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Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (May 20, 2009) is 5456 days in the past. Is this intentional? Checking references for intended status: Best Current Practice ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Unused Reference: 'RFC3986' is defined on line 199, but no explicit reference was found in the text Summary: 1 error (**), 0 flaws (~~), 2 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group C. Divilly 3 Internet-Draft N. Mehta 4 Intended status: BCP Oracle Corp. 5 Expires: November 21, 2009 May 20, 2009 7 AtomPub Guidelines for Collection Discovery 8 draft-divilly-atompub-discovery-00 10 Status of this Memo 12 This Internet-Draft is submitted to IETF in full conformance with the 13 provisions of BCP 78 and BCP 79. 15 Internet-Drafts are working documents of the Internet Engineering 16 Task Force (IETF), its areas, and its working groups. Note that 17 other groups may also distribute working documents as Internet- 18 Drafts. 20 Internet-Drafts are draft documents valid for a maximum of six months 21 and may be updated, replaced, or obsoleted by other documents at any 22 time. It is inappropriate to use Internet-Drafts as reference 23 material or to cite them other than as "work in progress." 25 The list of current Internet-Drafts can be accessed at 26 http://www.ietf.org/ietf/1id-abstracts.txt. 28 The list of Internet-Draft Shadow Directories can be accessed at 29 http://www.ietf.org/shadow.html. 31 This Internet-Draft will expire on November 21, 2009. 33 Copyright Notice 35 Copyright (c) 2009 IETF Trust and the persons identified as the 36 document authors. All rights reserved. 38 This document is subject to BCP 78 and the IETF Trust's Legal 39 Provisions Relating to IETF Documents in effect on the date of 40 publication of this document (http://trustee.ietf.org/license-info). 41 Please review these documents carefully, as they describe your rights 42 and restrictions with respect to this document. 44 Abstract 46 This document recommends best practices for discovering AtomPub 47 Collection resources as applicable to various content representation 48 formats. 50 Editorial Note 52 To provide feedback on this Internet-Draft, join the atom-protocol 53 mailing list (http://www.imc.org/atom-protocol/). 55 Table of Contents 57 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 58 1.1. Notational Conventions . . . . . . . . . . . . . . . . . . 3 59 1.2. Namespace . . . . . . . . . . . . . . . . . . . . . . . . . 3 60 2. Discovering Collections from a Feed Document . . . . . . . . . 3 61 3. Discovering Service from an HTML Document . . . . . . . . . . . 5 62 4. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 63 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 64 6. Normative References . . . . . . . . . . . . . . . . . . . . . 5 65 Appendix A. Revision History . . . . . . . . . . . . . . . . . . . 6 66 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6 68 1. Introduction 70 Atom Publishing Protocol [RFC5023] is used for several applications 71 that consume and produce an unbounded number of Collection resources. 72 This document introduces guidelines over existing syntactic 73 techniques for identifying Collection resources in use from various 74 Internet content representation formats, including feeds and HTML 75 type resources. 77 Previously, AtomPub [RFC5023] has introduced two mechanisms for 78 collection discovery. However, in the absence of suitable 79 guidelines, there is no clarity about which mechanism is suited for a 80 particular purpose. In general, where other Atom or AtomPub syntax 81 is in use, this document recommends the use of the app:collection 82 element. Where only a link element may be used, this document 83 recommends the use of the service link relation. 85 1.1. Notational Conventions 87 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 88 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 89 document are to be interpreted as described in [RFC2119]. 91 1.2. Namespace 93 This specification uses the prefix "atom:" for 94 "http://www.w3.org/2005/Atom", the namespace name of the Atom 95 Syndication Format [RFC4287]. The prefix "app:" is used for 96 "http://www.w3.org/2007/app", the namespace name of the Atom 97 Publishing Protocol [RFC5023]. These namespace prefixes are not 98 semantically significant. 100 2. Discovering Collections from a Feed Document 102 When an Atom Processor encounters an Atom Feed Document, and the 103 processor is capable of performing AtomPub operations, then it is 104 valuable to determine whether that feed is modifiable. Some 105 processors incorrectly assume that a feed may be modified at the 106 exact same URI from which it is obtained. 108 AtomPub Processors need a way to determine whether and where new 109 entries can be added to a Feed. If a syndicated feed document is 110 modifiable using AtomPub, then the processor can indeed manipulate 111 the feed. For this purpose, processors can benefit from Collection 112 metadata that is present in the feed document. 114 The alternative is obtaining the feed's service document by following 115 a link with the relation "service", followed by identifying the 116 Collection resources in the AtomPub Service Document, followed by 117 correlating these Collection resources to the feed at hand. 118 Naturally, this alternative is more complex, resource consuming, and 119 less likely to succeed in finding the exact Collection resource to be 120 manipulated. 122 Moreover, not every feed can be modified, and servers can indicate 123 this by omitting Collection metadata in such feeds. 125 Section 8.3.5 of [RFC5023] specifies the Collection metadata that may 126 occur in syndicated Atom feeds. The presence of an app:collection 127 element as a child of an atom:feed element signals server's 128 preparedness to modify a feed. This document therefore recommnds 129 that if a Feed is backed by a Collection, then the server SHOULD 130 identify the backing Collection using the app:collection element as a 131 child of the atom:feed element. 133 If the href attribute of this app:collection element is identical to 134 that of the parent atom:feed element's self link relation, then the 135 processor SHOULD treat the feed to be the Collection feed as defined 136 in Section 4.2 of [RFC5023]. 138 Example: Writable Collection backing a Feed 140 141 142 143 Writable Feed 144 application/atom+xml;type=entry 145 146 ... 147 149 Example: Read-only Collection backing a Feed 151 152 153 154 Read-only Feed 155 156 157 ... 158 159 Example: Writable Collection Feed 161 162 163 164 Collection Feed 165 166 ... 167 169 3. Discovering Service from an HTML Document 171 When an Atom processor encounters an HTML or XHTML document, and the 172 processor is capable of performing AtomPub operations, then it is 173 useful to determine the available AtomPub resources with which it can 174 interact. 176 The host format, though, limits the ability to specify metadata 177 embedded in the content being processed. Therefore, the best 178 approach for a server is to specify a link with relation "service" to 179 provide a URI to the AtomPub Service Document that includes all the 180 metadata corresponding to one or more Collections. The server can 181 also specify a link with relation "feed" to provide a URI to an Atom 182 feed with relevant content, which can in turn provide additional 183 metadata for manipulating AtomPub resources present on that server as 184 explained in the previous section. 186 4. Security Considerations 188 None 190 5. IANA Considerations 192 None 194 6. Normative References 196 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 197 Requirement Levels", BCP 14, RFC 2119, March 1997. 199 [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform 200 Resource Identifier (URI): Generic Syntax", STD 66, 201 RFC 3986, January 2005. 203 [RFC4287] Nottingham, M., Ed. and R. Sayre, Ed., "The Atom 204 Syndication Format", RFC 4287, December 2005. 206 [RFC5023] Gregorio, J. and B. de hOra, "The Atom Publishing 207 Protocol", RFC 5023, October 2007. 209 Appendix A. Revision History 211 00 - Initial Revision, created from 212 draft-divilly-atompub-hierarchy-00. 214 Authors' Addresses 216 Colm Divilly 217 Oracle Corp. 219 Email: colm.divilly@oracle.com 220 URI: http://cdivilly.wordpress.com 222 Nikunj Mehta 223 Oracle Corp. 225 Email: nikunj.mehta@oracle.com 226 URI: http://o-micron.blogspot.com/