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PROPOSED STANDARD
Errata Exist
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





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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].









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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"



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               />
             <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>



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           </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>





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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.








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   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>



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                         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.




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   <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.




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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:

      *  Andrew Newton <andy@hxr.us>

   o  XML:

      *  None

   o  XML Schema URN/URI:

      *  urn:ietf:params:xml:schema:iris-transport

   o  Contact:

      *  Andrew Newton <andy@hxr.us>

   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.










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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.













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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/


































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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
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Acknowledgement

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







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