Update 2004-06-16: On June 16, 2004 the IESG officially announced the formation of the IETF Atom WG: "IETF Forms New Atom Publishing Format and Protocol (atompub) Working Group." See general references in the topic document "Atom Publishing Format and Protocol."
Update 2004-05-05: On May 05, 2004 the Internet Engineering Steering Group (IESG) announced the proposal for a new IETF Atom Publishing Format and Protocol Working Group within the IETF Applications Area. See details in the news item "IESG Announces Proposal for IETF Atom Publishing Format and Protocol Working Group."
[October 22, 2003] The Atom Project, to the extent that anyone can declare authoritatively what it is, or is quintessentially meant to support, is "an initiative to develop a common syntax for syndication, archiving, and publishing." Sam Ruby (Emerging Technologies Group, IBM) is most often credited for originating the core ideas, and design work spread across several wikis and weblog Internet sites is now being shared by some of the brightest developer minds focused upon the future of Web content creation and distribution.
The developers agree that Atom "will be vendor neutral, implemented by everybody, freely extensible by anybody, and cleanly and thoroughly specified." Atom is sometimes characterized as the successor to RSS (Really Simple Syndication or RDF Site Summary), which is variably used for news headline syndication, website metadata description, and content syndication. Like RSS, Atom is being created through an informal consensus process by volunteers in the Web developer community at large.
Sam Ruby appears to recognize that the function of Atom will be revealed in unpredictable ways, escaping any telos imagined by the current designers. The key insights are these: design Atom such that content is not treated as a second class citizen (allow its conceptual model and syntax to blur the subjective distinction between metadata and data); insist upon a uniform mechanism for expressing the core concepts independent of the usage (e.g., allow multiple implementation designs conforming to abstract API requirements, and anticipate multiple schema formalisms for validation); keep the format open and simple (e.g., not requiring special serialization of the XML, implementable using simple POST and GET operations under HTTP).
The Atom design is envisioned as extensible for different application areas (license terms, access control, content categorization, versioning, related resources, etc.) The core features are those common to most creations of intellectual works: source/author, editing date(s), resource identifier/location, and content. Given these minimal but central goals, we can understand the simplicity and generality of the abstract for the draft Atom API specification: the API document "presents a technique for using XML and HTTP to edit content." In this context, "edit" means "read, write, modify, delete" (approximately: GET, POST, PUT, DELETE).
The goal of extreme generality remains in tension with the competing objective of ensuring that the new syndication format, while extensible, has predictable consistency at the semantic level. This probably means that the formalism in final draft will specify some required elements. In particular, if an agreed design goal is to capture time sensitive information, then an element for time information would be required. In the draft syntax description [as of 2003-10-22], the top-level <feed> element has required subelements title, link, modified (date in UTC), and author. An <entry> element would have required subelements title, link (URI permanent link), id, issued (W3DTF +/- timezone), and modified.
RoadMap snapshot for Atom (Echo/Pie) as of 2003-10-17: The project roadmap involves: "(1) Decide on the conceptual model of a log entry. Primer, ConceptualModel; (2) Decide on a syntax for this model. Syntax, SyntaxConsiderations; (3) Build a syndication format using this syntax; (4) Build an archiving format using this syntax; (5) Build a weblog editing protocol using this syntax (the Atom API)." According to this RoadMap document, sixty-some companies have pledged support for Atom (aka Echo/Pie/etc) along with 170+ individual developers.
The Internet domain intertwingly.net is host for Sam Ruby's weblog and for the Atom Project wiki, both serving as publication organs for Atom design and development. The www.intertwingly.net "It's Just Data" blog for Atom and related topics is built in XHTML 1.1 code. This is important to one of Sam Ruby's goals for the new syndication format: a desire to enable such things as XPath queries over the content. A blog entry for September 26, 2003 "Fun with XPath" documents some of the details.
Atom Entry and Content Model
The content, structure, and (lexical) syntax for Atom <entry> and <content> elements are still [2003-10] under discussion. Mark Pilgrim presents draft examples and some of the key concepts in his article "The Atom API," published by XML.com. Excerpts:
[An Atom entry has] "lots of information: a title, an excerpt or summary, and an author who has a name, email address, and URL of his own. The entry has a 'created' date and a 'modified' date (usually server-generated), and an 'issued' date (which is a date that the author would like to give to this entry, separate from when he actually posted it). The entry is viewable at a specific link, has an internal ID (a URN), and finally has some XHTML content.
The Atom content model is probably worth a whole article by itself, but for the moment let me just handwave and say that it can handle more than just XHTML. Any MIME type can be expressed (specify it in the @type attribute), and non-XML content (such as HTML or plain text) is simply escaped or put in a CDATA block, with a mode="escaped" attribute on the content element. It can even handle binary content (such as an image) by specifying @mode="base64" and including a base64-encoded representation of the data...
The Atom API has several other methods beyond add, edit, delete, retrieve, search. It can be used for posting comments on entries, managing users and user preferences, managing categories, managing site templates; eventually it will be usable for everything you can do manually with your weblog through your server's browser-based interface... [As for] Atom authentication: it does not involve sending plain text passwords in the clear..."
General and Overview:
- Intertwingly.net blog (Sam Ruby)
- "The Atom Syndication Format 0.3 (PRE-DRAFT)." From the APE (Atom/Pie/Echo) Working Group. Edited by Mark Nottingham. 'December 2003'. Reference: 'draft-nottingham-atom-format-02'. "This specification describes version 0.3 of the Atom, an XML-based Web content and metadata syndication format."
- "The Atom Syndication Format 0.3 (PRE-DRAFT)." By Mark Nottingham [WWW]. With contributions from Tim Bray, Mark Pilgrim, and Sam Ruby; the content and concepts within are a product of the Atom community. APE (Atom/Pie/Echo) Working Group. December  2003 [or later]. Reference: 'draft-nottingham-atom-format-01'. Supersedes: The Atom Syndication Format (PRE-DRAFT), 'draft-nottingham-atom-format-00a', August 2003. "Atom is an XML-based file format intended to allow lists of information, known as 'feeds', to be synchronised between publishers and consumers. Feeds are composed of a number of items, known as 'entries', each with an extensible set of attached metadata.
- The Atom Syndication Format (PRE-DRAFT). Ref: 'draft-nottingham-atom-format-00a'. APE (Atom/Pie/Echo) Working Group. August 2003. Note: interim/draft. [cache]
- The Atom Project. Atom Wiki front page.
- Atom Wiki Recent Changes
- Draft specifications
- What is Atom For? Possible Uses: (1) Feed: Use for computer-friendly syndication -- similar to RSS in functionality; (2) Editing: Use between atom-enabled clients and servers to create and update entries, comments, and either annotate or edit other resources; (3) Archiving: Use for internal storage, import, and export of entries, comments, and other resources; (4) Commenting: Use to post comments to an entry; (5) Cross-linking: Use to notify one entry about another entry..."
- Motivation [for Atom]
- Syndication Formats supported on Intertwingly.net blog.
An Atom (weblog) entry:
Draft Atom API:
- "The Atom API." By Mark Pilgrim. From XML.com (October 15, 2003).
- "The AtomAPI." Reference: 'draft-gregorio-08.html'. J.C. Gregorio (BitWorking, Inc). December 2003. Revision 08: 01-December-2003. "Refactored the specification, merging the Introspection file into the feed format. Also dropped the distinction between the type of URI used to create new entries and the kind used to create comments. Dropped user preferences."
- "The AtomAPI." Draft RFC. Reference: 'draft-gregorio-07.html'. By Joe C. Gregorio (BitWorking, Inc). July 2003. Published 06-Aug-2003.
- Proposed changes to draft-gregorio-07. Posted 2003-10-24.
- Draft API spec (possibly updated)
- API summary page
- AtomAPI URIs. By Joe Gregorio. An abbreviated description of the AtomAPI with all the example URIs contracted into short names.
Other Intertwingly.net Topics:
- FDML == Feed (Discovery / Directory / Detailing) Markup Language.
- Atom for Wikis
- Other Names for Atom
- ExtensibilityFramework. "The ExtensibilityFramework, EF, is a proposal for a syntax model that is freely extensible but with a well defined extensions model, and does not use RDF/XML but is transformable to other formats. The EF has a work-in-progress formal grammar, and XSLT and Python/SAX implementations... The purpose of this extensibility framework is to allow a uniform mechanism for handing text (with and without markup) and detecting URIs. The latter would also help with things like xml:base processing..."
Articles, Papers, News on Atom (Pie, Echo, !Echo):
- "Google Spurns RSS for Rising Blog Format [Atom]." By Paul Festa. In CNET News.com (February 11, 2004).
- "Atom in Depth." By Sam Ruby (Intertwingly.Net). December 2003. Sam Ruby (Senior Technical Staff Member in IBM Emerging Technologies Group, also VP, Apache Software Foundation) provided a state-of-affairs overview of the Atom news syndication format at the recent News Standards Summit. The 59 slides from the presentation cover the Background to Atom, Core model, Syndication, description of the 'API', and the Web Accessible Archive.
- "Atom Authentication." By Mark Pilgrim. From XML.com (December 17, 2003). "Atom is a new standard that uses XML over HTTP to publish and syndicate web-based content. It is initially targeted at weblogs, and most of the early adopters so far have been weblog vendors and users. It consists of the Atom API, which I discussed last month, and the Atom syndication format, which I will discuss next month. This month I want to talk about authentication..."
- "Escaped Markup Considered Harmful," by Norman Walsh (XML.com). See the followups from Norm on 2003-09-18 and 2003-09-16, and the EscapedHtmlDiscussion thread on Intertwingly.net. Norm takes a solid position against escaping markup; others feel (pragmatically) that allowing some form of escaping (with an explicit, unambiguous indication) is probably necessary, given the widespread lack of discipline in the use of (sic!) XML.
- "I Like Pie." By Tim Bray. From ongoing. June 23, 2003.
- "The Semantic Blog." By Jon Udell. April 15, 2003.
- Wikis and Blogs used in the Pie/Echo/Atom project.
- "Should Atom Use RDF?" By Mark Pilgrim. From XML.com. August 2003.
- See also: "WEBDAV (Extensions for Distributed Authoring and Versioning on the World Wide Web."
- See also: "RSS: 'Really Simple Syndication' | 'RDF Site Summary'."
- See also: "XML 2003 News Standards Summit Seeks Interoperability and Convergence." Sam Ruby presented Atom at this December 8, 2003 event.
- "Atom Publishing Format and Protocol" - General References.