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rfc:rfc4930

Network Working Group S. Hollenbeck Request for Comments: 4930 VeriSign, Inc. Obsoletes: 3730 May 2007 Category: Standards Track

               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 IETF Trust (2007).

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.  This document obsoletes RFC 3730.

Hollenbeck Standards Track [Page 1] RFC 4930 EPP May 2007

Table of Contents

 1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   1.1.  Conventions Used in This Document  . . . . . . . . . . . .  3
 2.  Protocol Description . . . . . . . . . . . . . . . . . . . . .  4
   2.1.  Transport Mapping Considerations . . . . . . . . . . . . .  7
   2.2.  Protocol Identification  . . . . . . . . . . . . . . . . .  8
   2.3.  Hello Format . . . . . . . . . . . . . . . . . . . . . . .  8
   2.4.  Greeting Format  . . . . . . . . . . . . . . . . . . . . .  8
   2.5.  Command Format . . . . . . . . . . . . . . . . . . . . . . 12
   2.6.  Response Format  . . . . . . . . . . . . . . . . . . . . . 13
   2.7.  Protocol Extension Framework . . . . . . . . . . . . . . . 18
     2.7.1.  Protocol Extension . . . . . . . . . . . . . . . . . . 18
     2.7.2.  Object Extension . . . . . . . . . . . . . . . . . . . 18
     2.7.3.  Command-Response Extension . . . . . . . . . . . . . . 19
   2.8.  Object Identification  . . . . . . . . . . . . . . . . . . 20
   2.9.  Protocol Commands  . . . . . . . . . . . . . . . . . . . . 21
     2.9.1.  Session Management Commands  . . . . . . . . . . . . . 21
       2.9.1.1.  EPP <login> Command  . . . . . . . . . . . . . . . 21
       2.9.1.2.  EPP <logout> Command . . . . . . . . . . . . . . . 24
     2.9.2.  Query Commands . . . . . . . . . . . . . . . . . . . . 25
       2.9.2.1.  EPP <check> Command  . . . . . . . . . . . . . . . 25
       2.9.2.2.  EPP <info> Command . . . . . . . . . . . . . . . . 27
       2.9.2.3.  EPP <poll> Command . . . . . . . . . . . . . . . . 28
       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 . . . . . . . . . . . . . . . 36
       2.9.3.3.  EPP <renew> Command  . . . . . . . . . . . . . . . 37
       2.9.3.4.  EPP <transfer> Command . . . . . . . . . . . . . . 39
       2.9.3.5.  EPP <update> Command . . . . . . . . . . . . . . . 41
 3.  Result Codes . . . . . . . . . . . . . . . . . . . . . . . . . 42
 4.  Formal Syntax  . . . . . . . . . . . . . . . . . . . . . . . . 48
   4.1.  Base Schema  . . . . . . . . . . . . . . . . . . . . . . . 48
   4.2.  Shared Structure Schema  . . . . . . . . . . . . . . . . . 58
 5.  Internationalization Considerations  . . . . . . . . . . . . . 60
 6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 61
 7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 62
 8.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 63
 9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 63
   9.1.  Normative References . . . . . . . . . . . . . . . . . . . 63
   9.2.  Informative References . . . . . . . . . . . . . . . . . . 64
 Appendix A.  Object Mapping Template . . . . . . . . . . . . . . . 66
 Appendix B.  Media Type Registration: application/epp+xml  . . . . 68
 Appendix C.  Changes from RFC 3730 . . . . . . . . . . . . . . . . 69

Hollenbeck Standards Track [Page 2] RFC 4930 EPP May 2007

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 [W3C.REC-xml-20040204] and XML Schema notation as described in
 [W3C.REC-xmlschema-1-20041028] and [W3C.REC-xmlschema-2-20041028].
 EPP meets and exceeds the requirements for a generic registry
 registrar protocol as described in [RFC3375].  This document
 obsoletes RFC 3730 [RFC3730].
 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
 layered protocol environment.  Bindings to specific transport and
 security protocols are outside the scope of this specification.
 The 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 are provided only to illustrate element
 relationships and are not a REQUIRED feature of this protocol.

Hollenbeck Standards Track [Page 3] RFC 4930 EPP May 2007

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 4] RFC 4930 EPP May 2007

            |
            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 +-----------------+
       |    |       Timeout                         |
       |    +-------------------------------+       | Auth OK
       |                                    |       V
       |   +-----------------+  <hello>  +-----------------+
       |   |     Prepare     |<----------|   Waiting for   |
       |   |     Greeting    |---------->|   Command or    |
       |   +-----------------+   Send    |     <hello>     |
       | Send x5xx             Greeting  +-----------------+
       | 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 object 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 5] RFC 4930 EPP May 2007

 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 XML namespace prefixes used in examples (such as the
 string "foo" in "xmlns:foo") are solely for illustrative purposes.  A
 conforming implementation MUST NOT require the use of these or any
 other specific namespace prefixes.
 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 3629 [RFC3629]) 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.  EPP clients and servers MUST accept a UTF-8 BOM if present,
 though emitting a UTF-8 BOM is NOT RECOMMENDED.
 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"?>

Hollenbeck Standards Track [Page 6] RFC 4930 EPP May 2007

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

[RFC0793] or Stream Control Transmission Protocol (SCTP) [RFC2960]

    that provides congestion avoidance that follows RFC 2914
    [RFC2914], or if it maps onto a protocol such as SMTP [RFC2821] or
    Blocks Extensible Exchange Protocol (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:
  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".

Hollenbeck Standards Track [Page 7] RFC 4930 EPP May 2007

  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 and the namespace
 used within the protocol.  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">
 </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 between a successful <login> command and a
 <logout> command by sending a <hello> to a server.  Use of this
 element is essential in a connection-less environment where a server
 cannot 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:  <hello/>
 C:</epp>

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.

Hollenbeck Standards Track [Page 8] RFC 4930 EPP May 2007

  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:
  1. <all/>: Access is given to all identified data.
  1. <none/>: No access is provided to identified data.
  1. <null/>: Data is not persistent, so no access is

possible.

Hollenbeck Standards Track [Page 9] RFC 4930 EPP May 2007

  1. <personal/>: Access is given to identified data relating

to individuals and organizational entities.

  1. <personalAndOther/>: Access is given to identified data

relating to individuals, organizational entities, and

             other data of a non-personal nature.
  1. <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:
  1. <admin/>: Administrative purposes. Information can be

used for administrative and technical support of the

             provisioning system.
  1. <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.
  1. <prov/>: Object provisioning purposes. Information can

be used to identify objects and inter-object

             relationships.
  1. <other/>: Other purposes. Information may be used in

other ways not captured by the above definitions.

  1. The <recipient> element MUST contain one or more of the

following child elements that describes the recipients of

          collected data:
  1. <other/>: Other entities following unknown practices.
  1. <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 10] RFC 4930 EPP May 2007

  1. <public/>: Public forums.
  1. <same/>: Other entities following server practices.
  1. <unrelated/>: Unrelated third parties.
  1. The <retention> element MUST contain one of the following

child elements that describes data retention practices:

  1. <business/>: Data persists per business practices.
  1. <indefinite/>: Data persists indefinitely.
  1. <legal/>: Data persists per legal requirements.
  1. <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.
  1. <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:
  1. <absolute/>: The policy is valid from the current date

and time until it expires on the specified date and time.

  1. <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
 [W3C.REC-P3P-20020416] specification.

Hollenbeck Standards Track [Page 11] RFC 4930 EPP May 2007

 Example greeting:
 S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
 S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
 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 12] RFC 4930 EPP May 2007

  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:  <command>
 C:    <info>
 C:      <obj:info xmlns:obj="urn:ietf:params:xml:ns:obj">
 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).
  1. Zero or more OPTIONAL <value> elements that identify a client-

provided element (including XML tag and value) or other

       information that caused a server error condition.

Hollenbeck Standards Track [Page 13] RFC 4930 EPP May 2007

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

elements specific to the command and associated object.

Hollenbeck Standards Track [Page 14] RFC 4930 EPP May 2007

  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:  <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 15] RFC 4930 EPP May 2007

 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:  <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:        <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>

Hollenbeck Standards Track [Page 16] RFC 4930 EPP May 2007

 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:  <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>
 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:  <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>

Hollenbeck Standards Track [Page 17] RFC 4930 EPP May 2007

 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:
 C:<epp>
 C:  <extension>
 C:    <!-- One or more extension elements. -->
 C:    <ext:foo xmlns:ext="urn:ietf:params:xml:ns:ext">
 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:

Hollenbeck Standards Track [Page 18] RFC 4930 EPP May 2007

 C:<EPPCommandName>
 C:  <object:command xmlns:object="urn:ietf:params:xml:ns:object">
 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:    <!-- One or more object-specific response elements. -->
 S:  </object:resData>
 S:</resData>
 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:      <!-- 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:

Hollenbeck Standards Track [Page 19] RFC 4930 EPP May 2007

 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>
 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.

Hollenbeck Standards Track [Page 20] RFC 4930 EPP May 2007

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 executions.  This
 section describes each EPP command, including examples with
 representative server responses.

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.

Hollenbeck Standards Track [Page 21] RFC 4930 EPP May 2007

  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.
  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 Simple Authentication and Security Layer (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.

Hollenbeck Standards Track [Page 22] RFC 4930 EPP May 2007

 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:  <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.
 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:  <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>

Hollenbeck Standards Track [Page 23] RFC 4930 EPP May 2007

 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.
 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:  <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:  <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>

Hollenbeck Standards Track [Page 24] RFC 4930 EPP May 2007

 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

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 identifies 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:  <command>
 C:    <check>
 C:      <obj:check xmlns:obj="urn:ietf:params:xml:ns:obj">
 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.  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> element
 contains the following child elements:

Hollenbeck Standards Track [Page 25] RFC 4930 EPP May 2007

  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 cannot be provisioned.
  1. An OPTIONAL <obj:reason> element that MAY be provided when an

object cannot be provisioned. If present, this element contains

    server-specific text to help explain why the object cannot 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:  <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:        <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>
 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.

Hollenbeck Standards Track [Page 26] RFC 4930 EPP May 2007

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:  <command>
 C:    <info>
 C:      <obj:info xmlns:obj="urn:ietf:params:xml:ns:obj">
 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 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 27] RFC 4930 EPP May 2007

 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:  <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:        <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.
 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 SHOULD be

Hollenbeck Standards Track [Page 28] RFC 4930 EPP May 2007

 created for passive clients affected by an action on an object.
 Service messages MAY also be created for active clients that request
 an action on an object, though such messages MUST NOT replace the
 normal protocol response to the request.  For example, <transfer>
 actions SHOULD be reported to the client that has the authority to
 approve or reject a transfer request.  Other methods of server-client
 action notification, such as offline reporting, are also possible and
 are beyond the scope of this specification.
 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:  <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 29] RFC 4930 EPP May 2007

 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:  <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:        <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.
 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:  <command>
 C:    <poll op="ack" msgID="12345"/>
 C:    <clTRID>ABC-12346</clTRID>
 C:  </command>
 C:</epp>
 A <poll> acknowledgement response notes the ID of the message that
 has been acknowledged and the number of messages remaining in the
 queue.

Hollenbeck Standards Track [Page 30] RFC 4930 EPP May 2007

 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:  <response>
 S:    <result code="1000">
 S:      <msg>Command completed successfully</msg>
 S:    </result>
 S:    <msgQ count="4" id="12345"/>
 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.
 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:  <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.

Hollenbeck Standards Track [Page 31] RFC 4930 EPP May 2007

 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:  <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>
 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.

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 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:  <command>
 C:    <transfer op="query">
 C:      <obj:transfer xmlns:obj="urn:ietf:params:xml:ns:obj">
 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.  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.

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 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:  <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:        <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.

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, <transfer> to manage changes in client
 sponsorship of an object, and <update> to change information
 associated with 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

Hollenbeck Standards Track [Page 34] RFC 4930 EPP May 2007

 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:  <command>
 C:    <create>
 C:      <obj:create xmlns:obj="urn:ietf:params:xml:ns:obj">
 C:        <!-- Object-specific elements. -->
 C:      </obj:create>
 C:    </create>
 C:    <clTRID>ABC-12345</clTRID>
 C:  </command>
 C:</epp>
 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.  The child elements of
 the <resData> element are object-specific.

Hollenbeck Standards Track [Page 35] RFC 4930 EPP May 2007

 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:  <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:        <!-- 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.

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 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:  <command>
 C:    <delete>
 C:      <obj:delete xmlns:obj="urn:ietf:params:xml:ns:obj">
 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.  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:  <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.

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:

Hollenbeck Standards Track [Page 37] RFC 4930 EPP May 2007

  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:  <command>
 C:    <renew>
 C:      <obj:renew xmlns:obj="urn:ietf:params:xml:ns:obj">
 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.  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:  <response>
 S:    <result code="1000">
 S:      <msg>Command completed successfully</msg>
 S:    </result>
 S:    <resData>
 S:      <obj:renData xmlns:obj="urn:ietf:params:xml:ns:obj">
 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.

Hollenbeck Standards Track [Page 38] RFC 4930 EPP May 2007

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
 either by queuing a service message for retrieval via the <poll>
 command or by using an out-of-band mechanism to inform the client of
 the request.  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.
 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.

Hollenbeck Standards Track [Page 39] RFC 4930 EPP May 2007

 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:  <command>
 C:    <transfer op="request">
 C:      <obj:transfer xmlns:obj="urn:ietf:params:xml:ns:obj">
 C:        <!-- Object-specific elements. -->
 C:      </obj:transfer>
 C:    </transfer>
 C:    <clTRID>ABC-12346</clTRID>
 C:  </command>
 C:</epp>
 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.  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.

Hollenbeck Standards Track [Page 40] RFC 4930 EPP May 2007

 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:  <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:        <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
 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.

Hollenbeck Standards Track [Page 41] RFC 4930 EPP May 2007

 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:  <command>
 C:    <update>
 C:      <obj:update xmlns:obj="urn:ietf:params:xml:ns:obj">
 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.  The child elements of
 the <resData> element are object-specific.
 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:  <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.

Hollenbeck Standards Track [Page 42] RFC 4930 EPP May 2007

 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 was accepted and
         processed by the system without error.
 2yzz    Negative completion reply.  The command was not accepted, and
         the requested action did not occur.
 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.
 Successful command completion responses:

Hollenbeck Standards Track [Page 43] RFC 4930 EPP May 2007

 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 that 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.
 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 cannot be
         executed due to a sequencing or context error.  For example,
         a <logout> command cannot be executed without having first
         completed a <login> command.

Hollenbeck Standards Track [Page 44] RFC 4930 EPP May 2007

 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.
 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 cannot 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.

Hollenbeck Standards Track [Page 45] RFC 4930 EPP May 2007

 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 of an object that is pending transfer due
         to an earlier transfer request.
 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.

Hollenbeck Standards Track [Page 46] RFC 4930 EPP May 2007

 2304    "Object status prohibits operation"
         This response code MUST be returned when a server receives a
         command to transform an object that cannot 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 cannot 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.
 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.

Hollenbeck Standards Track [Page 47] RFC 4930 EPP May 2007

 2500    "Command failed; server closing connection"
         This response code MUST be returned when a server receives a
         command that cannot 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 cannot 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.

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.
 -->

Hollenbeck Standards Track [Page 48] RFC 4930 EPP May 2007

   <import namespace="urn:ietf:params:xml:ns:eppcom-1.0"/>
   <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>
       <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>

Hollenbeck Standards Track [Page 49] RFC 4930 EPP May 2007

   </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">
     <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>

Hollenbeck Standards Track [Page 50] RFC 4930 EPP May 2007

   </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>
       <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"/>

Hollenbeck Standards Track [Page 51] RFC 4930 EPP May 2007

       <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.
 -->
   <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"/>

Hollenbeck Standards Track [Page 52] RFC 4930 EPP May 2007

         <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>
       <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"/>

Hollenbeck Standards Track [Page 53] RFC 4930 EPP May 2007

       <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>
   <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.
 -->

Hollenbeck Standards Track [Page 54] RFC 4930 EPP May 2007

   <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"/>
       <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"/>

Hollenbeck Standards Track [Page 55] RFC 4930 EPP May 2007

   </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>
     <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>

Hollenbeck Standards Track [Page 56] RFC 4930 EPP May 2007

   </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"/>
       <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>

Hollenbeck Standards Track [Page 57] RFC 4930 EPP May 2007

 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>
   </complexType>
 <!--
 <check> response types.
 -->
   <complexType name="reasonType">
     <simpleContent>
       <extension base="eppcom:reasonBaseType">
         <attribute name="lang" type="language"/>
       </extension>
     </simpleContent>
   </complexType>
   <simpleType name="reasonBaseType">

Hollenbeck Standards Track [Page 58] RFC 4930 EPP May 2007

     <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>
 <!--
 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">

Hollenbeck Standards Track [Page 59] RFC 4930 EPP May 2007

     <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].
 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
 [W3C.REC-xmlschema-2-20041028] 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.

Hollenbeck Standards Track [Page 60] RFC 4930 EPP May 2007

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

Hollenbeck Standards Track [Page 61] RFC 4930 EPP May 2007

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, confidentiality, and mutual strong client-server
 authentication.
 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.
 EPP instances SHOULD be protected using a transport mechanism or
 application protocol that provides anti-replay protection.  EPP
 provides some protection against replay attacks through command
 idempotency and client-initiated transaction identification.
 Consecutive command replays will not change the state of an object in
 any way.  There is, however, a chance of unintended or malicious
 consequence if a command is replayed after intervening commands have
 changed the object state and client identifiers are not used to
 detect replays.  For example, a replayed <create> command that
 follows a <delete> command might succeed without additional
 facilities to prevent or detect the replay.

Hollenbeck Standards Track [Page 62] RFC 4930 EPP May 2007

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.
 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.
 [RFC2914]  Floyd, S., "Congestion Control Principles", BCP 41,
            RFC 2914, September 2000.
 [RFC3066]  Alvestrand, H., "Tags for the Identification of
            Languages", RFC 3066, January 2001.
 [RFC3629]  Yergeau, F., "UTF-8, a transformation format of ISO
            10646", STD 63, RFC 3629, November 2003.
 [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
            January 2004.
 [W3C.REC-xml-20040204]
            Yergeau, F., Maler, E., Sperberg-McQueen, C., Bray, T.,
            and J. Paoli, "Extensible Markup Language (XML) 1.0 (Third
            Edition)", World Wide Web Consortium FirstEdition REC-xml-
            20040204, February 2004,
            <http://www.w3.org/TR/2004/REC-xml-20040204>.

Hollenbeck Standards Track [Page 63] RFC 4930 EPP May 2007

 [W3C.REC-xmlschema-1-20041028]
            Thompson, H., Maloney, M., Mendelsohn, N., and D. Beech,
            "XML Schema Part 1: Structures Second Edition", World Wide
            Web Consortium Recommendation REC-xmlschema-1-20041028,
            October 2004,
            <http://www.w3.org/TR/2004/REC-xmlschema-1-20041028>.
 [W3C.REC-xmlschema-2-20041028]
            Biron, P. and A. Malhotra, "XML Schema Part 2: Datatypes
            Second Edition", World Wide Web Consortium
            Recommendation REC-xmlschema-2-20041028, October 2004,
            <http://www.w3.org/TR/2004/REC-xmlschema-2-20041028>.

9.2. Informative References

 [RFC0793]  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.
 [RFC2781]  Hoffman, P. and F. Yergeau, "UTF-16, an encoding of ISO
            10646", RFC 2781, February 2000.
 [RFC2821]  Klensin, J., "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.
 [RFC3023]  Murata, M., St. Laurent, S., and D. Kohn, "XML Media
            Types", RFC 3023, January 2001.
 [RFC3080]  Rose, M., "The Blocks Extensible Exchange Protocol Core",
            RFC 3080, March 2001.
 [RFC3375]  Hollenbeck, S., "Generic Registry-Registrar Protocol
            Requirements", RFC 3375, September 2002.
 [RFC3730]  Hollenbeck, S., "Extensible Provisioning Protocol (EPP)",
            RFC 3730, March 2004.

Hollenbeck Standards Track [Page 64] RFC 4930 EPP May 2007

 [W3C.REC-P3P-20020416]
            Marchiori, M., "The Platform for Privacy Preferences 1.0
            (P3P1.0) Specification", World Wide Web Consortium
            Recommendation REC-P3P-20020416, April 2002,
            <http://www.w3.org/TR/2002/REC-P3P-20020416>.

Hollenbeck Standards Track [Page 65] RFC 4930 EPP May 2007

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 66] RFC 4930 EPP May 2007

 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.
 3.2.4.  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 67] RFC 4930 EPP May 2007

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

 MIME media type name: application
 MIME subtype name: epp+xml
 Required 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 WWW Distributed Authoring and Versioning (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 Section 2.9, "Standalone Document Declaration", and Section 5,
 "Conformance", of [W3C.REC-xml-20040204].
 Published specification: This document.
 Applications that 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 & 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 68] RFC 4930 EPP May 2007

Appendix C. Changes from RFC 3730

 1.   Minor reformatting as a result of converting I-D source format
      from nroff to XML.
 2.   Updated the state diagram in Section 2 to note that a <hello>
      can be received and processed at any time that a server is
      waiting for a command.  The text correctly describes how this
      works, but the state diagram was inconsistent with the text.
 3.   In Section 2, changed "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" to
      "The XML namespace prefixes used in examples (such as the string
      "foo" in "xmlns:foo") are solely for illustrative purposes.  A
      conforming implementation MUST NOT require the use of these or
      any other specific namespace prefixes".
 4.   Removed the last paragraph from Section 2 that described an
      error in the W3C XML reference specification.  This was
      corrected in a later edition.  References in this specification
      have been updated to cite the most current version.  Preserved
      the last sentence by appending it to the end of the previous
      paragraph.
 5.   Updated the description of the <value> element in Section 2.6 to
      add "or other information" to "a client-provided element
      (including XML tag and value)".
 6.   Changed text in Section 2.9.2.3 from this:
      "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."
      to this:
      "Service messages SHOULD be created for passive clients affected
      by an action on an object.  Service messages MAY also be created
      for active clients that request an action on an object, though
      such messages MUST NOT replace the normal protocol response to
      the request.  For example, <transfer> actions SHOULD be reported
      to the client that has the authority to approve or reject a
      transfer request.  Other methods of server-client action
      notification, such as offline reporting, are also possible and
      are beyond the scope of this specification."

Hollenbeck Standards Track [Page 69] RFC 4930 EPP May 2007

 7.   Changed text in Section 2.9.2.3 from this:
      "A <poll> acknowledgement response notes the number of messages
      remaining in the queue and the ID of the next message available
      for retrieval."
      to this:
      "A <poll> acknowledgement response notes the ID of the message
      that has been acknowledged and the number of messages remaining
      in the queue."
      Fixed the example to note the correct message ID.  This was done
      because the msgID isn't needed to retrieve a message, only to
      ack and dequeue it, so it doesn't need to be returned in the
      response.  Implementations are known to implement this feature
      as updated.
 8.   Changed text in Section 2.9.3.4 from this:
      "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."
      to this:
      "Once a transfer request has been received by the server, the
      server MUST notify the current sponsoring client of the
      requested transfer either by queuing a service message for
      retrieval via the <poll> command or by using an out-of-band
      mechanism to inform the client of the request."
 9.   Updated Security Considerations to note implemented required
      practices for authentication and replay protection.
 10.  Updated XML references.  Updated reference from RFC 2279 to RFC
      3629.
 11.  Removed text describing use of the XML Schema schemaLocation
      attribute.  This is an optional attribute that doesn't need to
      be mandated for use in EPP.
 12.  Moved RFCs 2781 and 3375 (Informational RFCs) from the normative
      reference section to the informative reference section.

Hollenbeck Standards Track [Page 70] RFC 4930 EPP May 2007

 13.  Moved RFC 3023 from the normative reference section to the
      informative reference section.  This reference is used only in
      an informative appendix.
 14.  Removed references to RFC 3339 and replaced them with references
      to the W3C XML Schema specification.

Author's Address

 Scott Hollenbeck
 VeriSign, Inc.
 21345 Ridgetop Circle
 Dulles, VA  20166-6503
 US
 EMail: shollenbeck@verisign.com

Hollenbeck Standards Track [Page 71] RFC 4930 EPP May 2007

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 contained in BCP 78, and except as set forth therein, the authors
 retain all their rights.
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Hollenbeck Standards Track [Page 72]

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