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rfc:rfc3730

Network Working Group S. Hollenbeck Request for Comments: 3730 VeriSign, Inc. Category: Standards Track March 2004

               Extensible Provisioning Protocol (EPP)

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 (2004).  All Rights Reserved.

Abstract

 This document describes an application layer client-server protocol
 for the provisioning and management of objects stored in a shared
 central repository.  Specified in XML, the protocol defines generic
 object management operations and an extensible framework that maps
 protocol operations to objects.  This document includes a protocol
 specification, an object mapping template, and an XML media type
 registration.

Table of Contents

 1.  Introduction. . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Conventions Used in This Document . . . . . . . . . . .   3
 2.  Protocol Description. . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Transport Mapping Considerations. . . . . . . . . . . .   6
     2.2.  Protocol Identification . . . . . . . . . . . . . . . .   7
     2.3.  Hello Format. . . . . . . . . . . . . . . . . . . . . .   7
     2.4.  Greeting Format . . . . . . . . . . . . . . . . . . . .   8
     2.5.  Command Format. . . . . . . . . . . . . . . . . . . . .  11
     2.6.  Response Format . . . . . . . . . . . . . . . . . . . .  12
     2.7.  Protocol Extension Framework. . . . . . . . . . . . . .  16
           2.7.1.  Protocol Extension. . . . . . . . . . . . . . .  16
           2.7.2.  Object Extension. . . . . . . . . . . . . . . .  17
           2.7.3.  Command-Response Extension. . . . . . . . . . .  18
     2.8.  Object Identification . . . . . . . . . . . . . . . . .  19
     2.9.  Protocol Commands . . . . . . . . . . . . . . . . . . .  19
           2.9.1.  Session Management Commands . . . . . . . . . .  20
                   2.9.1.1.  EPP <login> Command . . . . . . . . .  20

Hollenbeck Standards Track [Page 1] RFC 3730 EPP March 2004

                   2.9.1.2.  EPP <logout> Command. . . . . . . . .  22
           2.9.2.  Query Commands. . . . . . . . . . . . . . . . .  23
                   2.9.2.1.  EPP <check> Command . . . . . . . . .  24
                   2.9.2.2.  EPP <info> Command. . . . . . . . . .  26
                   2.9.2.3.  EPP <poll> Command. . . . . . . . . .  27
                   2.9.2.4.  EPP <transfer> Query Command. . . . .  32
           2.9.3.  Object Transform Commands . . . . . . . . . . .  34
                   2.9.3.1.  EPP <create> Command. . . . . . . . .  34
                   2.9.3.2.  EPP <delete> Command. . . . . . . . .  35
                   2.9.3.3.  EPP <renew> Command . . . . . . . . .  37
                   2.9.3.4.  EPP <transfer> Command. . . . . . . .  38
                   2.9.3.5.  EPP <update> Command. . . . . . . . .  41
 3.  Result Codes. . . . . . . . . . . . . . . . . . . . . . . . .  42
 4.  Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . .  48
     4.1.  Base Schema . . . . . . . . . . . . . . . . . . . . . .  49
     4.2.  Shared Structure Schema . . . . . . . . . . . . . . . .  58
 5.  Internationalization Considerations . . . . . . . . . . . . .  60
 6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  61
 7.  Security Considerations . . . . . . . . . . . . . . . . . . .  62
 8.  Acknowledgements. . . . . . . . . . . . . . . . . . . . . . .  62
 9.  References. . . . . . . . . . . . . . . . . . . . . . . . . .  63
     9.1.  Normative References. . . . . . . . . . . . . . . . . .  63
     9.2.  Informative References. . . . . . . . . . . . . . . . .  64
 Appendix A: Object Mapping Template . . . . . . . . . . . . . . .  65
 Appendix B: Media Type Registration: application/epp+xml. . . . .  67
 Author's Address. . . . . . . . . . . . . . . . . . . . . . . . .  68
 Full Copyright Statement. . . . . . . . . . . . . . . . . . . . .  69

1. Introduction

 This document describes specifications for the Extensible
 Provisioning Protocol (EPP) version 1.0, an XML text protocol that
 permits multiple service providers to perform object provisioning
 operations using a shared central object repository.  EPP is
 specified using the Extensible Markup Language (XML) 1.0 as described
 in [XML] and XML Schema notation as described in [XMLS-1] and [XMLS-
 2].  EPP meets and exceeds the requirements for a generic registry
 registrar protocol as described in [RFC3375].
 EPP content is identified by MIME media type application/epp+xml.
 Registration information for this media type is included in an
 appendix to this document.
 EPP is intended for use in diverse operating environments where
 transport and security requirements vary greatly.  It is unlikely
 that a single transport or security specification will meet the needs
 of all anticipated operators, so EPP was designed for use in a

Hollenbeck Standards Track [Page 2] RFC 3730 EPP March 2004

 layered protocol environment.  Bindings to specific transport and
 security protocols are outside the scope of this specification.
 This original motivation for this protocol was to provide a standard
 Internet domain name registration protocol for use between domain
 name registrars and domain name registries.  This protocol provides a
 means of interaction between a registrar's applications and registry
 applications.  It is expected that this protocol will have additional
 uses beyond domain name registration.
 XML is case sensitive.  Unless stated otherwise, XML specifications
 and examples provided in this document MUST be interpreted in the
 character case presented to develop a conforming implementation.

1.1. Conventions Used In This Document

 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 [RFC2119].
 In examples, "C:" represents lines sent by a protocol client and "S:"
 represents lines returned by a protocol server.  Indentation and
 white space in examples is provided only to illustrate element
 relationships and is not a REQUIRED feature of this protocol.

2. Protocol Description

 EPP is a stateful XML protocol that can be layered over multiple
 transport protocols.  Protected using lower-layer security protocols,
 clients exchange identification, authentication, and option
 information, and then engage in a series of client-initiated
 command-response exchanges.  All EPP commands are atomic (there is no
 partial success or partial failure) and designed so that they can be
 made idempotent (executing a command more than once has the same net
 effect on system state as successfully executing the command once).
 EPP provides four basic service elements: service discovery,
 commands, responses, and an extension framework that supports
 definition of managed objects and the relationship of protocol
 requests and responses to those objects.
 An EPP server MUST respond to client-initiated communication (which
 can be either a lower-layer connection request or an EPP service
 discovery message) by returning a greeting to a client.  A server
 MUST promptly respond to each EPP command with a coordinated response
 that describes the results of processing the command.  The following
 server state machine diagram illustrates the message exchange process
 in detail:

Hollenbeck Standards Track [Page 3] RFC 3730 EPP March 2004

         |
         V
 +-----------------+                  +-----------------+
 |   Waiting for   |     Connected    |     Prepare     |
 |      Client     |----------------->|     Greeting    |
 +-----------------+    or <hello>    +-----------------+
    ^                                           |
    | Close Connection                     Send |
    |     or Idle                      Greeting |
 +-----------------+                            V
 |       End       |     Timeout      +-----------------+
 |     Session     |<-----------------|   Waiting for   |
 +-----------------+                  |      Client     |
    ^    ^    ^        Send +-------->|  Authentication |
    |    |    |    Response |         +-----------------+
    |    |    |     +--------------+            |
    |    |    |     | Prepare Fail |            | <login>
    |    |    +-----|   Response   |            | Received
    |    |    Send  +--------------+            V
    |    |    2501          ^         +-----------------+
    |    |   Response       |         |   Processing    |
    |    |                  +---------|     <login>     |
    |    |                  Auth Fail +-----------------+
    |    |                                       |
    |    |                                       | Auth OK
    |    |                                       V
    |    |              Timeout       +-----------------+
    |    +----------------------------|   Waiting for   |
    |                                 |     Command     |
    | Send x5xx                       +-----------------+
    | Response  +-----------------+  Send    ^  |
    +-----------|     Prepare     | Response |  | Command
                |     Response    |----------+  | Received
                +-----------------+             V
                           ^          +-----------------+
                   Command |          |   Processing    |
                 Processed +----------|     Command     |
                                      +-----------------+
             Figure 1: EPP Server State Machine
 EPP commands fall into three categories: session management commands,
 query commands, and data transform commands.  Session management
 commands are used to establish and end persistent sessions with an
 EPP server.  Query commands are used to perform read-only object
 information retrieval operations.  Transform commands are used to
 perform read-write object management operations.

Hollenbeck Standards Track [Page 4] RFC 3730 EPP March 2004

 Commands are processed by a server in the order they are received
 from a client.  Though an immediate response confirming receipt and
 processing of the command is produced by the server, the protocol
 includes features that allow for offline review of transform commands
 before the requested action is actually completed.  In such
 situations the response from the server MUST clearly note that the
 command has been received and processed, but the requested action is
 pending.  The state of the corresponding object MUST clearly reflect
 processing of the pending action.  The server MUST also notify the
 client when offline processing of the action has been completed.
 Object mappings SHOULD describe standard formats for notices that
 describe completion of offline processing.
 EPP uses XML namespaces to provide an extensible object management
 framework and to identify schemas required for XML instance parsing
 and validation.  These namespaces and schema definitions are used to
 identify both the base protocol schema and the schemas for managed
 objects.  The specific strings used to associate URIs and namespaces
 (such as the string "foo" in "xmlns:foo") in EPP are illustrative and
 are not needed for interoperability.
 All XML instances SHOULD begin with an <?xml?> declaration to
 identify the version of XML that is being used, optionally identify
 use of the character encoding used, and optionally provide a hint to
 an XML parser that an external schema file is needed to validate the
 XML instance.  Conformant XML parsers recognize both UTF-8 (defined
 in RFC 2279 [RFC2279]) and UTF-16 (defined in RFC 2781 [RFC2781]);
 per RFC 2277 [RFC2277] UTF-8 is the RECOMMENDED character encoding
 for use with EPP.
 Character encodings other than UTF-8 and UTF-16 are allowed by XML.
 UTF-8 is the default encoding assumed by XML in the absence of an
 "encoding" attribute or a byte order mark (BOM), thus the "encoding"
 attribute in the XML declaration is OPTIONAL if UTF-8 encoding is
 used.
 Normative section 4.3.3 and non-normative appendix F of [XML]
 describe use of a BOM to identify the character encoding in the
 absence of an XML declaration or encapsulating headers.  Appendix F
 includes a BOM to represent UTF-8 encoding, though section 4.3.3
 notes that a BOM is not needed to identify UTF-8 encoding.  Section
 4.3.3 was later amended (see [XMLE]) to clarify that a BOM MAY be
 used to identify UTF-8 encoding.  EPP clients and servers MUST accept
 a UTF-8 BOM if present, though emitting a UTF-8 BOM is NOT
 RECOMMENDED.

Hollenbeck Standards Track [Page 5] RFC 3730 EPP March 2004

 Example XML declarations:
 <?xml version="1.0" encoding="UTF-8" standalone="no"?>
 <?xml version="1.0" standalone="no"?>
 <?xml version="1.0" encoding="UTF-8"?>
 <?xml version="1.0"?>

2.1. Transport Mapping Considerations

 As described previously, EPP can be layered over multiple transport
 protocols.  There are, however, a common set of considerations that
 MUST be addressed by any transport mapping defined for EPP.  These
 include:
  1. The transport mapping MUST preserve command order.
  1. The transport mapping MUST address the relationship between

sessions and the client-server connection concept.

  1. The transport mapping MUST preserve the stateful nature of the

protocol.

  1. The transport mapping MUST frame data units.
  1. The transport mapping MUST be onto a transport such as TCP

[RFC793] or SCTP [RFC2960] that provides congestion avoidance that

    follows RFC 2914 [RFC2914], or if it maps onto a protocol such as
    SMTP [RFC2821] or BEEP [RFC3080], then the performance issues need
    to take into account issues of overload, server availability and
    so forth.
  1. The transport mapping MUST ensure reliability.
  1. The transport mapping MUST explicitly allow or prohibit

pipelining.

 Pipelining, also known as command streaming, is when a client sends
 multiple commands to a server without waiting for each corresponding
 response.  After sending the commands, the client waits for the
 responses to arrive in the order corresponding to the completed
 commands.  Performance gains can sometimes be realized with
 pipelining, especially with high latency transports, but there are
 additional considerations associated with defining a transport
 mapping that supports pipelining:

Hollenbeck Standards Track [Page 6] RFC 3730 EPP March 2004

  1. Commands MUST be processed independent of each other.
  1. Depending on the transport, pipelining MAY be possible in the form

of sending a complete session in a well-defined "batch".

  1. The transport mapping MUST describe how an error in processing a

command affects continued operation of the session.

 A transport mapping MUST explain how all of these requirements are
 met given the transport protocol being used to exchange data.

2.2. Protocol Identification

 All EPP XML instances MUST begin with an <epp> element.  This element
 identifies the start of an EPP protocol element, the namespace used
 within the protocol, and the location of the protocol schema.  The
 <epp> start element and the associated </epp> ending element MUST be
 applied to all structures sent by both clients and servers.
 Example "start" and "end" EPP elements:
 <epp xmlns="urn:ietf:params:xml:ns:epp-1.0"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:schemaLocation="urn:ietf:params:xml:ns:epp-1.0
      epp-1.0.xsd">
 </epp>

2.3. Hello Format

 EPP MAY be carried over both connection-oriented and connection-less
 transport protocols.  An EPP client MAY request a <greeting> from an
 EPP server at any time by sending a <hello> to a server.  Use of this
 element is essential in a connection-less environment where a server
 can not return a <greeting> in response to a client-initiated
 connection.  An EPP <hello> MUST be an empty element with no child
 elements.
 Example <hello>:
 C:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
 C:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0"
 C:     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 C:     xsi:schemaLocation="urn:ietf:params:xml:ns:epp-1.0
 C:     epp-1.0.xsd">
 C:  <hello/>
 C:</epp>

Hollenbeck Standards Track [Page 7] RFC 3730 EPP March 2004

2.4. Greeting Format

 An EPP server responds to a successful connection and <hello> element
 by returning a <greeting> element to the client.  An EPP greeting
 contains the following elements:
  1. An <svID> element that contains the name of the server.
  1. An <svDate> element that contains the server's current date and

time in UTC.

  1. An <svcMenu> element that identifies the services supported by the

server, including:

  1. One or more <version> elements that identify the protocol versions

supported by the server.

  1. One or more <lang> elements that contain the identifiers of the

text response languages known by the server. Language identifiers

    MUST be structured as documented in [RFC3066].
  1. One or more <objURI> elements that contain namespace URIs

representing the objects that the server is capable of managing.

    A server MAY limit object management privileges on a per-client
    basis.
  1. An OPTIONAL <svcExtension> element that contains one or more

<extURI> elements that contain namespace URIs representing object

    extensions supported by the server.
  1. A <dcp> (data collection policy) element that contains child

elements used to describe the server's privacy policy for data

    collection and management.  Policy implications usually extend
    beyond the client-server relationship.  Both clients and servers
    can have relationships with other entities that need to know the
    server operator's data collection policy to make informed
    provisioning decisions.  Policy information MUST be disclosed to
    provisioning entities, though the method of disclosing policy data
    outside of direct protocol interaction is beyond the scope of this
    specification.  Child elements include the following:
  1. An <access> element that describes the access provided by the

server to the client on behalf of the originating data source.

    The <access> element MUST contain one of the following child
    elements:
       <all/>: Access is given to all identified data.

Hollenbeck Standards Track [Page 8] RFC 3730 EPP March 2004

       <none/>: No access is provided to identified data.
       <null/>: Data is not persistent, so no access is possible.
       <personal/>: Access is given to identified data relating to
       individuals and organizational entities.
       <personalAndOther/>: Access is given to identified data
       relating to individuals, organizational entities, and other
       data of a non-personal nature.
       <other/>: Access is given to other identified data of a non-
       personal nature.
  1. One or more <statement> elements that describe data collection

purposes, data recipients, and data retention. Each <statement>

    element MUST contain a <purpose> element, a <recipient> element,
    and a <retention> element.
 The <purpose> element MUST contain one or more of the following child
 elements that describe the purposes for which data is collected:
    <admin/>: Administrative purposes.  Information can be used for
    administrative and technical support of the provisioning system.
    <contact/>: Contact for marketing purposes.  Information can be
    used to contact individuals, through a communications channel
    other than the protocol, for the promotion of a product or
    service.
    <prov/>: Object provisioning purposes.  Information can be used to
    identify objects and inter-object relationships.
    <other/>: Other purposes.  Information may be used in other ways
    not captured by the above definitions.
    The <recipient> element MUST contain one or more of the following
    child elements that describes the recipients of collected data:
       <other/>: Other entities following unknown practices.
       <ours>: Server operator and/or entities acting as agents or
       entities for whom the server operator is acting as an agent.
       An agent in this instance is defined as a third party that
       processes data only on behalf of the service provider for the
       completion of the stated purposes.  The <ours> element contains
       an OPTIONAL <recDesc> element that can be used to describe the
       recipient.

Hollenbeck Standards Track [Page 9] RFC 3730 EPP March 2004

       <public/>: Public forums.
       <same/>: Other entities following server practices.
       <unrelated/>: Unrelated third parties.
    The <retention> element MUST contain one of the following child
    elements that describes data retention practices:
       <business/>: Data persists per business practices.
       <indefinite/>: Data persists indefinitely.
       <legal/>: Data persists per legal requirements.
       <none/>: Data is not persistent, and is not retained for more
       than a brief period of time necessary to make use of it during
       the course of a single online interaction.
       <stated/>: Data persists to meet the stated purpose.
  1. An OPTIONAL <expiry> element that describes the lifetime of the

policy. The <expiry> element MUST contain one of the following

    child elements:
       <absolute/>: The policy is valid from the current date and time
       until it expires on the specified date and time.
       <relative/>: The policy is valid from the current date and time
       until the end of the specified duration.
 Data collection policy elements are based on work described in the
 World Wide Web Consortium's Platform for Privacy Preferences [P3P]
 specification.

Hollenbeck Standards Track [Page 10] RFC 3730 EPP March 2004

 Example greeting:
 S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
 S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0"
 S:     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 S:     xsi:schemaLocation="urn:ietf:params:xml:ns:epp-1.0
 S:     epp-1.0.xsd">
 S:  <greeting>
 S:    <svID>Example EPP server epp.example.com</svID>
 S:    <svDate>2000-06-08T22:00:00.0Z</svDate>
 S:    <svcMenu>
 S:      <version>1.0</version>
 S:      <lang>en</lang>
 S:      <lang>fr</lang>
 S:      <objURI>urn:ietf:params:xml:ns:obj1</objURI>
 S:      <objURI>urn:ietf:params:xml:ns:obj2</objURI>
 S:      <objURI>urn:ietf:params:xml:ns:obj3</objURI>
 S:      <svcExtension>
 S:        <extURI>http://custom/obj1ext-1.0</extURI>
 S:      </svcExtension>
 S:    </svcMenu>
 S:    <dcp>
 S:      <access><all/></access>
 S:      <statement>
 S:        <purpose><admin/><prov/></purpose>
 S:        <recipient><ours/><public/></recipient>
 S:        <retention><stated/></retention>
 S:      </statement>
 S:    </dcp>
 S:  </greeting>
 S:</epp>

2.5. Command Format

 An EPP client interacts with an EPP server by sending a command to
 the server and receiving a response from the server.  In addition to
 the standard EPP elements, an EPP command contains the following
 elements:
  1. A command element whose tag corresponds to one of the valid EPP

commands described in this document. The command element MAY

    contain either protocol-specified or object-specified child
    elements.
  1. An OPTIONAL <extension> element that MAY be used for server-

defined command extensions.

Hollenbeck Standards Track [Page 11] RFC 3730 EPP March 2004

  1. An OPTIONAL <clTRID> (client transaction identifier) element that

MAY be used to uniquely identify the command to the client.

    Clients are responsible for maintaining their own transaction
    identifier space to ensure uniqueness.
 Example command with object-specified child elements:
 C:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
 C:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0"
 C:     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 C:     xsi:schemaLocation="urn:ietf:params:xml:ns:epp-1.0
 C:     epp-1.0.xsd">
 C:  <command>
 C:    <info>
 C:      <obj:info xmlns:obj="urn:ietf:params:xml:ns:obj"
 C:       xsi:schemaLocation="urn:ietf:params:xml:ns:obj obj.xsd">
 C:        <obj:name>example</obj:name>
 C:      </obj:info>
 C:    </info>
 C:    <clTRID>ABC-12345</clTRID>
 C:  </command>
 C:</epp>

2.6. Response Format

 An EPP server responds to a client command by returning a response to
 the client.  EPP commands are atomic, so a command will either
 succeed completely or fail completely.  Success and failure results
 MUST NOT be mixed.  In addition to the standard EPP elements, an EPP
 response contains the following elements:
  1. One or more <result> elements that document the success or failure

of command execution. If the command was processed successfully,

    only one <result> element MUST be returned.  If the command was
    not processed successfully, multiple <result> elements MAY be
    returned to document failure conditions.  Each <result> element
    contains the following attribute and child elements:
  1. A "code" attribute whose value is a four-digit, decimal number

that describes the success or failure of the command.

  1. A <msg> element containing a human-readable description of the

response code. The language of the response is identified via

       an OPTIONAL "lang" attribute.  If not specified, the default
       attribute value MUST be "en" (English).

Hollenbeck Standards Track [Page 12] RFC 3730 EPP March 2004

  1. Zero or more OPTIONAL <value> elements that identify a client-

provided element (including XML tag and value) that caused a

       server error condition.
  1. Zero or more OPTIONAL <extValue> elements that can be used to

provide additional error diagnostic information, including:

  1. A <value> element that identifies a client-provided element

(including XML tag and value) that caused a server error

          condition.
  1. A <reason> element containing a human-readable message that

describes the reason for the error. The language of the

          response is identified via an OPTIONAL "lang" attribute.  If
          not specified, the default attribute value MUST be "en"
          (English).
  1. An OPTIONAL <msgQ> element that describes messages queued for

client retrieval. A <msgQ> element MUST NOT be present if there

    are no messages queued for client retrieval.  A <msgQ> element MAY
    be present in responses to EPP commands other than the <poll>
    command if messages are queued for retrieval.  A <msgQ> element
    MUST be present in responses to the EPP <poll> command if messages
    are queued for retrieval.  The <msgQ> element contains the
    following attributes:
  1. A "count" attribute that describes the number of messages that

exist in the queue.

  1. An "id" attribute used to uniquely identify the message at the

head of the queue.

 The <msgQ> element contains the following OPTIONAL child elements
 that MUST be returned in response to a <poll> request command and
 MUST NOT be returned in response to any other command, including a
 <poll> acknowledgement:
  1. A <qDate> element that contains the date and time that the message

was enqueued.

  1. A <msg> element containing a human-readable message. The language

of the response is identified via an OPTIONAL "lang" attribute.

    If not specified, the default attribute value MUST be "en"
    (English).  This element MAY contain XML content for formatting
    purposes, but the XML content is not specified by the protocol and
    will thus not be processed for validity.

Hollenbeck Standards Track [Page 13] RFC 3730 EPP March 2004

  1. An OPTIONAL <resData> (response data) element that contains child

elements specific to the command and associated object.

  1. An OPTIONAL <extension> element that MAY be used for server-

defined response extensions.

  1. A <trID> (transaction identifier) element containing the

transaction identifier assigned by the server to the command for

    which the response is being returned.  The transaction identifier
    is formed using the <clTRID> associated with the command if
    supplied by the client and a <svTRID> (server transaction
    identifier) that is assigned by and unique to the server.
    Transaction identifiers provide command-response synchronization
    integrity.  They SHOULD be logged, retained, and protected to
    ensure that both the client and the server have consistent
    temporal and state management records.
 Example response without <value> or <resData>:
 S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
 S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0"
 S:     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 S:     xsi:schemaLocation="urn:ietf:params:xml:ns:epp-1.0
 S:     epp-1.0.xsd">
 S:  <response>
 S:    <result code="1000">
 S:      <msg lang="en">Command completed successfully</msg>
 S:    </result>
 S:    <trID>
 S:      <clTRID>ABC-12345</clTRID>
 S:      <svTRID>54321-XYZ</svTRID>
 S:    </trID>
 S:  </response>
 S:</epp>

Hollenbeck Standards Track [Page 14] RFC 3730 EPP March 2004

 Example response with <resData>:
 S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
 S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0"
 S:     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 S:     xsi:schemaLocation="urn:ietf:params:xml:ns:epp-1.0
 S:     epp-1.0.xsd">
 S:  <response>
 S:    <result code="1000">
 S:      <msg>Command completed successfully</msg>
 S:    </result>
 S:    <resData>
 S:      <obj:creData xmlns:obj="urn:ietf:params:xml:ns:obj"
 S:       xsi:schemaLocation="urn:ietf:params:xml:ns:obj obj.xsd">
 S:        <obj:name>example</obj:name>
 S:      </obj:creData>
 S:    </resData>
 S:    <trID>
 S:      <clTRID>ABC-12345</clTRID>
 S:      <svTRID>54321-XYZ</svTRID>
 S:    </trID>
 S:  </response>
 S:</epp>
 Example response with error value elements:
 S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
 S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0"
 S:     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 S:     xsi:schemaLocation="urn:ietf:params:xml:ns:epp-1.0
 S:     epp-1.0.xsd">
 S:  <response>
 S:    <result code="2004">
 S:      <msg>Parameter value range error</msg>
 S:      <value xmlns:obj="urn:ietf:params:xml:ns:obj">
 S:        <obj:elem1>2525</obj:elem1>
 S:      </value>
 S:    </result>
 S:    <result code="2005">
 S:      <msg>Parameter value syntax error</msg>
 S:      <value xmlns:obj="urn:ietf:params:xml:ns:obj">
 S:        <obj:elem2>ex(ample</obj:elem2>
 S:      </value>
 S:      <extValue>
 S:        <value xmlns:obj="urn:ietf:params:xml:ns:obj">
 S:          <obj:elem3>abc.ex(ample</obj:elem3>
 S:        </value>
 S:        <reason>Invalid character found.</reason>

Hollenbeck Standards Track [Page 15] RFC 3730 EPP March 2004

 S:      </extValue>
 S:    </result>
 S:    <trID>
 S:      <clTRID>ABC-12345</clTRID>
 S:      <svTRID>54321-XYZ</svTRID>
 S:    </trID>
 S:  </response>
 S:</epp>
 Example response with notice of waiting server messages:
 S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
 S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0"
 S:     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 S:     xsi:schemaLocation="urn:ietf:params:xml:ns:epp-1.0
 S:     epp-1.0.xsd">
 S:  <response>
 S:    <result code="1000">
 S:      <msg>Command completed successfully</msg>
 S:    </result>
 S:    <msgQ count="5" id="12345"/>
 S:    <trID>
 S:      <clTRID>ABC-12345</clTRID>
 S:      <svTRID>54321-XYZ</svTRID>
 S:    </trID>
 S:  </response>
 S:</epp>
 Command success or failure MUST NOT be assumed if no response is
 returned or if a returned response is malformed.  Protocol
 idempotency ensures the safety of retrying a command in cases of
 response delivery failure.

2.7. Protocol Extension Framework

 EPP provides an extension framework that allows features to be added
 at the protocol, object, and command-response levels.

2.7.1. Protocol Extension

 The EPP extension framework allows for definition of new protocol
 elements identified using XML namespace notation with a reference to
 an XML schema that defines the namespace.  The <epp> element that
 identifies the beginning of a protocol instance includes multiple
 child element choices, one of which is an <extension> element whose
 children define the extension.  For example, a protocol extension
 element would be described in generic terms as follows:

Hollenbeck Standards Track [Page 16] RFC 3730 EPP March 2004

 C:<epp>
 C:  <extension>
 C:    <!-- One or more extension elements. -->
 C:    <ext:foo xmlns:ext="urn:ietf:params:xml:ns:ext"
 C:     xsi:schemaLocation="urn:ietf:params:xml:ns:ext ext.xsd">
 C:      <!-- One or more extension child elements. -->
 C:    </ext:foo>
 C:  </extension>
 C:</epp>
 This document does not define mappings for specific extensions.
 Extension specifications MUST be described in separate documents that
 define the objects and operations subject to the extension.

2.7.2. Object Extension

 EPP provides an extensible object management framework that defines
 the syntax and semantics of protocol operations applied to a managed
 object.  This framework pushes the definition of each protocol
 operation into the context of a specific object, providing the
 ability to add mappings for new objects without having to modify the
 base protocol.
 Protocol elements that contain data specific to objects are
 identified using XML namespace notation with a reference to an XML
 schema that defines the namespace.  The schema for EPP supports use
 of dynamic object schemas on a per-command and per-response basis.
 For example, the start of an object-specific command element would be
 described in generic terms as follows:
 C:<EPPCommandName>
 C:  <object:command xmlns:object="urn:ietf:params:xml:ns:object"
 C:   xsi:schemaLocation="urn:ietf:params:xml:ns:object object.xsd">
 C:    <!-- One or more object-specific command elements. -->
 C:  </object:command>
 C:</EPPCommandName>
 An object-specific response element would be described similarly:
 S:<resData>
 S:  <object:resData xmlns:object="urn:ietf:params:xml:ns:object"
 S:   xsi:schemaLocation="urn:ietf:params:xml:ns:object object.xsd">
 S:    <!-- One or more object-specific response elements. -->
 S:  </object:resData>
 S:</resData>

Hollenbeck Standards Track [Page 17] RFC 3730 EPP March 2004

 This document does not define mappings for specific objects.  The
 mapping of EPP to an object MUST be described in separate documents
 that specifically address each command and response in the context of
 the object.  A suggested object mapping outline is included as an
 appendix to this document.

2.7.3. Command-Response Extension

 EPP provides a facility for protocol command and response extensions.
 Protocol commands and responses MAY be extended by an <extension>
 element that contains additional elements whose syntax and semantics
 are not explicitly defined by EPP or an EPP object mapping.  This
 element is OPTIONAL.  Extensions are typically defined by agreement
 between client and server and MAY be used to extend EPP for unique
 operational needs.  A server-extended command element would be
 described in generic terms as follows:
 C:<command>
 C:  <!-- EPPCommandName can be "create", "update", etc. -->
 C:  <EPPCommandName>
 C:    <object:command xmlns:object="urn:ietf:params:xml:ns:object"
 C:     xsi:schemaLocation="urn:ietf:params:xml:ns:object object.xsd">
 C:      <!-- One or more object-specific command elements. -->
 C:    </object:command>
 C:  </EPPCommandName>
 C:  <extension>
 C:    <!-- One or more server-defined elements. -->
 C:  </extension>
 C:</command>
 An server-extended response element would be described similarly:
 S:<response>
 S:  <result code="1000">
 S:    <msg lang="en">Command completed successfully</msg>
 S:  </result>
 S:  <extension>
 S:    <!-- One or more server-defined elements. -->
 S:  </extension>
 S:  <trID>
 S:    <clTRID>ABC-12345</clTRID>
 S:    <svTRID>54321-XYZ</svTRID>
 S:  </trID>
 S:</response>

Hollenbeck Standards Track [Page 18] RFC 3730 EPP March 2004

 This document does not define any specific server extensions.  The
 mapping of server extensions to EPP MUST be described in separate
 documents that specifically address extended commands and responses
 in the server's operational context.

2.8. Object Identification

 Some objects, such as name servers and contacts, can have utility in
 multiple repositories.  However, maintaining disjoint copies of
 object information in multiple repositories can lead to
 inconsistencies that have adverse consequences for the Internet.  For
 example, changing a name server name in one repository, but not in a
 second repository that refers to the server for domain name
 delegation, can produce unexpected DNS query results.
 Globally unique identifiers can help facilitate object information
 sharing between repositories.  A globally unique identifier MUST be
 assigned to every object when the object is created; the identifier
 MUST be returned to the client as part of any request to retrieve the
 detailed attributes of an object.  Specific identifier values are a
 matter of repository policy, but they SHOULD be constructed according
 to the following algorithm:
 a) Divide the provisioning repository world into a number of object
    repository classes.
 b) Each repository within a class is assigned an identifier that is
    maintained by IANA.
 c) Each repository is responsible for assigning a unique local
    identifier for each object within the repository.
 d) The globally unique identifier is a concatenation of the local
    identifier, followed by a hyphen ("-", ASCII value 0x002D),
    followed by the repository identifier.

2.9. Protocol Commands

 EPP provides commands to manage sessions, retrieve object
 information, and perform transformation operations on objects.  All
 EPP commands are atomic and designed so that they can be made
 idempotent, either succeeding completely or failing completely and
 producing predictable results in case of repeated execution.  This
 section describes each EPP command, including examples with
 representative server responses.

Hollenbeck Standards Track [Page 19] RFC 3730 EPP March 2004

2.9.1. Session Management Commands

 EPP provides two commands for session management: <login> to
 establish a session with a server, and <logout> to end a session with
 a server.  The <login> command establishes an ongoing server session
 that preserves client identity and authorization information during
 the duration of the session.

2.9.1.1. EPP <login> Command

 The EPP <login> command is used to establish a session with an EPP
 server in response to a greeting issued by the server.  A <login>
 command MUST be sent to a server before any other EPP command to
 establish an ongoing session.  A server operator MAY limit the number
 of failed login attempts N, 1 <= N <= infinity, after which a login
 failure results in the connection to the server (if a connection
 exists) being closed.
 A client identifier and initial password MUST be created on the
 server before a client can successfully complete a <login> command.
 The client identifier and initial password MUST be delivered to the
 client using an out-of-band method that protects the identifier and
 password from inadvertent disclosure.
 In addition to the standard EPP command elements, the <login> command
 contains the following child elements:
  1. A <clID> element that contains the client identifier assigned to

the client by the server.

  1. A <pw> element that contains the client's plain text password.

The value of this element is case sensitive.

  1. An OPTIONAL <newPW> element that contains a new plain text

password to be assigned to the client for use with subsequent

    <login> commands.  The value of this element is case sensitive.
  1. An <options> element that contains the following child elements:
  1. A <version> element that contains the protocol version to be

used for the command or ongoing server session.

  1. A <lang> element that contains the text response language to be

used for the command or ongoing server session commands.

 The values of the <version> and <lang> elements MUST exactly match
 one of the values presented in the EPP greeting.

Hollenbeck Standards Track [Page 20] RFC 3730 EPP March 2004

  1. A <svcs> element that contains one or more <objURI> elements that

contain namespace URIs representing the objects to be managed

    during the session.  The <svcs> element MAY contain an OPTIONAL
    <svcExtension> element that contains one or more <extURI> elements
    that identify object extensions to be used during the session.
 The PLAIN SASL mechanism presented in [RFC2595] describes a format
 for providing a user identifier, an authorization identifier, and a
 password as part of a single plain text string.  The EPP
 authentication mechanism is similar, though EPP does not require a
 session-level authorization identifier and the user identifier and
 password are separated into distinct XML elements.  Additional
 identification and authorization schemes MUST be provided at other
 protocol layers to provide more robust security services.
 Example <login> command:
 C:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
 C:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0"
 C:     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 C:     xsi:schemaLocation="urn:ietf:params:xml:ns:epp-1.0
 C:     epp-1.0.xsd">
 C:  <command>
 C:    <login>
 C:      <clID>ClientX</clID>
 C:      <pw>foo-BAR2</pw>
 C:      <newPW>bar-FOO2</newPW>
 C:      <options>
 C:        <version>1.0</version>
 C:        <lang>en</lang>
 C:      </options>
 C:      <svcs>
 C:        <objURI>urn:ietf:params:xml:ns:obj1</objURI>
 C:        <objURI>urn:ietf:params:xml:ns:obj2</objURI>
 C:        <objURI>urn:ietf:params:xml:ns:obj3</objURI>
 C:        <svcExtension>
 C:          <extURI>http://custom/obj1ext-1.0</extURI>
 C:        </svcExtension>
 C:      </svcs>
 C:    </login>
 C:    <clTRID>ABC-12345</clTRID>
 C:  </command>
 C:</epp>
 When a <login> command has been processed successfully, a server MUST
 respond with an EPP response with no <resData> element.  If
 successful, the server will respond by creating and maintaining a new
 session that SHOULD be terminated by a future <logout> command.

Hollenbeck Standards Track [Page 21] RFC 3730 EPP March 2004

 Example <login> response:
 S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
 S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0"
 S:     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 S:     xsi:schemaLocation="urn:ietf:params:xml:ns:epp-1.0
 S:     epp-1.0.xsd">
 S:  <response>
 S:    <result code="1000">
 S:      <msg>Command completed successfully</msg>
 S:    </result>
 S:    <trID>
 S:      <clTRID>ABC-12345</clTRID>
 S:      <svTRID>54321-XYZ</svTRID>
 S:    </trID>
 S:  </response>
 S:</epp>
 The EPP <login> command is used to establish a session with an EPP
 server.  A <login> command MUST be rejected if received within the
 bounds of an existing session.  This action MUST be open to all
 authorized clients.

2.9.1.2. EPP <logout> Command

 The EPP <logout> command is used to end a session with an EPP server.
 The <logout> command MUST be represented as an empty element with no
 child elements.
 A server MAY end a session due to client inactivity or excessive
 client session longevity.  The parameters for determining excessive
 client inactivity or session longevity are a matter of server policy
 and are not specified by this protocol.
 Transport mappings MUST explicitly describe any connection-oriented
 processing that takes place after processing a <logout> command and
 ending a session.

Hollenbeck Standards Track [Page 22] RFC 3730 EPP March 2004

 Example <logout> command:
 C:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
 C:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0"
 C:     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 C:     xsi:schemaLocation="urn:ietf:params:xml:ns:epp-1.0
 C:     epp-1.0.xsd">
 C:  <command>
 C:    <logout/>
 C:    <clTRID>ABC-12345</clTRID>
 C:  </command>
 C:</epp>
 When a <logout> command has been processed successfully, a server
 MUST respond with an EPP response with no <resData> element.  If
 successful, the server MUST also end the current session.
 Example <logout> response:
 S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
 S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0"
 S:     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 S:     xsi:schemaLocation="urn:ietf:params:xml:ns:epp-1.0
 S:     epp-1.0.xsd">
 S:  <response>
 S:    <result code="1500">
 S:      <msg>Command completed successfully; ending session</msg>
 S:    </result>
 S:    <trID>
 S:      <clTRID>ABC-12345</clTRID>
 S:      <svTRID>54321-XYZ</svTRID>
 S:    </trID>
 S:  </response>
 S:</epp>
 The EPP <logout> command is used to end a session with an EPP server.
 A <logout> command MUST be rejected if the command has not been
 preceded by a successful <login> command.  This action MUST be open
 to all authorized clients.

2.9.2. Query Commands

 EPP provides four commands to retrieve object information: <check> to
 determine if an object can be provisioned within a repository, <info>
 to retrieve detailed information associated with a known object,
 <poll> to receive service notifications from the server, and
 <transfer> to retrieve object transfer status information.

Hollenbeck Standards Track [Page 23] RFC 3730 EPP March 2004

2.9.2.1. EPP <check> Command

 The EPP <check> command is used to determine if an object can be
 provisioned within a repository.  It provides a hint that allows a
 client to anticipate the success or failure of provisioning an object
 using the <create> command as object provisioning requirements are
 ultimately a matter of server policy.
 The elements needed to identify an object are object-specific, so the
 child elements of the <check> command are specified using the EPP
 extension framework.  In addition to the standard EPP command
 elements, the <check> command contains the following child elements:
  1. An object-specific <obj:check> element that identify the objects

to be queried. Multiple objects of the same type MAY be queried

    within a single <check> command.
 Example <check> command:
 C:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
 C:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0"
 C:     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 C:     xsi:schemaLocation="urn:ietf:params:xml:ns:epp-1.0
 C:     epp-1.0.xsd">
 C:  <command>
 C:    <check>
 C:      <obj:check xmlns:obj="urn:ietf:params:xml:ns:obj"
 C:       xsi:schemaLocation="urn:ietf:params:xml:ns:obj obj.xsd">
 C:        <obj:name>example1</obj:name>
 C:        <obj:name>example2</obj:name>
 C:        <obj:name>example3</obj:name>
 C:      </obj:check>
 C:    </check>
 C:    <clTRID>ABC-12346</clTRID>
 C:  </command>
 C:</epp>
 When a <check> command has been processed successfully, a server MUST
 respond with an EPP <resData> element that MUST contain a child
 element that identifies the object namespace and the location of the
 object schema.  The child elements of the <resData> element are
 object-specific, though the EPP <resData> element MUST contain a
 child <obj:chkData> element that contains one or more <obj:cd> (check
 data) elements.  Each <obj:cd> elements contains the following child
 elements:

Hollenbeck Standards Track [Page 24] RFC 3730 EPP March 2004

  1. An object-specific element that identifies the queried object.

This element MUST contain an "avail" attribute whose value

    indicates object availability (can it be provisioned or not) at
    the moment the <check> command was completed.  A value of "1" or
    "true" means that the object can be provisioned.  A value of "0"
    or "false" means that the object can not be provisioned.
  1. An OPTIONAL <obj:reason> element that MAY be provided when an

object can not be provisioned. If present, this element contains

    server-specific text to help explain why the object can not be
    provisioned.  This text MUST be represented in the response
    language previously negotiated with the client; an OPTIONAL "lang"
    attribute MAY be present to identify the language if the
    negotiated value is something other than the default value of "en"
    (English).
 Example <check> response:
 S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
 S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0"
 S:     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 S:     xsi:schemaLocation="urn:ietf:params:xml:ns:epp-1.0
 S:     epp-1.0.xsd">
 S:  <response>
 S:    <result code="1000">
 S:      <msg>Command completed successfully</msg>
 S:    </result>
 S:    <resData>
 S:      <obj:chkData xmlns:obj="urn:ietf:params:xml:ns:obj"
 S:       xsi:schemaLocation="urn:ietf:params:xml:ns:obj obj.xsd">
 S:        <obj:cd>
 S:          <obj:name avail="1">example1</obj:name>
 S:        </obj:cd>
 S:        <obj:cd>
 S:          <obj:name avail="0">example2</obj:name>
 S:          <obj:reason>In use</obj:reason>
 S:        </obj:cd>
 S:        <obj:cd>
 S:          <obj:name avail="1">example3</obj:name>
 S:        </obj:cd>
 S:      </obj:chkData>
 S:    </resData>
 S:    <trID>
 S:      <clTRID>ABC-12346</clTRID>
 S:      <svTRID>54322-XYZ</svTRID>
 S:    </trID>
 S:  </response>
 S:</epp>

Hollenbeck Standards Track [Page 25] RFC 3730 EPP March 2004

 The EPP <check> command is used to determine if an object can be
 provisioned within a repository.  This action MUST be open to all
 authorized clients.

2.9.2.2. EPP <info> Command

 The EPP <info> command is used to retrieve information associated
 with an existing object.  The elements needed to identify an object
 and the type of information associated with an object are both
 object-specific, so the child elements of the <info> command are
 specified using the EPP extension framework.  In addition to the
 standard EPP command elements, the <info> command contains the
 following child elements:
  1. An object-specific <obj:info> element that identifies the object

to be queried.

 Example <info> command:
 C:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
 C:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0"
 C:     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 C:     xsi:schemaLocation="urn:ietf:params:xml:ns:epp-1.0
 C:     epp-1.0.xsd">
 C:  <command>
 C:    <info>
 C:      <obj:info xmlns:obj="urn:ietf:params:xml:ns:obj"
 C:       xsi:schemaLocation="urn:ietf:params:xml:ns:obj obj.xsd">
 C:        <!-- Object-specific elements. -->
 C:      </obj:info>
 C:    </info>
 C:    <clTRID>ABC-12346</clTRID>
 C:  </command>
 C:</epp>
 When an <info> command has been processed successfully, a server MUST
 respond with an EPP <resData> element that MUST contain a child
 element that identifies the object namespace and the location of the
 object schema and the Repository Object Identifier (ROID) that was
 assigned to the object when the object was created.  Other child
 elements of the <resData> element are object-specific.

Hollenbeck Standards Track [Page 26] RFC 3730 EPP March 2004

 Example <info> response:
 S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
 S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0"
 S:     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 S:     xsi:schemaLocation="urn:ietf:params:xml:ns:epp-1.0
 S:     epp-1.0.xsd">
 S:  <response>
 S:    <result code="1000">
 S:      <msg>Command completed successfully</msg>
 S:    </result>
 S:    <resData>
 S:      <obj:infData xmlns:obj="urn:ietf:params:xml:ns:obj"
 S:       xsi:schemaLocation="urn:ietf:params:xml:ns:obj obj.xsd">
 S:        <obj:roid>EXAMPLE1-REP</obj:roid>
 S:        <!-- Object-specific elements. -->
 S:      </obj:infData>
 S:    </resData>
 S:    <trID>
 S:      <clTRID>ABC-12346</clTRID>
 S:      <svTRID>54322-XYZ</svTRID>
 S:    </trID>
 S:  </response>
 S:</epp>
 The EPP <info> command is used to retrieve information associated
 with an existing object.  This action SHOULD be limited to authorized
 clients; restricting this action to the sponsoring client is
 RECOMMENDED.

2.9.2.3. EPP <poll> Command

 The EPP <poll> command is used to discover and retrieve service
 messages queued by a server for individual clients.  If the message
 queue is not empty, a successful response to a <poll> command MUST
 return the first message from the message queue.  Each response
 returned from the server includes a server-unique message identifier
 that MUST be provided to acknowledge receipt of the message, and a
 counter that indicates the number of messages in the queue.  After a
 message has been received by the client, the client MUST respond to
 the message with an explicit acknowledgement to confirm that the
 message has been received.  A server MUST dequeue the message and
 decrement the queue counter after receiving acknowledgement from the
 client, making the next message in the queue (if any) available for
 retrieval.

Hollenbeck Standards Track [Page 27] RFC 3730 EPP March 2004

 Servers can occasionally perform actions on objects that are not in
 direct response to a client request, or an action taken by one client
 can indirectly involve a second client.  Examples of such actions
 include deletion upon expiration, automatic renewal upon expiration,
 and transfer coordination; other types of service information MAY be
 defined as a matter of server policy.  Service messages MUST be
 created for all clients affected by an action on an object.  For
 example, <transfer> actions MUST be reported to both the client that
 requests an object transfer and the client that has the authority to
 approve or reject the transfer request.
 Message queues can consume server resources if clients do not
 retrieve and acknowledge messages on a regular basis.  Servers MAY
 implement other mechanisms to dequeue and deliver messages if queue
 maintenance needs exceed server resource consumption limits.  Server
 operators SHOULD consider time-sensitivity and resource management
 factors when selecting a delivery method for service information
 because some message types can be reasonably delivered using non-
 protocol methods that require fewer server resources.
 Some of the information returned in response to a <poll> command can
 be object-specific, so some child elements of the <poll> response MAY
 be specified using the EPP extension framework.  The <poll> command
 MUST be represented as an empty element with no child elements.  An
 "op" attribute with value "req" is REQUIRED to retrieve the first
 message from the server message queue.  An "op" attribute (with value
 "ack") and a "msgID" attribute (whose value corresponds to the value
 of the "id" attribute copied from the <msg> element in the message
 being acknowledged) are REQUIRED to acknowledge receipt of a message.
 Example <poll> command:
 C:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
 C:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0"
 C:     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 C:     xsi:schemaLocation="urn:ietf:params:xml:ns:epp-1.0
 C:     epp-1.0.xsd">
 C:  <command>
 C:    <poll op="req"/>
 C:    <clTRID>ABC-12345</clTRID>
 C:  </command>
 C:</epp>
 The returned result code notes that a message has been dequeued and
 returned in response to a <poll> command.

Hollenbeck Standards Track [Page 28] RFC 3730 EPP March 2004

 Example <poll> response with object-specific information:
 S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
 S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0"
 S:     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 S:     xsi:schemaLocation="urn:ietf:params:xml:ns:epp-1.0
 S:     epp-1.0.xsd">
 S:  <response>
 S:    <result code="1301">
 S:      <msg>Command completed successfully; ack to dequeue</msg>
 S:    </result>
 S:    <msgQ count="5" id="12345">
 S:      <qDate>2000-06-08T22:00:00.0Z</qDate>
 S:      <msg>Transfer requested.</msg>
 S:    </msgQ>
 S:    <resData>
 S:      <obj:trnData
 S:       xmlns:obj="urn:ietf:params:xml:ns:obj-1.0"
 S:       xsi:schemaLocation="urn:ietf:params:xml:ns:obj-1.0
 S:       obj-1.0.xsd">
 S:        <obj:name>example.com</obj:name>
 S:        <obj:trStatus>pending</obj:trStatus>
 S:        <obj:reID>ClientX</obj:reID>
 S:        <obj:reDate>2000-06-08T22:00:00.0Z</obj:reDate>
 S:        <obj:acID>ClientY</obj:acID>
 S:        <obj:acDate>2000-06-13T22:00:00.0Z</obj:acDate>
 S:        <obj:exDate>2002-09-08T22:00:00.0Z</obj:exDate>
 S:      </obj:trnData>
 S:    </resData>
 S:    <trID>
 S:      <clTRID>ABC-12345</clTRID>
 S:      <svTRID>54321-XYZ</svTRID>
 S:    </trID>
 S:  </response>
 S:</epp>
 A client MUST acknowledge each response to dequeue the message and
 make subsequent messages available for retrieval.

Hollenbeck Standards Track [Page 29] RFC 3730 EPP March 2004

 Example <poll> acknowledgement command:
 C:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
 C:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0"
 C:     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 C:     xsi:schemaLocation="urn:ietf:params:xml:ns:epp-1.0
 C:     epp-1.0.xsd">
 C:  <command>
 C:    <poll op="ack" msgID="12345"/>
 C:    <clTRID>ABC-12346</clTRID>
 C:  </command>
 C:</epp>
 A <poll> acknowledgement response notes the number of messages
 remaining in the queue and the ID of the next message available for
 retrieval.
 Example <poll> acknowledgement response:
 S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
 S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0"
 S:     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 S:     xsi:schemaLocation="urn:ietf:params:xml:ns:epp-1.0
 S:     epp-1.0.xsd">
 S:  <response>
 S:    <result code="1000">
 S:      <msg>Command completed successfully</msg>
 S:    </result>
 S:    <msgQ count="4" id="12346"/>
 S:    <trID>
 S:      <clTRID>ABC-12346</clTRID>
 S:      <svTRID>54322-XYZ</svTRID>
 S:    </trID>
 S:  </response>
 S:</epp>
 Service messages can also be returned without object information.

Hollenbeck Standards Track [Page 30] RFC 3730 EPP March 2004

 Example <poll> response with mixed message content and without
 object-specific information:
 S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
 S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0"
 S:     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 S:     xsi:schemaLocation="urn:ietf:params:xml:ns:epp-1.0
 S:     epp-1.0.xsd">
 S:  <response>
 S:    <result code="1301">
 S:      <msg>Command completed successfully; ack to dequeue</msg>
 S:    </result>
 S:    <msgQ count="4" id="12346">
 S:      <qDate>2000-06-08T22:10:00.0Z</qDate>
 S:      <msg lang="en">Credit balance low.
 S:        <limit>100</limit><bal>5</bal>
 S:      </msg>
 S:    </msgQ>
 S:    <trID>
 S:      <clTRID>ABC-12346</clTRID>
 S:      <svTRID>54321-XYZ</svTRID>
 S:    </trID>
 S:  </response>
 S:</epp>
 The returned result code and message is used to note an empty server
 message queue.
 Example <poll> response to note an empty message queue:
 S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
 S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0"
 S:     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 S:     xsi:schemaLocation="urn:ietf:params:xml:ns:epp-1.0
 S:     epp-1.0.xsd">
 S:  <response>
 S:    <result code="1300">
 S:      <msg>Command completed successfully; no messages</msg>
 S:    </result>
 S:    <trID>
 S:      <clTRID>ABC-12346</clTRID>
 S:      <svTRID>54321-XYZ</svTRID>
 S:    </trID>
 S:  </response>
 S:</epp>

Hollenbeck Standards Track [Page 31] RFC 3730 EPP March 2004

 The EPP <poll> command is used to discover and retrieve client
 service messages from a server.  This action SHOULD be limited to
 authorized clients; queuing service messages and limiting queue
 access on a per-client basis is RECOMMENDED.

2.9.2.4. EPP <transfer> Query Command

 The EPP <transfer> command provides a query operation that allows a
 client to determine real-time status of pending and completed
 transfer requests.  The elements needed to identify an object that is
 the subject of a transfer request are object-specific, so the child
 elements of the <transfer> query command are specified using the EPP
 extension framework.  In addition to the standard EPP command
 elements, the <transfer> command contains an "op" attribute with
 value "query", and the following child elements:
  1. An object-specific <obj:transfer> element that identifies the

object whose transfer status is requested.

 Transfer status is typically considered sensitive information by the
 clients involved in the operation.  Object mappings MUST provide
 features to restrict transfer queries to authorized clients, such as
 by requiring authorization information as part of the request.
 Example <transfer> query command:
 C:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
 C:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0"
 C:     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 C:     xsi:schemaLocation="urn:ietf:params:xml:ns:epp-1.0
 C:     epp-1.0.xsd">
 C:  <command>
 C:    <transfer op="query">
 C:      <obj:transfer xmlns:obj="urn:ietf:params:xml:ns:obj"
 C:       xsi:schemaLocation="urn:ietf:params:xml:ns:obj obj.xsd">
 C:        <!-- Object-specific elements. -->
 C:      </obj:transfer>
 C:    </transfer>
 C:    <clTRID>ABC-12346</clTRID>
 C:  </command>
 C:</epp>
 When a <transfer> query command has been processed successfully, a
 server MUST respond with an EPP <resData> element that MUST contain a
 child element that identifies the object namespace and the location
 of the object schema.  The child elements of the <resData> element
 are object-specific, but they MUST include elements that identify the
 object, the status of the transfer, the identifier of the client that

Hollenbeck Standards Track [Page 32] RFC 3730 EPP March 2004

 requested the transfer, the date and time that the request was made,
 the identifier of the client that is authorized to act on the
 request, the date and time by which an action is expected, and an
 OPTIONAL date and time noting changes in the object's validity period
 (if applicable) that occur as a result of the transfer.
 Example <transfer> query response:
 S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
 S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0"
 S:     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 S:     xsi:schemaLocation="urn:ietf:params:xml:ns:epp-1.0
 S:     epp-1.0.xsd">
 S:  <response>
 S:    <result code="1000">
 S:      <msg>Command completed successfully</msg>
 S:    </result>
 S:    <resData>
 S:      <obj:trnData xmlns:obj="urn:ietf:params:xml:ns:obj"
 S:       xsi:schemaLocation="urn:ietf:params:xml:ns:obj obj.xsd">
 S:        <obj:name>example</obj:name>
 S:        <obj:trStatus>pending</obj:trStatus>
 S:        <obj:reID>ClientX</obj:reID>
 S:        <obj:reDate>2000-06-08T22:00:00.0Z</obj:reDate>
 S:        <obj:acID>ClientY</obj:acID>
 S:        <obj:acDate>2000-06-13T22:00:00.0Z</obj:acDate>
 S:        <obj:exDate>2002-09-08T22:00:00.0Z</obj:exDate>
 S:      </obj:trnData>
 S:    </resData>
 S:    <trID>
 S:      <clTRID>ABC-12346</clTRID>
 S:      <svTRID>54322-XYZ</svTRID>
 S:    </trID>
 S:  </response>
 S:</epp>
 The EPP <transfer> command provides a query operation that allows a
 client to determine real-time status of pending and completed
 transfer requests.  This action SHOULD be limited to authorized
 clients; restricting queries to the requesting and responding clients
 is RECOMMENDED.  Object transfer MAY be unavailable or limited by
 object-specific policies.

Hollenbeck Standards Track [Page 33] RFC 3730 EPP March 2004

2.9.3. Object Transform Commands

 EPP provides five commands to transform objects: <create> to create
 an instance of an object with a server, <delete> to remove an
 instance of an object from a server, <renew> to extend the validity
 period of an object, <update> to change information associated with
 an object, and <transfer> to manage changes in client sponsorship of
 an object.

2.9.3.1. EPP <create> Command

 The EPP <create> command is used to create an instance of an object.
 An object can be created for an indefinite period of time, or an
 object can be created for a specific validity period.  The EPP
 mapping for an object MUST describe the status of an object with
 respect to time, to include expected client and server behavior if a
 validity period is used.
 The elements needed to identify an object and associated attributes
 are object-specific, so the child elements of the <create> command
 are specified using the EPP extension framework.  In addition to the
 standard EPP command elements, the <create> command contains the
 following child elements:
  1. An object-specific <obj:create> element that identifies the object

to be created and the elements that are required to create the

    object.
 Example <create> command:
 C:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
 C:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0"
 C:     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 C:     xsi:schemaLocation="urn:ietf:params:xml:ns:epp-1.0
 C:     epp-1.0.xsd">
 C:  <command>
 C:    <create>
 C:      <obj:create xmlns:obj="urn:ietf:params:xml:ns:obj"
 C:       xsi:schemaLocation="urn:ietf:params:xml:ns:obj obj.xsd">
 C:        <!-- Object-specific elements. -->
 C:      </obj:create>
 C:    </create>
 C:    <clTRID>ABC-12345</clTRID>
 C:  </command>
 C:</epp>

Hollenbeck Standards Track [Page 34] RFC 3730 EPP March 2004

 When a <create> command has been processed successfully, a server MAY
 respond with an EPP <resData> element that MUST contain a child
 element that identifies the object namespace and the location of the
 object schema.  The child elements of the <resData> element are
 object-specific.
 Example <create> response with <resData>:
 S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
 S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0"
 S:     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 S:     xsi:schemaLocation="urn:ietf:params:xml:ns:epp-1.0
 S:     epp-1.0.xsd">
 S:  <response>
 S:    <result code="1000">
 S:      <msg>Command completed successfully</msg>
 S:    </result>
 S:    <resData>
 S:      <obj:creData xmlns:obj="urn:ietf:params:xml:ns:obj"
 S:       xsi:schemaLocation="urn:ietf:params:xml:ns:obj obj.xsd">
 S:        <!-- Object-specific elements. -->
 S:      </obj:creData>
 S:    </resData>
 S:    <trID>
 S:      <clTRID>ABC-12345</clTRID>
 S:      <svTRID>54321-XYZ</svTRID>
 S:    </trID>
 S:  </response>
 S:</epp>
 The EPP <create> command is used to create an instance of an object.
 This action SHOULD be limited to authorized clients and MAY be
 restricted on a per-client basis.

2.9.3.2. EPP <delete> Command

 The EPP <delete> command is used to remove an instance of an existing
 object.  The elements needed to identify an object are object-
 specific, so the child elements of the <delete> command are specified
 using the EPP extension framework.  In addition to the standard EPP
 command elements, the <delete> command contains the following child
 elements:
  1. An object-specific <obj:delete> element that identifies the object

to be deleted.

Hollenbeck Standards Track [Page 35] RFC 3730 EPP March 2004

 Example <delete> command:
 C:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
 C:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0"
 C:     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 C:     xsi:schemaLocation="urn:ietf:params:xml:ns:epp-1.0
 C:     epp-1.0.xsd">
 C:  <command>
 C:    <delete>
 C:      <obj:delete xmlns:obj="urn:ietf:params:xml:ns:obj"
 C:       xsi:schemaLocation="urn:ietf:params:xml:ns:obj obj.xsd">
 C:        <!-- Object-specific elements. -->
 C:      </obj:delete>
 C:    </delete>
 C:    <clTRID>ABC-12346</clTRID>
 C:  </command>
 C:</epp>
 When a <delete> command has been processed successfully, a server MAY
 respond with an EPP <resData> element that MUST contain a child
 element that identifies the object namespace and the location of the
 object schema.  The child elements of the <resData> element are
 object-specific.
 Example <delete> response without <resData>:
 S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
 S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0"
 S:     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 S:     xsi:schemaLocation="urn:ietf:params:xml:ns:epp-1.0
 S:     epp-1.0.xsd">
 S:  <response>
 S:    <result code="1000">
 S:      <msg>Command completed successfully</msg>
 S:    </result>
 S:    <trID>
 S:      <clTRID>ABC-12346</clTRID>
 S:      <svTRID>54322-XYZ</svTRID>
 S:    </trID>
 S:  </response>
 S:</epp>
 The EPP <delete> command is used to remove an instance of an existing
 object.  This action SHOULD be limited to authorized clients;
 restricting this action to the sponsoring client is RECOMMENDED.

Hollenbeck Standards Track [Page 36] RFC 3730 EPP March 2004

2.9.3.3. EPP <renew> Command

 The EPP <renew> command is used to extend the validity period of an
 existing object.  The elements needed to identify and extend the
 validity period of an object are object-specific, so the child
 elements of the <renew> command are specified using the EPP extension
 framework.  In addition to the standard EPP command elements, the
 <renew> command contains the following child elements:
  1. An object-specific <obj:renew> element that identifies the object

to be renewed and the elements that are required to extend the

    validity period of the object.
 Example <renew> command:
 C:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
 C:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0"
 C:     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 C:     xsi:schemaLocation="urn:ietf:params:xml:ns:epp-1.0
 C:     epp-1.0.xsd">
 C:  <command>
 C:    <renew>
 C:      <obj:renew xmlns:obj="urn:ietf:params:xml:ns:obj"
 C:       xsi:schemaLocation="urn:ietf:params:xml:ns:obj obj.xsd">
 C:        <!-- Object-specific elements. -->
 C:      </obj:renew>
 C:    </renew>
 C:    <clTRID>ABC-12346</clTRID>
 C:  </command>
 C:</epp>
 When a <renew> command has been processed successfully, a server MAY
 respond with an EPP <resData> element that MUST contain a child
 element that identifies the object namespace and the location of the
 object schema.  The child elements of the <resData> element are
 object-specific.
 Example <renew> response with <resData>:
 S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
 S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0"
 S:     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 S:     xsi:schemaLocation="urn:ietf:params:xml:ns:epp-1.0
 S:     epp-1.0.xsd">
 S:  <response>
 S:    <result code="1000">
 S:      <msg>Command completed successfully</msg>
 S:    </result>

Hollenbeck Standards Track [Page 37] RFC 3730 EPP March 2004

 S:    <resData>
 S:      <obj:renData xmlns:obj="urn:ietf:params:xml:ns:obj"
 S:       xsi:schemaLocation="urn:ietf:params:xml:ns:obj obj.xsd">
 S:        <!-- Object-specific elements. -->
 S:      </obj:renData>
 S:    </resData>
 S:    <trID>
 S:      <clTRID>ABC-12346</clTRID>
 S:      <svTRID>54322-XYZ</svTRID>
 S:    </trID>
 S:  </response>
 S:</epp>
 The EPP <renew> command is used to extend the validity period of an
 existing object.  This action SHOULD be limited to authorized
 clients; restricting this action to the sponsoring client is
 RECOMMENDED.  Object renewal MAY be unavailable or limited by
 object-specific policies.

2.9.3.4. EPP <transfer> Command

 The EPP <transfer> command is used to manage changes in client
 sponsorship of an existing object.  Clients can initiate a transfer
 request, cancel a transfer request, approve a transfer request, and
 reject a transfer request using the "op" command attribute.
 A client who wishes to assume sponsorship of a known object from
 another client uses the <transfer> command with the value of the "op"
 attribute set to "request".  Once a transfer has been requested, the
 same client can cancel the request using a <transfer> command with
 the value of the "op" attribute set to "cancel".  A request to cancel
 the transfer MUST be sent to the server before the current sponsoring
 client either approves or rejects the transfer request and before the
 server automatically processes the request due to responding client
 inactivity.
 Once a transfer request has been received by the server, the server
 MUST notify the current sponsoring client of the requested transfer
 by queuing a service message for retrieval via the <poll> command.
 The current status of a pending <transfer> command for any object can
 be found using the <transfer> query command.  Transfer service
 messages MUST include the object-specific elements specified for
 <transfer> command responses.

Hollenbeck Standards Track [Page 38] RFC 3730 EPP March 2004

 The current sponsoring client MAY explicitly approve or reject the
 transfer request.  The client can approve the request using a
 <transfer> command with the value of the "op" attribute set to
 "approve".  The client can reject the request using a <transfer>
 command with the value of the "op" attribute set to "reject".
 A server MAY automatically approve or reject all transfer requests
 that are not explicitly approved or rejected by the current
 sponsoring client within a fixed amount of time.  The amount of time
 to wait for explicit action and the default server behavior are local
 matters not specified by EPP, but they SHOULD be documented in a
 server-specific profile document that describes default server
 behavior for client information.
 Objects eligible for transfer MUST have associated authorization
 information that MUST be provided to complete a <transfer> command.
 The type of authorization information required is object-specific;
 passwords or more complex mechanisms based on public key cryptography
 are typical.
 The elements needed to identify and complete the transfer of an
 object are object-specific, so the child elements of the <transfer>
 command are specified using the EPP extension framework.  In addition
 to the standard EPP command elements, the <transfer> command contains
 the following child elements:
  1. An object-specific <obj:transfer> element that identifies the

object to be transferred and the elements that are required to

    process the transfer command.
 Example <transfer> command:
 C:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
 C:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0"
 C:     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 C:     xsi:schemaLocation="urn:ietf:params:xml:ns:epp-1.0
 C:     epp-1.0.xsd">
 C:  <command>
 C:    <transfer op="request">
 C:      <obj:transfer xmlns:obj="urn:ietf:params:xml:ns:obj"
 C:       xsi:schemaLocation="urn:ietf:params:xml:ns:obj obj.xsd">
 C:        <!-- Object-specific elements. -->
 C:      </obj:transfer>
 C:    </transfer>
 C:    <clTRID>ABC-12346</clTRID>
 C:  </command>
 C:</epp>

Hollenbeck Standards Track [Page 39] RFC 3730 EPP March 2004

 When a <transfer> command has been processed successfully, a server
 MUST respond with an EPP <resData> element that MUST contain a child
 element that identifies the object namespace and the location of the
 object schema.  The child elements of the <resData> element are
 object-specific, but they MUST include elements that identify the
 object, the status of the transfer, the identifier of the client that
 requested the transfer, the date and time that the request was made,
 the identifier of the client that is authorized to act on the
 request, the date and time by which an action is expected, and an
 OPTIONAL date and time noting changes in the object's validity period
 (if applicable) that occur as a result of the transfer.
 Example <transfer> response with <resData>:
 S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
 S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0"
 S:     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 S:     xsi:schemaLocation="urn:ietf:params:xml:ns:epp-1.0
 S:     epp-1.0.xsd">
 S:  <response>
 S:    <result code="1001">
 S:      <msg>Command completed successfully; action pending</msg>
 S:    </result>
 S:    <resData>
 S:      <obj:trnData xmlns:obj="urn:ietf:params:xml:ns:obj"
 S:       xsi:schemaLocation="urn:ietf:params:xml:ns:obj obj.xsd">
 S:        <obj:name>example</obj:name>
 S:        <obj:trStatus>pending</obj:trStatus>
 S:        <obj:reID>ClientX</obj:reID>
 S:        <obj:reDate>2000-06-08T22:00:00.0Z</obj:reDate>
 S:        <obj:acID>ClientY</obj:acID>
 S:        <obj:acDate>2000-06-13T22:00:00.0Z</obj:acDate>
 S:        <obj:exDate>2002-09-08T22:00:00.0Z</obj:exDate>
 S:      </obj:trnData>
 S:    </resData>
 S:    <trID>
 S:      <clTRID>ABC-12346</clTRID>
 S:      <svTRID>54322-XYZ</svTRID>
 S:    </trID>
 S:  </response>
 S:</epp>
 The EPP <transfer> command is used to manage changes in client
 sponsorship of an existing object.  This action SHOULD be limited to
 authorized clients; restricting <transfer> requests to a client other
 than the current sponsoring client, <transfer> approval requests to

Hollenbeck Standards Track [Page 40] RFC 3730 EPP March 2004

 the current sponsoring client, and <transfer> cancellation requests
 to the original requesting client is RECOMMENDED.  Object transfer
 MAY be unavailable or limited by object-specific policies.

2.9.3.5. EPP <update> Command

 The EPP <update> command is used to change information associated
 with an existing object.  The elements needed to identify and modify
 an object are object-specific, so the child elements of the <update>
 command are specified using the EPP extension framework.  In addition
 to the standard EPP command elements, the <update> command contains
 the following child elements:
  1. An object-specific <obj:update> element that identifies the object

to be updated and the elements that are required to modify the

    object.  Object-specific elements MUST identify values to be
    added, values to be removed, or values to be changed.
 Example <update> command:
 C:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
 C:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0"
 C:     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 C:     xsi:schemaLocation="urn:ietf:params:xml:ns:epp-1.0
 C:     epp-1.0.xsd">
 C:  <command>
 C:    <update>
 C:      <obj:update xmlns:obj="urn:ietf:params:xml:ns:obj"
 C:       xsi:schemaLocation="urn:ietf:params:xml:ns:obj obj.xsd">
 C:        <!-- Object-specific elements. -->
 C:      </obj:update>
 C:    </update>
 C:    <clTRID>ABC-12346</clTRID>
 C:  </command>
 C:</epp>
 When an <update> command has been processed successfully, a server
 MAY respond with an EPP <resData> element that MUST contain a child
 element that identifies the object namespace and the location of the
 object schema.  The child elements of the <resData> element are
 object-specific.

Hollenbeck Standards Track [Page 41] RFC 3730 EPP March 2004

 Example <update> response without <resData>:
 S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
 S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0"
 S:     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 S:     xsi:schemaLocation="urn:ietf:params:xml:ns:epp-1.0
 S:     epp-1.0.xsd">
 S:  <response>
 S:    <result code="1000">
 S:      <msg>Command completed successfully</msg>
 S:    </result>
 S:    <trID>
 S:      <clTRID>ABC-12346</clTRID>
 S:      <svTRID>54322-XYZ</svTRID>
 S:    </trID>
 S:  </response>
 S:</epp>
 The EPP <update> command is used to change information associated
 with an existing object.  This action SHOULD be limited to authorized
 clients; restricting this action to the sponsoring client is
 RECOMMENDED.

3. Result Codes

 EPP result codes are based on the theory of reply codes described in
 section 4.2.1 of [RFC2821].  EPP uses four decimal digits to describe
 the success or failure of each EPP command.  Each of the digits of
 the reply have special significance.
 The first digit denotes command success or failure.  The second digit
 denotes the response category, such as command syntax or security.
 The third and fourth digits provide explicit response detail within
 each response category.
 There are two values for the first digit of the reply code:
 1yzz   Positive completion reply.  The command has been accepted and
 processed by the system without error.
 2yzz   Negative completion reply.  The command was not accepted and
 the requested action did not occur.

Hollenbeck Standards Track [Page 42] RFC 3730 EPP March 2004

 The second digit groups responses into one of six specific
 categories:
 x0zz   Protocol Syntax
 x1zz   Implementation-specific Rules
 x2zz   Security
 x3zz   Data Management
 x4zz   Server System
 x5zz   Connection Management
 The third and fourth digits provide response detail within the
 categories defined by the first and second digits.  Specific result
 codes are listed in the table below.
 Every EPP response MUST include a result code and a human-readable
 description of the result code.  The language used to represent the
 description MAY be identified using an instance of the "lang"
 attribute within the <msg> element.  If not specified, the default
 language is English, identified as "en".  A description of the
 structure of valid values for the "lang" attribute is described in
 [RFC3066].
 Response text MAY be translated into other languages, though the
 translation MUST preserve the meaning of the code as described here.
 Response code values MUST NOT be changed when translating text.
 Response text in the table below is enclosed in quotes to clearly
 mark the beginning and ending of each response string.  Quotes MUST
 NOT be used to delimit these strings when returning response text via
 the protocol.

Hollenbeck Standards Track [Page 43] RFC 3730 EPP March 2004

 Successful command completion responses:
 Code    Response text in English
 ___________________________________
 1000    "Command completed successfully"
 This is the usual response code for a successfully completed command
 that is not addressed by any other 1xxx-series response code.
 1001    "Command completed successfully; action pending"
 This response code MUST be returned when responding to a command the
 requires offline activity before the requested action can be
 completed.  See section 2 for a description of other processing
 requirements.
 1300    "Command completed successfully; no messages"
 This response code MUST be returned when responding to a <poll>
 request command and the server message queue is empty.
 1301    "Command completed successfully; ack to dequeue"
 This response code MUST be returned when responding to a <poll>
 request command and a message has been retrieved from the server
 message queue.
 1500    "Command completed successfully; ending session"
 This response code MUST be returned when responding to a successful
 <logout> command.

Hollenbeck Standards Track [Page 44] RFC 3730 EPP March 2004

 Command error responses:
 Code    Response text in English
 ___________________________________
 2000    "Unknown command"
 This response code MUST be returned when a server receives a command
 element that is not defined by EPP.
 2001    "Command syntax error"
 This response code MUST be returned when a server receives an
 improperly formed command element.
 2002    "Command use error"
 This response code MUST be returned when a server receives a properly
 formed command element, but the command can not be executed due to a
 sequencing or context error.  For example, a <logout> command can not
 be executed without having first completed a <login> command.
 2003    "Required parameter missing"
 This response code MUST be returned when a server receives a command
 for which a required parameter value has not been provided.
 2004    "Parameter value range error"
 This response code MUST be returned when a server receives a command
 parameter whose value is outside the range of values specified by the
 protocol.  The error value SHOULD be returned via a <value> element
 in the EPP response.
 2005    "Parameter value syntax error"
 This response code MUST be returned when a server receives a command
 containing a parameter whose value is improperly formed.  The error
 value SHOULD be returned via a <value> element in the EPP response.
 2100    "Unimplemented protocol version"
 This response code MUST be returned when a server receives a command
 element specifying a protocol version that is not implemented by the
 server.
 2101    "Unimplemented command"
 This response code MUST be returned when a server receives a valid
 EPP command element that is not implemented by the server.  For
 example, a <transfer> command can be unimplemented for certain object
 types.

Hollenbeck Standards Track [Page 45] RFC 3730 EPP March 2004

 2102    "Unimplemented option"
 This response code MUST be returned when a server receives a valid
 EPP command element that contains a protocol option that is not
 implemented by the server.
 2103    "Unimplemented extension"
 This response code MUST be returned when a server receives a valid
 EPP command element that contains a protocol command extension that
 is not implemented by the server.
 2104    "Billing failure"
 This response code MUST be returned when a server attempts to execute
 a billable operation and the command can not be completed due to a
 client billing failure.
 2105    "Object is not eligible for renewal"
 This response code MUST be returned when a client attempts to <renew>
 an object that is not eligible for renewal in accordance with server
 policy.
 2106    "Object is not eligible for transfer"
 This response code MUST be returned when a client attempts to
 <transfer> an object that is not eligible for transfer in accordance
 with server policy.
 2200    "Authentication error"
 This response code MUST be returned when a server notes an error when
 validating client credentials.
 2201    "Authorization error"
 This response code MUST be returned when a server notes a client
 authorization error when executing a command.  This error is used to
 note that a client lacks privileges to execute the requested command.
 2202    "Invalid authorization information"
 This response code MUST be returned when a server receives invalid
 command authorization information required to confirm authorization
 to execute a command.  This error is used to note that a client has
 the privileges required to execute the requested command, but the
 authorization information provided by the client does not match the
 authorization information archived by the server.
 2300    "Object pending transfer"
 This response code MUST be returned when a server receives a command
 to transfer an object that is pending transfer due to an earlier
 transfer request.

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 2301    "Object not pending transfer"
 This response code MUST be returned when a server receives a command
 to confirm, reject, or cancel the transfer an object when no command
 has been made to transfer the object.
 2302    "Object exists"
 This response code MUST be returned when a server receives a command
 to create an object that already exists in the repository.
 2303    "Object does not exist"
 This response code MUST be returned when a server receives a command
 to query or transform an object that does not exist in the
 repository.
 2304    "Object status prohibits operation"
 This response code MUST be returned when a server receives a command
 to transform an object that can not be completed due to server policy
 or business practices.  For example, a server can disallow <transfer>
 commands under terms and conditions that are matters of local policy,
 or the server might have received a <delete> command for an object
 whose status prohibits deletion.
 2305    "Object association prohibits operation"
 This response code MUST be returned when a server receives a command
 to transform an object that can not be completed due to dependencies
 on other objects that are associated with the target object.  For
 example, a server can disallow <delete> commands while an object has
 active associations with other objects.
 2306    "Parameter value policy error"
 This response code MUST be returned when a server receives a command
 containing a parameter value that is syntactically valid, but
 semantically invalid due to local policy.  For example, the server
 can support a subset of a range of valid protocol parameter values.
 The error value SHOULD be returned via a <value> element in the EPP
 response.
 2307    "Unimplemented object service"
 This response code MUST be returned when a server receives a command
 to operate on an object service that is not supported by the server.
 2308    "Data management policy violation"
 This response code MUST be returned when a server receives a command
 whose execution results in a violation of server data management
 policies.  For example, removing all attribute values or object
 associations from an object might be a violation of a server's data
 management policies.

Hollenbeck Standards Track [Page 47] RFC 3730 EPP March 2004

 2400    "Command failed"
 This response code MUST be returned when a server is unable to
 execute a command due to an internal server error that is not related
 to the protocol.  The failure can be transient.  The server MUST keep
 any ongoing session active.
 2500    "Command failed; server closing connection"
 This response code MUST be returned when a server receives a command
 that can not be completed due to an internal server error that is not
 related to the protocol.  The failure is not transient, and will
 cause other commands to fail as well.  The server MUST end the active
 session and close the existing connection.
 2501    "Authentication error; server closing connection"
 This response code MUST be returned when a server notes an error when
 validating client credentials and a server-defined limit on the
 number of allowable failures has been exceeded.  The server MUST
 close the existing connection.
 2502    "Session limit exceeded; server closing connection"
 This response code MUST be returned when a server receives a <login>
 command, and the command can not be completed because the client has
 exceeded a system-defined limit on the number of sessions that the
 client can establish.  It might be possible to establish a session by
 ending existing unused sessions and closing inactive connections.

4. Formal Syntax

 EPP is specified in XML Schema notation.  The formal syntax presented
 here is a complete schema representation of EPP suitable for
 automated validation of EPP XML instances.
 Two schemas are presented here.  The first schema is the base EPP
 schema.  The second schema defines elements and structures that can
 be used by both the base EPP schema and object mapping schemas.  The
 BEGIN and END tags are not part of the schema; they are used to note
 the beginning and ending of the schema for URI registration purposes.

Hollenbeck Standards Track [Page 48] RFC 3730 EPP March 2004

4.1. Base Schema

   BEGIN
   <?xml version="1.0" encoding="UTF-8"?>
   <schema targetNamespace="urn:ietf:params:xml:ns:epp-1.0"
           xmlns:epp="urn:ietf:params:xml:ns:epp-1.0"
           xmlns:eppcom="urn:ietf:params:xml:ns:eppcom-1.0"
           xmlns="http://www.w3.org/2001/XMLSchema"
           elementFormDefault="qualified">
   <!--
   Import common element types.
   -->
     <import namespace="urn:ietf:params:xml:ns:eppcom-1.0"
             schemaLocation="eppcom-1.0.xsd"/>
     <annotation>
       <documentation>
         Extensible Provisioning Protocol v1.0 schema.
       </documentation>
     </annotation>
   <!--
   Every EPP XML instance must begin with this element.
   -->
     <element name="epp" type="epp:eppType"/>
   <!--
   An EPP XML instance must contain a greeting, hello, command,
   response, or extension.
   -->
     <complexType name="eppType">
       <choice>
         <element name="greeting" type="epp:greetingType"/>
         <element name="hello"/>
         <element name="command" type="epp:commandType"/>
         <element name="response" type="epp:responseType"/>
         <element name="extension" type="epp:extAnyType"/>
       </choice>
     </complexType>
   <!--
   A greeting is sent by a server in response to a client connection
   or <hello>.
   -->
     <complexType name="greetingType">
       <sequence>

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         <element name="svID" type="epp:sIDType"/>
         <element name="svDate" type="dateTime"/>
         <element name="svcMenu" type="epp:svcMenuType"/>
         <element name="dcp" type="epp:dcpType"/>
       </sequence>
     </complexType>
   <!--
   Server IDs are strings with minimum and maximum length
   restrictions.
   -->
     <simpleType name="sIDType">
       <restriction base="normalizedString">
         <minLength value="3"/>
         <maxLength value="64"/>
       </restriction>
     </simpleType>
   <!--
   A server greeting identifies available object services.
   -->
     <complexType name="svcMenuType">
       <sequence>
         <element name="version" type="epp:versionType"
          maxOccurs="unbounded"/>
         <element name="lang" type="language"
          maxOccurs="unbounded"/>
         <element name="objURI" type="anyURI"
          maxOccurs="unbounded"/>
         <element name="svcExtension" type="epp:extURIType"
          minOccurs="0"/>
       </sequence>
     </complexType>
   <!--
   Data Collection Policy types.
   -->
     <complexType name="dcpType">
       <sequence>
         <element name="access" type="epp:dcpAccessType"/>
         <element name="statement" type="epp:dcpStatementType"
          maxOccurs="unbounded"/>
         <element name="expiry" type="epp:dcpExpiryType"
          minOccurs="0"/>
       </sequence>
     </complexType>
     <complexType name="dcpAccessType">

Hollenbeck Standards Track [Page 50] RFC 3730 EPP March 2004

       <choice>
         <element name="all"/>
         <element name="none"/>
         <element name="null"/>
         <element name="other"/>
         <element name="personal"/>
         <element name="personalAndOther"/>
       </choice>
     </complexType>
     <complexType name="dcpStatementType">
       <sequence>
         <element name="purpose" type="epp:dcpPurposeType"/>
         <element name="recipient" type="epp:dcpRecipientType"/>
         <element name="retention" type="epp:dcpRetentionType"/>
       </sequence>
     </complexType>
     <complexType name="dcpPurposeType">
       <sequence>
         <element name="admin"
          minOccurs="0"/>
         <element name="contact"
          minOccurs="0"/>
         <element name="other"
          minOccurs="0"/>
         <element name="prov"
          minOccurs="0"/>
       </sequence>
     </complexType>
     <complexType name="dcpRecipientType">
       <sequence>
         <element name="other"
          minOccurs="0"/>
         <element name="ours" type="epp:dcpOursType"
          minOccurs="0" maxOccurs="unbounded"/>
         <element name="public"
          minOccurs="0"/>
         <element name="same"
          minOccurs="0"/>
         <element name="unrelated"
          minOccurs="0"/>
       </sequence>
     </complexType>
     <complexType name="dcpOursType">
       <sequence>

Hollenbeck Standards Track [Page 51] RFC 3730 EPP March 2004

         <element name="recDesc" type="epp:dcpRecDescType"
          minOccurs="0"/>
       </sequence>
     </complexType>
     <simpleType name="dcpRecDescType">
       <restriction base="token">
         <minLength value="1"/>
         <maxLength value="255"/>
       </restriction>
     </simpleType>
     <complexType name="dcpRetentionType">
       <choice>
         <element name="business"/>
         <element name="indefinite"/>
         <element name="legal"/>
         <element name="none"/>
         <element name="stated"/>
       </choice>
     </complexType>
     <complexType name="dcpExpiryType">
       <choice>
         <element name="absolute" type="dateTime"/>
         <element name="relative" type="duration"/>
       </choice>
     </complexType>
   <!--
   Extension framework types.
   -->
     <complexType name="extAnyType">
       <sequence>
         <any namespace="##other"
          maxOccurs="unbounded"/>
       </sequence>
     </complexType>
     <complexType name="extURIType">
       <sequence>
         <element name="extURI" type="anyURI"
          maxOccurs="unbounded"/>
       </sequence>
     </complexType>
   <!--
 An EPP version number is a dotted pair of decimal numbers.

Hollenbeck Standards Track [Page 52] RFC 3730 EPP March 2004

<simpleType name="versionType">

     <restriction base="token">
       <pattern value="[1-9]+\.[0-9]+"/>
       <enumeration value="1.0"/>
     </restriction>
   </simpleType>
 <!--
 Command types.
 -->
   <complexType name="commandType">
     <sequence>
       <choice>
         <element name="check" type="epp:readWriteType"/>
         <element name="create" type="epp:readWriteType"/>
         <element name="delete" type="epp:readWriteType"/>
         <element name="info" type="epp:readWriteType"/>
         <element name="login" type="epp:loginType"/>
         <element name="logout"/>
         <element name="poll" type="epp:pollType"/>
         <element name="renew" type="epp:readWriteType"/>
         <element name="transfer" type="epp:transferType"/>
         <element name="update" type="epp:readWriteType"/>
       </choice>
       <element name="extension" type="epp:extAnyType"
        minOccurs="0"/>
       <element name="clTRID" type="epp:trIDStringType"
        minOccurs="0"/>
     </sequence>
   </complexType>
 <!--
 The <login> command.
 -->
   <complexType name="loginType">
     <sequence>
       <element name="clID" type="eppcom:clIDType"/>
       <element name="pw" type="epp:pwType"/>
       <element name="newPW" type="epp:pwType"
        minOccurs="0"/>
       <element name="options" type="epp:credsOptionsType"/>
       <element name="svcs" type="epp:loginSvcType"/>
     </sequence>
   </complexType>
   <complexType name="credsOptionsType">
     <sequence>

Hollenbeck Standards Track [Page 53] RFC 3730 EPP March 2004

       <element name="version" type="epp:versionType"/>
       <element name="lang" type="language"/>
     </sequence>
   </complexType>
   <simpleType name="pwType">
     <restriction base="token">
       <minLength value="6"/>
       <maxLength value="16"/>
     </restriction>
   </simpleType>
   <complexType name="loginSvcType">
     <sequence>
       <element name="objURI" type="anyURI"
        maxOccurs="unbounded"/>
       <element name="svcExtension" type="epp:extURIType"
        minOccurs="0"/>
     </sequence>
   </complexType>
 <!--
 The <poll> command.
 -->
   <complexType name="pollType">
     <attribute name="op" type="epp:pollOpType"
      use="required"/>
     <attribute name="msgID" type="token"/>
   </complexType>
   <simpleType name="pollOpType">
     <restriction base="token">
       <enumeration value="ack"/>
       <enumeration value="req"/>
     </restriction>
   </simpleType>
 <!--
 The <transfer> command.  This is object-specific, and uses attributes
 to identify the requested operation.
 -->
   <complexType name="transferType">
     <sequence>
       <any namespace="##other"/>
     </sequence>
     <attribute name="op" type="epp:transferOpType"
      use="required"/>
   </complexType>

Hollenbeck Standards Track [Page 54] RFC 3730 EPP March 2004

   <simpleType name="transferOpType">
     <restriction base="token">
       <enumeration value="approve"/>
       <enumeration value="cancel"/>
       <enumeration value="query"/>
       <enumeration value="reject"/>
       <enumeration value="request"/>
     </restriction>
   </simpleType>
 <!--
 All other object-centric commands. EPP doesn't specify the syntax or
 semantics of object-centric command elements.  The elements MUST be
 described in detail in another schema specific to the object.
 -->
   <complexType name="readWriteType">
     <sequence>
       <any namespace="##other"/>
     </sequence>
   </complexType>
   <complexType name="trIDType">
     <sequence>
       <element name="clTRID" type="epp:trIDStringType"
        minOccurs="0"/>
       <element name="svTRID" type="epp:trIDStringType"/>
     </sequence>
   </complexType>
   <simpleType name="trIDStringType">
     <restriction base="token">
       <minLength value="3"/>
       <maxLength value="64"/>
     </restriction>
   </simpleType>
 <!--
 Response types.
 -->
   <complexType name="responseType">
     <sequence>
       <element name="result" type="epp:resultType"
        maxOccurs="unbounded"/>
       <element name="msgQ" type="epp:msgQType"
        minOccurs="0"/>
       <element name="resData" type="epp:extAnyType"
        minOccurs="0"/>
       <element name="extension" type="epp:extAnyType"
        minOccurs="0"/>

Hollenbeck Standards Track [Page 55] RFC 3730 EPP March 2004

       <element name="trID" type="epp:trIDType"/>
     </sequence>
   </complexType>
   <complexType name="resultType">
     <sequence>
       <element name="msg" type="epp:msgType"/>
       <choice minOccurs="0" maxOccurs="unbounded">
         <element name="value" type="epp:errValueType"/>
         <element name="extValue" type="epp:extErrValueType"/>
       </choice>
     </sequence>
     <attribute name="code" type="epp:resultCodeType"
      use="required"/>
   </complexType>
   <complexType name="errValueType" mixed="true">
     <sequence>
       <any namespace="##any" processContents="skip"/>
     </sequence>
     <anyAttribute namespace="##any" processContents="skip"/>
   </complexType>
   <complexType name="extErrValueType">
     <sequence>
       <element name="value" type="epp:errValueType"/>
       <element name="reason" type="epp:msgType"/>
     </sequence>
   </complexType>
   <complexType name="msgQType">
     <sequence>
       <element name="qDate" type="dateTime"
        minOccurs="0"/>
       <element name="msg" type="epp:mixedMsgType"
        minOccurs="0"/>
     </sequence>
     <attribute name="count" type="unsignedLong"
      use="required"/>
     <attribute name="id" type="eppcom:minTokenType"
      use="required"/>
   </complexType>
   <complexType name="mixedMsgType" mixed="true">
     <sequence>
       <any processContents="skip"
        minOccurs="0" maxOccurs="unbounded"/>
     </sequence>

Hollenbeck Standards Track [Page 56] RFC 3730 EPP March 2004

     <attribute name="lang" type="language"
      default="en"/>
   </complexType>
 <!--
 Human-readable text may be expressed in languages other than English.
 -->
   <complexType name="msgType">
     <simpleContent>
       <extension base="normalizedString">
         <attribute name="lang" type="language"
          default="en"/>
       </extension>
     </simpleContent>
   </complexType>
 <!--
 EPP result codes.
 -->
   <simpleType name="resultCodeType">
     <restriction base="unsignedShort">
       <enumeration value="1000"/>
       <enumeration value="1001"/>
       <enumeration value="1300"/>
       <enumeration value="1301"/>
       <enumeration value="1500"/>
       <enumeration value="2000"/>
       <enumeration value="2001"/>
       <enumeration value="2002"/>
       <enumeration value="2003"/>
       <enumeration value="2004"/>
       <enumeration value="2005"/>
       <enumeration value="2100"/>
       <enumeration value="2101"/>
       <enumeration value="2102"/>
       <enumeration value="2103"/>
       <enumeration value="2104"/>
       <enumeration value="2105"/>
       <enumeration value="2106"/>
       <enumeration value="2200"/>
       <enumeration value="2201"/>
       <enumeration value="2202"/>
       <enumeration value="2300"/>
       <enumeration value="2301"/>
       <enumeration value="2302"/>
       <enumeration value="2303"/>
       <enumeration value="2304"/>
       <enumeration value="2305"/>

Hollenbeck Standards Track [Page 57] RFC 3730 EPP March 2004

       <enumeration value="2306"/>
       <enumeration value="2307"/>
       <enumeration value="2308"/>
       <enumeration value="2400"/>
       <enumeration value="2500"/>
       <enumeration value="2501"/>
       <enumeration value="2502"/>
     </restriction>
   </simpleType>
 <!--
 End of schema.
 -->
 </schema>
 END

4.2. Shared Structure Schema

   BEGIN
   <?xml version="1.0" encoding="UTF-8"?>
   <schema targetNamespace="urn:ietf:params:xml:ns:eppcom-1.0"
           xmlns:eppcom="urn:ietf:params:xml:ns:eppcom-1.0"
           xmlns="http://www.w3.org/2001/XMLSchema"
           elementFormDefault="qualified">
     <annotation>
       <documentation>
       Extensible Provisioning Protocol v1.0
       shared structures schema.
     </documentation>
   </annotation>
 <!--
 Object authorization information types.
 -->
   <complexType name="pwAuthInfoType">
     <simpleContent>
       <extension base="normalizedString">
         <attribute name="roid" type="eppcom:roidType"/>
       </extension>
     </simpleContent>
   </complexType>
   <complexType name="extAuthInfoType">
     <sequence>
       <any namespace="##other"/>
     </sequence>

Hollenbeck Standards Track [Page 58] RFC 3730 EPP March 2004

   </complexType>
 <!--
 <check> response types.
 -->
   <complexType name="reasonType">
     <simpleContent>
       <extension base="eppcom:reasonBaseType">
         <attribute name="lang" type="language"/>
       </extension>
     </simpleContent>
   </complexType>
   <simpleType name="reasonBaseType">
     <restriction base="token">
       <minLength value="1"/>
       <maxLength value="32"/>
     </restriction>
   </simpleType>
 <!--
 Abstract client and object identifier type.
 -->
   <simpleType name="clIDType">
     <restriction base="token">
       <minLength value="3"/>
       <maxLength value="16"/>
     </restriction>
   </simpleType>
 <!--
 DNS label type.
 -->
   <simpleType name="labelType">
     <restriction base="token">
       <minLength value="1"/>
       <maxLength value="255"/>
     </restriction>
   </simpleType>
 <!--
 Non-empty token type.
 -->
   <simpleType name="minTokenType">
     <restriction base="token">
       <minLength value="1"/>
     </restriction>
   </simpleType>

Hollenbeck Standards Track [Page 59] RFC 3730 EPP March 2004

 <!--
 Repository Object IDentifier type.
 -->
   <simpleType name="roidType">
     <restriction base="token">
       <pattern value="(\w|_){1,80}-\w{1,8}"/>
     </restriction>
   </simpleType>
 <!--
 Transfer status identifiers.
 -->
   <simpleType name="trStatusType">
     <restriction base="token">
       <enumeration value="clientApproved"/>
       <enumeration value="clientCancelled"/>
       <enumeration value="clientRejected"/>
       <enumeration value="pending"/>
       <enumeration value="serverApproved"/>
       <enumeration value="serverCancelled"/>
     </restriction>
   </simpleType>
 <!--
 End of schema.
 -->
 </schema>
 END

5. Internationalization Considerations

 EPP is represented in XML, which provides native support for encoding
 information using the Unicode character set and its more compact
 representations including UTF-8.  Conformant XML processors recognize
 both UTF-8 and UTF-16.  Though XML includes provisions to identify
 and use other character encodings through use of an "encoding"
 attribute in an <?xml?> declaration, use of UTF-8 is RECOMMENDED in
 environments where parser encoding support incompatibility exists.
 EPP includes a provision for returning a human-readable message with
 every result code.  This document describes result codes in English,
 but the actual text returned with a result MAY be provided in a
 language negotiated when a session is established.  Languages other
 than English MUST be noted through specification of a "lang"
 attribute for each message.  Valid values for the "lang" attribute
 and "lang" negotiation elements are described in [RFC3066].

Hollenbeck Standards Track [Page 60] RFC 3730 EPP March 2004

 All date-time values presented via EPP MUST be expressed in Universal
 Coordinated Time using the Gregorian calendar.  XML Schema allows use
 of time zone identifiers to indicate offsets from the zero meridian,
 but this option MUST NOT be used with EPP.  The extended date-time
 form using upper case "T" and "Z" characters defined in [RFC3339]
 MUST be used to represent date-time values as XML Schema does not
 support truncated date-time forms or lower case "T" and "Z"
 characters.

6. IANA Considerations

 This document uses URNs to describe XML namespaces and XML schemas
 conforming to a registry mechanism described in [RFC3688].  Four URI
 assignments have been registered by the IANA.
 Registration request for the EPP namespace:
    URI: urn:ietf:params:xml:ns:epp-1.0
 Registrant Contact: See the "Author's Address" section of this
 document.
    XML: None.  Namespace URIs do not represent an XML specification.
 Registration request for the EPP XML schema:
    URI: urn:ietf:params:xml:schema:epp-1.0
 Registrant Contact: See the "Author's Address" section of this
 document.
    XML: See the "Base Schema" section of this document.
 Registration request for the EPP shared structure namespace:
    URI: urn:ietf:params:xml:ns:eppcom-1.0
 Registrant Contact: See the "Author's Address" section of this
 document.
    XML: None.  Namespace URIs do not represent an XML specification.
 Registration request for the EPP shared structure XML schema:
    URI: urn:ietf:params:xml:schema:eppcom-1.0

Hollenbeck Standards Track [Page 61] RFC 3730 EPP March 2004

 Registrant Contact: See the "Author's Address" section of this
 document.
    XML: See the "Shared Structure Schema" section of this document.

7. Security Considerations

 EPP provides only simple client authentication services.  A passive
 attack is sufficient to recover client identifiers and passwords,
 allowing trivial command forgery.  Protection against most common
 attacks and more robust security services MUST be provided by other
 protocol layers.  Specifically, EPP instances MUST be protected using
 a transport mechanism or application protocol that provides integrity
 and confidentiality.
 EPP uses a variant of the PLAIN SASL mechanism described in [RFC2595]
 to provide a simple application-layer authentication service that
 augments or supplements authentication and identification services
 that might be available at other protocol layers.  Where the PLAIN
 SASL mechanism specifies provision of an authorization identifier,
 authentication identifier, and password as a single string separated
 by ASCII NUL characters, EPP specifies use of a combined
 authorization and authentication identifier and a password provided
 as distinct XML elements.
 Repeated password guessing attempts can be discouraged by limiting
 the number of <login> attempts that can be attempted on an open
 connection.  A server MAY close an open connection if multiple
 <login> attempts are made with either an invalid client identifier,
 an invalid password, or both an invalid client identifier and an
 invalid password.
 EPP uses authentication information associated with objects to
 confirm object transfer authority.  Authentication information
 exchanged between EPP clients and third party entities MUST be
 exchanged using a facility that provides privacy and integrity
 services to protect against unintended disclosure and modification
 while in transit.

8. Acknowledgements

 This document was originally written as an individual submission
 Internet-Draft.  The provreg working group later adopted it as a
 working group document and provided many invaluable comments and
 suggested improvements.  The author wishes to acknowledge the efforts
 of WG chairs Edward Lewis and Jaap Akkerhuis for their process and
 editorial contributions.

Hollenbeck Standards Track [Page 62] RFC 3730 EPP March 2004

 Specific suggestions that have been incorporated into this document
 were provided by Chris Bason, Eric Brunner-Williams, Jordyn Buchanan,
 Roger Castillo Cortazar, Dave Crocker, Ayesha Damaraju, Sheer El-
 Showk, Patrik Faltstrom, James Gould, John Immordino, Dan Kohn, Hong
 Liu, Klaus Malorny, Dan Manley, Michael Mealling, Patrick Mevzek,
 Andrew Newton, Budi Rahardjo, Asbjorn Steira, Rick Wesson, and Jay
 Westerdal.

9. References

9.1. Normative References

 [RFC2119]  Bradner, S., "Key Words for Use in RFCs to Indicate
            Requirement Levels", BCP 14, RFC 2119, March 1997.
 [RFC2277]  Alvestrand, H., "IETF Policy on Character Sets and
            Languages", BCP 18, RFC 2277, January 1998.
 [RFC2279]  Yergeau, F., "UTF-8, a transformation format of ISO
            10646", RFC 2279, January 1998.
 [RFC2781]  Hoffman, P. and F. Yergeau, "UTF-16, an encoding of ISO
            10646", RFC 2781, February 2000.
 [RFC2914]  Floyd, S., "Congestion Control Principles", BCP 41, RFC
            2914, September 2000.
 [RFC3023]  Murata, M., St.Laurent, S. and D. Kohn, "XML Media Types",
            RFC 3023, January 2001.
 [RFC3066]  Alvestrand, H., "Tags for the Identification of
            Languages", BCP 47, RFC 3066, January 2001.
 [RFC3339]  Klyne, G. and C. Newman, "Date and Time on the Internet:
            Timestamps", RFC 3339, July 2002.
 [RFC3375]  Hollenbeck, S., "Generic Registry-Registrar Protocol
            Requirements", RFC 3375, September 2002.
 [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
            January 2004.
 [XML]      Editor T. Bray et al.: "Extensible Markup Language (XML)
            1.0 (Second Edition)", W3C Recommendation 6 October 2000.
 [XMLE]     "XML 1.0 Second Edition Specification Errata", E22, 25
            July 2001, http://www.w3.org/XML/xml-V10-2e-errata#E22.

Hollenbeck Standards Track [Page 63] RFC 3730 EPP March 2004

 [XMLS-1]   Editors H. Thompson et al.: "XML Schema Part 1:
            Structures", W3C Recommendation 2 May 2001.
 [XMLS-2]   Editors P. Biron, A. Malhotra: "XML Schema Part 2:
            Datatypes", W3C Recommendation 2 May 2001.

9.2. Informative References

 [P3P]      Editor M. Marchiori: "The Platform for Privacy Preferences
            1.0 (P3P1.0) Specification", W3C Recommendation 16 April
            2002.
 [RFC793]   Postel, J., "Transmission Control Protocol", STD 7, RFC
            793, September 1981.
 [RFC2595]  Newman, C., "Using TLS with IMAP, POP3 and ACAP", RFC
            2595, June 1999.
 [RFC2821]  Klensin, J., Ed., "Simple Mail Transfer Protocol", RFC
            2821, April 2001.
 [RFC2960]  Stewart, R., Xie, Q., Morneault, K., Sharp, C.,
            Schwarzbauer, H., Taylor, T., Rytina, I., Kalla, M.,
            Zhang, L. and V. Paxson,  "Stream Control Transmission
            Protocol", RFC 2960, October 2000.
 [RFC3080]  Rose, M., "The Blocks Extensible Exchange Protocol Core",
            RFC 3080, March 2001.

Hollenbeck Standards Track [Page 64] RFC 3730 EPP March 2004

Appendix A: Object Mapping Template

 This appendix describes a recommended outline for documenting the EPP
 mapping of an object.  Documents that describe EPP object mappings
 SHOULD describe the mapping in a format similar to the one used here.
 Additional sections are required if the object mapping is written in
 Internet-Draft or RFC format.

1. Introduction

 Provide an introduction that describes the object and an overview of
 the mapping to EPP.

2. Object Attributes

 Describe the attributes associated with the object, including
 references to syntax specifications as appropriate.  Examples of
 object attributes include a name or identifier and dates associated
 with modification events.

3. EPP Command Mapping

3.1. EPP Query Commands

3.1.1. EPP <check> Command

 Describe the object-specific mappings required to implement the EPP
 <check> command.  Include both sample commands and sample responses.

3.1.2. EPP <info> Command

 Describe the object-specific mappings required to implement the EPP
 <info> command.  Include both sample commands and sample responses.

3.1.3. EPP <poll> Command

 Describe the object-specific mappings required to implement the EPP
 <poll> command.  Include both sample commands and sample responses.

3.1.4. EPP <transfer> Command

 Describe the object-specific mappings required to implement the EPP
 <transfer> query command.  Include both sample commands and sample
 responses.

Hollenbeck Standards Track [Page 65] RFC 3730 EPP March 2004

3.2. EPP Transform Commands

3.2.1. EPP <create> Command

 Describe the object-specific mappings required to implement the EPP
 <create> command.  Include both sample commands and sample responses.
 Describe the status of the object with respect to time, including
 expected client and server behavior if a validity period is used.

3.2.2. EPP <delete> Command

 Describe the object-specific mappings required to implement the EPP
 <delete> command.  Include both sample commands and sample responses.

3.2.3. EPP <renew> Command

 Describe the object-specific mappings required to implement the EPP
 <renew> command.  Include both sample commands and sample responses.

3.2.4. EPP <transfer> Command

 Describe the object-specific mappings required to implement the EPP
 <transfer> command.  Include both sample commands and sample
 responses.

3.2.5. EPP <update> Command

 Describe the object-specific mappings required to implement the EPP
 <update> command.  Include both sample commands and sample responses.

4. Formal Syntax

 Provide the XML schema for the object mapping.  An XML DTD MUST NOT
 be used as DTDs do not provide sufficient support for XML namespaces
 and strong data typing.

Hollenbeck Standards Track [Page 66] RFC 3730 EPP March 2004

Appendix B: Media Type Registration: application/epp+xml

 MIME media type name: application
 MIME subtype name: epp+xml
 Mandatory parameters: none
 Optional parameters: Same as the charset parameter of application/xml
 as specified in [RFC3023].
 Encoding considerations: Same as the encoding considerations of
 application/xml as specified in [RFC3023].
 Security considerations: This type has all of the security
 considerations described in [RFC3023] plus the considerations
 specified in the Security Considerations section of this document.
 Interoperability considerations: XML has proven to be interoperable
 across WebDAV clients and servers, and for import and export from
 multiple XML authoring tools.  For maximum interoperability,
 validating processors are recommended.  Although non-validating
 processors can be more efficient, they are not required to handle all
 features of XML.  For further information, see sub-section 2.9
 "Standalone Document Declaration" and section 5 "Conformance" of
 [XML].
 Published specification: This document.
 Applications which use this media type: EPP is device-, platform-,
 and vendor-neutral and is supported by multiple service providers.
 Additional information: If used, magic numbers, fragment identifiers,
 base URIs, and use of the BOM should be as specified in [RFC3023].
 Magic number(s): None.  File extension(s): .xml Macintosh File  Type
 Code(s): "TEXT"
 Person and email address for further information: See the "Author's
 Address" section of this document.
 Intended usage: COMMON
 Author/Change controller: IETF

Hollenbeck Standards Track [Page 67] RFC 3730 EPP March 2004

Author's Address

 Scott Hollenbeck
 VeriSign Global Registry Services
 21345 Ridgetop Circle
 Dulles, VA 20166-6503
 USA
 EMail: shollenbeck@verisign.com

Hollenbeck Standards Track [Page 68] RFC 3730 EPP March 2004

Full 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.
 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.

Intellectual Property

 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.

Acknowledgement

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

Hollenbeck Standards Track [Page 69]

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