Network Working Group R. Sayre Internet-Draft October 22, 2005 Expires: April 25, 2006 Feed Seek for the Atom Publishing Protocol draft-sayre-atompub-protocol-seek-00.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on April 25, 2006. Copyright Notice Copyright (C) The Internet Society (2005). Abstract This memo presents a set of URI parameters used identify segments of an Atom Publishing Protocol feed. It also presents a syntax for declaring the placement of those parameters in a URI. Sayre Expires April 25, 2006 [Page 1] Internet-Draft APP Feed Seek October 2005 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. The 'app:seek' Attribute . . . . . . . . . . . . . . . . . . . 4 4. Security Considerations . . . . . . . . . . . . . . . . . . . 5 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 6. Informative References . . . . . . . . . . . . . . . . . . . . 5 Author's Address . . . . . . . . . . . . . . . . . . . . . . . 6 A. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 6 B. Change History . . . . . . . . . . . . . . . . . . . . . . . . 6 Intellectual Property and Copyright Statements . . . . . . . . 7 Sayre Expires April 25, 2006 [Page 2] Internet-Draft APP Feed Seek October 2005 1. Introduction When Atom Publishing Protocol [APP-Basic] clients encounter an APP collection, they may require smaller or larger frames of entries than the server provides by default. Most servers provide between 5 and 25 entries per Atom Feed Document [AtomFormat]. This frame can be far too large for a bandwidth and resource-constrained device, which might only have room to display two or three titles at a time. This frame can be far too small for a client attempting to sync up with a collection that contains many thousands of members. 2. Parameters HTTP URIs [RFC3986] provide a useful mechanism for composing parameterized requests--the query string [RFC2616]. This document outlines four parameters that are generally useful to APP clients, but may not be useful for every APP collection. count: The maximum number of Atom Entries to be included in the response. The field is an integer. offset: The offset at which to begin the sequence of entries that match a given request. The field is an integer. begin: Atom entries in the returned feed have an atom:updated date later in time than the 'begin' date. The field matches the syntax of an Atom Date Construct [AtomFormat]. end: Atom entries in the returned feed have an atom:updated date equal or earlier in time than the 'end' date. The field matches the syntax of an Atom Date Construct [AtomFormat]. None of the parameters are required, and servers could add additional parameters. Example Selection URI (disregard line break) http://example.com/foo?begin=2003-12-13T18:30:02Z\ &end=2003-12-25T18:30:02Z&offset=2&count=4 Seek URIs are templated by surrounding the field names in brackets. For example, the 'count' field would appear as '{count}' in a template. An example seek template: http://example.com/app?b={begin}&e={end}&i={offset}&c={count} All parameters are optional, so servers interpret requests with missing parameters using the list below: Sayre Expires April 25, 2006 [Page 3] Internet-Draft APP Feed Seek October 2005 If no 'end' field is present: The 'end' date is considered to be the updated date of the collection's most recently updated member resource. If no 'begin' field is present: The 'begin' date is considered to be the update date of the collection's least recently updated member resource. If no 'offset' field is present: The 'offset' integer is considered to be 0. If no 'count' field is present: The 'count' integer is determined by the server. 3. The 'app:seek' Attribute The "app:seek" attribute can be added to an anchor element contained in a server's XOXO Service Outline [XOXO]. When present, this namespace-qualified attribute provides a template for the parameterized GET requests described by this document. After substitution of the appropriate parameters, the resulting URI reference is interpreted relative to the in-scope base URI. The APP namespace is "http://purl.org/atom/app#". This document refers to it by using the prefix "app", but that prefix is arbitrary. Sayre Expires April 25, 2006 [Page 4] Internet-Draft APP Feed Seek October 2005 An example Service Outline with an app:seek attribute: 4. Security Considerations Malicious or buggy clients could mount a Denial-of-Service attack by sending large date ranges or integers as parameter values. 5. IANA Considerations None 6. Informative References [APP-Basic] Sayre, R., "The Atom Publishing Protocol (Basic)", work- in-progress, October 2005. [AtomFormat] Nottingham, M. and R. Sayre, "The Atom Syndication Format", work-in-progress, August 2005. Sayre Expires April 25, 2006 [Page 5] Internet-Draft APP Feed Seek October 2005 [RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999. [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, January 2005. [XOXO] Marks, K., Celik, T., Pilgrim, M., and M. Peterson, "XOXO 1.0: Extensible Open XHTML Outlines", October 2004. Author's Address Robert Sayre Email: rfsayre@boswijck.com URI: http://boswijck.com Appendix A. Contributors This draft is a variant of the in-progress Atom Publishing Protocol specification from the IETF Atompub WG, and owes a debt to the WG's members. Appendix B. Change History -00: Split from draft-sayre-atompub-protocol-basic-00 / -02 Sayre Expires April 25, 2006 [Page 6] Internet-Draft APP Feed Seek October 2005 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. The IETF has been notified of intellectual property rights claimed in regard to some or all of the specification contained in this document. For more information consult the online list of claimed rights. Disclaimer of Validity This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Copyright Statement Copyright (C) The Internet Society (2005). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. Sayre Expires April 25, 2006 [Page 7] Internet-Draft APP Feed Seek October 2005 Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Sayre Expires April 25, 2006 [Page 8]