Network Working Group S. Hollenbeck Request for Comments: 5730 VeriSign, Inc. STD: 69 August 2009 Obsoletes: 4930 Category: Standards Track
Extensible Provisioning Protocol (EPP)
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 4930.
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) 2009 IETF Trust and the persons identified as the document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents in effect on the date of publication of this document (http://trustee.ietf.org/license-info). Please review these documents carefully, as they describe your rights and restrictions with respect to this document.
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 4930 [RFC4930].
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.
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 REQUIRED features of this protocol. A protocol client that is authorized to manage an existing object is described as a "sponsoring" client throughout this document.
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:
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.
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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 that 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.
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 [RFC0793] or Stream Control Transmission Protocol (SCTP) [RFC4960], that provides congestion avoidance that follows RFC 2914 [RFC2914]; or, if it maps onto a protocol such as SMTP [RFC5321] or Blocks Extensible Exchange Protocol (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:
- 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.
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A transport mapping MUST explain how all of these requirements are met, given the transport protocol being used to exchange data.
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.
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.
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:
- An <svID> element that contains the name of the server.
- An <svDate> element that contains the server's current date and time in Universal Coordinated Time (UTC).
- An <svcMenu> element that identifies the services supported by the server, including:
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o One or more <version> elements that identify the protocol versions supported by the server.
o 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 [RFC4646].
o 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.
o An OPTIONAL <svcExtension> element that contains one or more <extURI> elements that contain namespace URIs representing object extensions supported by the server.
o 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:
* An <access> element that describes the access provided by the server to the client on behalf of the originating data source. The <access> element MUST contain one of the following child elements:
+ <all/>: Access is given to all identified data.
+ <none/>: No access is provided to identified data.
+ <null/>: Data is not persistent, so no access is possible.
+ <personal/>: Access is given to identified data relating to individuals and organizational entities.
+ <personalAndOther/>: Access is given to identified data relating to individuals, organizational entities, and other data of a non-personal nature.
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+ <other/>: Access is given to other identified data of a non-personal nature.
* One or more <statement> elements that describe data collection purposes, data recipients, and data retention. Each <statement> element MUST contain a <purpose> element, a <recipient> element, and a <retention> element. The <purpose> element MUST contain one or more of the following child elements that describe the purposes for which data is collected:
+ <admin/>: Administrative purposes. Information can be used for administrative and technical support of the provisioning system.
+ <contact/>: Contact for marketing purposes. Information can be used to contact individuals, through a communications channel other than the protocol, for the promotion of a product or service.
+ <prov/>: Object-provisioning purposes. Information can be used to identify objects and inter-object relationships.
+ <other/>: Other purposes. Information may be used in other ways not captured by the above definitions.
* The <recipient> element MUST contain one or more of the following child elements that describes the recipients of collected data:
+ <other/>: Other entities following unknown practices.
+ <ours>: Server operator and/or entities acting as agents or entities for whom the server operator is acting as an agent. An agent in this instance is defined as a third party that processes data only on behalf of the service provider for the completion of the stated purposes. The <ours> element contains an OPTIONAL <recDesc> element that can be used to describe the recipient.
+ <public/>: Public forums.
+ <same/>: Other entities following server practices.
+ <unrelated/>: Unrelated third parties.
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* The <retention> element MUST contain one of the following child elements that describes data retention practices:
+ <business/>: Data persists per business practices.
+ <indefinite/>: Data persists indefinitely.
+ <legal/>: Data persists per legal requirements.
+ <none/>: Data is not persistent and is not retained for more than a brief period of time necessary to make use of it during the course of a single online interaction.
+ <stated/>: Data persists to meet the stated purpose.
* An OPTIONAL <expiry> element that describes the lifetime of the policy. The <expiry> element MUST contain one of the following child elements:
+ <absolute/>: The policy is valid from the current date and time until it expires on the specified date and time.
+ <relative/>: The policy is valid from the current date and time until the end of the specified duration.
Data collection policy elements are based on work described in the World Wide Web Consortium's Platform for Privacy Preferences [W3C.REC-P3P-20020416] specification.
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 <extension> element that MAY be used for server- defined command extensions.
- 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:
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 <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:
o A "code" attribute whose value is a four-digit, decimal number that describes the success or failure of the command.
o 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).
o 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.
o Zero or more OPTIONAL <extValue> elements that can be used to provide additional error diagnostic information, including:
* A <value> element that identifies a client-provided element (including XML tag and value) that caused a server error condition.
* 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).
- 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:
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o A "count" attribute that describes the number of messages that exist in the queue.
o 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:
o A <qDate> element that contains the date and time that the message was enqueued.
o 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.
- An OPTIONAL <resData> (response data) element that contains child elements specific to the command and associated object.
- An OPTIONAL <extension> element that MAY be used for server- defined response extensions.
- 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.
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.
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">
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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.
EPP provides an extensible object management framework that defines the syntax and semantics of protocol operations applied to a managed object. This framework pushes the definition of each protocol operation into the context of a specific object, providing the ability to add mappings for new objects without having to modify the base protocol.
Protocol elements that contain data specific to objects are identified using XML namespace notation with a reference to an XML schema that defines the namespace. The schema for EPP supports use of dynamic object schemas on a per-command and per-response basis. For example, the start of an object-specific command element would be described in generic terms as follows:
C:<EPPCommandName> C: <object:command xmlns:object="urn:ietf:params:xml:ns:object"> C: <!-- 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.
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>
A server-extended response element would be described similarly:
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.
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
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inconsistencies that have adverse consequences for the Internet. For example, changing the name of a name server 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.
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.
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.
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:
- A <clID> element that contains the client identifier assigned to the client by the server.
- A <pw> element that contains the client's plain text password. The value of this element is case sensitive.
- 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.
- An <options> element that contains the following child elements:
- A <version> element that contains the protocol version to be used for the command or ongoing server session.
- 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.
- 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.
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The PLAIN Simple Authentication and Security Layer (SASL) mechanism presented in [RFC4616] 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.
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.
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 command MUST be available to all clients.
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.
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.
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 command MUST be available to all clients.
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:
- 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.
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:
- 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.
- 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).
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:
- An object-specific <obj:info> element that identifies the object to be queried.
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.
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.
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 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
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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.
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.
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:
- 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.
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
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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.
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.
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.
The EPP <create> command is used to create an instance of an object. An object can be created for an indefinite period of time, or an object can be created for a specific validity period. The EPP mapping for an object MUST describe the status of an object with respect to time in order 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:
- An object-specific <obj:create> element that identifies the object to be created and the elements that are required to create the object.
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.
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.
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:
- An object-specific <obj:delete> element that identifies the object to be deleted.
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.
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.
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:
- 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.
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.
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.
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.
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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.
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:
- An object-specific <obj:transfer> element that identifies the object to be transferred and the elements that are required to process the transfer command.
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.
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
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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.
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:
- 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.
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.
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.
EPP result codes are based on the theory of reply codes described in section 4.2.1 of [RFC5321]. EPP uses four decimal digits to describe the success or failure of each EPP command. Each of the digits of the reply have special significance.
The first digit denotes command success or failure. The second digit denotes the response category, such as command syntax or security. The third and fourth digits provide explicit response detail within each response category.
There are two values for the first digit of the reply code:
1yzz Positive completion reply. The command 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. The complete list of valid result codes is enumerated below and in the normative schema.
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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 [RFC4646].
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
This response code MUST be returned when a server receives invalid command authorization information when attempting 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.
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.
This response code MUST be returned when a server receives a command to confirm, reject, or cancel the transfer of an object when no command has been made to transfer the object.
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
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conditions that are matters of local policy, or the server might have received a <delete> command for an object whose status prohibits deletion.
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.
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.
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.
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.
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.
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 schema. 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.
Copyright (c) 2009 IETF Trust and the persons identified as authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
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o Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
o Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
o Neither the name of Internet Society, IETF or IETF Trust, nor the names of specific contributors, may be used to endorse or promote products derived from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
<!-- Every EPP XML instance must begin with this element. -->
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<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> </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"/>
<!-- 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>
<!-- 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>
<!-- All other object-centric commands. EPP doesn't specify the syntax or semantics of object-centric command elements. The elements MUST be described in detail in another schema specific to the object. --> <complexType name="readWriteType"> <sequence> <any namespace="##other"/> </sequence> </complexType>
<!-- Human-readable text may be expressed in languages other than English. --> <complexType name="msgType"> <simpleContent> <extension base="normalizedString"> <attribute name="lang" type="language" default="en"/> </extension> </simpleContent> </complexType>
Copyright (c) 2009 IETF Trust and the persons identified as authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
o Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
o Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
o Neither the name of Internet Society, IETF or IETF Trust, nor the names of specific contributors, may be used to endorse or promote products derived from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 [RFC4646].
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.
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.
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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.
A MIME media type registration template is included in Appendix B.
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 [RFC4616] 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,
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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.
As described in Section 2, EPP includes features that allow for offline review of transform commands before the requested action is actually completed. The server is required to notify the client when offline processing of the action has been completed. Notifications can be sent using an out-of-band mechanism that is not protected by the mechanism used to provide EPP transport security. Notifications sent without EPP's transport-security services should be protected using another mechanism that provides an appropriate level of protection for the notification.
RFC 3730 is a product of the PROVREG working group, which suggested improvements and provided many invaluable comments. The author wishes to acknowledge the efforts of WG chairs Edward Lewis and Jaap Akkerhuis for their process and editorial contributions. RFC 4930 and this document are individual submissions, based on the work done in RFC 3730.
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.
[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.
[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.
[RFC4646] Phillips, A. and M. Davis, "Tags for Identifying Languages", BCP 47, RFC 4646, September 2006.
[W3C.REC-xml-20040204] Sperberg-McQueen, C., Maler, E., Yergeau, F., Paoli, J., and T. Bray, "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>.
[W3C.REC-xmlschema-1-20041028] Maloney, M., Thompson, H., 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] Malhotra, A. and P. Biron, "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>.
[RFC4960] Stewart, R., "Stream Control Transmission Protocol", RFC 4960, September 2007.
[RFC5321] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321, October 2008.
[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>.
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 gives 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.
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.
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.
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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.
7. Added "A protocol client that is authorized to manage an existing object is described as a "sponsoring" client throughout this document" in Section 1.1.
8. Changed "This action MUST be open to all authorized clients" to "This command MUST be available to all clients" in the descriptions of the <login> and <logout> commands.
9. Changed "Specific result codes are listed in the table below" to "The complete list of valid result codes is enumerated below and in the normative schema" in Section 3.
10. Added new paragraph to Section 7 to give guidance on the need to protect offline transaction notices.
11. Added reference to Appendix B in the IANA Considerations section.