draft-ietf-regext-rdap-partial-response-10.txt   draft-ietf-regext-rdap-partial-response-11.txt 
Registration Protocols Extensions M. Loffredo Registration Protocols Extensions M. Loffredo
Internet-Draft M. Martinelli Internet-Draft M. Martinelli
Intended status: Standards Track IIT-CNR/Registro.it Intended status: Standards Track IIT-CNR/Registro.it
Expires: October 30, 2020 April 28, 2020 Expires: November 30, 2020 May 29, 2020
Registration Data Access Protocol (RDAP) Partial Response Registration Data Access Protocol (RDAP) Partial Response
draft-ietf-regext-rdap-partial-response-10 draft-ietf-regext-rdap-partial-response-11
Abstract Abstract
The Registration Data Access Protocol (RDAP) does not include The Registration Data Access Protocol (RDAP) does not include
capabilities to request partial responses. In fact, according to the capabilities to request partial responses. Servers will only return
user authorization, the server can only return full responses. A full responses that includes all of the information that a client is
partial response capability, especially in the case of search authorized to receive. A partial response capability that limits the
amount of information returned, especially in the case of search
queries, could bring benefits to both clients and servers. This queries, could bring benefits to both clients and servers. This
document describes an RDAP query extension that allows clients to document describes an RDAP query extension that allows clients to
specify their preference for obtaining a partial response. specify their preference for obtaining a partial response.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on October 30, 2020. This Internet-Draft will expire on November 30, 2020.
Copyright Notice Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
skipping to change at page 2, line 34 skipping to change at page 2, line 35
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 10 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
10.1. Normative References . . . . . . . . . . . . . . . . . . 10 10.1. Normative References . . . . . . . . . . . . . . . . . . 10
10.2. Informative References . . . . . . . . . . . . . . . . . 11 10.2. Informative References . . . . . . . . . . . . . . . . . 11
Appendix A. Approaches to Partial Response Implementation . . . 11 Appendix A. Approaches to Partial Response Implementation . . . 11
A.1. Specific Issues Raised by RDAP . . . . . . . . . . . . . 12 A.1. Specific Issues Raised by RDAP . . . . . . . . . . . . . 12
Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 13 Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14
1. Introduction 1. Introduction
The use of partial response in RESTful API ([REST]) design is very The use of partial responses in RESTful API ([REST]) design is very
common. The rationale is quite simple: instead of returning objects common. The rationale is quite simple: instead of returning objects
in API responses with all data fields, only a subset of fields in in API responses with all data fields, only a subset of the fields in
each result object is returned. The benefit is obvious: less data each result object is returned. The benefit is obvious: less data
transferred over the network means less bandwidth usage, faster transferred over the network means less bandwidth usage, faster
server response, less CPU time spent both on the server and the server responses, less CPU time spent both on the server and the
client, as well as less memory usage on the client. client, and less memory usage on the client.
Several leading APIs providers (e.g. LinkedIn [LINKEDIN], Facebook Several leading API providers (e.g. LinkedIn [LINKEDIN], Facebook
[FACEBOOK], Google [GOOGLE]) implement the partial response feature [FACEBOOK], Google [GOOGLE]) implement partial response features by
by providing an optional query parameter by which users require the providing an optional query parameter by which clients identify the
fields they wish to receive. Partial response is also considered a fields they wish to receive. Support for partial responses is also
leading principle by many best practices guidelines in REST APIs considered a leading principle by many best practice guidelines in
implementation ([REST-API1], [REST-API2]) in order to improve REST API implementation ([REST-API1], [REST-API2]) in order to
performance, save on bandwidth and possibly accelerate the overall improve performance, save on bandwidth and possibly accelerate the
interaction. In other contexts, for example in digital libraries and overall interaction. In other contexts, for example in digital
bibliographic catalogues, servers can provide responses according to libraries and bibliographic catalogues, servers can provide responses
different element sets (i.e. "brief" to get back a short response and according to different element sets (i.e. "brief" to get back a short
"full" to get back the complete response) response and "full" to get back the complete response).
Currently, RDAP does not provide a client with any way to request a Currently, RDAP does not provide a client with any way to request a
partial response: the server can only provide the client with the partial response. Servers can only provide the client with a full
full response ([RFC7483]). Furthermore, servers cannot define the response ([RFC7483]). Servers cannot limit the amount of information
limits of the results according to partial responses and this causes returned in a response based on a client's preferences, and this
strong inefficiencies. creates inefficiencies.
The protocol described in this specification extends RDAP search The protocol described in this specification extends RDAP search
capabilities to enable partial responses through the provisioning of capabilities to enable partial responses through the provisioning of
pre-defined sets of fields the user can request to an RDAP service by pre-defined sets of fields that clients can submit to an RDAP service
adding a new query parameter. The service is implemented using the by adding a new query parameter. The service is implemented using
Hypertext Transfer Protocol (HTTP) ([RFC7230]) and the conventions the Hypertext Transfer Protocol (HTTP) ([RFC7230]) and the
described in RFC 7480 ([RFC7480]). conventions described in RFC 7480 ([RFC7480]).
1.1. Conventions Used in This Document 1.1. Conventions Used in This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 ([RFC2119]). document are to be interpreted as described in BCP 14 [RFC2119]
[RFC8174] when, and only when, they appear in all capitals, as shown
here.
2. RDAP Path Segment Specification 2. RDAP Path Segment Specification
The path segment defined in this section is an OPTIONAL extension of The path segment defined in this section is an OPTIONAL extension of
search path segments defined in RFC 7482 ([RFC7482]). This document search path segments defined in RFC 7482 ([RFC7482]). This document
defines an RDAP query parameter, "fieldSet", whose value is a string defines an RDAP query parameter, "fieldSet", whose value is a string
identifying a server pre-defined set of fields (Figure 1). identifying a server-defined set of supported fields (Figure 1).
This solution can be implemented by the RDAP providers with less
effort than fields selection and easily requested by consumers. The
considerations that has led to opt for this solution are reported in
more detail in Appendix A.
https://example.com/rdap/domains?name=example*.com&fieldSet=afieldset https://example.com/rdap/domains?name=example*.com&fieldSet=afieldset
Figure 1: Example of RDAP search query reporting the "fieldSet" Figure 1: Example of RDAP search query reporting the "fieldSet"
parameter parameter
This solution can be implemented by RDAP providers with less effort
than field selection and is easily requested by clients. The
considerations that have led to this solution are described in more
detail in Appendix A.
2.1. Subsetting Metadata 2.1. Subsetting Metadata
According to most advanced principles in REST design, collectively According to most advanced principles in REST design, collectively
known as HATEOAS (Hypermedia as the Engine of Application State) known as HATEOAS (Hypermedia as the Engine of Application State)
([HATEOAS]), a client entering a REST application through an initial ([HATEOAS]), a client entering a REST application through an initial
URI should use the server-provided links to dynamically discover URI should use server-provided links to dynamically discover
available actions and access the resources it needs. In this way, available actions and access the resources it needs. In this way,
the client is not requested to have prior knowledge of the service the client is not required to have prior knowledge of the service
and, consequently, to hard code the URIs of different resources. and, consequently, to hard code the URIs of different resources.
This would allow the server to make URI changes as the API evolves This allows the server to make URI changes as the API evolves without
without breaking the clients. Definitively, a REST service should be breaking clients. Definitively, a REST service should be as self-
as self-descriptive as possible. descriptive as possible.
Therefore, servers implementing the query parameter described in this Therefore, servers implementing the query parameter described in this
specification SHOULD provide additional information in their specification SHOULD provide additional information in their
responses about the available field sets. Such information is responses about the available field sets. Such information is
collected in a new data structure named "subsetting_metadata" collected in a new data structure named "subsetting_metadata"
containing the following properties: containing the following properties:
o "currentFieldSet": "String" (REQUIRED) either the value of o "currentFieldSet": "String" (REQUIRED) either the value of the
"fieldSet" parameter as specified in the query string or the field "fieldSet" parameter as specified in the query string, or the
set applied by default; field set applied by default;
o "availableFieldSets": "AvailableFieldSet[]" (OPTIONAL) an array of o "availableFieldSets": "AvailableFieldSet[]" (OPTIONAL) an array of
objects each one describing an alternate available field set. objects, with each element describing an available field set.
Members are: Members are:
* "name": "String" (REQUIRED) the field set name; * "name": "String" (REQUIRED) the field set name;
* "default": "Boolean" (REQUIRED) whether the field set is * "default": "Boolean" (REQUIRED) whether the field set is
applied by default; applied by default;
* "description": "String" (OPTIONAL) a human-readable description * "description": "String" (OPTIONAL) a human-readable description
of the field set; of the field set;
* "links": "Link[]" (OPTIONAL) an array of links as described in * "links": "Link[]" (OPTIONAL) an array of links as described in
RFC 8288 ([RFC8288]) containing the query string that applies RFC 8288 ([RFC8288]) containing the query string that applies
the field set. the field set.
skipping to change at page 5, line 43 skipping to change at page 5, line 43
... ...
"domainSearchResults": [ "domainSearchResults": [
... ...
] ]
} }
Figure 2: Example of a "subsetting_metadata" instance Figure 2: Example of a "subsetting_metadata" instance
3. Dealing with Relationships 3. Dealing with Relationships
Some additional considerations can be made about how second level Representation of second level objects within a field set produces
objects could be represented within a field set. In fact, since the additional considerations. Since the topmost objects could be
topmost objects could be returned according to different field sets, returned according to different field sets, the same field sets could
the same thing could go for their related objects. As a consequence, be applied to their related objects. As a consequence, the response
the response could contain either no relationship or associated could contain either no relationship or associated objects which are
objects which are in turn provided according to a field set. in turn provided according to a field set.
4. Basic Field Sets 4. Basic Field Sets
In order to improve interoperability between clients and servers, the This section defines three basic field sets which servers MAY
name, as well as the list of fields for each field set, should be implement to facilitate their interaction with clients:
shared by most of RDAP providers. This section defines three basic
field sets which servers MAY implement to facilitate their
interaction with clients:
o "id": the server provides only the key field, respectively: o "id": the server provides only the key field, respectively:
"handle" for entities, "ldhName" for domains and nameservers. If "handle" for entities, "ldhName" for domains and nameservers. If
a returned domain or nameserver is an IDN ([RFC5890]), then the a returned domain or nameserver is an Internationalized Domain
"unicodeName" field MUST be included in the response. This field Name (IDN, [RFC5890]), then the "unicodeName" field MUST be
set could be used when the client wants to simply obtain a included in the response. This field set could be used when the
collection of object identifiers (Figure 3); client wants to obtain a collection of object identifiers
(Figure 3);
o "brief": it contains the fields that can be included in a "short" o "brief": the field set contains the fields that can be included in
response. This field set could be used when the client is asking a "short" response. This field set could be used when the client
for a subset of the full response which gives a basic knowledge of is asking for a subset of the full response which provides only
each object; basic knowledge of each object;
o "full": it contains all the information the server can provide for o "full": the field set contains all of the information the server
a particular object. can provide for a particular object.
The "objectClassName" field is implicitly included in each of the The "objectClassName" field is implicitly included in each of the
above field sets. RDAP providers are RECOMMENDED to include a "self" above field sets. RDAP providers are RECOMMENDED to include a "self"
link in each field set. RDAP providers MAY also add any property link in each field set. RDAP providers MAY also add any property
providing service information. providing service information.
Fields included in "brief" and "full" field sets could be returned Fields included in the "brief" and "full" field sets MUST be returned
according to the user access levels. according to the user's access and authorization levels.
{ {
"rdapConformance": [ "rdapConformance": [
"rdap_level_0", "rdap_level_0",
"subsetting" "subsetting"
], ],
... ...
"domainSearchResults": [ "domainSearchResults": [
{ {
"objectClassName": "domain", "objectClassName": "domain",
skipping to change at page 7, line 44 skipping to change at page 7, line 44
] ]
}, },
... ...
] ]
} }
Figure 3: Example of RDAP response according to the "id" field set Figure 3: Example of RDAP response according to the "id" field set
5. Negative Answers 5. Negative Answers
Each request including an unsupported field set SHOULD obtain an HTTP Each request including an unsupported field set SHOULD produce an
400 (Bad Request) response code. HTTP 400 (Bad Request) response code. Optionally, the response MAY
include additional information regarding the negative answer in the
Optionally, the response MAY include additional information regarding HTTP entity body.
the negative answer in the HTTP entity body.
6. Implementation Status 6. Implementation Status
NOTE: Please remove this section and the reference to RFC 7942 prior NOTE: Please remove this section and the reference to RFC 7942 prior
to publication as an RFC. to publication as an RFC.
This section records the status of known implementations of the This section records the status of known implementations of the
protocol defined by this specification at the time of posting of this protocol defined by this specification at the time of posting of this
Internet-Draft, and is based on a proposal described in RFC 7942 Internet-Draft, and is based on a proposal described in RFC 7942
([RFC7942]). The description of implementations in this section is ([RFC7942]). The description of implementations in this section is
skipping to change at page 9, line 19 skipping to change at page 9, line 19
Extension identifier: subsetting Extension identifier: subsetting
Registry operator: Any Registry operator: Any
Published specification: This document. Published specification: This document.
Contact: IESG <iesg@ietf.org> Contact: IESG <iesg@ietf.org>
Intended usage: This extension describes a best practice for Intended usage: This extension describes a best practice for
partial response provisioning. partial response provisioning.
8. Security Considerations 8. Security Considerations
The search query typically requires more server resources (such as A search query typically requires more server resources (such as
memory, CPU cycles, and network bandwidth) when compared to the memory, CPU cycles, and network bandwidth) when compared to a lookup
lookup query. This increases the risk of server resource exhaustion query. This increases the risk of server resource exhaustion and
and subsequent denial of service due to abuse. Partial response can subsequent denial of service due to abuse. Thiss risk can be
contribute together with other strategies (e.g. restricting search mitigated by supporting return of partial responses combined with
functionality, limiting the rate of search requests, truncating and other strategies (e.g. restricting search functionality, limiting the
paging results) to mitigate this risk. rate of search requests, and truncating and paging results).
Furthermore, partial response can support RDAP operators to implement Support for partial responses gives RDAP operators the ability to
a versatile access control policy through the HTTP authentication implement data access control policies based on the HTTP
mechanisms as described in RFC 7481 ([RFC7481]). In fact, RDAP authentication mechanisms described in RFC 7481 ([RFC7481]). RDAP
operators can follow different, not alternative, approaches to the operators can vary the information returned in RDAP responses based
building of responses according to the user access levels: on a client's access and authorization levels. For example:
o the list of fields for each set can be different according to the o The list of fields for each set can differ based on the client's
user access levels; access and authorization levels;
o some field sets could be available only to some users. o The set of available field sets could be restricted based on the
client's access and authorization levels.
Servers can also define different results limits according to the Servers can also define different result limits according to the
available field sets, so a more flexible truncation strategy can be available field sets, so a more flexible truncation strategy can be
realized. implemented. The new query parameter presented in this document
provides RDAP operators with a way to implement a server that reduces
Therefore, the new query parameter presented in this document inefficiency risks.
provides the RDAP operators with a way to implement a secure server
without penalizing its efficiency.
9. Acknowledgements 9. Acknowledgements
The authors would like to acknowledge Scott Hollenbeck, Tom Harrison, The authors would like to acknowledge Scott Hollenbeck, Tom Harrison,
Karl Heinz Wolf, Jasdip Singh and Patrick Mevzek for their Karl Heinz Wolf, Jasdip Singh and Patrick Mevzek for their
contribution to this document. contribution to this document.
10. References 10. References
10.1. Normative References 10.1. Normative References
skipping to change at page 10, line 49 skipping to change at page 10, line 49
[RFC7483] Newton, A. and S. Hollenbeck, "JSON Responses for the [RFC7483] Newton, A. and S. Hollenbeck, "JSON Responses for the
Registration Data Access Protocol (RDAP)", RFC 7483, Registration Data Access Protocol (RDAP)", RFC 7483,
DOI 10.17487/RFC7483, March 2015, DOI 10.17487/RFC7483, March 2015,
<https://www.rfc-editor.org/info/rfc7483>. <https://www.rfc-editor.org/info/rfc7483>.
[RFC7942] Sheffer, Y. and A. Farrel, "Improving Awareness of Running [RFC7942] Sheffer, Y. and A. Farrel, "Improving Awareness of Running
Code: The Implementation Status Section", BCP 205, Code: The Implementation Status Section", BCP 205,
RFC 7942, DOI 10.17487/RFC7942, July 2016, RFC 7942, DOI 10.17487/RFC7942, July 2016,
<https://www.rfc-editor.org/info/rfc7942>. <https://www.rfc-editor.org/info/rfc7942>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8288] Nottingham, M., "Web Linking", RFC 8288, [RFC8288] Nottingham, M., "Web Linking", RFC 8288,
DOI 10.17487/RFC8288, October 2017, DOI 10.17487/RFC8288, October 2017,
<https://www.rfc-editor.org/info/rfc8288>. <https://www.rfc-editor.org/info/rfc8288>.
10.2. Informative References 10.2. Informative References
[CQL] Whitaker, G., "Catnap Query Language Reference", September [CQL] Whitaker, G., "Catnap Query Language Reference", September
2017, <https://github.com/gregwhitaker/catnap/wiki/Catnap- 2017, <https://github.com/gregwhitaker/catnap/wiki/Catnap-
Query-Language-Reference>. Query-Language-Reference>.
skipping to change at page 11, line 47 skipping to change at page 11, line 51
[REST-API1] [REST-API1]
Jobinesh, P., "RESTful Java Web Services - Second Jobinesh, P., "RESTful Java Web Services - Second
Edition", September 2015. Edition", September 2015.
[REST-API2] [REST-API2]
Masse, M., "REST API Design Rulebook", October 2011. Masse, M., "REST API Design Rulebook", October 2011.
Appendix A. Approaches to Partial Response Implementation Appendix A. Approaches to Partial Response Implementation
Looking at the implementation experiences described in Section 1, two Looking at the implementation experiences described in Section 1, two
approaches to the implementation of partial response can be detected: approaches to the implementation of partial response are observed:
o the client declares explicitly the data fields to get back; o The client explicitly describes the data fields to be returned;
o the client declares a name identifying a server pre-defined set of o The client describeds a name identifying a server-defined set of
data fields. data fields.
The former is more flexible than the latter because clients can The former is more flexible than the latter because clients can
specify all the data fields they need. However, it has some specify all the data fields they need. However, it has some
drawbacks: drawbacks:
o fields have to be declared according to a given syntax. This is a o Fields have to be declared according to a given syntax. This is a
simple task when the data structure of the object is flat, but it simple task when the data structure of the object is flat, but it
is much more difficult when the object has a tree structure like is much more difficult when the object has a tree structure like
the one of a JSON object. The presence of arrays and deep nested the one of a JSON object. The presence of arrays and deep nested
objects contributes to complicate both the syntax definition of objects complicate both the syntax definition of the query and,
the query and, consequently, the processing phase on the server consequently, the processing required on the server side;
side;
o clients should perfectly know the returned data structure to avoid o Clients need to recognize the returned data structure to avoid
cases when the requested fields are invalid; cases when the requested fields are invalid;
o the request of some fields might not match the user access levels. o The request of some fields might not match the client's access and
Clients might put unauthorized fields in their requests and authorization levels. Clients might request unauthorized fields
servers should define a strategy for providing a response: and servers should define a strategy for providing a response,
returning always an error response or returning a response that such as always returning an error response or returning a response
ignores the unauthorized fields. that ignores the unauthorized fields.
A.1. Specific Issues Raised by RDAP A.1. Specific Issues Raised by RDAP
In addition to those listed above, RDAP responses raise some specific In addition to those listed above, RDAP responses raise some specific
issues: issues:
o most of the relevant information of the entity object is included o Relevant entity object information is included in a jCard, but
in the jCard but such information cannot be easily selected such information cannot be easily selected because it is split
because it is split into the items of a jagged array; into the items of a jagged array;
o RDAP responses contain some properties providing service o RDAP responses contain some properties providing service
information (e.g. rdapConformance, links, notices, remarks, etc.) information (e.g. rdapConformance, links, notices, remarks, etc.)
which are not normally selected but they are just as important. which are not normally selected but they are just as important.
They could be returned anyway but, in this case, the server would They could be returned anyway but, in this case, the server would
provide unrequested data. provide unrequested data.
As an example compliant to the first approach, the Catnap Query It's possible to address these issues. For example, the Catnap Query
Language ([CQL]) is a comprehensive expression language that can be Language ([CQL]) is a comprehensive expression language that can be
used to customize the JSON response of a RESTful web service. The used to customize the JSON response of a RESTful web service.
practical application of CQL to RDAP responses points out that Application of CQL to RDAP responses would explicitly identify the
declaring explicitly the output fields would still be acceptable when output fields that would be acceptable when a few fields are
a few fields are requested but it would become very complicated if requested but it would become very complicated when processing some
the fields should be more. In the following, two CQL expressions for larger number of fields. In the following, two CQL expressions for a
a search domain query are shown (Figure 4): in the first, only domain search query are shown (Figure 4). In the first, only
objectClassName and ldhName are requested, in the second, the fields objectClassName and ldhName are requested. In the second, the fields
of a possible WHOIS-like response are listed. of a possible WHOIS-like response are listed.
https://example.com/rdap/domains?name=example*.com https://example.com/rdap/domains?name=example*.com
&fields=domainSearchResults(objectClassName,ldhName) &fields=domainSearchResults(objectClassName,ldhName)
https://example.com/rdap/domains?name=example*.com https://example.com/rdap/domains?name=example*.com
&fields=domainSearchResults(objectClassName,ldhName, &fields=domainSearchResults(objectClassName,ldhName,
unicodeName, unicodeName,
status, status,
events(eventAction,eventDate), events(eventAction,eventDate),
entities(objectClassName,handle,roles), entities(objectClassName,handle,roles),
nameservers(objectClassName,ldhName)) nameservers(objectClassName,ldhName))
Figure 4: Examples of CQL expressions for a search domain query Figure 4: Examples of CQL expressions for a domain search query
The latter approach seems to facilitate RDAP interoperability. In The latter approach seems to facilitate RDAP interoperability.
fact, servers can define some basic field sets which, if known to the Servers can define basic field sets which, if known to clients, can
clients, can increase the probability to get a valid response. The increase the probability to get a valid response. The usage of field
usage of field sets lets the query string be less complex. In sets lets the query string be less complex. In addition, the
addition, the definition of pre-defined sets of fields makes easier definition of pre-defined sets of fields makes it easier to establish
to establish the results limits. result limits.
Finally, considering that there is not a real need for RDAP users to Finally, considering that there is no real need for RDAP users to
have the maximum flexibility in defining all the possible sets of have the maximum flexibility in defining all the possible sets of
logically connected fields (e.g. users interested in domains usually logically connected fields (e.g. users interested in domains usually
need to know the status, the creation date, the expiry date of each need to know the status, the creation date, and the expiry date of
domain), the latter approach is preferred. each domain), the latter approach is preferred.
Appendix B. Change Log Appendix B. Change Log
00: Initial working group version ported from draft-loffredo-regext- 00: Initial working group version ported from draft-loffredo-regext-
rdap-partial-response-03 rdap-partial-response-03
01: Removed "FOR DISCUSSION" items. Changed the basic field sets 01: Removed "FOR DISCUSSION" items. Changed the basic field sets
from REQUIRED to OPTIONAL. Removed the definition of fields from REQUIRED to OPTIONAL. Removed the definition of fields
included in "brief" field set. Provided a more detailed included in "brief" field set. Provided a more detailed
description of "subsetting_metadata" structure. Removed some description of "subsetting_metadata" structure. Removed some
references. references.
skipping to change at page 14, line 15 skipping to change at page 14, line 18
07: Changed "only a subset is returned" to "only a subset of fields 07: Changed "only a subset is returned" to "only a subset of fields
in each result object is returned" in the "Introduction" section. in each result object is returned" in the "Introduction" section.
Moved the "RDAP Conformance" section up in the document. Updated Moved the "RDAP Conformance" section up in the document. Updated
the "Acknowledgements" section. the "Acknowledgements" section.
08: Changed the rdapConformance tag "subsetting_level_0" to 08: Changed the rdapConformance tag "subsetting_level_0" to
"subsetting". Moved [RFC7942] to the "Normative References". "subsetting". Moved [RFC7942] to the "Normative References".
09: Corrected the "rdapConformance" content in Figure 3. 09: Corrected the "rdapConformance" content in Figure 3.
10: Corrected the JSON content in Figure 2. Clarified the meaning 10: Corrected the JSON content in Figure 2. Clarified the meaning
of both context and target URIs in a result subset link defined in of both context and target URIs in a result subset link defined in
Section 2.1.2. Updated the "Acknowledgements" section. Section 2.1.2. Updated the "Acknowledgements" section.
11: Minor pre-AD review edits.
Authors' Addresses Authors' Addresses
Mario Loffredo Mario Loffredo
IIT-CNR/Registro.it IIT-CNR/Registro.it
Via Moruzzi,1 Via Moruzzi,1
Pisa 56124 Pisa 56124
IT IT
Email: mario.loffredo@iit.cnr.it Email: mario.loffredo@iit.cnr.it
 End of changes. 47 change blocks. 
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