1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
|
Internet Engineering Task Force (IETF) M. Amundsen
Request for Comments: 6573 April 2012
Category: Informational
ISSN: 2070-1721
The Item and Collection Link Relations
Abstract
RFC 5988 standardized a means of indicating the relationships between
resources on the Web. This specification defines a pair of reciprocal
link relation types that may be used to express the relationship
between a collection and its members.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are a candidate for any level of Internet
Standard; see Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6573.
Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Amundsen Informational [Page 1]
^L
RFC 6573 The Item and Collection Link Relations April 2012
1. Introduction
RFC 5988 standardized a means of indicating the relationships between
resources on the Web. This specification defines a pair of reciprocal
link relation types that may be used to express the relationship
between a collection and its members.
These link relation types can be applied to a wide range of use cases
across multiple media types. For example, the 'collection' and
'item' link relation types are used in these media types:
1. OpenSearch 1.1: see Section 4.5.4.1 of [OpenSearch]
2. Maze+XML: see [Maze]
3. Collection+JSON: see [CollectionJSON]
2. Link Relations
The following link relations are defined.
2.1. 'item'
When included in a resource that represents a collection, the 'item'
link relation identifies a target resource that represents a member
of that collection.
For example, if a resource represents a catalog of products, that
same representation may include one or more links to resources that
represent members of that catalog.
<html>
...
<h1>Product Group X Listing</h1>
...
<a href="..." rel="item">View Product X001</a>
<a href="..." rel="item">View Product X002</a>
...
</html>
or, in the case of a Link Header field
Link: <...>; rel="item"; title="View Product X001"
Link: <...>; rel="item"; title="View Product X002"
Amundsen Informational [Page 2]
^L
RFC 6573 The Item and Collection Link Relations April 2012
2.2. 'collection'
When included in a resource that represents a member of a collection,
the 'collection' link relation identifies a target resource that
represents a collection of which the context resource is a member.
For example, if a resource represents a single product in a catalog,
that same representation may include a link to a resource that
represents a product group to which this single product belongs:
<a href="..." rel="collection">Return to Product Group X</a>
or, in the case of a Link Header field
Link: <...>; rel="collection"; title="Return to Product Group X"
Since it is possible that a resource could be a member of multiple
collections, multiple 'collection' link relations may appear within
the same representation:
<a href="..." rel="collection">View other widgets</a>
<a href="..." rel="collection">View all discontinued items</a>
The target resource representation need not be restricted to
representing a list. It may simply be a document that provides
details on the collection of which the context resource is a member:
Link: <...>; rel="collection";
title="Shakespeare's Collected Works - A History"
It should also be noted that the same link might represent an 'item'
in one collection as well as a 'collection' itself. In this case,
both link relation values can be applied to the same link:
Link: <...>; rel="collection item";
title="A Review of Issac Asimov's Collected Works - Vol. I"
3. IANA Considerations
IANA has registered the 'collection' and 'item' link relations below
as per [RFC5988].
3.1. 'item' Link Relation Registration
Relation Name:
item
Amundsen Informational [Page 3]
^L
RFC 6573 The Item and Collection Link Relations April 2012
Description:
The target IRI points to a resource that is a member of the
collection represented by the context IRI.
Reference:
See Section 2
3.2. 'collection' Link Relation Registration
Relation Name:
collection
Description:
The target IRI points to a resource that represents the collection
resource for the context IRI.
Reference:
See Section 2
4. Security Considerations
The two link relation types defined in this document do not introduce
any new security issues to those which are discussed in Section 7 of
RFC5988 [RFC5988].
5. Internationalisation Considerations
The 'item' and 'collection' link relation types do not have any
internationalization considerations other than those which are
discussed in Section 8 of RFC5988 [RFC5988].
6. References
6.1. Normative References
[RFC5988] Nottingham, M., "Web Linking", RFC 5988,
October 2010.
6.2. Informative References
[CollectionJSON] Amundsen, M., "Collection+JSON - Document Format",
Web Page , July 2011,
<http://www.iana.org/assignments/media-types>.
Amundsen Informational [Page 4]
^L
RFC 6573 The Item and Collection Link Relations April 2012
[Maze] Amundsen, M., "Maze+XML - Format", Web Page ,
December 2010,
<http://www.iana.org/assignments/media-types>.
[OpenSearch] Clinton, D., "Open Search 1.1", Work in Progress ,
March 2011, <http://www.opensearch.org/
Specifications/OpenSearch/1.1/>.
Appendix A. Acknowledgements
The author gratefully acknowledges the contributions of Julian
Reschke and Mykyta Yevstifeyev.
Author's Address
Mike Amundsen
EMail: mca@amundsen.com
URI: http://amundsen.com
Amundsen Informational [Page 5]
^L
|
