From: http://www.ietf.org/internet-drafts/draft-snell-atompub-notification-00.txt Title: The Atom Notification Protocol Reference: IETF Network Working Group, Internet Draft, 'draft-snell-atompub-notification-00' Date: December 14, 2004 See: http://xml.coverpages.org/atom.html "Atom Publishing Format and Protocol" ======================================================================== Network Working Group J. Snell Internet-Draft December 14, 2004 Expires: June 14, 2005 The Atom Notification Protocol draft-snell-atompub-notification-00 Status of this Memo By submitting this Internet-Draft, I certify that any applicable patent or other IPR claims of which I am aware have been disclosed, and any of which I become aware will be disclosed, in accordance with RFC 3668. 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 June 14, 2005. Copyright Notice Copyright (C) The Internet Society (2004). All Rights Reserved. Abstract This memo presents a protocol for posting notifications of new or updated content using a combination of the Atom Syndication Format and HTTP POSTs. Snell Expires June 14, 2005 [Page 1] Internet-Draft The Atom Notification Protocol December 2004 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1 Notational Conventions . . . . . . . . . . . . . . . . . . 3 1.2 Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 2. The Atom Notification Protocol Model . . . . . . . . . . . . . 3 3. Functional Specification . . . . . . . . . . . . . . . . . . . 3 3.1 NotificationURI . . . . . . . . . . . . . . . . . . . . . 3 3.1.1 Locating the NotificationURI . . . . . . . . . . . . . 4 3.1.2 Request . . . . . . . . . . . . . . . . . . . . . . . 4 3.1.3 Response . . . . . . . . . . . . . . . . . . . . . . . 5 4. Atom Syntax Extensions . . . . . . . . . . . . . . . . . . . . 5 4.1 "atom:notification" Element . . . . . . . . . . . . . . . 5 5. Security Considerations . . . . . . . . . . . . . . . . . . . 6 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Author's Address . . . . . . . . . . . . . . . . . . . . . . . 7 Intellectual Property and Copyright Statements . . . . . . . . 8 Snell Expires June 14, 2005 [Page 2] Internet-Draft The Atom Notification Protocol December 2004 1. Introduction The Atom Notification Protocol is an application-level protocol for posting notification of new or updated content using HTTP and the Atom Syndication Format. 1.1 Notational Conventions The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [1]. 1.2 Terminology Atom Entry: An Atom Entry is a fragment of a full Atom feed. In this case, the fragment is a single 'entry' element and all its child elements. Each Atom Entry describes a single Web resource, providing metadata and optionally a textual representation of that resource. Atom Feed: In the context of an Atom Notification, an Atom Feed is a minimal "atom:feed" element containing an "atom:head" element and no "atom:entry" elements. NotificationURI: A URI that is used to receive notifications about new or updated Atom entries. 2. The Atom Notification Protocol Model The Atom Notification Protocol has been designed to complement the Atom Publishing Protocol by providing the means of sending notifications when Atom-based content is created or updated. The Atom Notification Protocol works by POSTing Atom Entries or Atom Feeds to a NotificationURI using HTTP POST. As is the case with the Atom Publishing Protocol, this document does not seek to specify the form of the URIs that are used. This document does, however, specify the formats of the entities posted to those URIs. 3. Functional Specification 3.1 NotificationURI The NotificationURI is used to POST notifications. A notification consists of a single Atom Entry or Atom Feed. The notification is essentially a one-way operation that implies no semantics or action on the part of the receiver. Snell Expires June 14, 2005 [Page 3] Internet-Draft The Atom Notification Protocol December 2004 3.1.1 Locating the NotificationURI The NotificationURI can be discovered in one of two ways. First, with an link element with a @rel of 'service.notification' in the "head" element of an HTML document. Second, using a "atom:notification" element as described in section 4.1. 3.1.2 Request The request contains a filled-in Atom Entry or Atom Feed. A notification request containing an Atom Entry is intended to notify the receiving endpoint that a specific entry has been created or updated. A notification request containing an Atom Feed is intended to notify the receiving endpoint that a specific feed has been created or updated. Atom Entries POSTed to a NotificationURI MAY contain a "atom:head" element that identifies the feed to which the entry belongs. Atom Feeds POSTed to a NotificationURI MUST NOT contain any "atom:entry" elements and SHOULD consist of only a minimal "atom:head" element using as few optional elements as possible. Example Feed 2003-12-13T18:30:02Z John Doe Snell Expires June 14, 2005 [Page 4] Internet-Draft The Atom Notification Protocol December 2004 3.1.3 Response The possible HTTP status codes from a POST are 202, 400 or 500. 3.1.3.1 Response Code 202 A response code of 202 indicates that the notification was successfully received and accepted. The body of the message SHOULD be empty. 3.1.3.2 Response Code 400 A response code of 400 indicates that the server believes the data sent constitutes an invalid request. For example, the data received may not be a well-formed Atom entry or feed. The server SHOULD include an entity containing an explanation of the error situation and whether it is a temporary or permanent condition. 3.1.3.3 Response Code 500 A response code of 500 indicates that the server detected an internal error while processing the notification request. The server SHOULD include an entity containing an explanation of the error situation, and whether it is a temporary or permanent condition. 4. Atom Syntax Extensions 4.1 "atom:notification" Element The "atom:notification" element is a Service construct that conveys the URI used to receive notifications related to an entry or feed. No more than one "atom:notification" element may be added to the "atom:head" or "atom:entry" elements. The "atom:notification" element uses the same namespace URI as the Atom core elements. Snell Expires June 14, 2005 [Page 5] Internet-Draft The Atom Notification Protocol December 2004 Example Feed 2003-12-13T18:30:02Z John Doe Atom-Powered Robots Run Amok vemmi://example.org/2003/32397 2003-12-13T18:30:02Z 5. Security Considerations The decision of whether or not to secure the Atom Notification Protocol will be made on a case-by-case decision. Some notification endpoints may be restricted to known authenticated users while others will be open for anyone who wishes to post notifications. If a given NotificationURI is restricted, the same authentication mechanisms used by the Atom Publishing Protocol SHOULD be used. Because of this, the Notification Protocol is open to the same threats as the Publication Protocol. One particular challenge that implementors of NotificationURI endpoints will need to be aware of is the potential for denial of service attacks and notification spamming. This document shall not deal with potential solutions to such attacks. 6. IANA Considerations This document has no actions for IANA. 7 References [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [2] Gregorio, J., Ed. and R. Sayre, Ed., "The Atom Publishing Snell Expires June 14, 2005 [Page 6] Internet-Draft The Atom Notification Protocol December 2004 Protocol", draft-ietf-atompub-protocol-02 (work in progress), September 2004. [3] Nottingham, M., Ed. and R. Sayre, Ed., "The Atom Syndication Format", draft-ietf-atompub-format-03 (work in progress), October 2004. Author's Address James M Snell EMail: james@snellspace.com URI: http://www.snellspace.com Snell Expires June 14, 2005 [Page 7] Internet-Draft The Atom Notification Protocol December 2004 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. 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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 (2004). 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. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Snell Expires June 14, 2005 [Page 8]