 Common Schema for IRIS Transfer Protocols August 2007

             />
           <attribute name="extensionIds" type="normalizedString" />
           <attribute name="authenticationIds"
             type="normalizedString" />
           <attribute name="responseSizeOctets"
             type="positiveInteger" />
           <attribute name="requestSizeOctets"
             type="positiveInteger" />
         </complexType>
       </element>
     </sequence>
   </complexType>
 </element>
 <element name="size">
   <complexType>
     <sequence>
       <element name="request"
         minOccurs="0"
         type="iristrans:octetsType" />
       <element name="response"
         minOccurs="0"
         type="iristrans:octetsType" />
     </sequence>
   </complexType>
 </element>
 <complexType name="octetsType">
   <choice>
     <element name="exceedsMaximum">
       <complexType/>
     </element>
     <element name="octets" type="positiveInteger" />
   </choice>
 </complexType>
 <element name="authenticationSuccess">
   <complexType>
     <sequence>
       <element name="description" minOccurs="0"
         maxOccurs="unbounded">
         <complexType>
           <simpleContent>
             <extension base="string">
               <attribute name="language" type="language"
                 use="required"/>
             </extension>
           </simpleContent>

Newton Standards Track [Page 4] RFC 4991 Common Schema for IRIS Transfer Protocols August 2007

         </complexType>
       </element>
       <element name="data" minOccurs="0" maxOccurs="1"
         type="base64Binary"/>
     </sequence>
   </complexType>
 </element>
 <element name="authenticationFailure">
   <complexType>
     <sequence>
       <element name="description" minOccurs="0"
         maxOccurs="unbounded">
         <complexType>
           <simpleContent>
             <extension base="string">
               <attribute name="language" type="language"
                 use="required"/>
             </extension>
           </simpleContent>
         </complexType>
       </element>
     </sequence>
   </complexType>
 </element>
 <element name="other">
   <complexType>
     <sequence>
       <element name="description" minOccurs="0"
         maxOccurs="unbounded">
         <complexType>
           <simpleContent>
             <extension base="string">
               <attribute name="language" type="language"
                 use="required"/>
             </extension>
           </simpleContent>
         </complexType>
       </element>
     </sequence>
     <attribute type="token" name="type" use="required"/>
   </complexType>
 </element>
 </schema>

Newton Standards Track [Page 5] RFC 4991 Common Schema for IRIS Transfer Protocols August 2007

4. Version Information

 The <versions> element is used to describe version information about
 the transfer protocol, the application protocol, and data models used
 by the application protocol.
 The <versions> element has one or more <transferProtocol> child
 elements. <transferProtocol> elements have zero or more <application>
 child elements.  And <application> elements have zero or more
 <dataModel> elements.  Each of these element types has a 'protocolId'
 attribute identifying the protocol they represent and an optional
 'extensionIds' attribute identifying the protocol extensions they
 support.
 During capabilities negotiation, it is expected that both sides of
 the negotiation recognize the 'protocolId' value of the
 <transferProtocol> element and at least one of the <application> and
 <dataModel> elements.  If the negotiation produces a situation where
 this is not possible, an error SHOULD be given and communication
 ended.  It is not expected that each side must recognize the
 'extensionIds' values, and unrecognized 'extensionIds' values MUST be
 ignored.
 Additionally, the <transferProtocol> element has optional
 'authenticationIds', 'responseSizeOctets', and 'requestSizeOctets'
 attributes.  The 'authenticationIds' attribute identifies
 authentication mechanisms supported by the associated transfer
 protocol.  The 'responseSizeOctets' attribute describes the maximum
 response size in octets the server will give.  The
 'requestSizeOctets' attribute describes the maximum request size in
 octets the server will accept.
 The protocol, extension, and authentication mechanism identifiers are
 of no specific type, and this document defines none.  Specifications
 using this XML Schema MUST define the identifiers for use with the
 <versions> element and its children.
 The meaning of octets for the transfer of data is counted in
 different ways for different transfer protocols.  Some transfer
 protocols need only to specify the octets of the data being
 transferred, while other transfer protocols need to account for
 additional octets used to transfer the data.  Specifications using
 this XML Schema MUST describe how these octet counts are calculated.

Newton Standards Track [Page 6] RFC 4991 Common Schema for IRIS Transfer Protocols August 2007

 The following is example XML describing version information.
 <versions xmlns="urn:ietf:params:xml:ns:iris-transport">
   <transferProtocol protocolId="iris.lwz"
     authenticationIds="PLAIN EXTERNAL">
     <application protocolId="urn:ietf:params:xml:ns:iris1"
       extensionIds="http://example.com/SIMPLEBAG">
       <dataModel protocolId="urn:ietf:params:xml:ns:dchk1"/>
       <dataModel protocolId="urn:ietf:params:xml:ns:dreg1"/>
     </application>
   </transferProtocol>
 </versions>
                      Version Information Example

5. Size Information

 The <size> element provides a means for a server to communicate to a
 client that a given request has exceeded a negotiated size
 (<request>) or that a response to a given request will exceed a
 negotiated size (<response>).
 A server may indicate one of two size conditions by specifying the
 following child elements:
    <exceedsMaximum> - this child element simply indicates that the
    size exceeded the negotiated size.
    <octets> - this child element indicates that the size exceeded the
    negotiated size and conveys the number of octets that is the
    maximum for a request if the parent element is a <request> element
    or the number of octets needed to provide the response if the
    parent element is a <response> element.
 The meaning of octets for the transfer of data is counted in
 different ways for different transfer protocols.  Some transfer
 protocols need only to specify the octets of the data being
 transferred, while other transfer protocols need to account for
 additional octets used to transfer the data.  Specifications using
 this XML Schema MUST describe how these octet counts are calculated.
 The following is example XML describing size information.
 <size xmlns="urn:ietf:params:xml:ns:iris-transport">
   <response>
     <octets>1211</octets>
   </response>
 </size>

Newton Standards Track [Page 7] RFC 4991 Common Schema for IRIS Transfer Protocols August 2007

                       Size Information Example

6. Authentication Success Information

 The <authenticationSuccess> element indicates that a client has
 successfully authenticated to a server.  Along with this indication,
 it can provide text that may be presented to a user with regard to
 this successful authentication using child <description> elements.
 Each <description> element MUST have a 'language' attribute
 describing the language of the content of the <description> element.
 Clients are not expected to concatenate multiple descriptions;
 therefore, servers MUST NOT provide multiple <description> elements
 with the same language descriptor.
 Finally, additional security data may be sent back with the
 authentication success message using the <data> element.  The content
 of this element is of the base64Binary simple type.
 The following is example XML describing authentication success
 information.
 <authenticationSuccess
   xmlns="urn:ietf:params:xml:ns:iris-transport">
   <description language="en">
     user 'bob' authenticates via password
   </description>
 </authenticationSuccess>
                    Authentication Success Example

7. Authentication Failure Information

 The <authenticationFailure> element indicates that a client has
 failed to properly authenticate to a server.  Along with this
 indication, it can provide text that may be presented to a user with
 regard to this authentication failure using child <description>
 elements.
 Each <description> element MUST have a 'language' attribute
 describing the language of the content of the <description> element.
 Clients are not expected to concatenate multiple descriptions;
 therefore, servers MUST NOT provide multiple <description> elements
 with the same language descriptor.
 The following is example XML describing authentication failure
 information.

Newton Standards Track [Page 8] RFC 4991 Common Schema for IRIS Transfer Protocols August 2007

 <authenticationFailure
   xmlns="urn:ietf:params:xml:ns:iris-transport">
   <description language="en">
     please consult your admin if you have forgotten your password
   </description>
 </authenticationFailure>
                    Authentication Failure Example

8. Other Information

 The <other> element conveys status information that may require
 interpretation by a human to be meaningful.  This element has a
 required 'type' attribute, which contains an identifier regarding the
 nature of the information.  This document does not define any
 identifiers for use in this attribute, but the intent is that these
 identifiers are well-known so that clients may take different classes
 of action based on the content of this attribute.  Therefore,
 specifications making use of this XML Schema MUST define these
 identifiers.
 The <other> element may have zero or more <description> elements.
 Each <description> element MUST have a 'language' attribute
 describing the language of the content of the <description> element.
 Servers may use these child elements to convey textual information to
 clients regarding the class (or type) of status information being
 specified by the <other> element.  Clients are not expected to
 concatenate multiple descriptions; therefore, servers MUST NOT
 provide multiple <description> elements with the same language
 descriptor.
 The following is example XML describing other information.
 <other xmlns="urn:ietf:params:xml:ns:iris-transport" type="system">
   <description language="en">unavailable, come back
     later</description>
 </other>
                       Other Information Example

9. Internationalization Considerations

 XML processors are obliged to recognize both UTF-8 and UTF-16 [1]
 encodings.  XML provides for mechanisms to identify and use other
 character encodings.  Application transfer protocols MUST define
 which additional character encodings, if any, are to be allowed in
 the use of the XML defined in this document.

Newton Standards Track [Page 9] RFC 4991 Common Schema for IRIS Transfer Protocols August 2007

10. IANA Considerations

10.1. XML Namespace URN Registration

 This document makes use of the XML namespace and schema registry
 specified in XML_URN [7].  Accordingly, the following registrations
 have been made by IANA:
 o  XML Namespace URN/URI:
  • urn:ietf:params:xml:ns:iris-transport
 o  Contact:
 o  XML:
  • None
 o  XML Schema URN/URI:
  • urn:ietf:params:xml:schema:iris-transport
 o  Contact:
 o  XML:
  • The XML Schema specified in Section 3

11. Security Considerations

 Transfer protocols using XML conformant to the XML Schema in this
 document and offering security properties such as authentication and
 confidentiality SHOULD offer an initial message from the server to
 the client using the <versions> element.  This <versions> element
 SHOULD contain all relevant authentication identifiers in its
 'authenticationId' attribute.  The purpose of providing this initial
 message is to help thwart downgrade attacks.

Newton Standards Track [Page 10] RFC 4991 Common Schema for IRIS Transfer Protocols August 2007

12. References

12.1. Normative References

 [1]   The Unicode Consortium, "The Unicode Standard, Version 3", ISBN
       0-201-61633-5, 2000, <The Unicode Standard, Version 3>.
 [2]   World Wide Web Consortium, "Extensible Markup Language (XML)
       1.0", W3C XML, February 1998, <http://www.w3.org/TR/1998/REC-
       xml-19980210>.
 [3]   World Wide Web Consortium, "Namespaces in XML", W3C XML
       Namespaces, January 1999, <http://www.w3.org/TR/1999/REC-xml-
       names-19990114>.
 [4]   World Wide Web Consortium, "XML Schema Part 2: Datatypes", W3C
       XML Schema, October 2004, <http://www.w3.org/TR/xmlschema-2/>.
 [5]   World Wide Web Consortium, "XML Schema Part 1: Structures", W3C
       XML Schema, October 2004, <http://www.w3.org/TR/xmlschema-1/>.
 [6]   Bradner, S., "Key words for use in RFCs to Indicate Requirement
       Levels", RFC 2119, BCP 14, March 1997.
 [7]   Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
       January 2004.

12.2. Informative References

 [8]   Newton, A. and M. Sanz, "IRIS: The Internet Registry
       Information Service (IRIS) Core Protocol", RFC 3981, January
       2005.
 [9]   Newton, A., "A Lightweight UDP Transfer Protocol for the
       Internet Registry Information Service", RFC 4993, August 2007.
 [10]  Newton, A., "XML Pipelining with Chunks for the Internet
       Registry Information Service", RFC 4992, August 2007.

Newton Standards Track [Page 11] RFC 4991 Common Schema for IRIS Transfer Protocols August 2007

Appendix A. Contributors

 Substantive contributions to this document have been provided by the
 members of the IETF's CRISP Working Group, especially Robert
 Martin-Legene, Milena Caires, and David Blacka.

Author's Address

 Andrew L. Newton
 VeriSign, Inc.
 21345 Ridgetop Circle
 Sterling, VA  20166
 USA
 Phone: +1 703 948 3382
 EMail: andy@hxr.us
 URI:   http://www.verisignlabs.com/

Newton Standards Track [Page 12] RFC 4991 Common Schema for IRIS Transfer Protocols August 2007

Full Copyright Statement

 Copyright (C) The IETF Trust (2007).
 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.
 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, THE IETF TRUST 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.

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 Intellectual Property Rights or other rights that might be claimed to
 pertain to the implementation or use of the technology described in
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 might or might not be available; nor does it represent that it has
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Acknowledgement

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

Newton Standards Track [Page 13]

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