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rfc:rfc3981

Network Working Group A. Newton Request for Comments: 3981 VeriSign, Inc. Category: Standards Track M. Sanz

                                                              DENIC eG
                                                          January 2005
IRIS: The Internet Registry Information Service (IRIS) Core Protocol

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 (2005).

Abstract

 This document describes an application layer client-server protocol
 for a framework to represent the query and result operations of the
 information services of Internet registries.  Specified in the
 Extensible Markup Language (XML), the protocol defines generic query
 and result operations and a mechanism for extending these operations
 for specific registry service needs.

Table of Contents

 1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  2
     1.1.  Use of XML . . . . . . . . . . . . . . . . . . . . . . .  2
     1.2.  General Concepts . . . . . . . . . . . . . . . . . . . .  3
     1.3.  Framework Layers . . . . . . . . . . . . . . . . . . . .  4
     1.4.  Definitions  . . . . . . . . . . . . . . . . . . . . . .  4
     1.5.  Further Reading  . . . . . . . . . . . . . . . . . . . .  5
 2.  Document Terminology . . . . . . . . . . . . . . . . . . . . .  5
 3.  Protocol Identification  . . . . . . . . . . . . . . . . . . .  5
 4.  Exchange Description . . . . . . . . . . . . . . . . . . . . .  6
     4.1.  Request Format . . . . . . . . . . . . . . . . . . . . .  6
     4.2.  Response Format  . . . . . . . . . . . . . . . . . . . .  6
     4.3.  Extension Framework  . . . . . . . . . . . . . . . . . .  9
           4.3.1.  Derived Elements . . . . . . . . . . . . . . . .  9
           4.3.2.  Registry Type Identifier Requirements  . . . . . 10
           4.3.3.  Entity Classes . . . . . . . . . . . . . . . . . 10
           4.3.4.  Names of Entities  . . . . . . . . . . . . . . . 11

Newton & Sanz Standards Track [Page 1] RFC 3981 IRIS-Core January 2005

           4.3.5.  References to Entities . . . . . . . . . . . . . 11
           4.3.6.  Temporary Entities . . . . . . . . . . . . . . . 12
           4.3.7.  <result> Derived Elements  . . . . . . . . . . . 13
           4.3.8.  <control> and <reaction> Elements  . . . . . . . 16
     4.4.  Relay Bags . . . . . . . . . . . . . . . . . . . . . . . 18
 5.  Database Serialization . . . . . . . . . . . . . . . . . . . . 19
 6.  Formal XML Syntax  . . . . . . . . . . . . . . . . . . . . . . 22
 7.  The IRIS URI . . . . . . . . . . . . . . . . . . . . . . . . . 37
     7.1.  URI Definition . . . . . . . . . . . . . . . . . . . . . 37
     7.2.  Transport Specific Schemes . . . . . . . . . . . . . . . 38
     7.3.  URI Resolution . . . . . . . . . . . . . . . . . . . . . 38
           7.3.1.  Registry Dependent Resolution  . . . . . . . . . 38
           7.3.2.  Direct Resolution  . . . . . . . . . . . . . . . 39
           7.3.3.  Transport and Service Location . . . . . . . . . 39
     7.4.  IRIS URI Examples  . . . . . . . . . . . . . . . . . . . 40
 8.  Checklists . . . . . . . . . . . . . . . . . . . . . . . . . . 41
     8.1.  Registry Definition Checklist  . . . . . . . . . . . . . 41
     8.2.  Transport Mapping Checklist  . . . . . . . . . . . . . . 42
 9.  Internationalization Considerations  . . . . . . . . . . . . . 42
 10. IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 43
 11. Security Considerations  . . . . . . . . . . . . . . . . . . . 43
 12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 43
     12.1. Normative References . . . . . . . . . . . . . . . . . . 43
     12.2. Informative References . . . . . . . . . . . . . . . . . 45
 A.  S-NAPTR and IRIS Uses  . . . . . . . . . . . . . . . . . . . . 46
     A.1.  Examples of S-NAPTR with IRIS. . . . . . . . . . . . . . 46
     A.2.  Using S-NAPTR for Cohabitation . . . . . . . . . . . . . 47
 B.  IRIS Design Philosophy . . . . . . . . . . . . . . . . . . . . 48
     B.1.  The Basic Premise  . . . . . . . . . . . . . . . . . . . 48
     B.2.  The Lure of a Universal Client . . . . . . . . . . . . . 49
     B.3.  Server Considerations  . . . . . . . . . . . . . . . . . 49
     B.4.  Lookups, Searches, and Entity Classes  . . . . . . . . . 50
     B.5.  Entities References, Search Continuations, and Scope . . 50
 C.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 51
 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 51
 Full Copyright Statement . . . . . . . . . . . . . . . . . . . . . 52

1. Introduction

 The specification outlined in this document is based on the
 functional requirements described in CRISP [17].

1.1. Use of XML

 This document describes the specification for the Internet Registry
 Information Service (IRIS), an XML text protocol intended to describe
 the query types and result types of various registry information
 services.  IRIS is specified by using the Extensible Markup Language

Newton & Sanz Standards Track [Page 2] RFC 3981 IRIS-Core January 2005

 (XML) 1.0 as described in [2], XML Schema notation as described in
 [4] and [5], and XML Namespaces as described in [3].

1.2. General Concepts

 Each kind of Internet registry is identified by a registry type.  The
 identifier for a registry type is a Uniform Resource Name (URN) used
 within the XML instances to identify the XML schema that formally
 describes the set of queries, results, and entity classes allowed
 within that type of registry.
 The structure of these URNs makes no assumptions or restrictions on
 the types of registries they identify.  Therefore, IRIS may support
 multiple registry types of a disparate or similar nature; it is only
 a matter of definition.  For instance, a single registry type may be
 defined for domain name registries, and multiple registry types for
 the various IP address registries.
 A registry information server may handle queries and serve results
 for multiple registry types.  Each registry type that a particular
 registry operator serves is a registry service instance.
 IRIS and the XML schema formally describing IRIS do not specify any
 registry, registry identifier, or knowledge of a particular service
 instance or set of instances.  IRIS is a specification for a
 framework with which these registries can be defined, used and, in
 some cases, interoperate.  The framework merely specifies the
 elements for registry identification and the elements that must be
 used to derive queries and results.
 This framework allows a registry type to define its own structure for
 naming, entities, queries, etc., through the use of XML namespaces
 and XML schemas (hence, a registry type MUST be identified by the
 same URI that identifies its XML namespace).  To be compliant, a
 registry type's specification must extend from this framework.
 The framework defines certain structures that can be common to all
 registry types, such as references to entities, search continuations,
 and entity classes.  A registry type may declare its own definitions
 for all of these, or it may mix its derived definitions with the base
 definitions.
 IRIS defines two types of referrals: an entity reference and a search
 continuation.  An entity reference indicates specific knowledge about
 an individual entity, and a search continuation allows distributed
 searches.  Both referrals may span differing registry types and
 instances.  No assumptions or specifications are made about the
 roots, bases, or meshes of entities.

Newton & Sanz Standards Track [Page 3] RFC 3981 IRIS-Core January 2005

1.3. Framework Layers

 The IRIS framework can be thought of as having three layers.
  1. —————————-

Registry-Specific |domain | address | etc… |

  1. —————————-

Common-Registry | IRIS |

  1. —————————-

Application-Transport | beep | iris-lwz | etc… |

  1. —————————-
 In this figure, "beep" refers to the Blocks Extensible Exchange
 Protocol (BEEP) (see [20]), and "iris-lwz" refers to a theoretical
 UDP binding that uses compression.
 The differing layers have the following responsibilities:
    Registry-Specific :: defines queries, results, and entity classes
    of a specific type of registry.  Each specific type of registry is
    identified by a URN.
    Common-Registry :: defines base operations and semantics common to
    all registry types such as search sets, result sets, and
    referrals.  It also defines the syntaxes for talking about
    specific registry types.
    Application-Transport :: defines the mechanisms for
    authentication, message passing, connection and session
    management, etc.  It also defines the URI syntax specific to the
    application-transport mechanism.

1.4. Definitions

 For clarity, the following definitions are supplied:
 o  registry type -- A registry serving a specific function, such as a
    domain registry or an address registry.  Each type of registry is
    assigned a URN.
 o  registry schema -- The definition for a registry type specifying
    the queries, results, and entity classes.
 o  authority -- A reference to the server or set of servers
    containing information.
 o  resolution method -- The technique used to locate an authority.
 o  entity class -- A group of entities with a common type or common
    set of characteristics.

Newton & Sanz Standards Track [Page 4] RFC 3981 IRIS-Core January 2005

 o  entity name -- The identifier used to refer to a single entity
    within an entity class.
 o  entity reference -- A pointer to an entity composed of an
    authority, an optional resolution method, a registry type, an
    entity class, and an entity name.  One type of entity reference is
    the IRIS URI (defined in Section 7).
 The terms "derivative", "derive", and "derivation" are used with the
 same meaning for deriving one type of element from another as
 specified in XML_SS [5].

1.5. Further Reading

 Appendix B contains text answering the question, "Why IRIS?".
 This document describes the structure at the core of IRIS.  The
 following documents describe the other aspects of IRIS relevant to
 CRISP [17]: iris-beep [1] and iris-dreg [18].

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 BCP 14, RFC 2119 [8].

3. Protocol Identification

 The root element of all request XML instances MUST be <request>.  The
 root element of all response XML instances MUST be <response>.  These
 elements identify the start of the IRIS elements, the XML namespace
 used as the identifier for IRIS, and, optionally, the location of the
 schema.  These elements and the associated closing tag MUST be
 applied to all requests and responses sent by both clients and
 servers.
 The use of the schema location attribute 'xsi:schemaLocation' is
 OPTIONAL with respect to this specification, and IRIS implementations
 MAY resolve it to retrieve the schema or MAY use a locally cached
 version of the schema.
 Versioning of the IRIS protocol is the responsibility of the
 application-transport layer but MUST be associated with the XML
 namespace [3] URI representing IRIS.  A change in this URI indicates
 a change of the underlying schema and, therefore, a new version of
 the protocol (and vice versa).

Newton & Sanz Standards Track [Page 5] RFC 3981 IRIS-Core January 2005

4. Exchange Description

 This section describes the request and response exchanges of the
 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 [8] to
 describe the specification outside the scope of the formal XML
 syntax.  While reading this section, please reference Section 6 for
 details on the formal XML syntax.

4.1. Request Format

 A <request> element contains an optional <control> element and a set
 of <searchSet> elements.
 The <searchSet> elements enable a client to query a particular
 registry type by using the URN identifying the registry type.  This
 can be found in one of its two children: <lookupEntity> and <query>.
 The <lookupEntity> element describes the lookup of an entity in a
 specific registry.  This element has three attributes:
 'registryType', 'entityClass', and 'entityName'.  The 'registryType'
 attribute contains the registry identifier for the registry type in
 which the lookup operation will take place.  The 'entityClass'
 attribute contains the token identifying the index for which the
 lookup operation will take place, and the 'entityName' attribute
 contains the name of the entity to look up.
 The <query> element is abstract and may not legally appear in an XML
 instance.  It provides the base type that registry schemas will use
 to define derived query types.  This derivation mechanism is
 described in Section 4.3.
 Each <searchSet> may also contain a <bag> element.  When this element
 appears as a child of <searchSet>, it MUST NOT contain the 'id'
 attribute.  For a description of the <bag> element, see Section 4.4.
 The <control> element may contain one child element of any XML
 namespace.  This child element allows a client to signal a server for
 special states or processing.  An example of one such <control> child
 element may be found in Section 4.3.8.

4.2. Response Format

 The <response> element contains an optional <reaction> element, a set
 of <resultSet> elements, and an optional <bags> element.

Newton & Sanz Standards Track [Page 6] RFC 3981 IRIS-Core January 2005

 The <resultSet> elements are responses to a <searchSet> request.  The
 contents of this element contain an <answer> element, an optional
 <additional> element, and error elements, if applicable.
 The children of the <answer> element are of the following types:
 o  <result> is an abstract element and may not be legally placed in
    an XML instance.  It provides the base type to be used by registry
    schemas to define derived result types.  This derivation mechanism
    is described in Section 4.3.
 o  <entity> is an element specifying an entity reference.  See
    Section 4.3.5.
 o  The <searchContinuation> element specifies a query referral.  Its
    one child is any element derived from <query> (see Section 4.3.1).
    To direct the query to a referent server, <searchContinuation> has
    a mandatory 'authority' attribute and an optional 'resolution'
    attribute.  The <searchContinuation> element may also contain a
    'bagRef' attribute.  For a description of the 'bagRef' attribute,
    see Section 4.4.
 When following entity references and search continuations, clients
 SHOULD only follow an <entity> or <searchContinuation> response once.
 Failure to do so may result in the client process getting stuck in a
 never-ending query loop, commonly known as a referral loop.
 The <additional> element only contains <result> elements, as
 described above.  This element allows a server to indicate to a
 client results that were not specifically queried but that are
 related to the queried results, thus enabling the client to display
 this distinction to a user properly.  The <additional> element use is
 optional.
 The following elements, which represent error conditions, may be
 returned:
 o  <insufficientResources> -- The corresponding query requires
    resources unobtainable by the server.
 o  <invalidName> -- A name given in a query is not syntactically
    correct.
 o  <invalidSearch> -- Parameters of the corresponding query are not
    semantically meaningful.
 o  <queryNotSupported> -- The corresponding query is not supported by
    this server.

Newton & Sanz Standards Track [Page 7] RFC 3981 IRIS-Core January 2005

 o  <limitExceeded> -- The corresponding query requires more resources
    than allowed.
 o  <nameNotFound> -- The name given in a query does not match a known
    entity.
 o  <permissionDenied> -- The authentication given does not allow
    access to a specific result entry.
 o  <bagUnrecognized> -- The contents of a bag were unrecognized.  See
    Section 4.4.
 o  <bagUnacceptable> -- The contents of a bag were not and never will
    be acceptable.  See Section 4.4.
 o  <bagRefused> -- The contents of a bag were not acceptable at this
    time.  See Section 4.4.
 o  A derivative of <genericCode>, as described in Section 4.3.
 The <resultSet> section is divided into the <answer> and <additional>
 sections to allow easier processing and navigation of the results by
 a client.  Servers MUST return the direct answers to queries in the
 <answer> element and MAY return results in the <additional> element
 for which a reference has been made in the <answer> element.  Results
 in the <additional> element MUST have been referenced in the
 <answer>, either as direct children of the <answer> element or as
 deeper descendants of the <answer> element.
 This serves two purposes.  First, it may eliminate a requery by the
 client for references contained in the <answer> element.  Second, it
 distinguishes between results that are a direct result of a query and
 those that would have been returned had the client followed the
 appropriate referrals, thus hinting how clients could process or
 display the returned results.  For instance, clients constructing
 complex displays with tree navigation widgets will know that results
 in the <answer> element should all be directly beneath the root node
 of the tree, while results in the <additional> element are leaf nodes
 of those produced from the <answer> element.
 A <reaction> element (child of <response>) is a response to a
 <control> element, and provides a means for a server to advise a
 client of the effect of a <control> element.
 The <bags> element (child of <response>) is optional.  It contains
 <bag> elements, and the contents of each <bag> element constitute one
 element in any XML namespace.  Each <bag> element has an 'id'
 attribute, which is referenced by the 'bagRef' attribute of entity

Newton & Sanz Standards Track [Page 8] RFC 3981 IRIS-Core January 2005

 references (<entity>) and search continuations
 (<searchContinuation>).  See Section 4.4.

4.3. Extension Framework

 Because the IRIS schema defines only one query type, and two stand-
 alone result types, and does not define a registry structure, it is
 of limited use by itself.  Extension of IRIS is accomplished through
 the use of a base IRIS schema, as defined in XML_SD [4] and XML_SS
 [5], and through extension of it by schemas constructed on top of
 IRIS.

4.3.1. Derived Elements

 The XML Schema definition of IRIS requires schemas of registry types
 to derive element types from base types in the IRIS definition.  The
 registry schemas MUST derive elements to define typed queries and
 results.
 While the IRIS schema definition does not prohibit the derivation of
 any elements, registry schemas SHOULD restrict the derivations to the
 following types:
 o  <query> -- As defined, this element contains no content and has no
    valid attributes.  It is abstract and therefore only its
    derivatives appear in XML instances.  Registry schemas derive from
    this element to define the queries allowed.
 o  <result> -- As defined, this element contains no content and has
    five valid attributes: 'authority', 'resolution' (optional),
    'registryType', 'entityClass', 'entityName', and
    'temporaryReference' (optional, see Section 4.3.6).  It is
    abstract and therefore only its derivatives appear in XML
    instances.  Registry schemas derive from this element to define
    results that may be returned from a query.
 o  <genericCode> -- As defined, this element is an instance of
    <codeType>.  It contains the optional elements <explanation> and
    <language>, which further describe the nature of the error.
 o  <entity> -- Identifies a reference to an entity.  Registry schemas
    SHOULD use elements derived from <entity> but MAY use <entity>
    directly.  The advantage of deriving from <entity> vs. direct use
    is the chance to define the name of the element and to use that
    name descriptively -- for instance, as the role the entity plays
    with respect to another entity.  See Section 4.3.5.

Newton & Sanz Standards Track [Page 9] RFC 3981 IRIS-Core January 2005

 o  <seeAlso> -- Indicates a reference to an entity that has indirect
    association with a parent element representing an entity.  This
    element is derived from the <entity> element (Section 4.3.5).
    Registry schemas MAY derive from this element or MAY use it
    directly.

4.3.2. Registry Type Identifier Requirements

 The identifier for a registry type and the XML namespace identifier
 used by the XML Schema describing the registry MUST be the same.
 These identifiers MUST be restricted to a URN [7] registered in the
 'ns' class of the IANA registry governed by XML_URN [9].  These
 identifiers are case insensitive.
 This is a restriction on XML_NS [3], which specifies that an XML
 namespace identifier is any valid URI [6].
 These identifiers MAY be abbreviated to the part following the class
 component and its separator of the URN.  For example, the full URN
 "urn:ietf:params:xml:ns:dreg1" may be abbreviated to "dreg1".
 In use with IRIS, this abbreviation MUST NOT be used inside of XML
 instances in which the XML Schema [4] specifies the use of a URI for
 schema identification or where XML_NS [3] specifies the use of a URI
 for XML namespace identification.

4.3.3. Entity Classes

 IRIS provides entity classes to help avoid collisions with entity
 names within any given registry type.  Their specification in queries
 also allows server implementations to narrow search or lookup scopes
 quickly to a single index.
 For instance, the entity name "192.0.2.0" might refer to separate
 entities in the "name-server" and "network" classes.  The entity
 "192.0.2.0" in the "name-server" class may refer to the name server
 host that is also multi-homed by address 192.0.2.255 and known in DNS
 as "ns.example.com", whereas the entity "192.0.2.0" in the "network"
 class may refer to the network 192.0.2/30.
 IRIS defines two default entity classes of "local" and "iris", which
 MUST NOT be redefined.  These entity classes MUST be valid in all
 registry types.
 The "local" class is reserved for entities defined locally by a
 server operator and does not denote any particular type of entity.  A
 lookup in this entity class MAY result in an entity reference or
 search continuation.  For example, "iris:dreg1//example.com/local/

Newton & Sanz Standards Track [Page 10] RFC 3981 IRIS-Core January 2005

 myhosts" may result in a search continuation yielding the nameservers
 for example.com.
 The "iris" class is reserved for entities specific to a particular
 service instance.  It MUST contain the following entity names (see
 Section 4.3.4):
 o  "id", which yields a result of <serviceIdentification> (see
    Section 4.3.7.1).
 o  "limits", which yields a result of <limits> (see Section 4.3.7.2).
    This entity class MAY contain other locally defined entities as
    well.
 The names of entity classes in a registry schema are of type token,
 as defined by XML_SD [4].  Their case sensitivity MUST be defined by
 the definition of the registry type.  In general, they SHOULD be case
 insensitive.

4.3.4. Names of Entities

 The names of entities in a registry schema are of type token, as
 defined by XML_SD [4].
 Names of entities SHOULD be unique within an instance of any
 particular entity class within a registry.  Two entities SHOULD NOT
 have the same name, but a single entity MAY be known by multiple
 names.  In situations where a single name may result in two entities,
 the registry schema SHOULD make allowances by defining result types
 that contain entity references to both entities (e.g., "example.com"
 can refer to both the domain example.com and the host example.com).
 However, this type of conflict SHOULD generally be avoided by the
 proper use of entity classes.
 The case sensitivity of entity names is dependent on the entity class
 in which they reside.  The definition of a registry type MUST specify
 the case sensitivity for entity names.  A registry type MAY define
 the entity names of differing entity classes as having different case
 sensitivity.

4.3.5. References to Entities

 The element <entity> allows references to entities in result sets,
 either as a direct child of <resultSet> or within a more complex
 structure deriving from <result>.  The <entity> element is defined by
 'entityType'.  Registry schemas SHOULD define elements derived from
 <entity> when referencing entities but may use the <entity> element
 directly.  Deriving a new element allows a registry schema to use the

Newton & Sanz Standards Track [Page 11] RFC 3981 IRIS-Core January 2005

 name of the new element to signify the relationship the referenced
 entity has with the referrer.  A derivative of <entity> MUST NOT be
 used as a substitute when the <entity> element is declared (such as
 in the <answer> section of the <resultSet>).
 The <entity> element (and elements of type 'entityType') can have
 child elements of <displayName> with an optional 'language'
 attribute.  These are provided so that servers may provide clients
 with a more human-friendly description of the entity reference.  This
 is often useful to users navigating referral structures.
 The <entity> element (and its derivations) have the following
 attributes:
 o  'authority', 'resolution' (optional), 'registryType',
    'entityClass', and 'entityName' -- These attributes specify where
    the entity may be found.
 o  'temporaryReference' -- This attribute is optional.  See Section
    4.3.6.
 o  'referentType' -- This attribute contains the expected type of the
    entity being referenced and may contain the word "ANY" or a
    qualified XML name.  Unlike the other attributes of <entity>, this
    attribute is qualified and declared in the IRIS XML namespace.
    Therefore it will also be qualified with the prefix associated
    with the IRIS XML namespace (e.g., 'iris:referentType').  This
    allows clients to recognize entity references using an element
    derived from <entity>.
 o  'bagRef' -- This attribute is optional.  If present, it must
    contain an XML identifier to a <bag> element in the <bags> section
    of the result set.  For a description of the 'bagRef' attribute,
    see Section 4.4.

4.3.6. Temporary Entities

 Instances may exist in which an entity reference needs to be
 temporary.  For example, a particular type of result may only have
 one unique key.  If that key contains semantic meaning that may not
 be exposed to all users, a synthetic key will have to be substituted.
 Furthermore, there may be times when data in the data store is not
 normalized in the same manner as that expressed by the registry
 schema.  In the registry schema, objects of type A may reference
 objects of type B.  But in the data store, objects of type A may
 contain objects of type B.  Again, a synthetic key will have to be
 temporarily produced.

Newton & Sanz Standards Track [Page 12] RFC 3981 IRIS-Core January 2005

 To support such use cases, results and entity references can be
 declared temporary by using the 'temporaryReference' attribute.  This
 attribute is of type boolean [4] and has a default value of "false".
 It is optional for <result> derivatives and elements of type
 'entityType'.
 When this attribute is used, the entity reference data (e.g.,
 'entityClass', 'entityName') is only valid within the response in
 which it appears and may not be consistent with subsequent responses.
 A server MUST include the referent of any temporary entity reference
 in the <additional> section of the same <resultSet>

4.3.7. <result> Derived Elements

 The base IRIS framework contains three elements directly derived from
 the <result> element for use by any registry type.

4.3.7.1. <serviceIdentification>

 An example of a <serviceIdentification> result:
 <serviceIdentification
   authority="example.com" registryType="dreg1"
   entityClass="iris"
   entityName="id" >
   <authorities>
     <authority> example.com </authority>
     <authority> example.net </authority>
     <authority> example.org </authority>
   </authorities>
   <operatorName>
     Internet Assigned Numbers Authority
   </operatorName>
   <eMail>
     iana@iana.org
   </eMail>
 </serviceIdentification>
 The <serviceIdentification> element is provided to allow IRIS clients
 to reference IRIS service instances.  It contains the following
 elements:
 o  <authorities> -- This element contains one or more <authority>
    elements.  Each <authority> element contains a URI authority
    component for which the server has results.  Although a server MAY
    only return a partial list of its authority areas, depending on
    operator policy, it MUST return the authority for which the client
    has requested.

Newton & Sanz Standards Track [Page 13] RFC 3981 IRIS-Core January 2005

 o  <operatorName> -- This element contains the name of the operator
    of the server.
 o  <eMail> -- These optional elements contain email addresses of the
    operator of the service instance.
 o  <phone> -- These optional elements contain phone numbers of the
    operator of the service instance.
 o  <seeAlso> -- See Section 4.3.1 for its definition.

4.3.7.2. <limits>

 An example of a <limits> result:
 <limits
   authority="example.com" registryType="dreg1"
   entityClass="iris" entityName="limits">
   <totalQueries>
     <perHour>2</perHour>
     <perDay>15</perDay>
   </totalQueries>
   <totalResults>
     <perHour>25</perHour>
     <perDay>200</perDay>
   </totalResults>
   <totalSessions>
     <perHour>2</perHour>
     <perDay>15</perDay>
   </totalSessions>
 </limits>
 The <limits> element provides a mechanism allowing a server to inform
 a client of the limits it may encounter from overuse of the service.
 The contents describe the service limitations to a client at the
 current level of access.  The contents of this element are as
 follows:
 o  <totalQueries> -- This element describes the total number of
    queries that the server will accept.  The children of this element
    indicate this number per unit of time.  The children are
    <perSecond>, <perMinute>, <perHour>, and <perDay>.  Each child
    MUST only appear once as a child of <totalQueries>, but more than
    one child MAY be present.  For example, a server could indicate
    that it will accept 15 queries a minute but only 60 queries a day.

Newton & Sanz Standards Track [Page 14] RFC 3981 IRIS-Core January 2005

 o  <totalResults> -- This element describes the total number of
    results that the server will send to a client.  The children of
    this element indicate this number per unit of time in the same
    manner as <totalQueries>.
 o  <totalSessions> -- This element describes the total number of
    sessions that the server will accept from a client.  The children
    of this element indicate this number per unit of time in the same
    manner as <totalQueries>.  The definition of a session is defined
    the by application transport layer.
 o  <otherRestrictions> -- This element describes other restrictions
    that may only be expressible outside of the structured syntax of
    the other child elements of <limits>.  This element may have
    optional <description> child elements, each with a mandatory
    'language' attribute.
 o  <seeAlso> -- These elements are provided to reference other
    entities, such as a <simpleEntity> (Section 4.3.7.3) describing a
    published policy.  See <seeAlso> (Section 4.3.1).
 All of these child elements are optional, and a server may express
 that it has no limits by using a <limits> element with no content
 (e.g., <limits authority=...  />).

4.3.7.3. <simpleEntity>

 An example of a <simpleEntity> result:
 <simpleEntity
   authority="example.com" registryType="dreg1"
   entityClass="local"
   entityName="notice" >
   <property name="legal" language="en">
     Example.com is reserved according to RFC 2606.
   </property>
 </simpleEntity>
 The <simpleEntity> element is provided so that service operators may
 make simple additions to other entities without deriving entirely new
 registry types.  Its definition allows service operators to reference
 it from other entities (using, for instance, a <seeAlso> element).
 The <simpleEntity> is meant to represent name and value pairs of
 strings, allowing each pair to be associated with a specific language
 qualifier and an optional URI pointing to more information.

Newton & Sanz Standards Track [Page 15] RFC 3981 IRIS-Core January 2005

 Clients may easily display such information in a two-column table.
 Applications using binary data or richer data structures are out of
 scope for this element.  When such usage scenarios arise, a client
 will likely need specific knowledge to handle such data, thus calling
 the need for a new registry type into question.

4.3.8. <control> and <reaction> Elements

 The <control> (Section 4.1) and <reaction> (Section 4.2) elements
 allow the client to request from the server special states for the
 processing of queries.  The intent of these elements is to allow
 extensibility so that some jurisdictions may adopt policies for query
 processing without requiring re-versioning of IRIS or any registry
 type.
 This document defines one control, <onlyCheckPermissions>, and its
 requisite reaction, <standardReaction>, for compliance with CRISP
 [17].
 When a client sends an <onlyCheckPermissions> control, it is only
 asking the server to check to see whether adequate permissions are
 available to execute the queries in the associated request.  A server
 MUST respond to this control with a <standardReaction> element.
 The <standardReaction> element provides a server with a standard
 means to respond to controls (it may be used by other controls, but
 this is left to their definition).  It contains four children:
 o  <controlAccepted> -- the processing or state needed by the control
    has been accepted.
 o  <controlDenied> -- the processing or state needed by the control
    has been denied (a transient failure).
 o  <controlDisabled> -- the processing or state needed by the control
    cannot be activated (a permanent failure).
 o  <controlUnrecognized> -- the control is not recognized (a
    permanent failure).
 If <onlyCheckPermissions> is rejected, then the server MUST return
 all appropriate result sets (i.e., for every search set in the
 request), but all result sets MUST be empty of results and MUST
 contain no errors (a reaction is not part of a result set and is
 therefore not a result set error).  This control applies to all
 search sets or none of them; therefore a server MUST issue a
 rejection if <onlyCheckPermissions> cannot be accepted for all search
 sets in a request.

Newton & Sanz Standards Track [Page 16] RFC 3981 IRIS-Core January 2005

 An example of an IRIS XML exchange using these elements follows:
 C: <?xml version="1.0"?>
 C: <request xmlns="urn:ietf:params:xml:ns:iris1"
 C:   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" >
 C:
 C:   <control>
 C:     <onlyCheckPermissions />
 C:   </control>
 C:
 C:   <searchSet>
 C:
 C:     <lookupEntity
 C:       registryType="dreg1"
 C:       entityClass="local"
 C:       entityName="AUP" />
 C:
 C:   </searchSet>
 C:
 C: </request>
 S: <?xml version="1.0"?>
 S: <response xmlns="urn:ietf:params:xml:ns:iris1"
 S:           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" >
 S:
 S:   <reaction>
 S:     <standardReaction>
 S:       <controlAccepted />
 S:     </standardReaction>
 S:   </reaction>
 S:
 S:   <resultSet>
 S:     <answer>
 S:
 S:       <simpleEntity
 S:         authority="example.com" registryType="dreg1"
 S:         entityClass="local" entityName="AUP" >
 S:         <property name="legal" language="en">
 S:           It is illegal to use information from this service
 S:           for the purposes of sending unsolicited bulk email.
 S:         </property>
 S:       </simpleEntity>
 S:
 S:     </answer>
 S:   </resultSet>
 S:
 S: </response>

Newton & Sanz Standards Track [Page 17] RFC 3981 IRIS-Core January 2005

4.4. Relay Bags

 IRIS employs bags to allow a server to relay information to a
 referent server via the client.  These bags are generated by the
 queried server, passed to the client as opaque data, and then passed
 to the referent server for processing.  The contents of the bags are
 not defined by IRIS, and the client MUST NOT make any assumptions
 about the contents of a bag when relaying it from one server to
 another.
 When a server returns a result set to a client, the <response>
 element may contain a <bags> child element.  This child element
 contains one or more <bag> elements.  Each of these MUST contain an
 'id' attribute containing the XML data type ID.  Entity references
 and search continuations that have to specify a bag to be used when
 they are followed MUST have a 'bagRef' attribute containing the XML
 data type IDREF.  See Section 4.2.  This allows the response to
 specify a bag only once but allows each entity reference or search
 continuation (in all result sets) to have a distinct bag, as needed.
 When following an entity reference or search continuation that
 specifies the use of a bag, the client MUST include the referenced
 bag in the search set as a child of the <searchSet> element.  See
 Section 4.1.
 See Section 4.2 for the list of errors a server may return to a
 client when a bag is received.  A server MUST NOT ignore a bag when
 it is received.  In case a bag cannot be recognized or accepted, one
 of the errors from Section 4.2 MUST be returned.
 An example of an IRIS XML exchange using these elements follows:
 C: <?xml version="1.0"?>
 C: <request xmlns="urn:ietf:params:xml:ns:iris1"
 C:   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" >
 C:
 C:   <searchSet>
 C:
 C:     <bag>
 C:       <simpleBag xmlns="http://example.com/">
 C:         XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
 C:       </simpleBag>
 C:     </bag>
 C:
 C:     <lookupEntity
 C:       registryType="dreg1"
 C:       entityClass="local"
 C:       entityName="AUP" />

Newton & Sanz Standards Track [Page 18] RFC 3981 IRIS-Core January 2005

 C:
 C:   </searchSet>
 C:
 C: </request>
 S: <?xml version="1.0"?>
 S: <response xmlns="urn:ietf:params:xml:ns:iris1"
 S:           xmlns:iris="urn:ietf:params:xml:ns:iris1"
 S:           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" >
 S:
 S:   <resultSet>
 S:     <answer>
 S:
 S:       <entity authority="example.com" bagRef="x1"
 S:         registryType="dreg1"
 S:         entityClass="local" entityName="AUP"
 S:         iris:referentType="ANY" >
 S:         <displayName language="en">
 S:           Acceptable Usage Policy
 S:         </displayName>
 S:       </entity>
 S:
 S:     </answer>
 S:   </resultSet>
 S:
 S:   <bags>
 S:
 S:     <bag id="x1">
 S:       <simpleBag xmlns="http://example.com/">
 S:         AAAAB3NzaC1yc2EAAAABIwAAAIEA0ddD+W3Agl0Lel98G1r77fZ
 S:       </simpleBag>
 S:     </bag>
 S:
 S:   </bags>
 S: </response>

5. Database Serialization

 This section describes a method for serializing IRIS registry
 entities.  The descriptions contained within this section refer to
 XML elements and attributes and their relation to this serialization
 process.  These descriptions also contain specifications outside the
 scope of the formal XML syntax.  This section will use terms defined
 by RFC 2119 [8] to describe these.  While reading this section,
 please reference Section 6 for needed details on the formal XML
 syntax.

Newton & Sanz Standards Track [Page 19] RFC 3981 IRIS-Core January 2005

 A database of IRIS entities can be serialized to file storage with
 XML [2] by using the IRIS defined <serialization> element.  This
 element contains <result> element derivatives and
 <serializedReferral> elements.
 Derivatives of the <result> element are entities.  Servers loading
 these entities MUST place the entity in the entity classes specified
 by the elements 'registryType', 'entityClass', and 'entityName'
 attributes and in any entity classes the entities may apply according
 to explicitly defined children of that element.  For instance, if a
 registry type has two entity classes "foo" and "bar" and a <result>
 derivative has the attributes entityClass="foo" and entityName="one"
 and a child element <bar>two</bar>, the server is to enter that
 entity into the entity class "foo" as the name "one" and into the
 entity class "bar" as the name "two".
 Servers loading entities as serialized derivatives of the <result>
 element MAY translate the authority attribute.  Servers will likely
 have to do this if the authority for the entity has changed.
 <serializedReferral> elements allow the serialization of explicit
 entity references and search continuations.  This element has a child
 <source> element containing the 'authority', 'resolution' (optional),
 'registryType', 'entityClass', and 'entityName' attributes.  The
 attributes of this element are used to signify the entity that can be
 referenced to yield this referral.
 As mentioned above, there may be times when a server needs to
 translate the authority attribute of a loaded entity.
 Implementations must also beware of this need for referrals.  During
 deserialization, servers MUST change the authority attribute of a
 referral (either <entity> or elements derived from <entity> or
 <source> child of <serializedReferral>) to contain a valid authority
 of the server if the serialized attribute is empty.  During
 serialization, servers and their related processes MUST leave the
 authority attribute empty for referrals in which the referent is an
 entity for which the server answers queries.
 The following is an example of serialized IRIS:
 <iris:serialization
   xmlns:iris="urn:ietf:params:xml:ns:iris1"
   xmlns="urn:ietf:params:xml:ns:iris1"
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">

Newton & Sanz Standards Track [Page 20] RFC 3981 IRIS-Core January 2005

   <serviceIdentification
     authority="iana.org" registryType="dreg1"
     entityClass="iris"
     entityName="id" >
     <authorities>
       <authority> iana.org </authority>
     </authorities>
     <operatorName>
       Internet Assigned Numbers Authority
     </operatorName>
     <eMail>
       dbarton@iana.org
     </eMail>
     <seeAlso
       iris:referentType="iris:simpleEntity"
       authority="iana.org" registryType="dreg1"
       entityClass="local"
       entityName="notice">
       <displayName language="en">
         Legal Notice
       </displayName>
     </seeAlso>
   </serviceIdentification>
   <serializedReferral>
     <source
       authority="example.com" registryType="dreg1"
       entityClass="iris"
       entityName="id"/>
     <entity
       iris:referentType="iris:serviceIdentification"
       authority="iana.org" registryType="dreg1"
       entityClass="iris" entityName="id"/>
   </serializedReferral>
   <simpleEntity
     authority="iana.org" registryType="dreg1"
     entityClass="local"
     entityName="notice" >
     <property name="legal" language="en">
       Please use the net wisely!
     </property>
   </simpleEntity>
 </iris:serialization>

Newton & Sanz Standards Track [Page 21] RFC 3981 IRIS-Core January 2005

6. Formal XML Syntax

 IRIS is specified in XML Schema notation.  The formal syntax
 presented here is a complete schema representation of IRIS suitable
 for automated validation of IRIS XML instances.
 <?xml version="1.0"?>
 <schema xmlns="http://www.w3.org/2001/XMLSchema"
         xmlns:iris="urn:ietf:params:xml:ns:iris1"
         targetNamespace="urn:ietf:params:xml:ns:iris1"
         elementFormDefault="qualified" >
   <annotation>
     <documentation>
       Internet Registry Information Service (IRIS) Schema v1
     </documentation>
   </annotation>
   <!-- ========================================= -->
   <!--                                           -->
   <!-- The Transactions                          -->
   <!--                                           -->
   <!-- ========================================= -->
   <element name="request">
     <complexType>
       <sequence>
         <element
           name="control"
           type="iris:controlType"
           minOccurs="0"
           maxOccurs="1" />
         <element
           name="searchSet"
           type="iris:searchSetType"
           minOccurs="1"
           maxOccurs="unbounded" />
       </sequence>
     </complexType>
   </element>
   <element name="response">
     <complexType>
       <sequence>
         <element
           name="reaction"
           type="iris:reactionType"
           minOccurs="0"

Newton & Sanz Standards Track [Page 22] RFC 3981 IRIS-Core January 2005

           maxOccurs="1" />
         <element
           name="resultSet"
           type="iris:resultSetType"
           minOccurs="1"
           maxOccurs="unbounded" />
         <element
           name="bags"
           type="iris:bagsType"
           minOccurs="0"
           maxOccurs="1" />
       </sequence>
     </complexType>
   </element>
   <!-- ========================================= -->
   <!--                                           -->
   <!-- Search Sets and Result Sets               -->
   <!--                                           -->
   <!-- ========================================= -->
   <complexType
     name="searchSetType" >
     <sequence>
       <element
         name="bag"
         type="iris:bagType"
         minOccurs="0"
         maxOccurs="1" />
       <choice>
         <element
           name="lookupEntity"
           type="iris:lookupEntityType" />
         <element
           ref="iris:query" />
       </choice>
     </sequence>
   </complexType>
   <complexType
     name="resultSetType" >
     <sequence>
       <element
         name="answer"
         minOccurs="1"
         maxOccurs="1">
         <complexType>
           <sequence>

Newton & Sanz Standards Track [Page 23] RFC 3981 IRIS-Core January 2005

             <element
               ref="iris:result"
               minOccurs="0"
               maxOccurs="unbounded" />
             <element
               ref="iris:entity"
               minOccurs="0"
               maxOccurs="unbounded" />
             <element
               ref="iris:searchContinuation"
               minOccurs="0"
               maxOccurs="unbounded" />
           </sequence>
         </complexType>
       </element>
       <element
         name="additional"
         minOccurs="0"
         maxOccurs="1">
         <complexType>
           <sequence>
             <element
               ref="iris:result"
               minOccurs="1"
               maxOccurs="unbounded" />
           </sequence>
         </complexType>
       </element>
       <choice
         minOccurs="0"
         maxOccurs="1" >
         <element
           name="insufficientResources"
           type="iris:codeType" />
         <element
           name="invalidName"
           type="iris:codeType" />
         <element
           name="invalidSearch"
           type="iris:codeType" />
         <element
           name="queryNotSupported"
           type="iris:codeType" />
         <element
           name="limitExceeded"
           type="iris:codeType" />
         <element
           name="nameNotFound"

Newton & Sanz Standards Track [Page 24] RFC 3981 IRIS-Core January 2005

           type="iris:codeType" />
         <element
           name="permissionDenied"
           type="iris:codeType" />
         <element
           name="bagUnrecognized"
           type="iris:codeType" />
         <element
           name="bagUnacceptable"
           type="iris:codeType" />
         <element
           name="bagRefused"
           type="iris:codeType" />
         <element
           ref="iris:genericCode"/>
       </choice>
     </sequence>
   </complexType>
   <!-- ========================================= -->
   <!--                                           -->
   <!-- Controls and Reactions                    -->
   <!--                                           -->
   <!-- ========================================= -->
   <complexType
     name="controlType">
     <sequence>
       <any
         namespace="##any"
         processContents="skip"
         minOccurs="1"
         maxOccurs="1" />
     </sequence>
   </complexType>
   <complexType
     name="reactionType">
     <sequence>
       <any
         namespace="##any"
         processContents="skip"
         minOccurs="1"
         maxOccurs="1" />
     </sequence>
   </complexType>
   <!-- ========================================= -->

Newton & Sanz Standards Track [Page 25] RFC 3981 IRIS-Core January 2005

   <!--                                           -->
   <!-- Queries and Lookups                       -->
   <!--                                           -->
   <!-- ========================================= -->
   <complexType
     name="queryType" />
   <element
     name="query"
     type="iris:queryType"
     abstract="true" />
   <complexType
     name="lookupEntityType" >
     <attribute
       name="registryType"
       type="anyURI"
       use="required" />
     <attribute
       name="entityClass"
       type="token"
       use="required" />
     <attribute
       name="entityName"
       type="token"
       use="required" />
   </complexType>
   <!-- ========================================= -->
   <!--                                           -->
   <!-- Results                                   -->
   <!--                                           -->
   <!-- ========================================= -->
   <complexType
     name="resultType">
     <attribute
       name="authority"
       use="required"
       type="token" />
     <attribute
       name="resolution"
       type="token" />
     <attribute
       name="registryType"
       use="required"
       type="anyURI" />

Newton & Sanz Standards Track [Page 26] RFC 3981 IRIS-Core January 2005

     <attribute
       name="entityClass"
       use="required"
       type="token" />
     <attribute
       name="entityName"
       use="required"
       type="token" />
     <attribute
       name="temporaryReference"
       default="false"
       type="boolean" />
   </complexType>
   <element
     name="result"
     type="iris:resultType"
     abstract="true" />
   <!-- ========================================= -->
   <!--                                           -->
   <!-- Errors                                    -->
   <!--                                           -->
   <!-- ========================================= -->
   <complexType
     name="codeType">
     <sequence
       minOccurs="0"
       maxOccurs="unbounded">
       <element
         name="explanation">
         <complexType>
           <simpleContent>
             <extension
               base="string">
               <attribute
                 use="required"
                 name="language"
                 type="language" />
             </extension>
           </simpleContent>
         </complexType>
       </element>
     </sequence>
   </complexType>
   <element
     name="genericCode"

Newton & Sanz Standards Track [Page 27] RFC 3981 IRIS-Core January 2005

     type="iris:codeType"
     abstract="true" />
   <!-- ========================================= -->
   <!--                                           -->
   <!-- Entity References and                     -->
   <!-- Search Continuations                      -->
   <!--                                           -->
   <!-- ========================================= -->
   <complexType
     name="entityType">
     <sequence>
       <element
         name="displayName"
         minOccurs="0"
         maxOccurs="unbounded">
         <complexType>
           <simpleContent>
             <extension
               base="string">
               <attribute
                 name="language"
                 use="required"
                 type="language" />
             </extension>
           </simpleContent>
         </complexType>
       </element>
     </sequence>
     <attribute
       name="authority"
       use="required"
       type="token" />
     <attribute
       name="resolution"
       type="token" />
     <attribute
       name="registryType"
       use="required"
       type="anyURI" />
     <attribute
       name="entityClass"
       use="required"
       type="token" />
     <attribute
       name="entityName"
       use="required"

Newton & Sanz Standards Track [Page 28] RFC 3981 IRIS-Core January 2005

       type="token" />
     <attribute
       name="referentType"
       use="required"
       form="qualified"
       type="iris:referentTypeType" />
     <attribute
       name="temporaryReference"
       default="false"
       type="boolean" />
     <attribute
       name="bagRef"
       type="IDREF" />
   </complexType>
   <element
     name="entity"
     type="iris:entityType" />
   <simpleType
     name="referentTypeType">
     <union
       memberTypes="QName iris:anyLiteralType" />
   </simpleType>
   <simpleType
     name="anyLiteralType">
     <restriction
       base="string">
       <enumeration
         value="ANY" />
     </restriction>
   </simpleType>
   <complexType
     name="searchContinuationType">
     <sequence>
       <element ref="iris:query" />
     </sequence>
     <attribute
       name="bagRef"
       type="IDREF" />
     <attribute
       name="authority"
       type="token"
       use="required" />
     <attribute
       name="resolution"

Newton & Sanz Standards Track [Page 29] RFC 3981 IRIS-Core January 2005

       type="token" />
   </complexType>
   <element
     name="searchContinuation"
     type="iris:searchContinuationType" />
   <!-- ========================================= -->
   <!--                                           -->
   <!-- Bags                                      -->
   <!--                                           -->
   <!-- ========================================= -->
   <complexType
     name="bagsType">
     <sequence>
       <element
         name="bag"
         minOccurs="1"
         maxOccurs="unbounded">
         <complexType>
           <complexContent>
             <extension
               base="iris:bagType">
               <attribute
                 use="required"
                 name="id"
                 type="ID" />
             </extension>
           </complexContent>
         </complexType>
       </element>
     </sequence>
   </complexType>
   <complexType
     name="bagType">
     <sequence>
       <any
         namespace="##any"
         processContents="skip"
         minOccurs="1"
         maxOccurs="1" />
     </sequence>
   </complexType>
   <!-- ========================================= -->
   <!--                                           -->
   <!-- Derived Results for use with all          -->

Newton & Sanz Standards Track [Page 30] RFC 3981 IRIS-Core January 2005

   <!-- registry types.                           -->
   <!--                                           -->
   <!-- ========================================= -->
   <!--                                           -->
   <!-- See Also                                  -->
   <!--                                           -->
   <element
     name="seeAlso"
     type="iris:entityType" />
   <!--                                           -->
   <!-- Service Identification                    -->
   <!--                                           -->
   <complexType
     name="serviceIdentificationType">
     <complexContent>
       <extension
         base="iris:resultType">
         <sequence>
           <element
             name="authorities"
             minOccurs="1"
             maxOccurs="1">
             <complexType>
               <sequence>
                 <element
                   name="authority"
                   type="token"
                   minOccurs="1"
                   maxOccurs="unbounded" />
               </sequence>
             </complexType>
           </element>
           <element
             name="operatorName"
             type="string"
             minOccurs="0"
             maxOccurs="1" />
           <element
             name="eMail"
             type="string"
             minOccurs="0"
             maxOccurs="unbounded" />
           <element
             name="phone"

Newton & Sanz Standards Track [Page 31] RFC 3981 IRIS-Core January 2005

             type="string"
             minOccurs="0"
             maxOccurs="unbounded" />
           <element
             ref="iris:seeAlso"
             minOccurs="0"
             maxOccurs="unbounded" />
         </sequence>
       </extension>
     </complexContent>
   </complexType>
   <element
     name="serviceIdentification"
     type="iris:serviceIdentificationType"
     substitutionGroup="iris:result" />
   <!--                                           -->
   <!-- Limits                                    -->
   <!--                                           -->
   <complexType
     name="limitsType">
     <complexContent>
       <extension
         base="iris:resultType">
         <sequence>
           <element
             name="totalQueries"
             minOccurs="0"
             maxOccurs="1" >
             <complexType>
               <group
                 ref="iris:timeLimitsGroup"
                 minOccurs="1"
                 maxOccurs="4" />
             </complexType>
           </element>
           <element
             name="totalResults"
             minOccurs="0"
             maxOccurs="1" >
             <complexType>
               <group
                 ref="iris:timeLimitsGroup"
                 minOccurs="1"
                 maxOccurs="4" />
             </complexType>

Newton & Sanz Standards Track [Page 32] RFC 3981 IRIS-Core January 2005

           </element>
           <element
             name="totalSessions"
             minOccurs="0"
             maxOccurs="1" >
             <complexType>
               <group
                 ref="iris:timeLimitsGroup"
                 minOccurs="1"
                 maxOccurs="4" />
             </complexType>
           </element>
           <element
             name="otherRestrictions"
             minOccurs="0"
             maxOccurs="1">
             <complexType>
               <sequence>
                 <element
                   name="description"
                   minOccurs="0"
                   maxOccurs="unbounded">
                   <complexType>
                     <simpleContent>
                       <extension
                         base="string">
                         <attribute
                           name="language"
                           type="language"
                           use="required" />
                       </extension>
                     </simpleContent>
                   </complexType>
                 </element>
               </sequence>
             </complexType>
           </element>
           <element
             ref="iris:seeAlso"
             minOccurs="0"
             maxOccurs="unbounded" />
         </sequence>
       </extension>
     </complexContent>
   </complexType>
   <element
     name="limits"
     type="iris:limitsType"

Newton & Sanz Standards Track [Page 33] RFC 3981 IRIS-Core January 2005

     substitutionGroup="iris:result" />
   <group
     name="timeLimitsGroup">
     <choice>
       <element
         name="perSecond"
         type="nonNegativeInteger" />
       <element
         name="perMinute"
         type="nonNegativeInteger" />
       <element
         name="perHour"
         type="nonNegativeInteger" />
       <element
         name="perDay"
         type="nonNegativeInteger" />
     </choice>
   </group>
   <!--                                           -->
   <!-- Simple Entity                             -->
   <!--                                           -->
   <complexType
     name="simpleEntityType">
     <complexContent>
       <extension
         base="iris:resultType">
         <sequence>
           <element
             name="property"
             minOccurs="1"
             maxOccurs="unbounded">
             <complexType>
               <simpleContent>
                 <extension
                   base="string">
                   <attribute
                     name="name"
                     type="string"
                     use="required" />
                   <attribute
                     name="language"
                     type="language"
                     use="required" />
                   <attribute
                     name="uri"

Newton & Sanz Standards Track [Page 34] RFC 3981 IRIS-Core January 2005

                     type="anyURI" />
                 </extension>
               </simpleContent>
             </complexType>
           </element>
         </sequence>
       </extension>
     </complexContent>
   </complexType>
   <element
     name="simpleEntity"
     type="iris:simpleEntityType"
     substitutionGroup="iris:result" />
   <!-- ========================================= -->
   <!--                                           -->
   <!-- Derived Controls and Reactions            -->
   <!--                                           -->
   <!-- ========================================= -->
   <!--                                           -->
   <!-- Only Check Permissions                    -->
   <!--                                           -->
   <element
     name="onlyCheckPermissions" >
     <complexType />
   </element>
   <!--                                           -->
   <!-- Standard Reaction                         -->
   <!--                                           -->
   <element
     name="standardReaction" >
     <complexType>
       <choice>
         <element
           name="controlAccepted">
           <complexType/>
         </element>
         <element
           name="controlDenied">
           <complexType/>
         </element>
         <element
           name="controlDisabled">

Newton & Sanz Standards Track [Page 35] RFC 3981 IRIS-Core January 2005

           <complexType/>
         </element>
         <element
           name="controlUnrecognized">
           <complexType/>
         </element>
       </choice>
     </complexType>
   </element>
   <!-- ========================================= -->
   <!--                                           -->
   <!-- Serialization                             -->
   <!--                                           -->
   <!-- ========================================= -->
   <complexType
     name="serializedReferralType">
     <sequence>
       <element name="source">
         <complexType>
           <attribute
             name="authority"
             use="required"
             type="token" />
           <attribute
             name="resolution"
             type="token" />
           <attribute
             name="registryType"
             type="anyURI"
             use="required" />
           <attribute
             name="entityClass"
             type="token"
             use="required" />
           <attribute
             name="entityName"
             type="token"
             use="required" />
         </complexType>
       </element>
       <choice>
         <element
           ref="iris:searchContinuation" />
         <element
           ref="iris:entity" />
       </choice>

Newton & Sanz Standards Track [Page 36] RFC 3981 IRIS-Core January 2005

     </sequence>
   </complexType>
   <element
     name="serialization">
     <complexType>
       <choice
         minOccurs="1"
         maxOccurs="unbounded">
         <element
           ref="iris:result" />
         <element
           name="serializedReferral"
           type="iris:serializedReferralType" />
       </choice>
     </complexType>
   </element>
 </schema>
                              Figure 8

7. The IRIS URI

 The IRIS URI has a very rigid structure.  All IRIS URIs have the same
 fields and look similar to users.
 But the IRIS URIs are flexible because they allow different methods
 to be employed to find servers and allow the use of multiple
 transports (with BEEP being the default).

7.1. URI Definition

 An IRIS URI [6] has the following general syntax.
 iris:<registry>/<resolution>/<authority>/<class>/<name>
 The full ABNF [11] follows, with certain values included from RFC
 2396 [6] and RFC 2732 [15].
    iris-uri           = scheme ":" registry-urn "/"
                         [ resolution-method ] "/" authority
                         [ "/" entity-class "/" entity-name ]
    scheme             = "iris"
    authority          = // as specified by RFC2396
    registry-urn       = // as specified by IRIS
    resolution-method  = *(unreserved | escaped)
    entity-class       = *(unreserved | escaped)

Newton & Sanz Standards Track [Page 37] RFC 3981 IRIS-Core January 2005

    entity-name        = *(unreserved | escaped)
    unreserved         = // as specified by RFC2396
    escaped            = // as specified by RFC2396
 An IRIS URI MUST NOT be a relative URI.  The resolution method,
 entity class, and entity name MUST be of the UTF-8 [12] character set
 encoded with "application/x-www-form-urlencoded", as specified by
 URL_ENC [14].
 When the entity-class and entity-name components are not specified,
 the defaults "iris" and "id" MUST be implied.  For example,
 "iris:dreg1//com" is interpreted as "iris:dreg1//com/iris/id".
 When the resolution-method is not specified, the default is the
 direct resolution method described in Section 7.3.2.

7.2. Transport Specific Schemes

 The "iris" scheme name is not application transport specific.  The
 URI resolution process MAY determine the application transport.  An
 example of such a process is direct resolution (Section 7.3.2), which
 uses the steps outlined in Section 7.3.3 to determine the application
 transport.
 A mapping between an application transport and IRIS MAY define a
 scheme name signifying its use with the semantics of the IRIS URI.
 The rules for determining which application transport to use are as
 follows:
 o  If an application transport specific scheme name is present, the
    application transport it signifies SHOULD be used if possible.
 o  If a client has a preferred transport and the resolution process
    allows for its use, the client MAY use that application transport.
 o  Otherwise, the default application transport specified by IRIS-
    BEEP [1] MUST be used.

7.3. URI Resolution

7.3.1. Registry Dependent Resolution

 Interpretation and resolution of the authority component of an IRIS
 URI may be altered with the specification of a resolution-method in
 the URI.  If no resolution-method component is specified in the URI,
 the default is the direct resolution method (see Section 7.3.2).

Newton & Sanz Standards Track [Page 38] RFC 3981 IRIS-Core January 2005

 Alternate resolution methods MAY be specified by registry types.  The
 identifiers for these methods MUST conform to the ABNF in Section
 7.1.

7.3.2. Direct Resolution

 In the direct resolution process, the authority component of an IRIS
 URI may only contain a domain name, a domain name accompanied by a
 port number, an IP address, or an IP address accompanied by a port
 number.  The authority component of the scheme indicates the server
 or set of servers authoritatively responsible for a domain according
 to records in DNS (Section 7.3.3) if a domain is specified.  If an IP
 address is specified, it indicates the specific server to be queried.
 The rules for resolution are as follows:
 o  If the authority component is a domain name accompanied by a port
    number as specified by RFC 2396, the domain name is converted to
    an IP address via an A or AAAA record to the DNS.
 o  If the authority component is a domain name by itself, the
    service/transport location (Section 7.3.3) process is used.  If
    this process produces no results, then the DNS is queried for the
    A or AAAA RRs corresponding to the domain name, and the port
    number used is the well-known port of the transport used according
    to Section 7.2.
 o  If the authority component is an IP address, then the DNS is not
    queried, and the IP address is used directly.  If the port number
    is present, it is used directly; otherwise, the port number used
    is the well-known port of the transport used according to Section
    7.2.
 The use of an IPv6 address in the authority component MUST conform to
 RFC 2732 [15].

7.3.3. Transport and Service Location

 The direct resolution method (Section 7.3.2) uses the profiled use of
 the NAPTR and SRV resource records defined in S-NAPTR [10] to
 determine both the location of a set of servers for a given service
 and the set of possible transports that may be used.  It is
 RECOMMENDED that any resolution method not making explicit use of the
 direct resolution process should use S-NAPTR [10] in whatever process
 it does define.

Newton & Sanz Standards Track [Page 39] RFC 3981 IRIS-Core January 2005

 S-NAPTR [10] requires an application service label.  The direct
 resolution method (Section 7.3.2) uses the abbreviated form of the
 registry URN as the application service label.  Other resolution
 methods MAY specify other application service labels.
 See Appendix A for sample uses of S-NAPTR.

7.4. IRIS URI Examples

 Here are some examples of IRIS URIs and their meaning:
 o  iris:dreg1//example.com/domain/example.com
    *  Finds a server authoritative for "example.com" according to the
       rules of direct resolution (Section 7.3.2).
    *  The server is asked for "example.com" in the "domain" index, or
       entity class, of the "dreg1" registry.
 o  iris:dreg1//example.com
    *  Finds a server authoritative for "example.com" according to the
       rules of direct resolution (Section 7.3.2).
    *  The server is asked for "id" in the "iris" index, or entity
       class, of the "dreg1" registry.
 o  iris:dreg1//com/domain/example.com
    *  Finds a server authoritative for "com" according to the rules
       of direct-resolution (Section 7.3.2).
    *  The server is asked for "example.com" in the "domain" index, or
       entity class, of the "dreg1" registry.
 o  iris:dreg1//192.0.2.1:44/domain/example.com
    *  Following the rules of direct-resolution (Section 7.3.2), the
       server at IP address 192.0.2.1 on port 44 is queried by using
       BEEP.
    *  The server is asked for "example.com" in the "domain" index, or
       entity class, of the "dreg1" registry.
 o  iris.lwz:dreg1//192.0.2.1:44/domain/example.com
    *  Following the rules of direct-resolution (Section 7.3.2), the
       server at IP address 192.0.2.1 on port 44 is queried by using a
       lightweight application transport.
    *  The server is asked for "example.com" in the "domain" index, or
       entity class, of the "dreg1" registry.

Newton & Sanz Standards Track [Page 40] RFC 3981 IRIS-Core January 2005

 o  iris.beep:dreg1//com/domain/example.com
    *  Finds a server authoritative for "com" according to the rules
       of direct-resolution (Section 7.3.2).
    *  Uses the BEEP application transport.
    *  The server is asked for "example.com" in the "domain" index, or
       entity class, of the "dreg1" registry.
 o  iris:dreg1/bottom/example.com/domain/example.com
    *  Finds a server authoritative for "example.com" according to the
       rules of the resolution method 'bottom' as defined by the
       registry type urn:ietf:params:xml:ns:dreg1.
    *  The application transport used is determined by the 'bottom'
       resolution method.
    *  The server is asked for "example.com" in the "domain" index, or
       entity class, of the "dreg1" registry.
 o  iris.beep:dreg1/bottom/example.com/domain/example.com
    *  Finds a server authoritative for "example.com" according to the
       rules of the resolution method 'bottom' as defined by the
       registry type urn:ietf:params:xml:ns:dreg1.
    *  Uses the BEEP application transport.
    *  The server is asked for "example.com" in the "domain" index, or
       entity class, of the "dreg1" registry.

8. Checklists

8.1. Registry Definition Checklist

 Specifications of registry types MUST include the following explicit
 definitions:
 o  Formal XML syntax deriving from the IRIS XML.
 o  An identifying registry URN.
 o  Any registry specific resolution methods.
 o  A registration of the abbreviated registry URN as an application
    service label for compliance with S-NAPTR [10].  Note that this is
    a different IANA registry than the registry type URN IANA
    registry.
 o  A list of well-known entity classes.
 o  A statement regarding the case sensitivity of the names in each
    entity class.

Newton & Sanz Standards Track [Page 41] RFC 3981 IRIS-Core January 2005

8.2. Transport Mapping Checklist

 Specifications of transport mappings MUST include the following
 explicit definitions:
 o  A URI scheme name specific to the transport.
 o  An application protocol label for compliance with S-NAPTR [10].
    See Section 7.3.3.  Note that although this is a different IANA
    registry than the URI scheme name IANA registry, it is RECOMMENDED
    that they be the same string of characters.
 o  The set of allowable character set encodings for the exchange of
    XML (see Section 9).
 o  The set of security mechanisms.

9. Internationalization Considerations

 IRIS is represented in XML.  XML processors are obliged to recognize
 both UTF-8 and UTF-16 [12] encodings.  XML provides for mechanisms to
 identify and use other character encodings by means of the "encoding"
 attribute in the <xml> declaration.  Absence of this attribute or a
 byte order mark (BOM) indicates a default of UTF-8 [13] encoding.
 Thus, for compatibility reasons and per RFC 2277 [16], use of UTF-8
 [13] is RECOMMENDED with IRIS.
 The complete list of character set encoding identifiers is maintained
 by IANA at [21].
 The application-transport layer MUST define a common set of character
 set encodings to be understood by both client and server.
 Localization of internationalized strings may require additional
 information from the client.  Entity definitions SHOULD use the
 "language" type defined by XML_SD [4] to aid clients in the
 localization process.  See Section 4.3.7.3 for an example.

Newton & Sanz Standards Track [Page 42] RFC 3981 IRIS-Core January 2005

10. IANA Considerations

 This document uses a proposed XML namespace and schema registry
 specified in XML_URN [9].  Accordingly, the following registration
 information is provided for the IANA:
 o  URN/URI:
    *  urn:ietf:params:xml:ns:iris1
 o  Contact:
    *  Andrew Newton <andy@hxr.us>
    *  Marcos Sanz <sanz@denic.de>
 o  XML:
    *  The XML Schema specified in Section 6

11. Security Considerations

 The IRIS XML layer provides no authentication or privacy facilities
 of its own.  It relies on the application-transport layer for all of
 these abilities.  Application-transports should explicitly define
 their security mechanisms (see Section 8.2).
 Referral IRIS registry results may contain entity lookups and search
 continuations that result in a client query operation against another
 registry service.  Clients SHOULD NOT use authentication credentials
 and mechanisms subject to replay attacks to conduct subsequent entity
 lookups and search continuations.

12. References

12.1. Normative References

 [1]  Newton, A. and M. Sanz, "Using the Internet Registry Information
      Service (IRIS) over the Blocks Extensible Exchange Protocol
      (BEEP)", RFC 3983, January 2005.
 [2]  World Wide Web Consortium, "Extensible Markup Language (XML)
      1.0", W3C XML, February 1998, <http://www.w3.org/TR/1998/REC-
      xml-19980210>.
 [3]  World Wide Web Consortium, "Namespaces in XML", W3C XML
      Namespaces, January 1999, <http://www.w3.org/TR/1999/REC-xml-
      names-19990114>.
 [4]  World Wide Web Consortium, "XML Schema Part 2: Datatypes", W3C
      XML Schema, October 2000, <http://www.w3.org/TR/2001/REC-
      xmlschema-2-20010502/>.

Newton & Sanz Standards Track [Page 43] RFC 3981 IRIS-Core January 2005

 [5]  World Wide Web Consortium, "XML Schema Part 1: Structures", W3C
      XML Schema, October 2000, <http://www.w3.org/TR/2001/REC-
      xmlschema-1-20010502/>.
 [6]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
      Resource Identifiers (URI): Generic Syntax", RFC 2396, August
      1998.
 [7]  Moats, R., "URN Syntax", RFC 2141, May 1997.
 [8]  Bradner, S., "Key words for use in RFCs to Indicate Requirement
      Levels", BCP 14, RFC 2119, March 1997.
 [9]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, January
      2004.
 [10] Daigle, L. and A. Newton, "Domain-based Application Service
      Location Using SRV RRs and the Dynamic Delegation Discovery
      Service (DDDS)", RFC 3958, January 2005.
 [11] Crocker, D. and P. Overell, "Augmented BNF for Syntax
      Specifications: ABNF", RFC 2234, November 1997.
 [12] The Unicode Consortium, "The Unicode Standard, Version 3", ISBN
      0-201-61633-5, 2000, <The Unicode Standard, Version 3>.
 [13] Yergeau, F., "UTF-8, a transformation format of ISO 10646", STD
      63, RFC 3629, November 2003.
 [14] Connolly, D. and L. Masinter, "The 'text/html' Media Type", RFC
      2854, June 2000.
 [15] Hinden, R., Carpenter, B., and L. Masinter, "Format for Literal
      IPv6 Addresses in URL's", RFC 2732, December 1999.
 [16] Alvestrand, H., "IETF Policy on Character Sets and Languages",
      BCP 18, RFC 2277, January 1998.

Newton & Sanz Standards Track [Page 44] RFC 3981 IRIS-Core January 2005

12.2. Informative References

 [17] Newton, A., "Cross Registry Internet Service Protocol (CRISP)
      Requirements", RFC 3707, February 2004.
 [18] Newton, A. and M. Sanz, "IRIS:  A Domain Registry (dreg) Type
      for the Internet Registry Information Service (IRIS)", RFC 3982,
      January 2005.
 [19] Daigle, L., "WHOIS Protocol Specification", RFC 3912, September
      2004.
 [20] Rose, M., "The Blocks Extensible Exchange Protocol Core", RFC
      3080, March 2001.

URIs

 [21] <http://www.iana.org/assignments/character-sets>

Newton & Sanz Standards Track [Page 45] RFC 3981 IRIS-Core January 2005

Appendix A. S-NAPTR and IRIS Uses

A.1. Example of S-NAPTR with IRIS

 This section shows an example of S-NAPTR [10] use by IRIS.  In this
 example, there are two registry types: REGA and REGB.  There are also
 two IRIS application transports: iris-a and iris-b.  Given this, the
 use of S-NAPTR offers the following:
 1. A means by which an operator can split the set of servers running
    REGA from the set of servers running REGB.  This is to say, the
    operator is able to split out the set of servers serving up data
    for REGA from the set of servers serving up data for REGB.
 2. A means by which an operator can distinguish the set of servers
    running iris-a from the set of servers running iris-b.  This is to
    say, the operator is able to split out the set of servers running
    protocol iris-a serving REGA and REGB data from the set of servers
    running protocol iris-b serving REGA and REGB data.
 3. A means by which an operator can specify which set of the servers
    to operate and which set of the above servers to delegate to
    another operator.
 To implement the first feature, the operator deploys the following in
 his or her DNS zone:

example.com. ;; order pref flags service re replacement IN NAPTR 100 10 "" "REGA:iris-a:iris-b" "" rega.example.com IN NAPTR 100 10 "" "REGB:iris-a:iris-b" "" regb.example.com

 To implement the second feature, the operator then adds the following
 in their DNS zone:

rega.example.com. ;; order pref flags service re replacement IN NAPTR 100 10 "s" "REGA:iris-a" "" _iris-a._udp.example.com regb.example.com. IN NAPTR 100 10 "s" "REGA:iris-b" "" _iris-b._tcp.example.com

_iris-a._udp.example.com. ;; pref weight port target IN SRV 10 0 34 big-a.example.com. IN SRV 20 0 34 small-a.example.com.

Newton & Sanz Standards Track [Page 46] RFC 3981 IRIS-Core January 2005

_iris-b._tcp.example.com. ;; pref weight port target IN SRV 10 0 34 big-b.example.com. IN SRV 20 0 34 small-b.example.com.

 Finally, an operator may decide to operate the REGA services while
 delegating the REGB services to somebody else.  Here is how that is
 done:

example.com. ;; order pref flags service re replacement IN NAPTR 100 10 "" "REGA:iris-a:iris-b" "" rega.example.com IN NAPTR 100 10 "" "REGB:iris-a:iris-b" "" somebodyelse.com

 Or the operator may decide to operate REGB services under the iris-a
 protocol/transport while delegating the REGB services under the
 iris-b protocol/transport to somebody else.

example.com. ;; order pref flags service re replacement IN NAPTR 100 10 "" "REGB:iris-a:iris-b" "" regb.example.com IN NAPTR 100 10 "s" "REGB:iris-a" "" _iris-a._udp.example.com IN NAPTR 100 10 "s" "REGB:iris-b" "" _iris-b._tcp.somebodyelse.com

_iris-a._udp.example.com. ;; pref weight port target IN SRV 10 0 34 big-a.example.com. IN SRV 20 0 34 small-a.example.com.

 Note that while this last example is possible, it is probably not
 advisable because of the operational issues involved in synchronizing
 the data between example.com and somebodyelse.com.  It is provided
 here as an example of what is possible.

A.2. Using S-NAPTR for Cohabitation

 Given the examples in Appendix A.1, the use of S-NAPTR could be part
 of a transition strategy for cohabitation of protocols solving the
 problems of CRISP [17].
 For example, the type of data for domain information could be given
 the application service label of "DREG1".  Given this, the service
 field of an S-NAPTR compliant NAPTR record could read
    "DREG1:whois:iris-beep"

Newton & Sanz Standards Track [Page 47] RFC 3981 IRIS-Core January 2005

 This service field conveys that domain data, as defined by CRISP, is
 available via both the iris-beep protocol and the whois protocol.
 The whois application protocol label refers to RFC 954 [19].

Appendix B. IRIS Design Philosophy

 Beyond the concrete arguments that could be placed behind a
 thoughtful analysis of the bits flying across the ether, there are
 other abstract reasons for the development of IRIS.  This section
 attempts an explanation.

B.1. The Basic Premise

 IRIS has been designed as a directory service for public-facing
 registries of Internet resources.  The basic premise is this:
 o  A client should be able to look up any single piece of data from
    any type of registry.  This lookup should involve a straight-
    forward and consistent definition for finding the registry and
    should entail a hit to a single data index in the registry.
 o  Anything more, such as searches up and down the DNS tree to find
    the registry or searches across multiple indexes in a registry,
    requires a client with special knowledge of the data relationships
    contained within a registry.
 Therefore, IRIS does the following:
 o  It specifies the basic schema language used by all registries to
    specify their schemas.
    o  It provides the basic framework for a registry to make a
    reference to an entity in another type of registry.
 And, therefore, IRIS does not do the following:
 o  It does not specify a common query language across all types of
    registries.  A common query language imposed across multiple types
    of registries usually results in the disabling of certain
    functions by a server operator in order to meet acceptable levels
    of performance, leaving a common query language that does not
    commonly work.
 o  It does not impose any relationship between sets of data in any
    type of registry, such as specifying a tree.  There are many types
    of Internet resources, and they do not all share the same style of

Newton & Sanz Standards Track [Page 48] RFC 3981 IRIS-Core January 2005

    relationship with their contained sets of data.  When it is not a
    natural fit, an imposition of a common relationship is often a
    concern and not a benefit.

B.2. The Lure of a Universal Client

 The design premise of IRIS signifies that, for directory services,
 there is no such thing as a universal client (or that if there is
 one, it is commonly called the "web browser").
 For IRIS, the closest thing to a universal client is one that may
 "look up" data and may be able to display the data in a rudimentary
 fashion.  For a client to be able to "search" data or display it in a
 truly user-friendly manner, it must have specific knowledge about the
 type of data it is retrieving.
 Attempts to outfit a universal client with a common query language
 are also not very useful.  A common query language may be applied to
 a specific problem domain, which would require a user to have
 expertise in both the common query language and the problem domain.
 In the end, the outcome is usually the development of a client
 specific to the problem domain but saddled with translation of the
 user's desires and the lowest-common-denominator aspect of the query
 language.

B.3. Server Considerations

 As mentioned above, IRIS was designed for the directory service needs
 of public-facing registries.  In this light, certain aspects of more
 generalized directory services are a hindrance in an environment that
 does not have the same control and safety considerations as a managed
 network.
 For instance, a common query language can provide great flexibility
 to both the power user and the abusive user.  An abusive user could
 easily submit a query across multiple indexes with partial values.
 Such a query would have no utility other than to cause denial of
 service to other users.  To combat this, a service operator must
 restrict the types of queries that cause harm to overall performance,
 and this act obsoletes the benefit of a common query language.
 Another consideration for server performance is the lack of a
 required data relationship.  Because sets of data often have
 differing relationships, a one-size-fits-all approach does not fit
 well with all types of registries.  In addition, public-facing
 services tend to have service level requirements that cannot
 reasonably be met by transforming complete data stores from a native
 format into a format enforcing an artificial set of relationships.

Newton & Sanz Standards Track [Page 49] RFC 3981 IRIS-Core January 2005

 To combat these issues, operators of public-facing services tend to
 create their own custom query parsers and back-end data stores.  But
 doing so brings into question the use of a generalized directory
 service.
 Finally, IRIS is built upon a set of standard technological layers.
 This allows service operators to switch components to meet the needs
 of their particular environment.

B.4. Lookups, Searches, and Entity Classes

 IRIS supports both lookups and searches.  Conceptually, the
 difference between the two is as follows:
    A "lookup" is a single query with a discrete value on a single
    index.
    Anything more, such as partial value queries, queries across
    multiple indexes, or multiple queries to a single index is a
    "search".
 Lookups are accomplished through the defined query <lookupEntity>.
 This query specifies a discrete name, called the entity name, to be
 queried in a single index, called the entity class.  Therefore,
 implementations may consider a type of registry to be composed of
 multiple indexes, one for each defined entity class.
 There are no standard searches in IRIS.  Each type of registry
 defines its own set of searches.

B.5. Entities References, Search Continuations, and Scope

 Due to its effect on client behavior and the side effects such
 behavior may have on servers, IRIS makes a clear distinction between
 entity references (<entity>) and search continuations
 (<searchContinuation>).  It is not an add-on, but a fundamental core
 of the protocol.
 The distinction is very important to a client:
    "Go look over there and you will find what you seek."  "Go look
    over there and you may find what you seek, or you may find some
    other stuff, or you may find nothing."
 Finally, because IRIS makes no assumptions about and places no
 requirements on the relationship of data in a registry, this also
 extends to data of the same registry type spread across multiple
 authority areas.  This means that IRIS makes no requirements as to

Newton & Sanz Standards Track [Page 50] RFC 3981 IRIS-Core January 2005

 the scope of entity references or search continuations.  The scope is
 determined by what the registry type needs and by what the registry
 type allows a service operator.

Appendix C. Acknowledgments

 The terminology used in this document to describe namespaces and
 namespaces of namespaces is now much clearer thanks to the skillful
 debate tactics of Leslie Daigle.  Previously, it was much more
 confusing.  In addition, Leslie has provided great insight into the
 details of URIs, URNs, and NAPTR/SRV resource records.
 Many other technical complexities were proved unnecessary by David
 Blacka and have been removed.  And his IRIS implementation has helped
 smooth out the rougher edges.

Authors' Addresses

 Andrew L. Newton
 VeriSign, Inc.
 21345 Ridgetop Circle
 Sterling, VA  20166
 USA
 Phone: +1 703 948 3382
 EMail: anewton@verisignlabs.com; andy@hxr.us
 URI:   http://www.verisignlabs.com/
 Marcos Sanz
 DENIC eG
 Wiesenhuettenplatz 26
 D-60329 Frankfurt
 Germany
 EMail: sanz@denic.de
 URI:   http://www.denic.de/

Newton & Sanz Standards Track [Page 51] RFC 3981 IRIS-Core January 2005

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Newton & Sanz Standards Track [Page 52]

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