LinuxDig.com Request For Comments

RFC Number : 3730 Title : Extensible Provisioning Protocol (EPP). 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 Hollenbeck Standards Track [Page 1]  RFC 3730 EPP March 2004 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 Hollenbeck Standards Track [Page 2]  RFC 3730 EPP March 2004 layered protocol environment. Bindings to specific transport and security protocols are outside the scope of this specification. This original motivation for this protocol was to provide a standard Internet domain name registration protocol for use between domain name registrars and domain name registries. This protocol provides a means of interaction between a registrar's applications and registry applications. It is expected that this protocol will have additional uses beyond domain name registration. XML is case sensitive. Unless stated otherwise, XML specifications and examples provided in this document MUST be interpreted in the character case presented to develop a conforming implementation. 1.1. Conventions Used In This Document The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'MAY', and 'OPTIONAL' in this document are to be interpreted as described in [RFC2119]. In examples, 'C:' represents lines sent by a protocol client and 'S:' represents lines returned by a protocol server. Indentation and white space in examples is provided only to illustrate element relationships and is not a REQUIRED feature of this protocol. 2. Protocol Description EPP is a stateful XML protocol that can be layered over multiple transport protocols. Protected using lower-layer security protocols, clients exchange identification, authentication, and option information, and then engage in a series of client-initiated command-response exchanges. All EPP commands are atomic (there is no partial success or partial failure) and designed so that they can be made idempotent (executing a command more than once has the same net effect on system state as successfully executing the command once). EPP provides four basic service elements: service discovery, commands, responses, and an extension framework that supports definition of managed objects and the relationship of protocol requests and responses to those objects. An EPP server MUST respond to client-initiated communication (which can be either a lower-layer connection request or an EPP service discovery message) by returning a greeting to a client. A server MUST promptly respond to each EPP command with a coordinated response that describes the results of processing the command. The following server state machine diagram illustrates the message exchange process in detail: Hollenbeck Standards Track [Page 3]  RFC 3730 EPP March 2004 | V +-----------------+ +-----------------+ | Waiting for | Connected | Prepare | | Client |----------------->| Greeting | +-----------------+ or +-----------------+ ^ | | 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. Hollenbeck Standards Track [Page 4]  RFC 3730 EPP March 2004 Commands are processed by a server in the order they are received from a client. Though an immediate response confirming receipt and processing of the command is produced by the server, the protocol includes features that allow for offline review of transform commands before the requested action is actually completed. In such situations the response from the server MUST clearly note that the command has been received and processed, but the requested action is pending. The state of the corresponding object MUST clearly reflect processing of the pending action. The server MUST also notify the client when offline processing of the action has been completed. Object mappings SHOULD describe standard formats for notices that describe completion of offline processing. EPP uses XML namespaces to provide an extensible object management framework and to identify schemas required for XML instance parsing and validation. These namespaces and schema definitions are used to identify both the base protocol schema and the schemas for managed objects. The specific strings used to associate URIs and namespaces (such as the string 'foo' in 'xmlns:foo') in EPP are illustrative and are not needed for interoperability. All XML instances SHOULD begin with an declaration to identify the version of XML that is being used, optionally identify use of the character encoding used, and optionally provide a hint to an XML parser that an external schema file is needed to validate the XML instance. Conformant XML parsers recognize both UTF-8 (defined in RFC 2279 [RFC2279]) and UTF-16 (defined in RFC 2781 [RFC2781]); per RFC 2277 [RFC2277] UTF-8 is the RECOMMENDED character encoding for use with EPP. Character encodings other than UTF-8 and UTF-16 are allowed by XML. UTF-8 is the default encoding assumed by XML in the absence of an 'encoding' attribute or a byte order mark (BOM), thus the 'encoding' attribute in the XML declaration is OPTIONAL if UTF-8 encoding is used. Normative section 4.3.3 and non-normative appendix F of [XML] describe use of a BOM to identify the character encoding in the absence of an XML declaration or encapsulating headers. Appendix F includes a BOM to represent UTF-8 encoding, though section 4.3.3 notes that a BOM is not needed to identify UTF-8 encoding. Section 4.3.3 was later amended (see [XMLE]) to clarify that a BOM MAY be used to identify UTF-8 encoding. EPP clients and servers MUST accept a UTF-8 BOM if present, though emitting a UTF-8 BOM is NOT RECOMMENDED. Hollenbeck Standards Track [Page 5]  RFC 3730 EPP March 2004 Example XML declarations: 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: Hollenbeck Standards Track [Page 6]  RFC 3730 EPP March 2004 - 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: xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' xsi:schemaLocation='urn:ietf:params:xml:ns:epp-1.0 epp-1.0.xsd'> 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: xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' C: xsi:schemaLocation='urn:ietf:params:xml:ns:epp-1.0 C: epp-1.0.xsd'> C: C: Hollenbeck Standards Track [Page 7]  RFC 3730 EPP March 2004 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. Hollenbeck Standards Track [Page 8]  RFC 3730 EPP March 2004 : 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. Hollenbeck Standards Track [Page 9]  RFC 3730 EPP March 2004 : 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. Hollenbeck Standards Track [Page 10]  RFC 3730 EPP March 2004 Example greeting: S: S: S: xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' S: xsi:schemaLocation='urn:ietf:params:xml:ns:epp-1.0 S: epp-1.0.xsd'> S: 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. Hollenbeck Standards Track [Page 11]  RFC 3730 EPP March 2004 - 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: xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' C: xsi:schemaLocation='urn:ietf:params:xml:ns:epp-1.0 C: epp-1.0.xsd'> C: C: C: C: xsi:schemaLocation='urn:ietf:params:xml:ns:obj obj.xsd'> 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). Hollenbeck Standards Track [Page 12]  RFC 3730 EPP March 2004 - 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. Hollenbeck Standards Track [Page 13]  RFC 3730 EPP March 2004 - 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: xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' S: xsi:schemaLocation='urn:ietf:params:xml:ns:epp-1.0 S: epp-1.0.xsd'> S: S: S: Command completed successfully S: S: S: ABC-12345 S: 54321-XYZ S: S: S: Hollenbeck Standards Track [Page 14]  RFC 3730 EPP March 2004 Example response with : S: S: S: xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' S: xsi:schemaLocation='urn:ietf:params:xml:ns:epp-1.0 S: epp-1.0.xsd'> S: S: S: Command completed successfully S: S: S: S: xsi:schemaLocation='urn:ietf:params:xml:ns:obj obj.xsd'> S: example S: S: S: S: ABC-12345 S: 54321-XYZ S: S: S: Example response with error value elements: S: S: S: xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' S: xsi:schemaLocation='urn:ietf:params:xml:ns:epp-1.0 S: epp-1.0.xsd'> S: 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. Hollenbeck Standards Track [Page 15]  RFC 3730 EPP March 2004 S: S: S: S: ABC-12345 S: 54321-XYZ S: S: S: Example response with notice of waiting server messages: S: S: S: xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' S: xsi:schemaLocation='urn:ietf:params:xml:ns:epp-1.0 S: epp-1.0.xsd'> S: 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: Hollenbeck Standards Track [Page 16]  RFC 3730 EPP March 2004 C: C: C: C: C: xsi:schemaLocation='urn:ietf:params:xml:ns:ext ext.xsd'> 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: xsi:schemaLocation='urn:ietf:params:xml:ns:object object.xsd'> C: C: C: An object-specific response element would be described similarly: S: S: S: xsi:schemaLocation='urn:ietf:params:xml:ns:object object.xsd'> S: S: S: Hollenbeck Standards Track [Page 17]  RFC 3730 EPP March 2004 This document does not define mappings for specific objects. The mapping of EPP to an object MUST be described in separate documents that specifically address each command and response in the context of the object. A suggested object mapping outline is included as an appendix to this document. 2.7.3. Command-Response Extension EPP provides a facility for protocol command and response extensions. Protocol commands and responses MAY be extended by an 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: xsi:schemaLocation='urn:ietf:params:xml:ns:object object.xsd'> 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: Hollenbeck Standards Track [Page 18]  RFC 3730 EPP March 2004 This document does not define any specific server extensions. The mapping of server extensions to EPP MUST be described in separate documents that specifically address extended commands and responses in the server's operational context. 2.8. Object Identification Some objects, such as name servers and contacts, can have utility in multiple repositories. However, maintaining disjoint copies of object information in multiple repositories can lead to inconsistencies that have adverse consequences for the Internet. For example, changing a name server name in one repository, but not in a second repository that refers to the server for domain name delegation, can produce unexpected DNS query results. Globally unique identifiers can help facilitate object information sharing between repositories. A globally unique identifier MUST be assigned to every object when the object is created; the identifier MUST be returned to the client as part of any request to retrieve the detailed attributes of an object. Specific identifier values are a matter of repository policy, but they SHOULD be constructed according to the following algorithm: a) Divide the provisioning repository world into a number of object repository classes. b) Each repository within a class is assigned an identifier that is maintained by IANA. c) Each repository is responsible for assigning a unique local identifier for each object within the repository. d) The globally unique identifier is a concatenation of the local identifier, followed by a hyphen ('-', ASCII value 0x002D), followed by the repository identifier. 2.9. Protocol Commands EPP provides commands to manage sessions, retrieve object information, and perform transformation operations on objects. All EPP commands are atomic and designed so that they can be made idempotent, either succeeding completely or failing completely and producing predictable results in case of repeated execution. This section describes each EPP command, including examples with representative server responses. Hollenbeck Standards Track [Page 19]  RFC 3730 EPP March 2004 2.9.1. Session Management Commands EPP provides two commands for session management: 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. Hollenbeck Standards Track [Page 20]  RFC 3730 EPP March 2004 - 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: xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' C: xsi:schemaLocation='urn:ietf:params:xml:ns:epp-1.0 C: epp-1.0.xsd'> C: 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. Hollenbeck Standards Track [Page 21]  RFC 3730 EPP March 2004 Example response: S: S: S: xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' S: xsi:schemaLocation='urn:ietf:params:xml:ns:epp-1.0 S: epp-1.0.xsd'> S: 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. Hollenbeck Standards Track [Page 22]  RFC 3730 EPP March 2004 Example command: C: C: C: xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' C: xsi:schemaLocation='urn:ietf:params:xml:ns:epp-1.0 C: epp-1.0.xsd'> C: 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: xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' S: xsi:schemaLocation='urn:ietf:params:xml:ns:epp-1.0 S: epp-1.0.xsd'> S: 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. Hollenbeck Standards Track [Page 23]  RFC 3730 EPP March 2004 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: xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' C: xsi:schemaLocation='urn:ietf:params:xml:ns:epp-1.0 C: epp-1.0.xsd'> C: C: C: C: xsi:schemaLocation='urn:ietf:params:xml:ns:obj obj.xsd'> 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: Hollenbeck Standards Track [Page 24]  RFC 3730 EPP March 2004 - 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: xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' S: xsi:schemaLocation='urn:ietf:params:xml:ns:epp-1.0 S: epp-1.0.xsd'> S: S: S: Command completed successfully S: S: S: S: xsi:schemaLocation='urn:ietf:params:xml:ns:obj obj.xsd'> 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: Hollenbeck Standards Track [Page 25]  RFC 3730 EPP March 2004 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: xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' C: xsi:schemaLocation='urn:ietf:params:xml:ns:epp-1.0 C: epp-1.0.xsd'> C: C: C: C: xsi:schemaLocation='urn:ietf:params:xml:ns:obj obj.xsd'> 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. Hollenbeck Standards Track [Page 26]  RFC 3730 EPP March 2004 Example response: S: S: S: xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' S: xsi:schemaLocation='urn:ietf:params:xml:ns:epp-1.0 S: epp-1.0.xsd'> S: S: S: Command completed successfully S: S: S: S: xsi:schemaLocation='urn:ietf:params:xml:ns:obj obj.xsd'> 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. Hollenbeck Standards Track [Page 27]  RFC 3730 EPP March 2004 Servers can occasionally perform actions on objects that are not in direct response to a client request, or an action taken by one client can indirectly involve a second client. Examples of such actions include deletion upon expiration, automatic renewal upon expiration, and transfer coordination; other types of service information MAY be defined as a matter of server policy. Service messages MUST be created for all clients affected by an action on an object. For example, 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: xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' C: xsi:schemaLocation='urn:ietf:params:xml:ns:epp-1.0 C: epp-1.0.xsd'> C: C: C: ABC-12345 C: C: The returned result code notes that a message has been dequeued and returned in response to a command. Hollenbeck Standards Track [Page 28]  RFC 3730 EPP March 2004 Example response with object-specific information: S: S: S: xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' S: xsi:schemaLocation='urn:ietf:params:xml:ns:epp-1.0 S: epp-1.0.xsd'> S: S: S: Command completed successfully; ack to dequeue S: S: S: 2000-06-08T22:00:00.0Z S: Transfer requested. S: S: S: S: xmlns:obj='urn:ietf:params:xml:ns:obj-1.0' S: xsi:schemaLocation='urn:ietf:params:xml:ns:obj-1.0 S: obj-1.0.xsd'> S: 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. Hollenbeck Standards Track [Page 29]  RFC 3730 EPP March 2004 Example acknowledgement command: C: C: C: xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' C: xsi:schemaLocation='urn:ietf:params:xml:ns:epp-1.0 C: epp-1.0.xsd'> C: 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: xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' S: xsi:schemaLocation='urn:ietf:params:xml:ns:epp-1.0 S: epp-1.0.xsd'> S: 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. Hollenbeck Standards Track [Page 30]  RFC 3730 EPP March 2004 Example response with mixed message content and without object-specific information: S: S: S: xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' S: xsi:schemaLocation='urn:ietf:params:xml:ns:epp-1.0 S: epp-1.0.xsd'> S: 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: xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' S: xsi:schemaLocation='urn:ietf:params:xml:ns:epp-1.0 S: epp-1.0.xsd'> S: S: S: Command completed successfully; no messages S: S: S: ABC-12346 S: 54321-XYZ S: S: S: Hollenbeck Standards Track [Page 31]  RFC 3730 EPP March 2004 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: xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' C: xsi:schemaLocation='urn:ietf:params:xml:ns:epp-1.0 C: epp-1.0.xsd'> C: C: C: C: xsi:schemaLocation='urn:ietf:params:xml:ns:obj obj.xsd'> 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 Hollenbeck Standards Track [Page 32]  RFC 3730 EPP March 2004 requested the transfer, the date and time that the request was made, the identifier of the client that is authorized to act on the request, the date and time by which an action is expected, and an OPTIONAL date and time noting changes in the object's validity period (if applicable) that occur as a result of the transfer. Example query response: S: S: S: xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' S: xsi:schemaLocation='urn:ietf:params:xml:ns:epp-1.0 S: epp-1.0.xsd'> S: S: S: Command completed successfully S: S: S: S: xsi:schemaLocation='urn:ietf:params:xml:ns:obj obj.xsd'> 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. Hollenbeck Standards Track [Page 33]  RFC 3730 EPP March 2004 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: xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' C: xsi:schemaLocation='urn:ietf:params:xml:ns:epp-1.0 C: epp-1.0.xsd'> C: C: C: C: xsi:schemaLocation='urn:ietf:params:xml:ns:obj obj.xsd'> C: C: C: C: ABC-12345 C: C: Hollenbeck Standards Track [Page 34]  RFC 3730 EPP March 2004 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: xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' S: xsi:schemaLocation='urn:ietf:params:xml:ns:epp-1.0 S: epp-1.0.xsd'> S: S: S: Command completed successfully S: S: S: S: xsi:schemaLocation='urn:ietf:params:xml:ns:obj obj.xsd'> 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. Hollenbeck Standards Track [Page 35]  RFC 3730 EPP March 2004 Example command: C: C: C: xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' C: xsi:schemaLocation='urn:ietf:params:xml:ns:epp-1.0 C: epp-1.0.xsd'> C: C: C: C: xsi:schemaLocation='urn:ietf:params:xml:ns:obj obj.xsd'> 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: xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' S: xsi:schemaLocation='urn:ietf:params:xml:ns:epp-1.0 S: epp-1.0.xsd'> S: 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. Hollenbeck Standards Track [Page 36]  RFC 3730 EPP March 2004 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: xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' C: xsi:schemaLocation='urn:ietf:params:xml:ns:epp-1.0 C: epp-1.0.xsd'> C: C: C: C: xsi:schemaLocation='urn:ietf:params:xml:ns:obj obj.xsd'> 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: xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' S: xsi:schemaLocation='urn:ietf:params:xml:ns:epp-1.0 S: epp-1.0.xsd'> S: S: S: Command completed successfully S: Hollenbeck Standards Track [Page 37]  RFC 3730 EPP March 2004 S: S: S: xsi:schemaLocation='urn:ietf:params:xml:ns:obj obj.xsd'> 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. Hollenbeck Standards Track [Page 38]  RFC 3730 EPP March 2004 The current sponsoring client MAY explicitly approve or reject the transfer request. The client can approve the request using a 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: xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' C: xsi:schemaLocation='urn:ietf:params:xml:ns:epp-1.0 C: epp-1.0.xsd'> C: C: C: C: xsi:schemaLocation='urn:ietf:params:xml:ns:obj obj.xsd'> C: C: C: C: ABC-12346 C: C: Hollenbeck Standards Track [Page 39]  RFC 3730 EPP March 2004 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: xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' S: xsi:schemaLocation='urn:ietf:params:xml:ns:epp-1.0 S: epp-1.0.xsd'> S: S: S: Command completed successfully; action pending S: S: S: S: xsi:schemaLocation='urn:ietf:params:xml:ns:obj obj.xsd'> 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 Hollenbeck Standards Track [Page 40]  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 command: C: C: C: xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' C: xsi:schemaLocation='urn:ietf:params:xml:ns:epp-1.0 C: epp-1.0.xsd'> C: C: C: C: xsi:schemaLocation='urn:ietf:params:xml:ns:obj obj.xsd'> C: C: C: C: ABC-12346 C: C: When an 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. Hollenbeck Standards Track [Page 41]  RFC 3730 EPP March 2004 Example response without : S: S: S: xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' S: xsi:schemaLocation='urn:ietf:params:xml:ns:epp-1.0 S: epp-1.0.xsd'> S: S: S: Command completed successfully S: S: S: ABC-12346 S: 54322-XYZ S: S: S: The EPP command is used to change information associated with an existing object. This action SHOULD be limited to authorized clients; restricting this action to the sponsoring client is RECOMMENDED. 3. Result Codes EPP result codes are based on the theory of reply codes described in section 4.2.1 of [RFC2821]. EPP uses four decimal digits to describe the success or failure of each EPP command. Each of the digits of the reply have special significance. The first digit denotes command success or failure. The second digit denotes the response category, such as command syntax or security. The third and fourth digits provide explicit response detail within each response category. There are two values for the first digit of the reply code: 1yzz Positive completion reply. The command has been accepted and processed by the system without error. 2yzz Negative completion reply. The command was not accepted and the requested action did not occur. Hollenbeck Standards Track [Page 42]  RFC 3730 EPP March 2004 The second digit groups responses into one of six specific categories: x0zz Protocol Syntax x1zz Implementation-specific Rules x2zz Security x3zz Data Management x4zz Server System x5zz Connection Management The third and fourth digits provide response detail within the categories defined by the first and second digits. Specific result codes are listed in the table below. Every EPP response MUST include a result code and a human-readable description of the result code. The language used to represent the description MAY be identified using an instance of the 'lang' attribute within the element. If not specified, the default language is English, identified as 'en'. A description of the structure of valid values for the 'lang' attribute is described in [RFC3066]. Response text MAY be translated into other languages, though the translation MUST preserve the meaning of the code as described here. Response code values MUST NOT be changed when translating text. Response text in the table below is enclosed in quotes to clearly mark the beginning and ending of each response string. Quotes MUST NOT be used to delimit these strings when returning response text via the protocol. Hollenbeck Standards Track [Page 43]  RFC 3730 EPP March 2004 Successful command completion responses: Code Response text in English ___________________________________ 1000 'Command completed successfully' This is the usual response code for a successfully completed command that is not addressed by any other 1xxx-series response code. 1001 'Command completed successfully; action pending' This response code MUST be returned when responding to a command the requires offline activity before the requested action can be completed. See section 2 for a description of other processing requirements. 1300 'Command completed successfully; no messages' This response code MUST be returned when responding to a 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 request command and a message has been retrieved from the server message queue. 1500 'Command completed successfully; ending session' This response code MUST be returned when responding to a successful command. Hollenbeck Standards Track [Page 44]  RFC 3730 EPP March 2004 Command error responses: Code Response text in English ___________________________________ 2000 'Unknown command' This response code MUST be returned when a server receives a command element that is not defined by EPP. 2001 'Command syntax error' This response code MUST be returned when a server receives an improperly formed command element. 2002 'Command use error' This response code MUST be returned when a server receives a properly formed command element, but the command can not be executed due to a sequencing or context error. For example, a command can not be executed without having first completed a command. 2003 'Required parameter missing' This response code MUST be returned when a server receives a command for which a required parameter value has not been provided. 2004 'Parameter value range error' This response code MUST be returned when a server receives a command parameter whose value is outside the range of values specified by the protocol. The error value SHOULD be returned via a element in the EPP response. 2005 'Parameter value syntax error' This response code MUST be returned when a server receives a command containing a parameter whose value is improperly formed. The error value SHOULD be returned via a element in the EPP response. 2100 'Unimplemented protocol version' This response code MUST be returned when a server receives a command element specifying a protocol version that is not implemented by the server. 2101 'Unimplemented command' This response code MUST be returned when a server receives a valid EPP command element that is not implemented by the server. For example, a command can be unimplemented for certain object types. Hollenbeck Standards Track [Page 45]  RFC 3730 EPP March 2004 2102 'Unimplemented option' This response code MUST be returned when a server receives a valid EPP command element that contains a protocol option that is not implemented by the server. 2103 'Unimplemented extension' This response code MUST be returned when a server receives a valid EPP command element that contains a protocol command extension that is not implemented by the server. 2104 'Billing failure' This response code MUST be returned when a server attempts to execute a billable operation and the command can not be completed due to a client billing failure. 2105 'Object is not eligible for renewal' This response code MUST be returned when a client attempts to an object that is not eligible for renewal in accordance with server policy. 2106 'Object is not eligible for transfer' This response code MUST be returned when a client attempts to an object that is not eligible for transfer in accordance with server policy. 2200 'Authentication error' This response code MUST be returned when a server notes an error when validating client credentials. 2201 'Authorization error' This response code MUST be returned when a server notes a client authorization error when executing a command. This error is used to note that a client lacks privileges to execute the requested command. 2202 'Invalid authorization information' This response code MUST be returned when a server receives invalid command authorization information required to confirm authorization to execute a command. This error is used to note that a client has the privileges required to execute the requested command, but the authorization information provided by the client does not match the authorization information archived by the server. 2300 'Object pending transfer' This response code MUST be returned when a server receives a command to transfer an object that is pending transfer due to an earlier transfer request. Hollenbeck Standards Track [Page 46]  RFC 3730 EPP March 2004 2301 'Object not pending transfer' This response code MUST be returned when a server receives a command to confirm, reject, or cancel the transfer an object when no command has been made to transfer the object. 2302 'Object exists' This response code MUST be returned when a server receives a command to create an object that already exists in the repository. 2303 'Object does not exist' This response code MUST be returned when a server receives a command to query or transform an object that does not exist in the repository. 2304 'Object status prohibits operation' This response code MUST be returned when a server receives a command to transform an object that can not be completed due to server policy or business practices. For example, a server can disallow commands under terms and conditions that are matters of local policy, or the server might have received a command for an object whose status prohibits deletion. 2305 'Object association prohibits operation' This response code MUST be returned when a server receives a command to transform an object that can not be completed due to dependencies on other objects that are associated with the target object. For example, a server can disallow commands while an object has active associations with other objects. 2306 'Parameter value policy error' This response code MUST be returned when a server receives a command containing a parameter value that is syntactically valid, but semantically invalid due to local policy. For example, the server can support a subset of a range of valid protocol parameter values. The error value SHOULD be returned via a element in the EPP response. 2307 'Unimplemented object service' This response code MUST be returned when a server receives a command to operate on an object service that is not supported by the server. 2308 'Data management policy violation' This response code MUST be returned when a server receives a command whose execution results in a violation of server data management policies. For example, removing all attribute values or object associations from an object might be a violation of a server's data management policies. Hollenbeck Standards Track [Page 47]  RFC 3730 EPP March 2004 2400 'Command failed' This response code MUST be returned when a server is unable to execute a command due to an internal server error that is not related to the protocol. The failure can be transient. The server MUST keep any ongoing session active. 2500 'Command failed; server closing connection' This response code MUST be returned when a server receives a command that can not be completed due to an internal server error that is not related to the protocol. The failure is not transient, and will cause other commands to fail as well. The server MUST end the active session and close the existing connection. 2501 'Authentication error; server closing connection' This response code MUST be returned when a server notes an error when validating client credentials and a server-defined limit on the number of allowable failures has been exceeded. The server MUST close the existing connection. 2502 'Session limit exceeded; server closing connection' This response code MUST be returned when a server receives a command, and the command can not be completed because the client has exceeded a system-defined limit on the number of sessions that the client can establish. It might be possible to establish a session by ending existing unused sessions and closing inactive connections. 4. Formal Syntax EPP is specified in XML Schema notation. The formal syntax presented here is a complete schema representation of EPP suitable for automated validation of EPP XML instances. Two schemas are presented here. The first schema is the base EPP schema. The second schema defines elements and structures that can be used by both the base EPP schema and object mapping schemas. The BEGIN and END tags are not part of the schema; they are used to note the beginning and ending of the schema for URI registration purposes. Hollenbeck Standards Track [Page 48]  RFC 3730 EPP March 2004 4.1. Base Schema BEGIN xmlns:epp='urn:ietf:params:xml:ns:epp-1.0' xmlns:eppcom='urn:ietf:params:xml:ns:eppcom-1.0' xmlns='http://www.w3.org/2001/XMLSchema' elementFormDefault='qualified'> schemaLocation='eppcom-1.0.xsd'/> Extensible Provisioning Protocol v1.0 schema. Hollenbeck Standards Track [Page 49]  RFC 3730 EPP March 2004 maxOccurs='unbounded'/> maxOccurs='unbounded'/> maxOccurs='unbounded'/> minOccurs='0'/> maxOccurs='unbounded'/> minOccurs='0'/> Hollenbeck Standards Track [Page 50]  RFC 3730 EPP March 2004 minOccurs='0'/> minOccurs='0'/> minOccurs='0'/> minOccurs='0'/> minOccurs='0'/> minOccurs='0' maxOccurs='unbounded'/> minOccurs='0'/> minOccurs='0'/> minOccurs='0'/> Hollenbeck Standards Track [Page 51]  RFC 3730 EPP March 2004 minOccurs='0'/> maxOccurs='unbounded'/> maxOccurs='unbounded'/> minOccurs='0'/> minOccurs='0'/> minOccurs='0'/> Hollenbeck Standards Track [Page 53]  RFC 3730 EPP March 2004 maxOccurs='unbounded'/> minOccurs='0'/> use='required'/> use='required'/> Hollenbeck Standards Track [Page 54]  RFC 3730 EPP March 2004 minOccurs='0'/> maxOccurs='unbounded'/> minOccurs='0'/> minOccurs='0'/> minOccurs='0'/> Hollenbeck Standards Track [Page 55]  RFC 3730 EPP March 2004 use='required'/> minOccurs='0'/> minOccurs='0'/> use='required'/> use='required'/> minOccurs='0' maxOccurs='unbounded'/> Hollenbeck Standards Track [Page 56]  RFC 3730 EPP March 2004