Extensible Provisioning Protocol (EPP) :: RFC3730
Network Working Group S. Hollenbeck
Request for Comments: 3730 VeriSign, Inc.
Category: Standards Track March 2004
Extensible Provisioning Protocol (EPP)
Status of this Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2004). All Rights Reserved.
Abstract
This document describes an application layer client-server protocol
for the provisioning and management of objects stored in a shared
central repository. Specified in XML, the protocol defines generic
object management operations and an extensible framework that maps
protocol operations to objects. This document includes a protocol
specification, an object mapping template, and an XML media type
registration.
Table of Contents
1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Conventions Used in This Document . . . . . . . . . . . 3
2. Protocol Description. . . . . . . . . . . . . . . . . . . . . 3
2.1. Transport Mapping Considerations. . . . . . . . . . . . 6
2.2. Protocol Identification . . . . . . . . . . . . . . . . 7
2.3. Hello Format. . . . . . . . . . . . . . . . . . . . . . 7
2.4. Greeting Format . . . . . . . . . . . . . . . . . . . . 8
2.5. Command Format. . . . . . . . . . . . . . . . . . . . . 11
2.6. Response Format . . . . . . . . . . . . . . . . . . . . 12
2.7. Protocol Extension Framework. . . . . . . . . . . . . . 16
2.7.1. Protocol Extension. . . . . . . . . . . . . . . 16
2.7.2. Object Extension. . . . . . . . . . . . . . . . 17
2.7.3. Command-Response Extension. . . . . . . . . . . 18
2.8. Object Identification . . . . . . . . . . . . . . . . . 19
2.9. Protocol Commands . . . . . . . . . . . . . . . . . . . 19
2.9.1. Session Management Commands . . . . . . . . . . 20
2.9.1.1. EPP Command . . . . . . . . . 20
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2.9.1.2. EPP Command. . . . . . . . . 22
2.9.2. Query Commands. . . . . . . . . . . . . . . . . 23
2.9.2.1. EPP Command . . . . . . . . . 24
2.9.2.2. EPP Command. . . . . . . . . . 26
2.9.2.3. EPP Command. . . . . . . . . . 27
2.9.2.4. EPP Query Command. . . . . 32
2.9.3. Object Transform Commands . . . . . . . . . . . 34
2.9.3.1. EPP Command. . . . . . . . . 34
2.9.3.2. EPP Command. . . . . . . . . 35
2.9.3.3. EPP Command . . . . . . . . . 37
2.9.3.4. EPP Command. . . . . . . . 38
2.9.3.5. EPP Command. . . . . . . . . 41
3. Result Codes. . . . . . . . . . . . . . . . . . . . . . . . . 42
4. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . . 48
4.1. Base Schema . . . . . . . . . . . . . . . . . . . . . . 49
4.2. Shared Structure Schema . . . . . . . . . . . . . . . . 58
5. Internationalization Considerations . . . . . . . . . . . . . 60
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 61
7. Security Considerations . . . . . . . . . . . . . . . . . . . 62
8. Acknowledgements. . . . . . . . . . . . . . . . . . . . . . . 62
9. References. . . . . . . . . . . . . . . . . . . . . . . . . . 63
9.1. Normative References. . . . . . . . . . . . . . . . . . 63
9.2. Informative References. . . . . . . . . . . . . . . . . 64
Appendix A: Object Mapping Template . . . . . . . . . . . . . . . 65
Appendix B: Media Type Registration: application/epp+xml. . . . . 67
Author's Address. . . . . . . . . . . . . . . . . . . . . . . . . 68
Full Copyright Statement. . . . . . . . . . . . . . . . . . . . . 69
1. Introduction
This document describes specifications for the Extensible
Provisioning Protocol (EPP) version 1.0, an XML text protocol that
permits multiple service providers to perform object provisioning
operations using a shared central object repository. EPP is
specified using the Extensible Markup Language (XML) 1.0 as described
in [XML] and XML Schema notation as described in [XMLS-1] and [XMLS-
2]. EPP meets and exceeds the requirements for a generic registry
registrar protocol as described in [RFC3375].
EPP content is identified by MIME media type application/epp+xml.
Registration information for this media type is included in an
appendix to this document.
EPP is intended for use in diverse operating environments where
transport and security requirements vary greatly. It is unlikely
that a single transport or security specification will meet the needs
of all anticipated operators, so EPP was designed for use in a
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layered protocol environment. Bindings to specific transport and
security protocols are outside the scope of this specification.
This original motivation for this protocol was to provide a standard
Internet domain name registration protocol for use between domain
name registrars and domain name registries. This protocol provides a
means of interaction between a registrar's applications and registry
applications. It is expected that this protocol will have additional
uses beyond domain name registration.
XML is case sensitive. Unless stated otherwise, XML specifications
and examples provided in this document MUST be interpreted in the
character case presented to develop a conforming implementation.
1.1. Conventions Used In This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
In examples, "C:" represents lines sent by a protocol client and "S:"
represents lines returned by a protocol server. Indentation and
white space in examples is provided only to illustrate element
relationships and is not a REQUIRED feature of this protocol.
2. Protocol Description
EPP is a stateful XML protocol that can be layered over multiple
transport protocols. Protected using lower-layer security protocols,
clients exchange identification, authentication, and option
information, and then engage in a series of client-initiated
command-response exchanges. All EPP commands are atomic (there is no
partial success or partial failure) and designed so that they can be
made idempotent (executing a command more than once has the same net
effect on system state as successfully executing the command once).
EPP provides four basic service elements: service discovery,
commands, responses, and an extension framework that supports
definition of managed objects and the relationship of protocol
requests and responses to those objects.
An EPP server MUST respond to client-initiated communication (which
can be either a lower-layer connection request or an EPP service
discovery message) by returning a greeting to a client. A server
MUST promptly respond to each EPP command with a coordinated response
that describes the results of processing the command. The following
server state machine diagram illustrates the message exchange process
in detail:
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|
V
+-----------------+ +-----------------+
| Waiting for | Connected | Prepare |
| Client |----------------->| Greeting |
+-----------------+ or +-----------------+
^ |
| Close Connection Send |
| or Idle Greeting |
+-----------------+ V
| End | Timeout +-----------------+
| Session |<-----------------| Waiting for |
+-----------------+ | Client |
^ ^ ^ Send +-------->| Authentication |
| | | Response | +-----------------+
| | | +--------------+ |
| | | | Prepare Fail | |
| | +-----| Response | | Received
| | Send +--------------+ V
| | 2501 ^ +-----------------+
| | Response | | Processing |
| | +---------| |
| | Auth Fail +-----------------+
| | |
| | | Auth OK
| | V
| | Timeout +-----------------+
| +----------------------------| Waiting for |
| | Command |
| Send x5xx +-----------------+
| Response +-----------------+ Send ^ |
+-----------| Prepare | Response | | Command
| Response |----------+ | Received
+-----------------+ V
^ +-----------------+
Command | | Processing |
Processed +----------| Command |
+-----------------+
Figure 1: EPP Server State Machine
EPP commands fall into three categories: session management commands,
query commands, and data transform commands. Session management
commands are used to establish and end persistent sessions with an
EPP server. Query commands are used to perform read-only object
information retrieval operations. Transform commands are used to
perform read-write object management operations.
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Commands are processed by a server in the order they are received
from a client. Though an immediate response confirming receipt and
processing of the command is produced by the server, the protocol
includes features that allow for offline review of transform commands
before the requested action is actually completed. In such
situations the response from the server MUST clearly note that the
command has been received and processed, but the requested action is
pending. The state of the corresponding object MUST clearly reflect
processing of the pending action. The server MUST also notify the
client when offline processing of the action has been completed.
Object mappings SHOULD describe standard formats for notices that
describe completion of offline processing.
EPP uses XML namespaces to provide an extensible object management
framework and to identify schemas required for XML instance parsing
and validation. These namespaces and schema definitions are used to
identify both the base protocol schema and the schemas for managed
objects. The specific strings used to associate URIs and namespaces
(such as the string "foo" in "xmlns:foo") in EPP are illustrative and
are not needed for interoperability.
All XML instances SHOULD begin with an declaration to
identify the version of XML that is being used, optionally identify
use of the character encoding used, and optionally provide a hint to
an XML parser that an external schema file is needed to validate the
XML instance. Conformant XML parsers recognize both UTF-8 (defined
in RFC 2279 [RFC2279]) and UTF-16 (defined in RFC 2781 [RFC2781]);
per RFC 2277 [RFC2277] UTF-8 is the RECOMMENDED character encoding
for use with EPP.
Character encodings other than UTF-8 and UTF-16 are allowed by XML.
UTF-8 is the default encoding assumed by XML in the absence of an
"encoding" attribute or a byte order mark (BOM), thus the "encoding"
attribute in the XML declaration is OPTIONAL if UTF-8 encoding is
used.
Normative section 4.3.3 and non-normative appendix F of [XML]
describe use of a BOM to identify the character encoding in the
absence of an XML declaration or encapsulating headers. Appendix F
includes a BOM to represent UTF-8 encoding, though section 4.3.3
notes that a BOM is not needed to identify UTF-8 encoding. Section
4.3.3 was later amended (see [XMLE]) to clarify that a BOM MAY be
used to identify UTF-8 encoding. EPP clients and servers MUST accept
a UTF-8 BOM if present, though emitting a UTF-8 BOM is NOT
RECOMMENDED.
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Example XML declarations:
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:
- The transport mapping MUST preserve command order.
- The transport mapping MUST address the relationship between
sessions and the client-server connection concept.
- The transport mapping MUST preserve the stateful nature of the
protocol.
- The transport mapping MUST frame data units.
- The transport mapping MUST be onto a transport such as TCP
[RFC793] or SCTP [RFC2960] that provides congestion avoidance that
follows RFC 2914 [RFC2914], or if it maps onto a protocol such as
SMTP [RFC2821] or BEEP [RFC3080], then the performance issues need
to take into account issues of overload, server availability and
so forth.
- The transport mapping MUST ensure reliability.
- 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:
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- Commands MUST be processed independent of each other.
- Depending on the transport, pipelining MAY be possible in the form
of sending a complete session in a well-defined "batch".
- 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 element. This element
identifies the start of an EPP protocol element, the namespace used
within the protocol, and the location of the protocol schema. The
start element and the associated ending element MUST be
applied to all structures sent by both clients and servers.
Example "start" and "end" EPP elements:
2.3. Hello Format
EPP MAY be carried over both connection-oriented and connection-less
transport protocols. An EPP client MAY request a from an
EPP server at any time by sending a to a server. Use of this
element is essential in a connection-less environment where a server
can not return a in response to a client-initiated
connection. An EPP MUST be an empty element with no child
elements.
Example :
C:
C:
C:
C:
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2.4. Greeting Format
An EPP server responds to a successful connection and element
by returning a element to the client. An EPP greeting
contains the following elements:
- An element that contains the name of the server.
- An element that contains the server's current date and
time in UTC.
- An element that identifies the services supported by the
server, including:
- One or more elements that identify the protocol versions
supported by the server.
- One or more elements that contain the identifiers of the
text response languages known by the server. Language identifiers
MUST be structured as documented in [RFC3066].
- One or more 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.
- An OPTIONAL element that contains one or more
elements that contain namespace URIs representing object
extensions supported by the server.
- A (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:
- An element that describes the access provided by the
server to the client on behalf of the originating data source.
The element MUST contain one of the following child
elements:
: Access is given to all identified data.
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: No access is provided to identified data.
: Data is not persistent, so no access is possible.
: Access is given to identified data relating to
individuals and organizational entities.
: Access is given to identified data
relating to individuals, organizational entities, and other
data of a non-personal nature.
: Access is given to other identified data of a non-
personal nature.
- One or more elements that describe data collection
purposes, data recipients, and data retention. Each
element MUST contain a element, a element,
and a element.
The element MUST contain one or more of the following child
elements that describe the purposes for which data is collected:
: Administrative purposes. Information can be used for
administrative and technical support of the provisioning system.
: 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.
: Object provisioning purposes. Information can be used to
identify objects and inter-object relationships.
: Other purposes. Information may be used in other ways
not captured by the above definitions.
The element MUST contain one or more of the following
child elements that describes the recipients of collected data:
: Other entities following unknown practices.
: 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 element contains
an OPTIONAL element that can be used to describe the
recipient.
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: Public forums.
: Other entities following server practices.
: Unrelated third parties.
The element MUST contain one of the following child
elements that describes data retention practices:
: Data persists per business practices.
: Data persists indefinitely.
: Data persists per legal requirements.
: 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.
: Data persists to meet the stated purpose.
- An OPTIONAL element that describes the lifetime of the
policy. The element MUST contain one of the following
child elements:
: The policy is valid from the current date and time
until it expires on the specified date and time.
: The policy is valid from the current date and time
until the end of the specified duration.
Data collection policy elements are based on work described in the
World Wide Web Consortium's Platform for Privacy Preferences [P3P]
specification.
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Example greeting:
S:
S:
S:
S: Example EPP server epp.example.com
S: 2000-06-08T22:00:00.0Z
S:
S: 1.0
S: en
S: fr
S: urn:ietf:params:xml:ns:obj1
S: urn:ietf:params:xml:ns:obj2
S: urn:ietf:params:xml:ns:obj3
S:
S: http://custom/obj1ext-1.0
S:
S:
S:
S:
S:
S:
S:
S:
S:
S:
S:
S:
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:
- 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.
- An OPTIONAL element that MAY be used for server-
defined command extensions.
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- An OPTIONAL (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:
C:
C:
C:
C:
C: example
C:
C:
C: ABC-12345
C:
C:
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:
- One or more elements that document the success or failure
of command execution. If the command was processed successfully,
only one element MUST be returned. If the command was
not processed successfully, multiple elements MAY be
returned to document failure conditions. Each element
contains the following attribute and child elements:
- A "code" attribute whose value is a four-digit, decimal number
that describes the success or failure of the command.
- A 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).
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- Zero or more OPTIONAL elements that identify a client-
provided element (including XML tag and value) that caused a
server error condition.
- Zero or more OPTIONAL elements that can be used to
provide additional error diagnostic information, including:
- A element that identifies a client-provided element
(including XML tag and value) that caused a server error
condition.
- A 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).
- An OPTIONAL element that describes messages queued for
client retrieval. A element MUST NOT be present if there
are no messages queued for client retrieval. A element MAY
be present in responses to EPP commands other than the
command if messages are queued for retrieval. A element
MUST be present in responses to the EPP command if messages
are queued for retrieval. The element contains the
following attributes:
- A "count" attribute that describes the number of messages that
exist in the queue.
- An "id" attribute used to uniquely identify the message at the
head of the queue.
The element contains the following OPTIONAL child elements
that MUST be returned in response to a request command and
MUST NOT be returned in response to any other command, including a
acknowledgement:
- A element that contains the date and time that the message
was enqueued.
- A 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.
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- An OPTIONAL (response data) element that contains child
elements specific to the command and associated object.
- An OPTIONAL element that MAY be used for server-
defined response extensions.
- A (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 associated with the command if
supplied by the client and a (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 or :
S:
S:
S:
S:
S: Command completed successfully
S:
S:
S: ABC-12345
S: 54321-XYZ
S:
S:
S:
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Example response with :
S:
S:
S:
S:
S: Command completed successfully
S:
S:
S:
S: example
S:
S:
S:
S: ABC-12345
S: 54321-XYZ
S:
S:
S:
Example response with error value elements:
S:
S:
S:
S:
S: Parameter value range error
S:
S: 2525
S:
S:
S:
S: Parameter value syntax error
S:
S: ex(ample
S:
S:
S:
S: abc.ex(ample
S:
S: Invalid character found.
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S:
S:
S:
S: ABC-12345
S: 54321-XYZ
S:
S:
S:
Example response with notice of waiting server messages:
S:
S:
S:
S:
S: Command completed successfully
S:
S:
S:
S: ABC-12345
S: 54321-XYZ
S:
S:
S:
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 element that
identifies the beginning of a protocol instance includes multiple
child element choices, one of which is an element whose
children define the extension. For example, a protocol extension
element would be described in generic terms as follows:
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C:
C:
C:
C:
C:
C:
C:
C:
This document does not define mappings for specific extensions.
Extension specifications MUST be described in separate documents that
define the objects and operations subject to the extension.
2.7.2. Object Extension
EPP provides an extensible object management framework that defines
the syntax and semantics of protocol operations applied to a managed
object. This framework pushes the definition of each protocol
operation into the context of a specific object, providing the
ability to add mappings for new objects without having to modify the
base protocol.
Protocol elements that contain data specific to objects are
identified using XML namespace notation with a reference to an XML
schema that defines the namespace. The schema for EPP supports use
of dynamic object schemas on a per-command and per-response basis.
For example, the start of an object-specific command element would be
described in generic terms as follows:
C:
C:
C:
C:
C:
An object-specific response element would be described similarly:
S:
S:
S:
S:
S:
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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
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:
C:
C:
C:
C:
C:
C:
C:
C:
C:
C:
An server-extended response element would be described similarly:
S:
S:
S: Command completed successfully
S:
S:
S:
S:
S:
S: ABC-12345
S: 54321-XYZ
S:
S:
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This document does not define any specific server extensions. The
mapping of server extensions to EPP MUST be described in separate
documents that specifically address extended commands and responses
in the server's operational context.
2.8. Object Identification
Some objects, such as name servers and contacts, can have utility in
multiple repositories. However, maintaining disjoint copies of
object information in multiple repositories can lead to
inconsistencies that have adverse consequences for the Internet. For
example, changing a name server name in one repository, but not in a
second repository that refers to the server for domain name
delegation, can produce unexpected DNS query results.
Globally unique identifiers can help facilitate object information
sharing between repositories. A globally unique identifier MUST be
assigned to every object when the object is created; the identifier
MUST be returned to the client as part of any request to retrieve the
detailed attributes of an object. Specific identifier values are a
matter of repository policy, but they SHOULD be constructed according
to the following algorithm:
a) Divide the provisioning repository world into a number of object
repository classes.
b) Each repository within a class is assigned an identifier that is
maintained by IANA.
c) Each repository is responsible for assigning a unique local
identifier for each object within the repository.
d) The globally unique identifier is a concatenation of the local
identifier, followed by a hyphen ("-", ASCII value 0x002D),
followed by the repository identifier.
2.9. Protocol Commands
EPP provides commands to manage sessions, retrieve object
information, and perform transformation operations on objects. All
EPP commands are atomic and designed so that they can be made
idempotent, either succeeding completely or failing completely and
producing predictable results in case of repeated execution. This
section describes each EPP command, including examples with
representative server responses.
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2.9.1. Session Management Commands
EPP provides two commands for session management: to
establish a session with a server, and to end a session with
a server. The command establishes an ongoing server session
that preserves client identity and authorization information during
the duration of the session.
2.9.1.1. EPP Command
The EPP command is used to establish a session with an EPP
server in response to a greeting issued by the server. A
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 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 command
contains the following child elements:
- A element that contains the client identifier assigned to
the client by the server.
- A element that contains the client's plain text password.
The value of this element is case sensitive.
- An OPTIONAL element that contains a new plain text
password to be assigned to the client for use with subsequent
commands. The value of this element is case sensitive.
- An element that contains the following child elements:
- A element that contains the protocol version to be
used for the command or ongoing server session.
- A element that contains the text response language to be
used for the command or ongoing server session commands.
The values of the and elements MUST exactly match
one of the values presented in the EPP greeting.
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- A element that contains one or more elements that
contain namespace URIs representing the objects to be managed
during the session. The element MAY contain an OPTIONAL
element that contains one or more elements
that identify object extensions to be used during the session.
The PLAIN SASL mechanism presented in [RFC2595] describes a format
for providing a user identifier, an authorization identifier, and a
password as part of a single plain text string. The EPP
authentication mechanism is similar, though EPP does not require a
session-level authorization identifier and the user identifier and
password are separated into distinct XML elements. Additional
identification and authorization schemes MUST be provided at other
protocol layers to provide more robust security services.
Example command:
C:
C:
C:
C:
C: ClientX
C: foo-BAR2
C: bar-FOO2
C:
C: 1.0
C: en
C:
C:
C: urn:ietf:params:xml:ns:obj1
C: urn:ietf:params:xml:ns:obj2
C: urn:ietf:params:xml:ns:obj3
C:
C: http://custom/obj1ext-1.0
C:
C:
C:
C: ABC-12345
C:
C:
When a command has been processed successfully, a server MUST
respond with an EPP response with no element. If
successful, the server will respond by creating and maintaining a new
session that SHOULD be terminated by a future command.
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Example response:
S:
S:
S:
S:
S: Command completed successfully
S:
S:
S: ABC-12345
S: 54321-XYZ
S:
S:
S:
The EPP command is used to establish a session with an EPP
server. A 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 Command
The EPP command is used to end a session with an EPP server.
The 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 command and
ending a session.
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Example command:
C:
C:
C:
C:
C: ABC-12345
C:
C:
When a command has been processed successfully, a server
MUST respond with an EPP response with no element. If
successful, the server MUST also end the current session.
Example response:
S:
S:
S:
S:
S: Command completed successfully; ending session
S:
S:
S: ABC-12345
S: 54321-XYZ
S:
S:
S:
The EPP command is used to end a session with an EPP server.
A command MUST be rejected if the command has not been
preceded by a successful command. This action MUST be open
to all authorized clients.
2.9.2. Query Commands
EPP provides four commands to retrieve object information: to
determine if an object can be provisioned within a repository,
to retrieve detailed information associated with a known object,
to receive service notifications from the server, and
to retrieve object transfer status information.
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2.9.2.1. EPP Command
The EPP 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 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 command are specified using the EPP
extension framework. In addition to the standard EPP command
elements, the command contains the following child elements:
- An object-specific element that identify the objects
to be queried. Multiple objects of the same type MAY be queried
within a single command.
Example command:
C:
C:
C:
C:
C:
C: example1
C: example2
C: example3
C:
C:
C: ABC-12346
C:
C:
When a command has been processed successfully, a server MUST
respond with an EPP element that MUST contain a child
element that identifies the object namespace and the location of the
object schema. The child elements of the element are
object-specific, though the EPP element MUST contain a
child element that contains one or more (check
data) elements. Each elements contains the following child
elements:
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- 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 command was completed. A value of "1" or
"true" means that the object can be provisioned. A value of "0"
or "false" means that the object can not be provisioned.
- An OPTIONAL element that MAY be provided when an
object can not be provisioned. If present, this element contains
server-specific text to help explain why the object can not be
provisioned. This text MUST be represented in the response
language previously negotiated with the client; an OPTIONAL "lang"
attribute MAY be present to identify the language if the
negotiated value is something other than the default value of "en"
(English).
Example response:
S:
S:
S:
S:
S: Command completed successfully
S:
S:
S:
S:
S: example1
S:
S:
S: example2
S: In use
S:
S:
S: example3
S:
S:
S:
S:
S: ABC-12346
S: 54322-XYZ
S:
S:
S:
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The EPP command is used to determine if an object can be
provisioned within a repository. This action MUST be open to all
authorized clients.
2.9.2.2. EPP Command
The EPP 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 command are
specified using the EPP extension framework. In addition to the
standard EPP command elements, the command contains the
following child elements:
- An object-specific element that identifies the object
to be queried.
Example command:
C:
C:
C:
C:
C:
C:
C:
C:
C: ABC-12346
C:
C:
When an command has been processed successfully, a server MUST
respond with an EPP element that MUST contain a child
element that identifies the object namespace and the location of the
object schema and the Repository Object Identifier (ROID) that was
assigned to the object when the object was created. Other child
elements of the element are object-specific.
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Example response:
S:
S:
S:
S:
S: Command completed successfully
S:
S:
S:
S: EXAMPLE1-REP
S:
S:
S:
S:
S: ABC-12346
S: 54322-XYZ
S:
S:
S:
The EPP 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 Command
The EPP 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 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.
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Servers can occasionally perform actions on objects that are not in
direct response to a client request, or an action taken by one client
can indirectly involve a second client. Examples of such actions
include deletion upon expiration, automatic renewal upon expiration,
and transfer coordination; other types of service information MAY be
defined as a matter of server policy. Service messages MUST be
created for all clients affected by an action on an object. For
example, actions MUST be reported to both the client that
requests an object transfer and the client that has the authority to
approve or reject the transfer request.
Message queues can consume server resources if clients do not
retrieve and acknowledge messages on a regular basis. Servers MAY
implement other mechanisms to dequeue and deliver messages if queue
maintenance needs exceed server resource consumption limits. Server
operators SHOULD consider time-sensitivity and resource management
factors when selecting a delivery method for service information
because some message types can be reasonably delivered using non-
protocol methods that require fewer server resources.
Some of the information returned in response to a command can
be object-specific, so some child elements of the response MAY
be specified using the EPP extension framework. The 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 element in the message
being acknowledged) are REQUIRED to acknowledge receipt of a message.
Example command:
C:
C:
C:
C:
C: ABC-12345
C:
C:
The returned result code notes that a message has been dequeued and
returned in response to a command.
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Example response with object-specific information:
S:
S:
S:
S:
S: Command completed successfully; ack to dequeue
S:
S:
S: 2000-06-08T22:00:00.0Z
S: Transfer requested.
S:
S:
S:
S: example.com
S: pending
S: ClientX
S: 2000-06-08T22:00:00.0Z
S: ClientY
S: 2000-06-13T22:00:00.0Z
S: 2002-09-08T22:00:00.0Z
S:
S:
S:
S: ABC-12345
S: 54321-XYZ
S:
S:
S:
A client MUST acknowledge each response to dequeue the message and
make subsequent messages available for retrieval.
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Example acknowledgement command:
C:
C:
C:
C:
C: ABC-12346
C:
C:
A acknowledgement response notes the number of messages
remaining in the queue and the ID of the next message available for
retrieval.
Example acknowledgement response:
S:
S:
S:
S:
S: Command completed successfully
S:
S:
S:
S: ABC-12346
S: 54322-XYZ
S:
S:
S:
Service messages can also be returned without object information.
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Example response with mixed message content and without
object-specific information:
S:
S:
S:
S:
S: Command completed successfully; ack to dequeue
S:
S:
S: 2000-06-08T22:10:00.0Z
S: Credit balance low.
S: 1005
S:
S:
S:
S: ABC-12346
S: 54321-XYZ
S:
S:
S:
The returned result code and message is used to note an empty server
message queue.
Example response to note an empty message queue:
S:
S:
S:
S:
S: Command completed successfully; no messages
S:
S:
S: ABC-12346
S: 54321-XYZ
S:
S:
S:
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The EPP 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 Query Command
The EPP 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 query command are specified using the EPP
extension framework. In addition to the standard EPP command
elements, the command contains an "op" attribute with
value "query", and the following child elements:
- An object-specific element that identifies the
object whose transfer status is requested.
Transfer status is typically considered sensitive information by the
clients involved in the operation. Object mappings MUST provide
features to restrict transfer queries to authorized clients, such as
by requiring authorization information as part of the request.
Example query command:
C:
C:
C:
C:
C:
C:
C:
C:
C: ABC-12346
C:
C:
When a query command has been processed successfully, a
server MUST respond with an EPP element that MUST contain a
child element that identifies the object namespace and the location
of the object schema. The child elements of the element
are object-specific, but they MUST include elements that identify the
object, the status of the transfer, the identifier of the client that
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requested the transfer, the date and time that the request was made,
the identifier of the client that is authorized to act on the
request, the date and time by which an action is expected, and an
OPTIONAL date and time noting changes in the object's validity period
(if applicable) that occur as a result of the transfer.
Example query response:
S:
S:
S:
S:
S: Command completed successfully
S:
S:
S:
S: example
S: pending
S: ClientX
S: 2000-06-08T22:00:00.0Z
S: ClientY
S: 2000-06-13T22:00:00.0Z
S: 2002-09-08T22:00:00.0Z
S:
S:
S:
S: ABC-12346
S: 54322-XYZ
S:
S:
S:
The EPP 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.
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2.9.3. Object Transform Commands
EPP provides five commands to transform objects: to create
an instance of an object with a server, to remove an
instance of an object from a server, to extend the validity
period of an object, to change information associated with
an object, and to manage changes in client sponsorship of
an object.
2.9.3.1. EPP Command
The EPP command is used to create an instance of an object.
An object can be created for an indefinite period of time, or an
object can be created for a specific validity period. The EPP
mapping for an object MUST describe the status of an object with
respect to time, to include expected client and server behavior if a
validity period is used.
The elements needed to identify an object and associated attributes
are object-specific, so the child elements of the command
are specified using the EPP extension framework. In addition to the
standard EPP command elements, the command contains the
following child elements:
- An object-specific element that identifies the object
to be created and the elements that are required to create the
object.
Example command:
C:
C:
C:
C:
C:
C:
C:
C:
C: ABC-12345
C:
C:
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When a command has been processed successfully, a server MAY
respond with an EPP element that MUST contain a child
element that identifies the object namespace and the location of the
object schema. The child elements of the element are
object-specific.
Example response with :
S:
S:
S:
S:
S: Command completed successfully
S:
S:
S:
S:
S:
S:
S:
S: ABC-12345
S: 54321-XYZ
S:
S:
S:
The EPP 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 Command
The EPP 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 command are specified
using the EPP extension framework. In addition to the standard EPP
command elements, the command contains the following child
elements:
- An object-specific element that identifies the object
to be deleted.
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Example command:
C:
C:
C:
C:
C:
C:
C:
C:
C: ABC-12346
C:
C:
When a command has been processed successfully, a server MAY
respond with an EPP element that MUST contain a child
element that identifies the object namespace and the location of the
object schema. The child elements of the element are
object-specific.
Example response without :
S:
S:
S:
S:
S: Command completed successfully
S:
S:
S: ABC-12346
S: 54322-XYZ
S:
S:
S:
The EPP 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.
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2.9.3.3. EPP Command
The EPP 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 command are specified using the EPP extension
framework. In addition to the standard EPP command elements, the
command contains the following child elements:
- An object-specific element that identifies the object
to be renewed and the elements that are required to extend the
validity period of the object.
Example command:
C:
C:
C:
C:
C:
C:
C:
C:
C: ABC-12346
C:
C:
When a command has been processed successfully, a server MAY
respond with an EPP element that MUST contain a child
element that identifies the object namespace and the location of the
object schema. The child elements of the element are
object-specific.
Example response with :
S:
S:
S:
S:
S: Command completed successfully
S:
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S:
S:
S:
S:
S:
S:
S: ABC-12346
S: 54322-XYZ
S:
S:
S:
The EPP command is used to extend the validity period of an
existing object. This action SHOULD be limited to authorized
clients; restricting this action to the sponsoring client is
RECOMMENDED. Object renewal MAY be unavailable or limited by
object-specific policies.
2.9.3.4. EPP Command
The EPP 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 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 command with
the value of the "op" attribute set to "cancel". A request to cancel
the transfer MUST be sent to the server before the current sponsoring
client either approves or rejects the transfer request and before the
server automatically processes the request due to responding client
inactivity.
Once a transfer request has been received by the server, the server
MUST notify the current sponsoring client of the requested transfer
by queuing a service message for retrieval via the command.
The current status of a pending command for any object can
be found using the query command. Transfer service
messages MUST include the object-specific elements specified for
command responses.
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The current sponsoring client MAY explicitly approve or reject the
transfer request. The client can approve the request using a
command with the value of the "op" attribute set to
"approve". The client can reject the request using a
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 command.
The type of authorization information required is object-specific;
passwords or more complex mechanisms based on public key cryptography
are typical.
The elements needed to identify and complete the transfer of an
object are object-specific, so the child elements of the
command are specified using the EPP extension framework. In addition
to the standard EPP command elements, the command contains
the following child elements:
- An object-specific element that identifies the
object to be transferred and the elements that are required to
process the transfer command.
Example command:
C:
C:
C:
C:
C:
C:
C:
C:
C: ABC-12346
C:
C:
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When a command has been processed successfully, a server
MUST respond with an EPP element that MUST contain a child
element that identifies the object namespace and the location of the
object schema. The child elements of the element are
object-specific, but they MUST include elements that identify the
object, the status of the transfer, the identifier of the client that
requested the transfer, the date and time that the request was made,
the identifier of the client that is authorized to act on the
request, the date and time by which an action is expected, and an
OPTIONAL date and time noting changes in the object's validity period
(if applicable) that occur as a result of the transfer.
Example response with :
S:
S:
S:
S:
S: Command completed successfully; action pending
S:
S:
S:
S: example
S: pending
S: ClientX
S: 2000-06-08T22:00:00.0Z
S: ClientY
S: 2000-06-13T22:00:00.0Z
S: 2002-09-08T22:00:00.0Z
S:
S:
S:
S: ABC-12346
S: 54322-XYZ
S:
S:
S:
The EPP command is used to manage changes in client
sponsorship of an existing object. This action SHOULD be limited to
authorized clients; restricting requests to a client other
than the current sponsoring client, approval requests to
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RFC 3730 EPP March 2004
the current sponsoring client, and 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 Command
The EPP 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
command are specified using the EPP extension framework. In addition
to the standard EPP command elements, the command contains
the following child elements:
- An object-specific element that identifies the object
to be updated and the elements that are required to modify the
object. Object-specific elements MUST identify values to be
added, values to be removed, or values to be changed.
Example 