Network Working Group A. Newton

Network Working Group A. Newton
Request for Comments: 5144 American Registry for Internet Numbers
Category: Standards Track M. Sanz
DENIC eG
February 2008

A Domain Availability Check (DCHK) Registry Type for
the Internet Registry Information Service (IRIS)

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.

Abstract

This document describes a lightweight domain availability service
using the Internet Registry Information Service (IRIS) framework and
the data model of the IRIS Domain Registry (DREG) service.

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Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Document Terminology . . . . . . . . . . . . . . . . . . . . . 3
3. Domain Availability Check Registry . . . . . . . . . . . . . . 3
3.1. Schema Description . . . . . . . . . . . . . . . . . . . . 4
3.1.1. The <domain> Result . . . . . . . . . . . . . . . . . 4
3.1.2. Support for <iris:lookupEntity> . . . . . . . . . . . 7
3.2. DCHK Formal XML Syntax . . . . . . . . . . . . . . . . . . 7
3.3. Blocks Extensible Exchange Protocol (BEEP) Transport
Compliance . . . . . . . . . . . . . . . . . . . . . . . . 12
3.3.1. Message Pattern . . . . . . . . . . . . . . . . . . . 12
3.3.2. Server Authentication . . . . . . . . . . . . . . . . 12
3.4. URI Resolution . . . . . . . . . . . . . . . . . . . . . . 13
3.4.1. Application Service Label . . . . . . . . . . . . . . 13
3.4.2. Bottom-Up Resolution . . . . . . . . . . . . . . . . . 13
3.4.3. Top-Down Resolution . . . . . . . . . . . . . . . . . 13
4. Internationalization Considerations . . . . . . . . . . . . . 13
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
5.1. XML Namespace Registration . . . . . . . . . . . . . . . . 14
5.2. XML Schema Registration . . . . . . . . . . . . . . . . . 14
5.3. S-NAPTR Registration . . . . . . . . . . . . . . . . . . . 14
5.4. BEEP Registration . . . . . . . . . . . . . . . . . . . . 15
6. Security Considerations . . . . . . . . . . . . . . . . . . . 15
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 15
7.1. Normative References . . . . . . . . . . . . . . . . . . . 15
7.2. Informative References . . . . . . . . . . . . . . . . . . 16

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1. Introduction

This document describes a lightweight service for checking the
availability of domain names. This service is based on the IRIS
framework and uses the data model defined by RFC 3982 [7]. By doing
this, the domain availability service has the advantages provided by
IRIS and DREG, such as well-known methods for server navigation,
structured queries and results, and layered extensibility.

The use of IRIS for this service also allows seamless integration
between the domain availability service and the service provided by
DREG. This allows a user to find the availability status of a domain
and reference the full registration information in DREG.

The data model in this service (called a registry schema in IRIS
terms) is a strict subset of the DREG data model. This enables
implementors to directly reuse DREG code paths and allows operators
to deploy the service in either the same server processes as a DREG
service (same host and port) or in a different server process
(different port) or machine (different host).

As an example, an operator may wish to deploy both types of service
on the same set of machines. As time goes on, the operator may then
decide to segregate the services, placing the domain availability
service on one set of machines and the DREG service on a separate set
of machines with a stricter set of controls. Either deployment
scenario is transparent to the end user and always appears to be
seamlessly complementary.

When coupled with [9], this domain availability service is
lightweight and extremely efficient for high-volume, public-facing
service.

2. Document Terminology

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 RFC 2119 [2].

3. Domain Availability Check Registry

The data model used for the domain availability check (DCHK) service
is a strict subset of the DREG data model. This section describes
the DCHK registry type.

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3.1. Schema Description

References to XML elements with no namespace qualifier are from the
schema defined in Section 3.2. References to elements and attributes
with the "iris" XML namespace qualifier are from the schema defined
in IRIS [6].

The schema present in this document is tied to the protocol version
associated with the XML namespace URI defined in Section 5.2.
Extensions to the present DCHK schema are allowed, though not
recommended, but would require a new version. Please refer to RFC
3981 [6] for more details about versioning the IRIS protocol.

The descriptions contained within this section refer to XML elements
and attributes and their relation to the exchange of data within the
protocol. These descriptions also contain specifications outside the
scope of the formal XML syntax. Therefore, this section will use
terms defined by RFC 2119 [2] to describe the specification outside
the scope of the formal XML syntax. While reading this section,
please reference Section 3.2 for needed details on the formal XML
syntax.

3.1.1. The <domain> Result

An example of a <domain> result:

<domain
authority="iana.org" registryType="dchk1"
entityClass="domain-name" entityName="example.com">
<domainName>example.com</domainName>
<status><active/></status>
</domain>

<domain> Example

The <domain> result represents an instance of a domain assignment.
The children of the <domain> element are as follows:

o <domainName> - the full name of the domain as it is in DNS. The
contents of this element MUST be a domain name as specified by RFC
1035 [1].

o <idn> - the name of the domain in nameprep form, if applicable.
See RFC 3491 [3].

o <status> - this element may contain child elements representing
domain status information. It defines the following status types:

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* <active> - available via DNS (either via delegation or direct
publication).

* <inactive> - unavailable via DNS.

* <dispute> - registrant assignment is in dispute.

* <addPeriod> - the domain is in the grace period after creation
or activation (see RFC 3915 [5]).

* <renewPeriod> - the domain is in the grace period after renewal
(see RFC 3915 [5]).

* <autoRenewPeriod> - the domain is in the grace period after
automatic renewal (see RFC 3915 [5]).

* <transferPeriod> - the domain is in the grace period after
transfer (see RFC 3915 [5]).

* <redemptionPeriod> - the domain is in the grace period after
deletion (see RFC 3915 [5]).

* <policyCompliant> - the domain is considered compliant
according to a given policy specified by the substatus
identifier.

* <policyNoncompliant> - the domain is not considered compliant
according to a given policy specified by the substatus
identifier.

* <reserved> - the domain is reserved and is not available for
registration under normal registration procedures.

* <create> - specifies the creation of the domain in the
registration system. This status is usually further refined by
the disposition attribute.

* <delete> - specifies the deletion of the domain in the
registration system. This status is usually further refined by
the disposition attribute.

* <renew> - specifies the renewal of domain registration. This
status is usually further refined by the disposition attribute.

* <restore> - specifies the restoration to the previous state of
the domain before it was deleted. This status is usually
further refined by the disposition attribute.

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* <transfer> - specifies the transfer of the domain from one
responsible or owning entity in the registration system to
another. This status is usually further refined by the
disposition attribute.

* <update> - specifies a general modification of the domain
information. This status is usually be further refined by the
disposition attribute.

* <other> - specifies a registration system specific status of
the domain.

o <registrationReference> - an element containing an entity
reference, the referent of which MUST be either a <domain>
(Section 3.1.1) or a <domain> as defined by RFC 3982 [7]. The
intent of this element is to point to the downstream registration
reference. Therefore, if this is a result given back by a domain
registry, it should point to the domain in the domain registrar or
registrant service.

o <createdDateTime> - an element containing the date and time of the
creation of this domain.

o <initialDelegationDateTime> - an element containing the date and
time of the initial delegation of this domain.

o <expirationDateTime> - an element containing the date and time of
the expiration of this domain.

o <lastDatabaseUpdateDateTime> - an element containing the date and
time of the last actualization of the database that is the source
for this result.

o <iris:seeAlso> - an element containing an entity reference
specifying a referent that is indirectly associated with this
domain.

3.1.1.1. Domain Status Type

Each element of type 'domainStatusType' has the following
composition:

o <appliedDate> - an optional child element containing the date
applicable to creation of the status.

o <ticket> - an optional child element containing a service ticket
identifier relevant to the status.

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o <description> - zero or more child elements with text to describe
the status in natural language. Each of these elements MUST have
a 'language' attribute describing the language of the description
element.

o <subStatus> - a child element indicating further status
information. Values for this element are not defined by this
specification. This child element has a required 'authority'
attribute to indicate the origin of the specification of the value
of this element.

o 'actor' - an optional attribute indicating the acting entity for
which this status is applied. The values may be "registry",
"registrar", or "registrationServiceProvider".

o 'disposition' - an optional attribute indicating the nature of
this status. The values may be "pending" or "prohibited".

o 'scope' - an optional attribute indicating the context or origin
of the status value.

3.1.2. Support for <iris:lookupEntity>

The following types of entity classes are recognized by the
<lookupEntity> query of IRIS for this registry:

o domain-name - the fully qualified name of a domain. This is a
domain name as specified by RFC 1035 [1]. Yields a <domain>
(Section 3.1.1) in the response.

o idn - the fully qualified name of a domain in nameprep form (see
RFC 3491 [3]). Yields a <domain> (Section 3.1.1) in the response.

3.2. DCHK Formal XML Syntax

This registry schema is specified in the XML Schema notation (see
[10] and [11]). The formal syntax presented here is a complete
schema representation of an XML instance when combined with the
formal schema syntax of IRIS.

<?xml version="1.0"?>
<schema xmlns="http://www.w3.org/2001/XMLSchema"
xmlns:dchk="urn:ietf:params:xml:ns:dchk1"
xmlns:iris="urn:ietf:params:xml:ns:iris1"
targetNamespace="urn:ietf:params:xml:ns:dchk1"
elementFormDefault="qualified" >

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<import namespace="urn:ietf:params:xml:ns:iris1" />

<annotation>
<documentation>
Domain availability check schema
derived from IRIS schema
</documentation>
</annotation>











<complexType
name="domainType">
<complexContent>
<extension
base="iris:resultType">
<sequence>
<element
name="domainName"
type="token" />
<element
name="idn"
type="token"
minOccurs="0"
maxOccurs="1" />
<element name="status"
minOccurs="0"
maxOccurs="1">
<complexType>
<choice minOccurs="0" maxOccurs="unbounded">
<element
name="active"
type="dchk:domainStatusType" />
<element
name="inactive"
type="dchk:domainStatusType" />
<element
name="dispute"
type="dchk:domainStatusType" />
<element

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name="renew"
type="dchk:domainStatusType" />
<element
name="addPeriod"
type="dchk:domainStatusType" />
<element
name="renewPeriod"
type="dchk:domainStatusType" />
<element
name="autoRenewPeriod"
type="dchk:domainStatusType" />
<element
name="transferPeriod"
type="dchk:domainStatusType" />
<element
name="redemptionPeriod"
type="dchk:domainStatusType" />
<element
name="restore"
type="dchk:domainStatusType" />
<element
name="policyCompliant"
type="dchk:domainStatusType" />
<element
name="policyNoncompliant"
type="dchk:domainStatusType" />
<element
name="reserved"
type="dchk:domainStatusType" />
<element
name="create"
type="dchk:domainStatusType" />
<element
name="delete"
type="dchk:domainStatusType" />
<element
name="transfer"
type="dchk:domainStatusType" />
<element
name="update"
type="dchk:domainStatusType" />
<element
name="other"
type="dchk:domainStatusType" />
</choice>
</complexType>
</element>
<element

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name="registrationReference"
type="iris:entityType"
minOccurs="0"
maxOccurs="1" />
<element
name="createdDateTime"
type="dateTime"
minOccurs="0"
maxOccurs="1" />
<element
name="initialDelegationDateTime"
type="dateTime"
minOccurs="0"
maxOccurs="1" />
<element
name="expirationDateTime"
type="dateTime"
minOccurs="0"
maxOccurs="1" />
<element
name="lastDatabaseUpdateDateTime"
type="dateTime"
minOccurs="0"
maxOccurs="1" />
<element
ref="iris:seeAlso"
minOccurs="0"
maxOccurs="unbounded" />
</sequence>
</extension>
</complexContent>
</complexType>

<element
name="domain"
type="dchk:domainType"
substitutionGroup="iris:result" />

<complexType
name="domainStatusType">
<sequence>
<element
name="appliedDate"
type="dateTime"
minOccurs="0"
maxOccurs="1" />
<element
name="ticket"

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type="token"
minOccurs="0"
maxOccurs="unbounded" />
<element
name="description"
minOccurs="0"
maxOccurs="unbounded">
<complexType>
<simpleContent>
<extension
base="string">
<attribute
name="language"
type="language"
use="required" />
</extension>
</simpleContent>
</complexType>
</element>
<element
name="subStatus"
minOccurs="0"
maxOccurs="1">
<complexType>
<simpleContent>
<extension
base="token">
<attribute
type="token"
use="required"
name="authority"/>
</extension>
</simpleContent>
</complexType>
</element>
</sequence>
<attribute
name="actor">
<simpleType>
<restriction
base="string">
<enumeration
value="registry"/>
<enumeration
value="registrar"/>
<enumeration
value="registrationServiceProvider"/>
</restriction>

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</simpleType>
</attribute>
<attribute
name="disposition">
<simpleType>
<restriction
base="string">
<enumeration
value="prohibited"/>
<enumeration
value="pending"/>
</restriction>
</simpleType>
</attribute>
<attribute
name="scope"
type="token" />
</complexType>
</schema>

Figure 1: dchk.xsd

3.3. Blocks Extensible Exchange Protocol (BEEP) Transport Compliance

All DCHK clients and servers MUST implement the Lightweight UDP
Transport Protocol (IRIS-LWZ) [9]. The use of other transports like
the XML Pipelining with Chunks (IRIS-XPC) transport [12] or the BEEP
transport [8] is optional and completely at the discretion of the
server operator. The XPC transport is in any case preferable to the
BEEP transport.

IRIS allows several extensions of the core capabilities. This
section outlines those extensions allowable by IRIS-BEEP [8].

3.3.1. Message Pattern

This registry type uses the default message pattern as described in
IRIS-BEEP [8].

3.3.2. Server Authentication

This registry type uses the default server authentication method as
described in IRIS-BEEP [8].

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3.4. URI Resolution

3.4.1. Application Service Label

The application service label associated with this registry type MUST
be "DCHK1". This is the abbreviated form of the URN for this
registry type, urn:ietf:params:xml:ns:dchk1.

3.4.2. Bottom-Up Resolution

The bottom-up alternative resolution method MUST be identified as
'bottom' in IRIS URI's. Its process is identical to the 'bottom'
process described by RFC 3982 [7].

3.4.3. Top-Down Resolution

The top-down alternative resolution method MUST be identified as
'top' in IRIS URI's. Its process is identical to the 'top' process
described by RFC 3982 [7].

4. Internationalization Considerations

Implementors should be aware of considerations for
internationalization in IRIS [6].

Clients needing to localize the data tags in this protocol should
take note that localization is only needed on the names of XML
elements and attributes, with the exception of elements containing
date and time information. The schema for this registry has been
designed so that clients need not interpret the content of elements
or attributes for localization, other than those elements containing
date and time information.

Clients should also make use of the <language> elements provided in
many of the results. Results containing internationalized data can
be accompanied by these elements in order to aid better localization
of the data by the user.

All date and time elements make use of the XML Schema [10] data type
"dateTime". If their contents are Coordinated Universal Time (UTC)
timestamps, they MUST be specified by using the capitalized 'Z'
indicator (instead of 'z').

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5. IANA Considerations

5.1. XML Namespace Registration

This document makes use of the XML registry specified in RFC 3688
[4]. Accordingly, IANA has made the following registration:

o XML Namespace URN/URI:

* urn:ietf:params:xml:ns:dchk1

o Contact:

* Andrew Newton <[email protected]>

* Marcos Sanz <[email protected]>

o XML:

* None.

5.2. XML Schema Registration

This document makes use of the XML registry specified in RFC 3688
[4]. Accordingly, IANA has made the following registration:

o XML Schema URN/URI:

* urn:ietf:params:xml:schema:dchk1

o Contact:

* Andrew Newton <[email protected]>

* Marcos Sanz <[email protected]>

o XML:

* The XML Schema specified in Section 3.2

5.3. S-NAPTR Registration

The following Sraightforwarad-NAPTR (S-NAPTR) application service
label has been registered with IANA according to the IANA
considerations defined in IRIS [6]:

DCHK1

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5.4. BEEP Registration

The following BEEP Profile URI has been registered with IANA, in
addition to the registration provided in IRIS-BEEP [8].

http://iana.org/beep/iris1/dchk1

6. Security Considerations

Being a proper subset of RFC 3982 [7], the registry described in this
document introduces no security considerations beyond those
documented in RFC 3981 [6].

7. References

7.1. Normative References

[1] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, November 1987.

[2] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.

[3] Hoffman, P. and M. Blanchet, "Nameprep: A Stringprep Profile
for Internationalized Domain Names (IDN)", RFC 3491,
March 2003.

[4] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
January 2004.

[5] Hollenbeck, S., "Domain Registry Grace Period Mapping for the
Extensible Provisioning Protocol (EPP)", RFC 3915,
September 2004.

[6] Newton, A. and M. Sanz, "IRIS: The Internet Registry
Information Service (IRIS) Core Protocol", RFC 3981,
January 2005.

[7] Newton, A. and M. Sanz, "IRIS: A Domain Registry (dreg) Type
for the Internet Registry Information Service (IRIS)",
RFC 3982, January 2005.

[8] Newton, A. and M. Sanz, "Using the Internet Registry
Information Service (IRIS) over the Blocks Extensible Exchange
Protocol (BEEP)", RFC 3983, January 2005.

[9] Newton, A., "A Lightweight UDP Transfer Protocol for the
Internet Registry Information Service", RFC 4993, August 2007.

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[10] World Wide Web Consortium, "XML Schema Part 2: Datatypes",
W3C XML Schema, October 2004,
<http://www.w3.org/TR/xmlschema-2/>.

[11] World Wide Web Consortium, "XML Schema Part 1: Structures",
W3C XML Schema, October 2004,
<http://www.w3.org/TR/xmlschema-1/>.

7.2. Informative References

[12] Newton, A., "XML Pipelining with Chunks for the Internet
Registry Information Service", RFC 4992, August 2007.

Authors' Addresses

Andrew L. Newton
American Registry for Internet Numbers
3635 Concorde Parkway, Suite 200
Chantilly, VA 20151
USA

Phone: +1 703 227 9884
EMail: [email protected]
URI: http://www.arin.net/

Marcos Sanz
DENIC eG
Kaiserstrasse 75-77
D-60329 Frankfurt
Germany

EMail: [email protected]
URI: http://www.denic.de/

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