<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE rfc SYSTEM"http://xml.resource.org/authoring/rfc2629.dtd" [ <!ENTITY RFC2119 PUBLIC '' 'http://xml.resource.org/public/rfc/bibxml/reference.RFC.2119.xml'> <!ENTITY RFC5234 PUBLIC '' 'http://xml.resource.org/public/rfc/bibxml/reference.RFC.5234.xml'> <!ENTITY RFC5890 PUBLIC '' 'http://xml.resource.org/public/rfc/bibxml/reference.RFC.5890.xml'> <!ENTITY RFC6350 PUBLIC '' 'http://xml.resource.org/public/rfc/bibxml/reference.RFC.6350.xml'> <!ENTITY RFC6901 PUBLIC '' 'http://xml.resource.org/public/rfc/bibxml/reference.RFC.6901.xml'> <!ENTITY RFC7095 PUBLIC '' 'http://xml.resource.org/public/rfc/bibxml/reference.RFC.7095.xml'> <!ENTITY RFC7230 PUBLIC '' 'http://xml.resource.org/public/rfc/bibxml/reference.RFC.7230.xml'> <!ENTITY RFC7231 PUBLIC '' 'http://xml.resource.org/public/rfc/bibxml/reference.RFC.7231.xml'> <!ENTITY RFC7480 PUBLIC '' 'http://xml.resource.org/public/rfc/bibxml/reference.RFC.7480.xml'> <!ENTITY RFC7481 PUBLIC '' 'http://xml.resource.org/public/rfc/bibxml/reference.RFC.7481.xml'> <!ENTITY RFC7482 PUBLIC '' 'http://xml.resource.org/public/rfc/bibxml/reference.RFC.7482.xml'> <!ENTITY RFC7483 PUBLIC '' 'http://xml.resource.org/public/rfc/bibxml/reference.RFC.7483.xml'> <!ENTITY RFC7942 PUBLIC '' 'http://xml.resource.org/public/rfc/bibxml/reference.RFC.7942.xml'> <!ENTITY RFC8174 PUBLIC '' 'http://xml.resource.org/public/rfc/bibxml/reference.RFC.8174.xml'> <!ENTITY RFC8259 PUBLIC '' 'http://xml.resource.org/public/rfc/bibxml/reference.RFC.8259.xml'> <!ENTITY RFC8288 PUBLIC '' 'http://xml.resource.org/public/rfc/bibxml/reference.RFC.8288.xml'> <!ENTITY RFC8605 PUBLIC '' 'http://xml.resource.org/public/rfc/bibxml/reference.RFC.8605.xml'> <!ENTITY W3C.CR-xpath-31-20161213 PUBLIC '' 'https://xml2rfc.tools.ietf.org/public/rfc/bibxml4/reference.W3C.CR-xpath-31-20161213.xml'> ]> <?xml-stylesheet type="text/xsl" href="rfc2629.xslt"?> <?rfc toc="yes"?> <?rfc tocompact="yes"?> <?rfc tocdepth="4"?> <?rfc compact="yes"?> <?rfc subcompact="yes"?> <?rfc sortrefs="yes"?> <?rfc symrefs="yes"?> <?rfc iprnotified="no"?>"rfc2629-xhtml.ent"> <rfc xmlns:xi="http://www.w3.org/2001/XInclude" xml:lang="en" submissionType="IETF" category="std" consensus="true" docName="draft-ietf-regext-rdap-sorting-and-paging-20"ipr="trust200902">number="8977" updates="" obsoletes="" ipr="trust200902" tocInclude="true" tocDepth="4" sortRefs="true" symRefs="true" version="3"> <front> <title abbrev="RDAP Sorting and Paging">Registration Data Access Protocol (RDAP) Query Parameters for Result Sorting and Paging</title> <seriesInfo name="RFC" value="8977"/> <author fullname="Mario Loffredo" initials="M." surname="Loffredo"> <organization>IIT-CNR/Registro.it</organization> <address> <postal> <street>Via Moruzzi,1</street> <city>Pisa</city><country>IT</country><country>Italy</country> <code>56124</code> </postal> <email>mario.loffredo@iit.cnr.it</email><uri>http://www.iit.cnr.it</uri><uri>https://www.iit.cnr.it</uri> </address> </author> <author fullname="Maurizio Martinelli" initials="M." surname="Martinelli"> <organization>IIT-CNR/Registro.it</organization> <address> <postal> <street>Via Moruzzi,1</street> <city>Pisa</city><country>IT</country><country>Italy</country> <code>56124</code> </postal> <email>maurizio.martinelli@iit.cnr.it</email><uri>http://www.iit.cnr.it</uri><uri>https://www.iit.cnr.it</uri> </address> </author> <author initials="S." surname="Hollenbeck" fullname="Scott Hollenbeck"> <organization>Verisign Labs</organization> <address> <postal> <street>12061 Bluemont Way</street> <city>Reston</city> <region>VA</region> <code>20190</code><country>USA</country><country>United States of America</country> </postal> <email>shollenbeck@verisign.com</email> <uri>https://www.verisignlabs.com/</uri> </address> </author><date/><date year="2021" month="January" /> <area>Applications and Real-Time</area> <workgroup>Registration Protocols Extensions</workgroup> <keyword>RDAP</keyword> <keyword>Sorting</keyword> <keyword>Paging</keyword> <abstract> <t>The Registration Data Access Protocol (RDAP) does not include core functionality for clients to provide sorting and paging parameters for control of large result sets. This omission can lead to unpredictable server processing of queries and client processing of responses. This unpredictability can be greatly reduced if clients can provide servers with their preferences for managing large responses. This document describes RDAP query extensions that allow clients to specify their preferences for sorting and paging result sets.</t> </abstract> </front> <middle><section title="Introduction"><section> <name>Introduction</name> <t>The availability of functionality for result sorting and paging provides benefits to both clients and servers in the implementation of RESTful services <xref target="REST"/>. These benefits include:</t><t><list style="symbols"> <t>reducing<ul> <li>reducing the server response bandwidthrequirements;</t> <t>improvingrequirements</li> <li>improving server responsetime;</t> <t>improvingtime</li> <li>improving query precision and, consequently, obtaining more relevantresults;</t> <t>decreasingresults</li> <li>decreasing server query processingload;</t> <t>reducingload</li> <li>reducing client response processingtime.</t> </list></t>time</li> </ul> <t>Approaches to implementing features for result sorting and paging can be grouped into two main categories:</t><t><list style="numbers"> <t>sorting<ol type="1"><li> <t>Sorting and paging are implemented through the introduction of additional parameters in the query string(e.g. ODATA protocol(e.g., the Open Data Protocol (ODATA) <xreftarget="OData-Part1"/>);<vspace blankLines='1' /></t> <t>informationtarget="ODATA-PART1"/>).</t> </li> <li>Information related to the number of results and the specific portion of the result set to be returned, in addition to a set of ready-made links for the result set scrolling, are inserted in the HTTP header of the request/response <xreftarget="RFC7231"/>.</t> </list></t>target="RFC7231"/>.</li> </ol> <t>However, there are some drawbacks associated with the use of the HTTP header. First, the header properties cannot be set directly from a web browser. Moreover, in an HTTP session, the information on the status(i.e.(i.e., the session identifier) is usually inserted in the header or a cookie, while the information on the resource identification or the search type is included in the query string. Finally, providing custom information through HTTP headers assumes the clientto have ahas prior knowledge of the serverimplementationimplementation, which is widely considered aRESTRepresentational State Transfer (REST) design anti-pattern. As a result, this document describes a specification based on the use of query parameters.</t> <t>Currently,theRDAPprotocol<xref target="RFC7482"/> defines two query types:</t><t><list style="symbols"> <t>lookup: the<dl> <dt>lookup: </dt> <dd>the server returns only oneobject;</t> <t>search: theobject </dd> <dt>search: </dt> <dd>the server returns a collection ofobjects.</t> </list></t>objects </dd> </dl> <t>While the lookup query does not raise issues regarding response size management, the search query can potentially generate a large result set that is often truncated according to server limits. Besides, it is not possible to obtain the total number of objects found that might be returned in a search query response <xref target="RFC7483"/>. Lastly, there is no way to specify sort criteria to return the most relevant objects at the beginning of the result set. Therefore, the client might traverse the whole result set to find the relevant objects or, due to truncation, might not find them at all.</t> <t>The specification described in this document extends RDAP query capabilities to enable result sorting andpaging,paging by adding new query parameters that can be applied to RDAP search path segments. The service is implemented using the Hypertext Transfer Protocol (HTTP) <xref target="RFC7230"/> and the conventions described in <xref target="RFC7480"/>.</t> <t>The implementation of the new parameters is technically feasible, as operators for counting,sortingsorting, and paging rows are currently supported by the major relational database management systems.</t><section title="Conventions<section> <name>Conventions Used in ThisDocument"> <t>TheDocument</name> <t> The key words"MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY","<bcp14>MUST</bcp14>", "<bcp14>MUST NOT</bcp14>", "<bcp14>REQUIRED</bcp14>", "<bcp14>SHALL</bcp14>", "<bcp14>SHALL NOT</bcp14>", "<bcp14>SHOULD</bcp14>", "<bcp14>SHOULD NOT</bcp14>", "<bcp14>RECOMMENDED</bcp14>", "<bcp14>NOT RECOMMENDED</bcp14>", "<bcp14>MAY</bcp14>", and"OPTIONAL""<bcp14>OPTIONAL</bcp14>" in this document are to be interpreted as described inBCP 14BCP 14 <xref target="RFC2119"/> <xref target="RFC8174"/> when, and only when, they appear in all capitals, as shownhere.</t>here. </t> </section> </section> <sectionanchor="rdap-query-parameter-specification" title="RDAPanchor="rdap-query-parameter-specification"> <name>RDAP Query ParameterSpecification">Specification</name> <t>The new query parameters areOPTIONAL<bcp14>OPTIONAL</bcp14> extensions of path segments defined in <xref target="RFC7482"/>. They are as follows:</t><t><list style="symbols"> <t>"count": a<dl> <dt>"count": </dt> <dd>a boolean value that allows a client to request the return of the total number of objectsfound;<vspace blankLines='1'/></t> <t>"sort": afound </dd> <dt>"sort": </dt> <dd>a string value that allows a client to request a specific sort order for the resultset;<vspace blankLines='1'/></t> <t>"cursor": aset </dd> <dt>"cursor": </dt> <dd>a string value representing a pointer to a specificfixed sizefixed-size portion of the resultset.</t> </list></t>set </dd> </dl> <t>Augmented Backus-Naur Form (ABNF) <xref target="RFC5234"/> is used in the following sections to describe the formal syntax of these new parameters.</t> <sectionanchor="sorting_and_paging_metadata" title="Sortinganchor="sorting_and_paging_metadata"> <name>Sorting and PagingMetadata">Metadata</name> <t>According to most advanced principles in REST design, collectively known as HATEOAS (Hypermedia as the Engine of Application State) <xref target="HATEOAS"/>, a client entering a REST application through an initial URI should use server-provided links to dynamically discover available actions and access the resources it needs. In this way, the client isnotneither required to have prior knowledge of the serviceand,nor, consequently, to hard code the URIs of different resources. This allows the server to make URI changes as the API evolves without breaking clients. Definitively, a REST service should be as self-descriptive as possible.</t> <t>Therefore, servers implementing the query parameters described in this specificationSHOULD<bcp14>SHOULD</bcp14> provide additional information in their responses about both the available sorting criteria and possible pagination. Such information is collected in twoOPTIONAL<bcp14>OPTIONAL</bcp14> response elements named"sorting_metadata""sorting_metadata" and"paging_metadata".</t>"paging_metadata".</t> <t>The"sorting_metadata""sorting_metadata" element contains the following properties:</t><t><list style="symbols"> <t>"currentSort": "String" (OPTIONAL) either<dl newline="true"> <dt>"currentSort": "String" (<bcp14>OPTIONAL</bcp14>) </dt> <dd>Either the value of"sort"the "sort" parameter as specified in the query string or the sort applied by default, ifany;<vspace blankLines='1'/></t> <t>"availableSorts": "AvailableSort[]" (OPTIONAL) anany. </dd> <dt>"availableSorts": "AvailableSort[]" (<bcp14>OPTIONAL</bcp14>) </dt> <dd><t>An array of objects, with each element describing an available sort criterion. The AvailableSort object includes the followingmembers: <list style="symbols"> <t>"property": "String" (REQUIRED) themembers:</t> <dl newline="true"> <dt>"property": "String" (<bcp14>REQUIRED</bcp14>) </dt> <dd>The name that can be used by the client to request the sortcriterion;</t> <t>"default": "Boolean" (REQUIRED)criterion. </dd> <dt>"default": "Boolean" (<bcp14>REQUIRED</bcp14>) </dt> <dd>Indicator of whether the sort criterion is applied by default. An RDAP serverMUST<bcp14>MUST</bcp14> define only one default sorting property for each objectclass;</t> <t>"jsonPath": "String" (OPTIONAL) theclass. </dd> <dt>"jsonPath": "String" (<bcp14>OPTIONAL</bcp14>) </dt> <dd>The JSONPath expression of the RDAP field corresponding to theproperty;</t> <t>"links": "Link[]" (OPTIONAL) anproperty. </dd> <dt>"links": "Link[]" (<bcp14>OPTIONAL</bcp14>) </dt> <dd>An array of links as described in <xref target="RFC8288"/> containing the query string that applies the sortcriterion.</t> </list></t> </list></t>criterion. </dd> </dl> </dd> </dl> <t>At least one of the"currentSort""currentSort" and"availableSorts""availableSorts" propertiesMUST<bcp14>MUST</bcp14> be present.</t> <t>The"paging_metadata""paging_metadata" element contains the following fields:</t><t><list style="symbols"> <t>"totalCount": "Numeric" (OPTIONAL) a<dl newline="true"> <dt>"totalCount": "Numeric" (<bcp14>OPTIONAL</bcp14>) </dt> <dd>A numeric value representing the total number of objects found. ItMUST<bcp14>MUST</bcp14> be provided if and only if the query string contains the"count" parameter;<vspace blankLines='1'/></t> <t>"pageSize": "Numeric" (OPTIONAL) a"count" parameter. </dd> <dt>"pageSize": "Numeric" (<bcp14>OPTIONAL</bcp14>) </dt> <dd>A numeric value representing the number of objects that should have been returned in the current page. ItMUST<bcp14>MUST</bcp14> be provided if and only if the total number of objects exceeds the page size. This property is redundant for RDAP clients because the page size can be derived from the length of the search resultsarray but,array, but it can be helpful if the end user interacts with the server through a webbrowser;<vspace blankLines='1'/></t> <t>"pageNumber": "Numeric" (OPTIONAL) abrowser. </dd> <dt>"pageNumber": "Numeric" (<bcp14>OPTIONAL</bcp14>) </dt> <dd>A numeric value representing the number of the current page in the result set. ItMUST<bcp14>MUST</bcp14> be provided if and only if the total number of objects found exceeds the pagesize;<vspace blankLines='1'/></t> <t>"links": "Link[]" (OPTIONAL) ansize. </dd> <dt>"links": "Link[]" (<bcp14>OPTIONAL</bcp14>) </dt> <dd>An array of links as described in <xref target="RFC8288"/> containing the reference to the next page. In this specification, only forward pagination is described because it is all that is necessary to traverse the resultset.</t> </list></t>set. </dd> </dl> <sectionanchor="rdap-conformance" title="RDAP Conformance">anchor="rdap-conformance"> <name>RDAP Conformance</name> <t>Servers returning the"paging_metadata""paging_metadata" element in their responseMUST<bcp14>MUST</bcp14> include the string literal"paging""paging" in the rdapConformance array. Servers returning the"sorting_metadata""sorting_metadata" elementMUST<bcp14>MUST</bcp14> include the string literal"sorting".</t>"sorting".</t> </section> </section> <sectionanchor="count-parameter" title=""count" Parameter">anchor="count-parameter"> <name>"count" Parameter</name> <t>Currently,theRDAPprotocoldoes not allow a client to determine the total number oftheresults in a query response when the result set is truncated. This is inefficient because the user cannot determine if the result set is complete.</t> <t>The"count""count" parameter provides additional functionality that allows a client to request information from the server that specifies the total number of objects matching the search pattern.</t> <t>The following is an example of an RDAP query including the"count""count" parameter:</t><t>https://example.com/rdap/domains?name=example*.com&count=true</t><t>https://example.com/rdap/domains?name=example*.com&count=true </t> <t>The ABNF syntax is the following:</t><t><list style="empty"> <t>count<sourcecode type="abnf"> count ="count=""count=" ( trueValue / falseValue)</t> <t>trueValue) trueValue =("true"("true" /"yes""yes" /"1")</t> <t>falseValue"1") falseValue =("false"("false" /"no""no" /"0")</t> </list></t>"0") </sourcecode> <t>A trueValue means that the serverMUST<bcp14>MUST</bcp14> provide the total number oftheobjects in the"totalCount""totalCount" field of the"paging_metadata""paging_metadata" element (<xref target="count-in-response-example"/>). A falseValue means that the serverMUST NOT<bcp14>MUST NOT</bcp14> provide this number.</t> <figureanchor="count-in-response-example" title="Exampleanchor="count-in-response-example"> <name>Example of RDAPresponseResponse with"paging_metadata" element containing the "totalCount" field"> <artwork xml:space="preserve">"paging_metadata" Element Containing the "totalCount" Field</name> <sourcecode type="json"> { "rdapConformance": [ "rdap_level_0", "paging" ], ... "paging_metadata": { "totalCount": 43 }, "domainSearchResults": [ ... ] }</artwork></sourcecode> </figure> </section> <sectionanchor="sort-parameter" title=""sort" Parameter"> <t>The RDAP protocolanchor="sort-parameter"> <name>"sort" Parameter</name> <t>RDAP does not provide any capability to specify the result set sort criteria. A server could implement a default sorting scheme according to the object class, but this feature is not mandatory and might not meet user requirements. Sorting can be addressed by the client, but this solution is rather inefficient. Sorting features provided by the RDAP server could help avoid truncation of relevant results.</t> <t>The"sort""sort" parameter allows the client to ask the server to sort the results according to the values of one or more properties and according to the sort direction of each property. The ABNF syntax is the following:</t><t><list style="empty"> <t>sort<sourcecode type="abnf"> sort ="sort=""sort=" sortItem *(",""," sortItem ) sortItem)</t> <t>sortItem= property-ref[":"[":" ("a""a" /"d""d" )]</t> <t>property-ref] property-ref = ALPHA *( ALPHA / DIGIT /"_""_" )</t> </list></t> <t>"a"</sourcecode> <t>"a" means that an ascending sortMUST<bcp14>MUST</bcp14> beapplied, "d"applied; "d" means that a descending sortMUST<bcp14>MUST</bcp14> be applied. If the sort direction is absent, an ascending sortMUST<bcp14>MUST</bcp14> be applied.</t> <t>The following are examples of RDAP queriesincludingthat include the"sort""sort" parameter:</t><t>https://example.com/rdap/domains?name=example*.com&sort=name</t> <t>https://example.com/rdap/domains?name=example*.com&sort=registrationDate:d</t> <t>https://example.com/rdap/domains?name=example*.com&sort=lockedDate,name</t><t> https://example.com/rdap/domains?name=example*.com&sort=name </t> <t> https://example.com/rdap/ domains?name=example*.com&sort=registrationDate:d </t> <t> https://example.com/rdap/ domains?name=example*.com&sort=lockedDate,name </t> <t>Except for sorting IP addresses and values denoting dates and times, serversMUST<bcp14>MUST</bcp14> implement sorting according to the JSON value type of the RDAP field the sorting property refers to. That is, JSON stringsMUST<bcp14>MUST</bcp14> be sortedlexicographicallylexicographically, and JSON numbersMUST<bcp14>MUST</bcp14> be sorted numerically. Values denoting dates and timesMUST<bcp14>MUST</bcp14> be sorted in chronological order. If IP addresses are represented as JSON strings, theyMUST<bcp14>MUST</bcp14> be sorted based on their numeric conversion.</t> <t>The conversion of an IPv4 address to a number is possible since each dotted format IPv4 address is a representation of a number written in a 256-basedmanner:manner; for example, 192.168.0.1 means 1*256^0 + 0*256^1 + 168*256^2 + 192*256^3 = 3232235521. Similarly, an IPv6 address can be converted into a number by applying the base 65536. Therefore, the numerical representation of the IPv6 address 2001:0db8:85a3:0:0:8a2e:0370:7334 is 42540766452641154071740215577757643572.BuiltinBuilt-in functions and libraries for converting IP addresses into numbers are available in most known programming languages and relational database management systems.</t> <t>If the"sort""sort" parameter presents an allowed sorting property, itMUST<bcp14>MUST</bcp14> be provided in the"currentSort""currentSort" field of the"sorting_metadata""sorting_metadata" element.</t> <sectionanchor="sorting_properties" title="Sortinganchor="sorting_properties"> <name>Sorting PropertiesDeclaration">Declaration</name> <t>In the"sort""sort" parameter ABNF syntax, the element named"property-ref""property-ref" represents a reference to a property of an RDAP object. Such a reference could be expressed by using a JSONPath expression (named "jsonpath" in the following).</t> <t>JSONPath is a syntax, originally based on the XML XPath notation <xreftarget="W3C.CR-xpath-31-20161213"/>,target="W3C.CR-xpath-31-20170321"/>, which represents a path to select an element (or a set of elements) in a JSON document <xref target="RFC8259"/>. For example, the jsonpath to select the value of the ASCII name inside an RDAP domain lookup response is"$.ldhName","$.ldhName", where $ identifies the root of the document object model (DOM). Another way to select a value inside a JSON document is the JSON Pointer <xref target="RFC6901"/>.</t> <t>While JSONPathorand JSON Pointer are both commonly adopted notations to select any value inside JSON data, neither is particularlycoinciseconcise and easy to use(e.g. "$.domainSearchResults[*].events[?(@.eventAction='registration')].eventDate"(e.g., "$.domainSearchResults[*].events[?(@.eventAction='registration')].eventDate" is the jsonpath of the registration date in an RDAP domain search response).</t> <t>Therefore, this specification defines the"property-ref""property-ref" element in terms of names identifying RDAP properties. However, not all the RDAP properties are suitable to be used in sortcriteria, such as:</t> <t><list style="symbols">criteria. These properties include:</t> <ul> <li> <t>properties providing service information(e.g.(e.g., links, notices,remarks);<vspace blankLines='1' /></t>and remarks)</t> </li> <li> <t>multivalued properties(e.g.(e.g., status, roles,variants);<vspace blankLines='1' /></t> <t>propertiesand variants)</t> </li> <li>properties representing relationships to other objects(e.g. entities).</t> </list></t>(e.g., entities)</li> </ul> <t>On the contrary, properties expressed as values of other properties(e.g.(e.g., registration date) could be used in such a context.</t> <t>A list of properties an RDAP serverMAY<bcp14>MAY</bcp14> implement is defined. The properties are divided into two groups:object commonobject-common properties andobject specificobject-specific properties.</t><t><list style="symbols"> <t>Object common<ul> <li><t>Object-common properties.Object commonObject-common properties are derived from merging the"eventAction""eventAction" and the"eventDate""eventDate" properties. The following values of the"sort""sort" parameter aredefined: <list style="symbols"> <t>registrationDate</t> <t>reregistrationDate</t> <t>lastChangedDate</t> <t>expirationDate</t> <t>deletionDate</t> <t>reinstantiationDate</t> <t>transferDate</t> <t>lockedDate</t> <t>unlockedDate</t> </list></t> </list></t> <t><list style="symbols"> <t>Object specificdefined:</t> <ul> <li>registrationDate </li> <li>reregistrationDate </li> <li>lastChangedDate </li> <li>expirationDate </li> <li>deletionDate </li> <li>reinstantiationDate </li> <li>transferDate </li> <li>lockedDate </li> <li>unlockedDate </li> </ul> </li> <li><t>Object-specific properties. Note that some of these properties are also defined as query path segments. These propertiesinclude: <list style="symbols"> <t>Domain: name</t> <t>Nameserver:include:</t> <ul> <li>Domain: name </li> <li>Nameserver: name, ipv4,ipv6.</t> <t>Entity:ipv6 </li> <li>Entity: fn, handle, org, email, voice, country, cc,city.</t> </list></t> </list></t>city </li> </ul> </li> </ul> <t>The correspondence between these sorting properties and the RDAP object classes is shown in <xref target="table_sorting_properties_definition"/>. Some of the sorting properties defined for the RDAP entity class are related to jCard elements <xreftarget="RFC7095"/> but, beingtarget="RFC7095"/>, but because jCard is the JSON format forvCard <xref target="RFC6350"/>,vCard, the corresponding definitions are included in the vCardspecification.</t>specification <xref target="RFC6350"/>.</t> <t>An RDAP serverMUST NOT<bcp14>MUST NOT</bcp14> use the defined sorting properties with a meaning other thanthe onethat described in <xref target="table_sorting_properties_definition"/>.</t><texttable anchor="table_sorting_properties_definition" title="Sorting properties definition"> <ttcol<table anchor="table_sorting_properties_definition"> <name>Definitions of Sorting Properties</name> <thead> <tr> <th align="left">Objectclass</ttcol> <ttcolclass</th> <th align="left">Sortingproperty</ttcol> <ttcolproperty</th> <th align="left">RDAPproperty</ttcol> <ttcolproperty</th> <th align="left">RFC7483</ttcol> <ttcol7483</th> <th align="left">RFC6350</ttcol> <ttcol6350</th> <th align="left">RFC8605</ttcol> <c>Searchable objects</c><c>Common properties</c><c>eventAction8605</th> </tr> </thead> <tbody> <tr> <td align="left">Searchable objects</td> <td align="left">Common properties</td> <td align="left">eventAction values suffixed by"Date"</c><c>4.5</c><c></c><c></c> <c></c><c></c><c></c><c></c><c></c><c></c> <c>Domain</c><c>name</c><c>unicodeName/ ldhName</c><c>5.3</c><c></c><c></c> <c></c><c></c><c></c><c></c><c></c><c></c> <c>Nameserver</c><c>name</c><c>unicodeName/ ldhName</c><c>5.2</c><c></c><c></c> <c></c><c>ipv4</c><c>v4 ipAddress</c><c>5.2</c><c></c><c></c> <c></c><c>ipv6</c><c>v6 ipAddress</c><c>5.2</c><c></c><c></c> <c></c><c></c><c></c><c></c><c></c><c></c> <c>Entity</c><c>handle</c><c>handle</c><c>5.1</c><c></c><c></c> <c></c><c>fn</c><c>jCard fn</c><c>5.1</c><c>6.2.1</c><c></c> <c></c><c>org</c><c>jCard org</c><c>5.1</c><c>6.6.4</c><c></c> <c></c><c>voice</c><c>jCard"Date"</td> <td align="left"><xref target="RFC7483" section="4.5" sectionFormat="bare"/></td> <td align="left"/> <td align="left"/> </tr> <tr> <td align="left">Domain</td> <td align="left">name</td> <td align="left">unicodeName/ ldhName</td> <td align="left"><xref target="RFC7483" section="5.3" sectionFormat="bare"/></td> <td align="left"/> <td align="left"/> </tr> <tr> <td align="left">Nameserver</td> <td align="left">name</td> <td align="left">unicodeName/ ldhName</td> <td align="left"><xref target="RFC7483" section="5.2" sectionFormat="bare"/></td> <td align="left"/> <td align="left"/> </tr> <tr> <td align="left"/> <td align="left">ipv4</td> <td align="left">v4 ipAddress</td> <td align="left"><xref target="RFC7483" section="5.2" sectionFormat="bare"/></td> <td align="left"/> <td align="left"/> </tr> <tr> <td align="left"/> <td align="left">ipv6</td> <td align="left">v6 ipAddress</td> <td align="left"><xref target="RFC7483" section="5.2" sectionFormat="bare"/></td> <td align="left"/> <td align="left"/> </tr> <tr> <td align="left">Entity</td> <td align="left">handle</td> <td align="left">handle</td> <td align="left"><xref target="RFC7483" section="5.1" sectionFormat="bare"/></td> <td align="left"/> <td align="left"/> </tr> <tr> <td align="left"/> <td align="left">fn</td> <td align="left">jCard fn</td> <td align="left"><xref target="RFC7483" section="5.1" sectionFormat="bare"/></td> <td align="left"><xref target="RFC6350" section="6.2.1" sectionFormat="bare"/></td> <td align="left"/> </tr> <tr> <td align="left"/> <td align="left">org</td> <td align="left">jCard org</td> <td align="left"><xref target="RFC7483" section="5.1" sectionFormat="bare"/></td> <td align="left"><xref target="RFC6350" section="6.6.4" sectionFormat="bare"/></td> <td align="left"/> </tr> <tr> <td align="left"/> <td align="left">voice</td> <td align="left">jCard tel withtype="voice"</c><c>5.1</c><c>6.4.1</c><c></c> <c></c><c>email</c><c>jCard email</c><c>5.1</c><c>6.4.2</c><c></c> <c></c><c>country</c><c>countrytype="voice"</td> <td align="left"><xref target="RFC7483" section="5.1" sectionFormat="bare"/></td> <td align="left"><xref target="RFC6350" section="6.4.1" sectionFormat="bare"/></td> <td align="left"/> </tr> <tr> <td align="left"/> <td align="left">email</td> <td align="left">jCard email</td> <td align="left"><xref target="RFC7483" section="5.1" sectionFormat="bare"/></td> <td align="left"><xref target="RFC6350" section="6.4.2" sectionFormat="bare"/></td> <td align="left"/> </tr> <tr> <td align="left"/> <td align="left">country</td> <td align="left">country name in jCardadr</c><c>5.1</c><c>6.3.1</c><c></c> <c></c><c>cc</c><c>countryadr</td> <td align="left"><xref target="RFC7483" section="5.1" sectionFormat="bare"/></td> <td align="left"><xref target="RFC6350" section="6.3.1" sectionFormat="bare"/></td> <td align="left"/> </tr> <tr> <td align="left"/> <td align="left">cc</td> <td align="left">country code in jCardadr</c><c>5.1</c><c></c><c>3.1</c> <c></c><c>city</c><c>localityadr</td> <td align="left"><xref target="RFC7483" section="5.1" sectionFormat="bare"/></td> <td align="left"/> <td align="left"><xref target="RFC8605" section="3.1" sectionFormat="bare"/></td> </tr> <tr> <td align="left"/> <td align="left">city</td> <td align="left">locality in jCardadr</c><c>5.1</c><c>6.3.1</c><c></c> </texttable>adr</td> <td align="left"><xref target="RFC7483" section="5.1" sectionFormat="bare"/></td> <td align="left"><xref target="RFC6350" section="6.3.1" sectionFormat="bare"/></td> <td align="left"/> </tr> </tbody> </table> <t>Regarding the definitions in <xref target="table_sorting_properties_definition"/>, some further considerations are needed to disambiguate some cases:</t><t><list style="symbols"> <t>since<ul> <li> <t>Since the response to a search on either domains or nameservers might include both A-labels and U-labels <xref target="RFC5890"/> in general, a consistent sorting policyMUST<bcp14>MUST</bcp14> treat the unicodeName and ldhName as two representations of the same value. The unicodeName valueMUST<bcp14>MUST</bcp14> be used while sorting if it is present; when the unicodeName is unavailable, the value of the ldhNameMUST<bcp14>MUST</bcp14> be usedinstead;<vspace blankLines='1' /></t> <t>theinstead.</t> </li> <li> <t>The jCard"sort-as""sort-as" parameterMUST<bcp14>MUST</bcp14> be ignored for the sorting capability described in thisdocument;<vspace blankLines='1' /></t> <t>evendocument.</t> </li> <li> <t>Even if a nameserver can have multiple IPv4 and IPv6 addresses, the most common configuration includes one address for each IP version. Therefore, this specification makes the assumption that nameservers have a single IPv4 and/or IPv6 value. When more than one address per IP version is presented, sortingMUST<bcp14>MUST</bcp14> be applied to the firstvalue;<vspace blankLines='1' /></t> <t>multiplevalue.</t> </li> <li> <t>Multiple events with a given action on an object might be returned. If this occurs, sortingMUST<bcp14>MUST</bcp14> be applied to the most recentevent;<vspace blankLines='1' /></t> <t>exceptevent.</t> </li> <li>Except for handle values, all the sorting properties defined for entity objects can be multivalued according to the definition of vCard as given in <xref target="RFC6350"/>. When more than one value is presented, sortingMUST<bcp14>MUST</bcp14> be applied to the preferred value identified by the parameterpref="1".pref="1". If thepref"pref" parameter is missing, sortingMUST<bcp14>MUST</bcp14> be applied to the firstvalue.</t> </list></t>value.</li> </ul> <t>The"jsonPath""jsonPath" field in the"sorting_metadata""sorting_metadata" element is used to clarify the RDAP response field the sorting property refers to. The mapping between the sorting properties and the jsonpaths of the RDAP response fields is shown below. The JSONPath operators used herein are described in <xref target="jsonpath-operators"/>.</t><t><list style="symbols"><ul > <li> <t>Searchable objects<list style="hanging"> <t hangText="registrationDate"><vspace blankLines='1' />$.domainSearchResults[*].events[?(@.eventAction=="registration")].eventDate<vspace blankLines='1' /></t> <t hangText="reregistrationDate"><vspace blankLines='1' />$.domainSearchResults[*].events[?(@.eventAction=="reregistration")].eventDate<vspace blankLines='1' /></t> <t hangText="lastChangedDate"><vspace blankLines='1' />$.domainSearchResults[*].events[?(@.eventAction=="last changed")].eventDate<vspace blankLines='1' /></t> <t hangText="expirationDate"><vspace blankLines='1' />$.domainSearchResults[*].events[?(@.eventAction=="expiration")].eventDate<vspace blankLines='1' /></t> <t hangText="deletionDate"><vspace blankLines='1' />$.domainSearchResults[*].events[?(@.eventAction=="deletion")].eventDate<vspace blankLines='1' /></t> <t hangText="reinstantiationDate"><vspace blankLines='1' />$.domainSearchResults[*].events[?(@.eventAction=="reinstantiation")].eventDate<vspace blankLines='1' /></t> <t hangText="transferDate"><vspace blankLines='1' />$.domainSearchResults[*].events[?(@.eventAction=="transfer")].eventDate<vspace blankLines='1' /></t> <t hangText="lockedDate"><vspace blankLines='1' />$.domainSearchResults[*].events[?(@.eventAction=="locked")].eventDate<vspace blankLines='1' /></t> <t hangText="unlockedDate"><vspace blankLines='1' />$.domainSearchResults[*].events[?(@.eventAction=="unlocked")].eventDate<vspace blankLines='1' /></t> </list></t> <dl newline="true"> <dt>registrationDate</dt> <dd> <t>$.domainSearchResults[*].events[?(@.eventAction=="registration")].eventDate</t> </dd> <dt>reregistrationDate</dt> <dd> <t>$.domainSearchResults[*].events[?(@.eventAction=="reregistration")].eventDate</t> </dd> <dt>lastChangedDate</dt> <dd> <t>$.domainSearchResults[*].events[?(@.eventAction=="last changed")].eventDate</t> </dd> <dt>expirationDate</dt> <dd> <t>$.domainSearchResults[*].events[?(@.eventAction=="expiration")].eventDate</t> </dd> <dt>deletionDate</dt> <dd> <t>$.domainSearchResults[*].events[?(@.eventAction=="deletion")].eventDate</t> </dd> <dt>reinstantiationDate</dt> <dd> <t>$.domainSearchResults[*].events[?(@.eventAction=="reinstantiation")].eventDate</t> </dd> <dt>transferDate</dt> <dd> <t>$.domainSearchResults[*].events[?(@.eventAction=="transfer")].eventDate</t> </dd> <dt>lockedDate</dt> <dd> <t>$.domainSearchResults[*].events[?(@.eventAction=="locked")].eventDate</t> </dd> <dt>unlockedDate</dt> <dd> <t>$.domainSearchResults[*].events[?(@.eventAction=="unlocked")].eventDate</t> </dd> </dl> </li> <li> <t>Domain<list style="hanging"> <t hangText="name"><vspace blankLines='1' />$.domainSearchResults[*].[unicodeName,ldhName]<vspace blankLines='1' /></t> </list></t> <dl newline="true"> <dt>name</dt> <dd> <t>$.domainSearchResults[*].[unicodeName,ldhName]</t> </dd> </dl> </li> <li> <t>Nameserver<list style="hanging"> <t hangText="name"><vspace blankLines='1' />$.nameserverSearchResults[*].[unicodeName,ldhName]<vspace blankLines='1' /></t> <t hangText="ipv4"><vspace blankLines='1' />$.nameserverSearchResults[*].ipAddresses.v4[0]<vspace blankLines='1' /></t> <t hangText="ipv6"><vspace blankLines='1' />$.nameserverSearchResults[*].ipAddresses.v6[0]<vspace blankLines='1' /></t> </list></t> <dl newline="true"> <dt>name</dt> <dd> <t>$.nameserverSearchResults[*].[unicodeName,ldhName]</t> </dd> <dt>ipv4</dt> <dd> <t>$.nameserverSearchResults[*].ipAddresses.v4[0]</t> </dd> <dt>ipv6</dt> <dd> <t>$.nameserverSearchResults[*].ipAddresses.v6[0]</t> </dd> </dl> </li> <li> <t>Entity<list style="hanging"> <t hangText="handle"><vspace blankLines='1' />$.entitySearchResults[*].handle<vspace blankLines='1' /></t> <t hangText="fn"><vspace blankLines='1' />$.entitySearchResults[*].vcardArray[1][?(@[0]=="fn")][3]<vspace blankLines='1' /></t> <t hangText="org"><vspace blankLines='1' />$.entitySearchResults[*].vcardArray[1][?(@[0]=="org")][3]<vspace blankLines='1' /></t> <t hangText="voice"><vspace blankLines='1' />$.entitySearchResults[*].vcardArray[1][?(@[0]=="tel" && @[1].type=="voice")][3]<vspace blankLines='1' /></t> <t hangText="email"><vspace blankLines='1' />$.entitySearchResults[*].vcardArray[1][?(@[0]=="email")][3]<vspace blankLines='1' /></t> <t hangText="country"><vspace blankLines='1' />$.entitySearchResults[*].vcardArray[1][?(@[0]=="adr")][3][6]<vspace blankLines='1' /></t> <t hangText="cc"><vspace blankLines='1' />$.entitySearchResults[*].vcardArray[1][?(@[0]=="adr")][1].cc<vspace blankLines='1' /></t> <t hangText="city"><vspace blankLines='1' />$.entitySearchResults[*].vcardArray[1][?(@[0]=="adr")][3][3]<vspace blankLines='1' /></t> </list></t></list></t><dl newline="true"> <dt>handle</dt> <dd> <t>$.entitySearchResults[*].handle</t> </dd> <dt>fn</dt> <dd> <t>$.entitySearchResults[*].vcardArray[1][?(@[0]=="fn")][3]</t> </dd> <dt>org</dt> <dd> <t>$.entitySearchResults[*].vcardArray[1][?(@[0]=="org")][3]</t> </dd> <dt>voice</dt> <dd> <t>$.entitySearchResults[*].vcardArray[1][?(@[0]=="tel" && @[1].type=="voice")][3]</t> </dd> <dt>email</dt> <dd> <t>$.entitySearchResults[*].vcardArray[1][?(@[0]=="email")][3]</t> </dd> <dt>country</dt> <dd> <t>$.entitySearchResults[*].vcardArray[1][?(@[0]=="adr")][3][6]</t> </dd> <dt>cc</dt> <dd> <t>$.entitySearchResults[*].vcardArray[1][?(@[0]=="adr")][1].cc</t> </dd> <dt>city</dt> <dd> <t>$.entitySearchResults[*].vcardArray[1][?(@[0]=="adr")][3][3]</t> </dd> </dl> </li> </ul> <t>Additional notes on the provided jsonpaths:</t><t><list style="symbols"> <t>those<ul> <li> <t>Those related to the event dates are defined only for the"domain""domain" object. To obtain the equivalent jsonpaths for"entity""entity" and"nameserver","nameserver", the path segment"domainSearchResults""domainSearchResults" must be replaced with"entitySearchResults""entitySearchResults" and"nameserverSearchResults" respectively;<vspace blankLines='1' /></t> <t>those"nameserverSearchResults", respectively.</t> </li> <li>Those related to jCard elements are specified without taking into account the"pref""pref" parameter. Servers that sort those values identified by thepref"pref" parameterSHOULD<bcp14>SHOULD</bcp14> update a jsonpath by adding an appropriate filter. For example, if the email values identified bypref="1"pref="1" are considered for sorting, the jsonpath of the"email""email" sorting property shouldbe: $.entitySearchResults[*].vcardArray[1][?(@[0]=="email"be $.entitySearchResults[*].vcardArray[1][?(@[0]=="email" &&@[1].pref=="1")][3]</t> </list></t>@[1].pref=="1")][3].</li> </ul> </section> <sectionanchor="sorting_links" title="Representinganchor="sorting_links"> <name>Representing SortingLinks">Links</name> <t>An RDAP serverMAY<bcp14>MAY</bcp14> use the"links""links" array of the"sorting_metadata""sorting_metadata" element to provide ready-made references <xref target="RFC8288"/> to the available sort criteria (<xref target="sort-link-in-response-example"/>). Each link represents a reference to an alternate view of the results.</t> <t>The"value", "rel""value", "rel", and"href""href" JSON valuesMUST<bcp14>MUST</bcp14> be specified. All other JSON values areOPTIONAL.</t><bcp14>OPTIONAL</bcp14>.</t> <figureanchor="sort-link-in-response-example" title="Exampleanchor="sort-link-in-response-example"> <name>Example of a"sorting_metadata" instance"sorting_metadata" Instance toimplement result sorting"> <artwork xml:space="preserve"><![CDATA[Implement Result Sorting</name> <sourcecode type="json"> { "rdapConformance": [ "rdap_level_0", "sorting" ], ... "sorting_metadata": { "currentSort": "name", "availableSorts": [ { "property": "registrationDate", "jsonPath": "$.domainSearchResults[*] .events[?(@.eventAction==\"registration\")].eventDate", "default": false, "links": [ { "value": "https://example.com/rdap/domains?name=example*.com&sort=name",&sort=name", "rel": "alternate", "href": "https://example.com/rdap/domains?name=example*.com&sort=registrationDate",&sort=registrationDate", "title": "Result Ascending Sort Link", "type": "application/rdap+json" }, { "value": "https://example.com/rdap/domains?name=example*.com&sort=name",&sort=name", "rel": "alternate", "href": "https://example.com/rdap/domains?name=example*.com&sort=registrationDate:d",&sort=registrationDate:d", "title": "Result Descending Sort Link", "type": "application/rdap+json" } ] }, ... ] }, "domainSearchResults": [ ... ] }]]></artwork></sourcecode> </figure> </section> </section> <sectionanchor="cursor-parameter" title=""cursor" Parameter">anchor="cursor-parameter"> <name>"cursor" Parameter</name> <t>Thecursor"cursor" parameter defined in this specification can be used to encode information about any pagination method. For example, in the case of a simple implementation of thecursor"cursor" parameter to represent offset pagination information, thecursor"cursor" value"b2Zmc2V0PTEwMCxsaW1pdD01MA==""b2Zmc2V0PTEwMCxsaW1pdD01MA==" is theBase64base64 encoding of"offset=100,limit=50"."offset=100,limit=50". Likewise, in a simple implementation to represent keyset pagination information, thecursor"cursor" value"ZXhhbXBsZS1OLmNvbQ==""ZXhhbXBsZS1OLmNvbQ==" represents theBase64base64 encoding of"key=example-N.com""key=example-N.com" whereby the key value identifies the last row of the current page.</t> <t>Note that this specification uses aBase64base64 encoding for cursor obfuscation just for example. RDAP servers areNOT RECOMMENDED<bcp14>NOT RECOMMENDED</bcp14> to obfuscatea cursorthe "cursor" value through a mereBase64base64 encoding.</t> <t>This solution lets RDAP providers implement a pagination method according to their needs, a user's access level, and the submitted query. Besides, servers can change the method over time without announcing anything to clients. The considerations that have led to this solution are described in more detail in <xref target="approaches-to-result-pagination"/>.</t> <t>The ABNF syntax of thecursor"cursor" parameter is the following:</t><t><list style="empty"> <t>cursor<sourcecode type="abnf"> cursor ="cursor=""cursor=" 1*( ALPHA / DIGIT /"/""/" /"=""=" /"-""-" /"_" )</t> </list></t>"_" ) </sourcecode> <t>The following is an example of an RDAP query including the"cursor""cursor" parameter:</t> <t>https://example.com/rdap/domains?name=example*.com &cursor=wJlCDLIl6KTWypN7T6vc6nWEmEYe99Hjf1XY1xmqV-M= </t> <sectionanchor="cursor_paging_links" title="Representinganchor="cursor_paging_links"> <name>Representing PagingLinks">Links</name> <t>An RDAP serverSHOULD<bcp14>SHOULD</bcp14> use the"links""links" array of the"paging_metadata""paging_metadata" element to provide a ready-made reference <xref target="RFC8288"/> to the next page of the result set (<xref target="cursor-pagination-link-in-response-example"/>). Examples of additional"rel""rel" values a serverMAY<bcp14>MAY</bcp14> implement are"first", "last","first", "last", and"prev".</t>"prev".</t> <figureanchor="cursor-pagination-link-in-response-example" title="Exampleanchor="cursor-pagination-link-in-response-example"> <name>Example of a"paging_metadata" instance"paging_metadata" Instance toimplement cursor pagination"> <artwork xml:space="preserve"><![CDATA[Implement Cursor Pagination</name> <sourcecode type="json"> { "rdapConformance": [ "rdap_level_0", "paging" ], ... "notices": [ { "title": "Search query limits", "type": "result set truncated due to excessive load", "description": [ "search results for domains are limited to 50" ] } ], "paging_metadata": { "totalCount": 73, "pageSize": 50, "pageNumber": 1, "links": [ { "value": "https://example.com/rdap/domains?name=example*.com", "rel": "next", "href": "https://example.com/rdap/domains?name=example*.com&cursor=wJlCDLIl6KTWypN7T6vc6nWEmEYe99Hjf1XY1xmqV-M=",&cursor=wJlCDLIl6KTWypN7T6vc6nWEmEYe99Hjf1XY1xmqV-M=", "title": "Result Pagination Link", "type": "application/rdap+json" } ] }, "domainSearchResults": [ ... ] }]]></artwork></sourcecode> </figure> </section> </section> </section> <sectionanchor="negative-answers" title="Negative Answers">anchor="negative-answers"> <name>Negative Answers</name> <t>The constraints for theparametersvalues of parameters are defined by their ABNF syntax. Therefore, each request that includes an invalid value for a parameterSHOULD<bcp14>SHOULD</bcp14> produce an HTTP 400 (Bad Request) response code. The same responseSHOULD<bcp14>SHOULD</bcp14> be returned in the following cases:<list style="symbols"></t> <ul> <li> <t>ifin bothsorting by either singleand multi sortor multiple properties, the client provides an unsupported value for the"sort""sort" parameter, as well as a value related to an object property not included in theresponse;<vspace blankLines='1' /></t> <t>ifresponse </t> </li> <li>if the client submits an invalid value for the"cursor" parameter.</t> </list></t>"cursor" parameter</li> </ul> <t>Optionally, the responseMAY<bcp14>MAY</bcp14> include additional information regarding either the supported sorting properties or the correctcursor values"cursor" value in the HTTP entity body (<xref target="sorting-property-error"/>).</t> <figureanchor="sorting-property-error" title="Exampleanchor="sorting-property-error"> <name>Example of RDAPerror response dueError Response Due to aninvalid domain sorting property includedInvalid Domain Sorting Property Included in therequest"> <artwork xml:space="preserve">Request</name> <sourcecode type="json"> { "errorCode": 400, "title": "Domain sorting property'unknownproperty''unknown' is not valid", "description": [ "Supported domain sorting propertiesare: 'aproperty', 'anotherproperty'."are:" "'aproperty', 'anotherproperty'" ] }</artwork></sourcecode> </figure> </section> <sectionanchor="implementation-considerations" title="Implementation Considerations">anchor="implementation-considerations"> <name>Implementation Considerations</name> <t>Implementation of the new parameters is technically feasible, as operators for counting,sortingsorting, and paging are currently supported by the major relational database management systems. Similar operators are completely or partially supported by the most well-known NoSQL databases(e.g.(e.g., MongoDB, CouchDB, HBase, Cassandra,Hadoop).Hadoop, etc.). Additional implementation notes are included in <xref target="additional-implementation-notes"/>.</t> </section> <sectionanchor="IANA-considerations" title="IANA Considerations">anchor="IANA-considerations"> <name>IANA Considerations</name> <t>IANAis requested to registerhas registered the following values in theRDAP Extensions Registry:</t> <t><list style="none"> <t>Extension"RDAP Extensions" registry:</t> <dl spacing="compact"> <dt>Extension identifier:paging</t> <t>Registry</dt> <dd>paging </dd> <dt>Registry operator:Any</t> <t>Published</dt> <dd>Any </dd> <dt>Published specification:This document.</t> <t>Contact: IETF <iesg@ietf.org></t> <t>Intended</dt> <dd>RFC 8977 </dd> <dt>Contact: </dt> <dd>IETF <iesg@ietf.org> </dd> <dt>Intended usage:This</dt> <dd>This extension describes a best practice for result setpaging.</t> </list></t> <t><list style="none"> <t>Extensionpaging. </dd> </dl> <dl spacing="compact"> <dt>Extension identifier:sorting</t> <t>Registry</dt> <dd>sorting </dd> <dt>Registry operator:Any</t> <t>Published</dt> <dd>Any </dd> <dt>Published specification:This document.</t> <t>Contact: IETF <iesg@ietf.org></t> <t>Intended</dt> <dd>RFC 8977 </dd> <dt>Contact: </dt> <dd>IETF <iesg@ietf.org> </dd> <dt>Intended usage:This</dt> <dd>This extension describes a best practice for result setsorting.</t> </list></t>sorting. </dd> </dl> </section> <sectionanchor="impl-status" title="Implementation Status"> <t>NOTE: Please removeanchor="security-considerations"> <name>Security Considerations</name> <t>Security services for the operations specified in thissectiondocument are described in <xref target="RFC7481"/>.</t> <t>A search query typically requires more server resources (such as memory, CPU cycles, andthe reference to RFC 7942 priornetwork bandwidth) when compared topublication as an RFC.</t> <t>This section recordsa lookup query. This increases thestatusrisk ofknown implementations of the protocol defined by this specification at the time of posting of this Internet-Draft, and is based on a proposal described in <xref target="RFC7942"/>. The description of implementations in this section is intended to assist the IETF in its decision processes in progressing drafts to RFCs. Please note that the listing of any individual implementation here does not imply endorsement by the IETF. Furthermore, no effort has been spent to verify the information presented here that was supplied by IETF contributors. This is not intended as, and must not be construed to be, a catalog of available implementations or their features. Readers are advised to note that other implementations may exist.</t> <t>According to RFC 7942, "this will allow reviewers and working groups to assign due consideration to documents that have the benefit of running code, which may serve as evidence of valuable experimentation and feedback that have made the implemented protocols more mature. It is up to the individual working groups to use this information as they see fit".</t> <section anchor="iit-cnr-registro-it" title="IIT-CNR/Registro.it"> <t><list style="none"> <t>Responsible Organization: Institute of Informatics and Telematics of the National Research Council (IIT-CNR)/Registro.it</t> <t>Location: https://rdap.pubtest.nic.it/</t> <t>Description: This implementation includes support for RDAP queries using data from .it public test environment.</t> <t>Level of Maturity: This is an "alpha" test implementation.</t> <t>Coverage: This implementation includes all of the features described in this specification.</t> <t>Contact Information: Mario Loffredo, mario.loffredo@iit.cnr.it</t> </list></t> </section> <section anchor="apnic" title="APNIC"> <t><list style="none"> <t>Responsible Organization: Asia-Pacific Network Information Centre</t> <t>Location: https://github.com/APNIC-net/rdap-rmp-demo/tree/sorting-and-paging</t> <t>Description: A proof-of-concept for RDAP mirroring.</t> <t>Level of Maturity: This is a proof-of-concept implementation.</t> <t>Coverage: This implementation includes all of the features described in the specification except for nameserver sorting and unicodeName sorting.</t> <t>Contact Information: Tom Harrison, tomh@apnic.net</t> </list></t> </section> </section> <section anchor="security-considerations" title="Security Considerations"> <t>Security services for the operations specified in this document are described in <xref target="RFC7481"/>.</t> <t>A search query typically requires more server resources (such as memory, CPU cycles, and network bandwidth) when compared to a lookup query. This increases the risk of server resource exhaustion and subsequent denialserver resource exhaustion and subsequent denial of service. This risk can be mitigated by either restricting search functionality or limiting the rate of search requests. Servers can also reduce their load by truncating the results in a response. However, this last security policy can result in a higher inefficiency or risk due to acting on incomplete information if the RDAP server does not provide any functionality to return the truncated results.</t> <t>The new parameters presented in this document provide RDAP operators with a way to implement a server that reduces inefficiency risks. The"count""count" parameter gives the client the ability to evaluate the completeness of a response. The"sort""sort" parameter allows the client to obtain the most relevant information at the beginning of the result set. This can reduce the number of unnecessary search requests. Finally, the"cursor""cursor" parameter enables the user to scroll the result set by submitting a sequence of sustainable queries within server-acceptable limits.</t> </section> </middle> <back><references title="Normative References"> &RFC2119; &RFC5234; &RFC5890; &RFC6350; &RFC7095; &RFC7230; &RFC7231; &RFC7480; &RFC7481; &RFC7482; &RFC7483; &RFC7942; &RFC8174; &RFC8259; &RFC8288; &RFC8605;<references> <name>References</name> <references> <name>Normative References</name> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.2119.xml"/> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.5234.xml"/> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.5890.xml"/> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.6350.xml"/> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.7095.xml"/> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.7230.xml"/> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.7231.xml"/> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.7480.xml"/> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.7481.xml"/> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.7482.xml"/> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.7483.xml"/> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8174.xml"/> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8259.xml"/> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8288.xml"/> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8605.xml"/> </references><references title="Informative References"><references> <name>Informative References</name> <referenceanchor='CURSOR' target='https://www.sitepoint.com/paginating-real-time-data-cursor-based-pagination/'>anchor="CURSOR" target="https://www.sitepoint.com/paginating-real-time-data-cursor-based-pagination/"> <front> <title>Paginating Real-Time Data withKeysetCursor Based Pagination</title> <authorinitials='R.' surname='Nimesh' fullname='Rakhitha Nimesh'>initials="R." surname="Nimesh" fullname="Rakhitha Nimesh"> </author> <dateyear='2014' month='July' />year="2014" month="July"/> </front> </reference> <referenceanchor='CURSOR-API1' target='https://developers.facebook.com/docs/graph-api/using-graph-api'>anchor="CURSOR-API1" target="https://developers.facebook.com/docs/graph-api/using-graph-api"> <front><title>facebook<title>Facebook fordevelopers -Developers -- Using the Graph API</title> <author><organization>facebook.com</organization><organization>Facebook</organization> </author> <dateyear='2017' month='July'/> </front> </reference> <referenceanchor='CURSOR-API2' target='https://developer.twitter.com/en/docs/ads/general/guides/pagination.html'>anchor="CURSOR-API2" target="https://developer.twitter.com/en/docs/twitter-ads-api"> <front><title>Pagination</title><title>Twitter Ads API</title> <author><organization>twitter.com</organization><organization>Twitter</organization> </author> <dateyear='2017'/>/> </front> </reference> <referenceanchor='GOESSNER-JSON-PATH' target='http://goessner.net/articles/JsonPath/'>anchor="GOESSNER-JSON-PATH" target="https://goessner.net/articles/JsonPath/"> <front> <title>JSONPath - XPath for JSON</title> <authorinitials='S.' surname='Goessner' fullname='Stefan Goessner'>initials="S." surname="Goessner" fullname="Stefan Goessner"> </author> <dateyear='2007'/>year="2007" month="February"/> </front> </reference> <referenceanchor='HATEOAS' target='https://www.e4developer.com/2018/02/16/hateoas-simple-explanation/'>anchor="HATEOAS" target="https://www.e4developer.com/2018/02/16/hateoas-simple-explanation/"> <front> <title>HATEOAS - a simple explanation</title> <authorinitials='B.' surname='Jedrzejewski' fullname='Bartosz Jedrzejewski'>initials="B." surname="Jedrzejewski" fullname="Bartosz Jedrzejewski"> </author> <dateyear='2018'/>year="2018" month="February"/> </front> </reference> <referenceanchor='JSONPATH-COMPARISON' target='https://cburgmer.github.io/json-path-comparison/'>anchor="JSONPATH-COMPARISON" target="https://cburgmer.github.io/json-path-comparison/"> <front> <title>JSONPath Comparison</title> <author/> <dateyear='2020'/>/> </front> </reference> <referenceanchor='JSONPATH-WG' target='https://datatracker.ietf.org/wg/jsonpath/documents/'>anchor="JSONPATH-WG" target="https://datatracker.ietf.org/wg/jsonpath/about/"> <front> <title>JSON Path (jsonpath)</title><author/> <date year='2020'/><author><organization>IETF</organization></author> <date/> </front> </reference> <referenceanchor='OData-Part1' target='http://docs.oasis-open.org/odata/odata/v4.0/errata03/os/complete/part1-protocol/odata-v4.0-errata03-os-part1-protocol-complete.pdf'>anchor="ODATA-PART1" target="https://docs.oasis-open.org/odata/odata/v4.0/errata03/os/complete/part1-protocol/odata-v4.0-errata03-os-part1-protocol-complete.pdf"> <front> <title>OData Version 4.0. Part 1: Protocol Plus Errata 03</title> <authorinitials='M.' surname='Pizzo' fullname='Michael Pizzo'>initials="M." surname="Pizzo" fullname="Michael Pizzo"> </author> <authorinitials='R.' surname='Handl' fullname='Ralf Handl'>initials="R." surname="Handl" fullname="Ralf Handl"> </author> <authorinitials='M.' surname='Zurmuehl' fullname='Martin Zurmuehl'>initials="M." surname="Zurmuehl" fullname="Martin Zurmuehl"> </author> <dateyear='2016' month='June' />year="2016" month="June"/> </front> </reference> <referenceanchor='REST' target='http://www.ics.uci.edu/~fielding/pubs/dissertation/fielding_dissertation.pdf'>anchor="REST" target="https://www.ics.uci.edu/~fielding/pubs/dissertation/fielding_dissertation.pdf"> <front> <title>Architectural Styles and the Design of Network-based Software Architectures</title> <authorinitials='R.' surname='Fielding' fullname='Royinitials="R." surname="Fielding" fullname="Roy ThomasFielding'>Fielding"> <organization>PH.D. DISSERTATION, UNIVERSITY OF CALIFORNIA, IRVINE</organization> </author> <dateyear='2000'/>year="2000"/> </front> </reference>&RFC6901;<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.6901.xml"/> <referenceanchor='SEEK' target='https://www.eversql.com/faster-pagination-in-mysql-why-order-by-with-limit-and-offset-is-slow/'>anchor="SEEK" target="https://www.eversql.com/faster-pagination-in-mysql-why-order-by-with-limit-and-offset-is-slow/"> <front> <title>Faster Pagination in Mysql - Why Order By With Limit and Offset is Slow?</title> <author><organization>EverSQL.com</organization><organization>EverSQL</organization> </author> <dateyear='2017' month='July' />year="2017" month="July"/> </front> </reference> <reference anchor="W3C.CR-xpath-31-20170321" target="https://www.w3.org/TR/2017/REC-xpath-31-20170321/"> <front> <title>XML Path Language (XPath) 3.1</title> <author initials="J." surname="Robie" fullname="Jonathan Robie"> <organization/> </author> <author initials="M." surname="Dyck" fullname="Michael Dyck"> <organization/> </author> <author initials="J." surname="Spiegel" fullname="Josh Spiegel"> <organization/> </author> <date month="March" year="2017"/> </front> <refcontent>World Wide Web Consortium Recommendation REC-xpath-31-20170321</refcontent> </reference>&W3C.CR-xpath-31-20161213;</references> </references> <sectionanchor="jsonpath-operators" title="JSONPath operators">anchor="jsonpath-operators"> <name>JSONPath Operators</name> <t>The jsonpaths used in this document are provided according to the Goessnerv.0.8.0proposal <xref target="GOESSNER-JSON-PATH"/>.</t> <t>Such specification requires that implementations support a set of"basic operators"."basic operators". These operators are used to access the elements of a JSON structure like objects and arrays,andas well as theirsubelements, respectively, objectsubelements (object members and arrayitems.items, respectively). No operations are defined for retrieving parent or sibling elements of a given element. The root element is always referred to as $ regardless of it being an object or array.</t> <t>Additionally, the specification permits implementations to support arbitrary script expressions. These can be used to index into an object or array, or to filter elements from an array. While script expression behavior is implementation-defined, most implementations support the basic relational and logicaloperators,operators as well as both object member and array item access, sufficiently similar for the purpose of this document.Commonly-supportedCommonly supported operators/functions divided into"top-level operators""top-level operators" and"filter operators""filter operators" are documented in Tables <xreftarget="table_json_path_top_level_operators"/>target="table_json_path_top_level_operators" format="counter"/> and <xreftarget="table_json_path_filter_operators"/>target="table_json_path_filter_operators" format="counter"/>, respectively.</t> <t>For more information on implementation interoperability issues, see[JSONPATH-COMPARISON]. As at<xref target="JSONPATH-COMPARISON" format="default"/>. At the time of writing, work is beginning on a standardizationeffort, too: see [JSONPATH-WG].</t> <texttable anchor="table_json_path_top_level_operators" title="JSONPath Top-Level Operators"> <ttcol align="left">Operator</ttcol> <ttcol align="left">Description</ttcol> <c>$</c><c>Root element</c> <c>.<name></c><c>Object membereffort too (see <xref target="JSONPATH-WG" format="default"/>).</t> <table anchor="table_json_path_top_level_operators"> <name>JSONPath Top-Level Operators</name> <thead> <tr> <th align="left">Operator</th> <th align="left">Description</th> </tr> </thead> <tbody> <tr> <td align="left">$</td> <td align="left">Root element</td> </tr> <tr> <td align="left">.<name></td> <td align="left">Object member access(dot-notation)</c> <c>['<name>']</c><c>Object(dot-notation)</td> </tr> <tr> <td align="left">['<name>']</td> <td align="left">Object member access(bracket-notation)</c> <c>[<number>]</c><c>Array(bracket-notation)</td> </tr> <tr> <td align="left">[<number>]</td> <td align="left">Array itemaccess</c> <c>*</c><c>Allaccess</td> </tr> <tr> <td align="left">*</td> <td align="left">All elements within the specifiedscope</c> <c>[?(<expression>)]</c><c>Filter expression</c> </texttable> <texttable anchor="table_json_path_filter_operators" title="JSONPathscope</td> </tr> <tr> <td align="left">[?(<expression>)]</td> <td align="left">Filter expression</td> </tr> </tbody> </table> <table anchor="table_json_path_filter_operators"> <name>JSONPath FilterOperators"> <ttcol align="left">Operator</ttcol> <ttcol align="left">Description</ttcol> <c>@</c><c>CurrentOperators</name> <thead> <tr> <th align="left">Operator</th> <th align="left">Description</th> </tr> </thead> <tbody> <tr> <td align="left">@</td> <td align="left">Current element beingprocessed</c> <c>.<name></c><c>Objectprocessed</td> </tr> <tr> <td align="left">.<name></td> <td align="left">Object memberaccess</c> <c>.[<name1>,<name2>]</c><c>Unionaccess</td> </tr> <tr> <td align="left">.[<name1>,<name2>]</td> <td align="left">Union of objectmembers</c> <c>[<number>]</c><c>Arraymembers</td> </tr> <tr> <td align="left">[<number>]</td> <td align="left">Array itemaccess</c> <c>==</c><c>Leftaccess</td> </tr> <tr> <td align="left">==</td> <td align="left">Left is equal toright</c> <c>!=</c><c>Leftright</td> </tr> <tr> <td align="left">!=</td> <td align="left">Left is not equal toright</c> <c><</c><c>Leftright</td> </tr> <tr> <td align="left"><</td> <td align="left">Left is less thanright</c> <c><=</c><c>Leftright</td> </tr> <tr> <td align="left"><=</td> <td align="left">Left is less than or equal toright</c> <c>></c><c>Leftright</td> </tr> <tr> <td align="left">></td> <td align="left">Left is greater thanright</c> <c>>=</c><c>Leftright</td> </tr> <tr> <td align="left">>=</td> <td align="left">Left is greater than or equal toright</c> <c>&&</c><c>Logical conjunction</c> <c>||</c><c>Logical disjunction</c> </texttable>right</td> </tr> <tr> <td align="left">&&</td> <td align="left">Logical conjunction</td> </tr> <tr> <td align="left">||</td> <td align="left">Logical disjunction</td> </tr> </tbody> </table> </section> <sectionanchor="approaches-to-result-pagination" title="Approachesanchor="approaches-to-result-pagination"> <name>Approaches to ResultPagination">Pagination</name> <t>An RDAP query could return a response with hundreds, even thousands, of objects, especially when partial matching is used. For this reason, thecursor"cursor" parameter addressing result pagination is defined to make responses easier to handle.</t> <t>Presently, the most popular methods to implement pagination in a REST API include offset pagination and keyset pagination. Neither pagination method requires the server to handle the result set in a storage area across multiple requests since a new result set is generated each time a request is submitted. Therefore, they are preferred to any other method requiring the management of a REST session.</t> <t>Using limit and offset operators represents the traditionally used method to implement result pagination. Both of them can be used individually:<list style="symbols"> <t>"limit=N": means</t> <dl> <dt>"limit=N": </dt> <dd>means that the server returns the first N objects of the resultset;<vspace blankLines='1' /></t> <t>"offset=N": meansset </dd> <dt>"offset=N": </dt> <dd>means that the server skips the first N objects and returns objects starting from positionN+1.</t> </list></t>N+1 </dd> </dl> <t>When limit and offset are used together, they provide the ability to identify a specific portion of the result set. For example, the pair"offset=100,limit=50""offset=100,limit=50" returns the first 50 objects starting from position 101 of the result set.</t> <t>Though easy to implement, offset pagination also includes drawbacks:<list style="symbols"> <t>when</t> <ul> <li> <t>When offset has a very high value, scrolling the result set could take sometime;<vspace blankLines='1' /></t> <t>ittime.</t> </li> <li> <t>It always requires fetching all rows before dropping as many rows as specified byoffset;<vspace blankLines='1' /></t> <t>itoffset.</t> </li> <li>It may return inconsistent pages when data are frequently updated(i.e.(i.e., real-timedata).</t> </list></t>data).</li> </ul> <t>Keyset pagination <xref target="SEEK"/> adds a query condition that enables the selection of the only data not yet returned. This method has been taken as the basis for the implementation of a"cursor""cursor" parameter <xref target="CURSOR"/> by some REST API providers <xref target="CURSOR-API1"/> <xref target="CURSOR-API2"/>. The cursor isana URL-safe string opaque to the clientURL-safe stringand representing a logical pointer to the first result of the next page.</t> <t>Nevertheless, even keyset pagination can be troublesome:<list style="symbols"> <t>it</t> <ul> <li> <t>It needs at least one keyfield;<vspace blankLines='1' /></t> <t>itfield.</t> </li> <li> <t>It does not allow sorting simply by any field because the sorting criterion must contain akey;<vspace blankLines='1' /></t> <t>itkey.</t> </li> <li> <t>It works best with full composite valuessupportsupported bydata basedatabase management systems(i.e. [x,y]>[a,b]),(i.e., [x,y]>[a,b]); emulation is possible but inelegant and lessefficient;<vspace blankLines='1' /></t> <t>itefficient.</t> </li> <li> <t>It does not allow direct navigation to arbitrary pages because the result set must be scrolled in sequential order starting from the initialpage;<vspace blankLines='1' /></t> <t>implementing bi-directionalpage.</t> </li> <li>Implementing bidirectional navigation is tedious because all comparison and sort operations have to bereversed.</t> </list></t>reversed.</li> </ul> <sectionanchor="pagination-in-rdap" title="Specificanchor="pagination-in-rdap"> <name>Specific Issues Raised byRDAP">RDAP</name> <t>Some additional considerations can be made in the RDAP context:<list style="symbols"> <t>an</t> <ul> <li> <t>An RDAP object is a conceptual aggregation of information generally collected from more than one data structure(e.g. table)(e.g., table), and this makes it even harder to implement keyset pagination, a task that is already quite difficult. For example, the entity object can include information from different data structures (registrars, registrants, contacts, resellers), each one with its key field mapping the RDAP entityhandle;<vspace blankLines='1' /></t> <t>dependinghandle.</t> </li> <li> <t>Depending on the number of page results as well as the number and the complexity of the properties of each RDAP object in the response, the time required by offset pagination to skip the previous pages could be much faster than the processing time needed to build the current page. In fact, RDAP objects are usually formed by information belonging to multiple data structures and containing multivalued properties(i.e. arrays) and,(i.e., arrays); therefore, data selection mightthereforebe atime consumingtime-consuming process. This situation occurs even though the selection is supported byindexes;<vspace blankLines='1' /></t> <t>dependingindexes.</t> </li> <li>Depending on the access levels defined by each RDAP operator, the increase in complexity and the decrease in flexibility of keyset pagination in comparison to offset pagination could be consideredimpractical.</t> </list></t>impractical.</li> </ul> <t>Ultimately, both pagination methods have benefits and drawbacks.</t> </section> </section> <sectionanchor="additional-implementation-notes" title="Additional Implementation Notes">anchor="additional-implementation-notes"> <name>Implementation Notes</name> <t>This section contains an overview of the main choices made during the implementation of the capabilities definedabovein this document in the RDAP public test server of Registro.it at the Institute of Informatics and Telematics of the National ResearchCounciCouncil (IIT-CNR). The content of this section can representaguidance forthoseimplementers who plan to provide RDAP users with those capabilities. The RDAP public test server can be accessed athttps://rdap.pubtest.nic.it/.<eref target="https://rdap.pubtest.nic.it/" brackets="angle"/>. Further documentation about the server features is available athttps://rdap.pubtest.nic.it/doc/README.html.</t> <section title="Sorting"><eref target="https://rdap.pubtest.nic.it/doc/README.html" brackets="angle"/>.</t> <section> <name>Sorting</name> <t>If no sort criterion is specified in the query string, the results are sorted by a default property:"name""name" for domains and nameservers,"handle"and "handle" for entities. The server supports multiple property sorting but the"sorting_metadata""sorting_metadata" object includes only the links to alternative result set views sorted by a single property just to show the list of sorting properties allowed for each searchable object. The server supports all theobject specificobject-specific sorting properties described in the specification except for nameserver sorting based on unicodeName, that is, the"name""name" sorting property is mapped onto the"ldhName""ldhName" response field. Regarding theobject commonobject-common properties,thesorting by registrationDate, expirationDate,lastChangedDatelastChangedDate, and transferDate is supported.</t> </section><section title="Counting"><section> <name>Counting</name> <t>The counting operation is implemented through a separate query. Some relational database management systems support custom operators to get the total count together with the rows, but the resulting query can be considerably more expensive than that performed without the total count. Therefore, as"totalCount""totalCount" is an optional response information,fetchingalways fetching the total number of rows has been considered an inefficient solution. Furthermore, to avoid the processing of unnecessary queries, when the"count""count" parameter is included in the submitted query, it is not also repeated in the query strings of the"links""links" array provided in both"paging_metadata""paging_metadata" and"sorting_metadata""sorting_metadata" objects.</t> </section><section title="Paging"><section> <name>Paging</name> <t>The server implements the cursor pagination through the keyset pagination when sorting by a unique property is requested or the default sort isapplied,applied. Otherwise, it implements the cursor pagination through the offsetpagination otherwise.pagination. As mostof therelational database management systems don't support the comparison of full composite values natively, the implementation of full keyset pagination seem to be troublesome so, at least initially, a selective applicability of keyset pagination is advisable. Moreover, the"cursor""cursor" value encodes not only information about pagination but also about the search pattern and the other query parameters in order to check the consistency of the entire query string. If the"cursor""cursor" value is inconsistent with the rest of the query string, the server returns an error response.</t> </section> </section> <sectiontitle="Acknowledgements" numbered="no">numbered="false"> <name>Acknowledgements</name> <t>The authors would like to acknowledgeBrian Mountford, Tom Harrison, Karl<contact fullname="Brian Mountford"/>, <contact fullname="Tom Harrison"/>, <contact fullname="Karl HeinzWolf, Jasdip Singh, Erik Kline, Éric Vyncke, Benjamin Kaduk and Roman DanyliwWolf"/>, <contact fullname="Jasdip Singh"/>, <contact fullname="Erik Kline"/>, <contact fullname="Éric Vyncke"/>, <contact fullname="Benjamin Kaduk"/>, and <contact fullname="Roman Danyliw"/> for theircontributioncontributions to the development of this document.</t></section> <section title="Change Log" numbered="no"> <t> <list style="hanging"> <t hangText="00:">Initial working group version ported from draft-loffredo-regext-rdap-sorting-and-paging-05</t> <t hangText="01:">Removed both "offset" and "nextOffset" to keep "paging_metadata" consistent between the pagination methods. Renamed "Considerations about Paging Implementation" section in ""cursor" Parameter". Removed "FOR DISCUSSION" items. Provided a more detailed description of both "sorting_metadata" and "paging_metadata" objects.</t> <t hangText="02:">Removed both "offset" and "limit" parameters. Added ABNF syntax of the cursor parameter. Rearranged the layout of some sections. Removed some items from "Informative References" section. Changed "IANA Considerations" section.</t> <t hangText="03:">Added "cc" to the list of sorting properties in "Sorting Properties Declaration" section. Added RFC8605 to the list of "Informative References".</t> <t hangText="04:">Replaced "ldhName" with "name" in the "Sorting Properties Declaration" section. Clarified the sorting logic for the JSON value types and the sorting policy for multivalued fields.</t> <t hangText="05:">Clarified the logic of sorting on IP addresses. Clarified the mapping between the sorting properties and the RDAP response fields. Updated "Acknowledgements" section.</t> <t hangText="06:">Renamed "pageCount" to "pageSize" and added "pageNumber" in the "paging_metadata" object.</t> <t hangText="07:">Added "Paging Responses to POST Requests" section.</t> <t hangText="08:">Added "Approaches to Result Pagination" section to appendix. Added the case of requesting a sort on a property not included in the response to the errors listed in the "Negative Answers" section.</t> <t hangText="09:">Updated the "Implementation Status" section to include APNIC implementation. Moved the "RDAP Conformance" section up in the document. Removed the "Paging Responses to POST Requests" section. Updated the "Acknowledgements" section. Removed unused references. In the "Sorting Properties Declaration" section: <list style="symbols"> <t>clarified the logic of sorting on events;</t> <t>corrected the jsonpath of the "lastChanged" sorting property;</t> <t>provided a JSONPath example taking into account the vCard "pref" parameter.</t> </list> </t> <t hangText="10:">Corrected the jsonpaths of both "fn" and "org" sorting properties in Table 2. Corrected JSON content in <xref target="sort-link-in-response-example"/>. Moved <xref target="W3C.CR-xpath-31-20161213"/> and <xref target="RFC7942"/> to the "Normative References". Changed the rdapConformance tags "sorting_level_0" and "paging_level_0" to "sorting" and "paging" respectively.</t> <t hangText="11:">Added the "JSONPath operators" section to appendix.</t> <t hangText="12:">Changed the content of "JSONPath operators" section.</t> <t hangText="13:">Minor pre-AD review edits.</t> <t hangText="14:">Additionl minor pre-AD review edits.</t> <t hangText="15:">In section ""sort" Parameter" added a paragraph providing conversions of IP addresses into their numerical representations. In section "Sorting Properties Declaration" rearranged Table 2 in a list to make the content more readable. Other minor edits due to AD review.</t> <t hangText="16:">In section "Introduction" replaced "... large result set that could be truncated ..." with "... large result set that is often truncated ..." as suggested by Gen-ART reviewer. Added <xref target="additional-implementation-notes"/>.</t> <t hangText="17:">Edits made: <list style="symbols"> <t>in the "Sorting and Paging Metadata" section: <list style="symbols"> <t>replaced "Members are:" with "The AvailableSort object includes the following members:";</t> <t>clarified that an RDAP server MUST define only one default sorting property for each object class;</t> </list> </t> <t>in the "Negative Answers" section: <list style="symbols"> <t>replaced the phrase "the response MAY include additional information regarding the negative answer" with the phrase "the response MAY include additional information regarding either the supported sorting properties or the correct cursor value";</t> <t>added a new example;</t> </list> </t> <t>clarified the required members of a Link object in the "Representing Sorting Links" section;</t> <t>corrected the [REST] reference in the "Informative References" section;</t> <t>replaced the phrase "and subsequent denial of service due to abuse" with the phrase "and subsequent denial of service" in "Security Considerations" section.</t> </list> </t> <t hangText="18:">Edits made: <list style="symbols"> <t>in the "Introduction" section: <list style="symbols"> <t>revised the reasons for using query parameters instead of HTTP headers;</t> </list> </t> <t>in the "Sorting and Paging Metadata" section: <list style="symbols"> <t>replaced the phrase "number of objects returned in the current page" with the phrase "number of objects that should have been returned in the current page" in the definition of the "pageSize" field;</t> </list> </t> <t>in the ""sort" Parameter" section: <list style="symbols"> <t>clarified the sorting logic for values denoting dates and times;</t> <t>replaced the IPv6 address "2001:0db8:85a3:0000:0000:8a2e:0370:7334" with "2001:0db8:85a3:0:0:8a2e:0370:7334";</t> </list> </t> <t>in the "Sorting Properties Declaration" section: <list style="symbols"> <t>replaced the sorting properties "ipV4" and "ipV6" with "ipv4" and "ipv6";</t> <t>replaced the sentence "Therefore, the assumption of having a single IPv4 and/or IPv6 value for a nameserver cannot be considered too stringent." with the sentence "Therefore, this specification makes the assumption that nameservers have a single IPv4 and/or IPv6 value."</t> <t>clarified that the sorting properties MUST NOT be used with a with a meaning other than the one described this document;</t> <t>specified that JSONPath operators used in this section are those defined in "Appendix A";</t> </list> </t> <t>in the ""cursor" Parameter" section: <list style="symbols"> <t>corrected the Base64 encoding of "offset=100,limit=50";</t> <t>clarified that RDAP servers are NOT RECOMMENDED to obfuscate a cursor value through a mere Base64 encoding;</t> </list> </t> <t>changed last sentence of second paragraph of the "Security Considerations" section;</t> <t>updated the "Acknowledgements" section;</t> <t>in "Appendix A": <list style="symbols"> <t>changed introductory paragraph;</t> <t>replaced "opaque URL-safe string" with "opaque to client URL-safe string";</t> </list> </t> <t>added JSONPath union operator in Table 2 of "Appendix B"</t> <t>changed the explanation of offset and limit operators in "Appendix B";</t> <t>converted the figures containing only RDAP queries into texts;</t> <t>changed the wildcard prefixed patterns into wildcard suffixed in all the RDAP queries;</t> <t>cleaned the text.</t> </list> </t> <t hangText="19:">Replaced the words "encryption/encrypt" with "obfuscation/obfuscate" in the ""cursor" Parameter" section.</t> <t hangText="20:">Added a final paragraph to <xref target="jsonpath-operators"/> to reference the comparison between JSONPath operators and IETF JSONPath WG web site.</t> </list> </t></section> </back> </rfc>