Revision as of 21:56, 3 February 2006

hAtom

hAtom is a microformat for content that can be syndicated, primarily but not exclusively weblog postings. hAtom is based on a subset of the Atom syndication format.

This microformat is a draft; please address your concerns, issues, comments, etc. in hatom-issues.

Draft Specification

Editor/Author

David Janes, BlogMatrix, Inc.

Contributors

Benjamin Carlyle

Copyright

This specification is (C) 2005-2024 by the authors. However, the authors intend to submit (or already have submitted, see details in the spec) this specification to a standards body with a liberal copyright/licensing policy such as the GMPG, IETF, and/or W3C. Anyone wishing to contribute should read their copyright principles, policies and licenses (e.g. the GMPG Principles) and agree to them, including licensing of all contributions under all required licenses (e.g. CC-by 1.0 and later), before contributing.

Patents

This specification is subject to a royalty free patent policy, e.g. per the W3C Patent Policy, and IETF RFC3667 & RFC3668.

Introduction

Semantic XHTML Design Principles

Note: the Semantic XHTML Design Principles were written primarily within the context of developing hCard and hCalendar, thus it may be easier to understand these principles in the context of the hCard design methodology (i.e. read that first). Tantek

XHTML is built on XML, and thus XHTML based formats can be used not only for convenient display presentation, but also for general purpose data exchange. In many ways, XHTML based formats exemplify the best of both HTML and XML worlds. However, when building XHTML based formats, it helps to have a guiding set of principles.

Reuse the schema (names, objects, properties, values, types, hierarchies, constraints) as much as possible from pre-existing, established, well-supported standards by reference. Avoid restating constraints expressed in the source standard. Informative mentions are ok.
1. For types with multiple components, use nested elements with class names equivalent to the names of the components.
2. Plural components are made singular, and thus multiple nested elements are used to represent multiple text values that are comma-delimited.
Use the most accurately precise semantic XHTML building block for each object etc.
Otherwise use a generic structural element (e.g. <span> or <div>), or the appropriate contextual element (e.g. an <li> inside a <ul> or <ol>).
Use class names based on names from the original schema, unless the semantic XHTML building block precisely represents that part of the original schema. If names in the source schema are case-insensitive, then use an all lowercase equivalent. Components names implicit in prose (rather than explicit in the defined schema) should also use lowercase equivalents for ease of use. Spaces in component names become dash '-' characters.
Finally, if the format of the data according to the original schema is too long and/or not human-friendly, use <abbr> instead of a generic structural element, and place the literal data into the 'title' attribute (where abbr expansions go), and the more brief and human readable equivalent into the element itself. Further informative explanation of this use of <abbr>: Human vs. ISO8601 dates problem solved

Format

In General

The Atom Syndication Format provides the conceptual basis for this microformat, with the following caveats:

Atom provides a lot more functionality that we need for a "blog post" microformat, so we've taken the minimal number of elements needed. This can (and probably should) be expanded.
the "logical" model of hAtom is that of Atom. If there is a conflict, Atom should be taken as correct.
the "physical" model of hAtom -- the actual writing of elements -- is a lot more varied than Atom provides for, due to the variety of ways weblogs are actually produced in the wild. The hAtom microformat provides a number of rules for "briding the gap"

for example, if an entry is missing an author (required by Atom), it is assumed to be that of the XHTML page

Schema

Schema elements are based on the Atom nomenclature and follow the microformat pattern of prefixing a unique identifier (in this case, 'h') on the outermost container elements -- the Feed or Entry. The parts of this microformat are based on analysis of many weblog, bulletin board and media posts and can be read blog-post-brainstorming#Discovered_Elements. Note the renaming of 'EntryGroup' to 'Feed' to be more consistent with Atom ternminology.

Nomenclature

Note: Please see the hatom-issues document for discussion on property names.

Concept	Atom Identifier	hAtom Microformat Usage
Feed	`atom:feed`	Add `class="hfeed"`
Entry	`atom:entry`	Add class name `hentry`; if practical, also define `id="unique-identifier"` to the Entry.
Entry Title	`atom:title`	Add class name `headline`. Using `<h#>` also is encouraged.
Entry Content	`atom:content`	Add class name `content` to all appropriate blocks. Multiple Entry Content blocks are logically considered one concatenated `atom:content` equivalent.
Entry Summary	`atom:summary`	Add class name `excerpt` to all appropriate blocks. Multiple Entry Summary blocks are logically considered one concatenated `atom:summary` equivalent.
Entry Permalink	`atom:link`	Add a rel value of `bookmark`.
Entry Published	`atom:published`	Use class name `published`, optionally with the datetime-design-pattern.
Entry Updated	`atom:updated`	Use class name`updated`, with an ISO8601 absolute datetime, optionally with the datetime-design-pattern.
Entry Author	`atom:author`	Add class name `"author`. Using an `address` element is recommended. A hCard SHOULD be added.

Nesting Rules

Concept	Nests In	hAtom Opaque	Cardinality	Logical Cardinality Informative
Feed	HTML document	No	1-N	1-N
Entry	Feed	No	0-N	0-N
Entry Title	Entry Entry Permalink	No	0-N	0-1
Entry Content	Entry	Yes	0-N	0-1
Entry Summary	Entry	Yes	0-N	0-1
Entry Permalink	Entry Entry Title Entry Published	No	0-N	1
Entry Published	Entry Entry Permalink	No	0-N	0-1
Entry Updated	Entry Entry Permalink	No	0-N	1
Entry Author	Entry	Yes	0-N	1-N

hAtom Opaque

"hAtom Opaque" specifies whether a hAtom parser should not "look inside" the element for further hAtom content. If there are multiple rules applied to the same element take the OR of the two (i.e. "Yes/Opaque" always wins)

hAtom Opaque is designed to make parsing rules less ambiguous. In particular, it allows "quoted" hAtom elements (from another blog being blockquoted, for example) ti be ignored. It also allows 'embedded' hAtom to be potentially delivered within hAtom itself, and to prevent accidental 'leaking' of other microformat information up into the hAtom container. A general concept of opaqueness (need link) has also been proposed but it will complement, not replace this.

Cardinality

How many times can an element of the given type appear in it's nesting/parent element.

Logical Cardinality

This column is informative -- Atom has a number of rules for deciding what is required depending on the context and other elements, many which aren't strictly applicable to here.

From a modeling/logical perspective, the number of times can an element appear.

This is all rule dependent, see below. For example, an Entry Permalink may appear 6 times, but each one must be the same value; an Entry Content element may appear 3 times, but they are all concatenated together to make a single logical element.

Rules and Definitions

See the Nesting Rules section above for placement of these elements.

Feed

an XHTML Feed element is identified by the class name hfeed
a Feed element represents the concept of an atom feed

In particular, as a container for Entrys.

the Feed element is required, even if there is a single Entry
hAtom documents MAY have multiple, non-nested Feed elements

This may happen on news pages, or weblogs with "mini-blogs" on the sidebar.

DavidJanes: We need to work on this section. Is hfeed always going to be required?

Entry

an Entry element is identified by class="hentry"
an Entry element represents the concept of an atom entry
a weblog entry MUST be enclosed in a single Entry element
an Entry MUST have an enclosing Feed element
This enclosing element can be the same as the Entry -- i.e. class="hfeed hentry" is OK for feeds with a single entry.

Entry Title

an Entry Title element is identified by the class name headline
an Entry Title element alternately be identified by <h#>
an Entry Title element represents the concept of an atom entry title

Disambiguation

the first hAtom valid element with a class name of headline is the Entry Title

hAtom valid meaning somewhere where we expect it (like not inside Entry Content, for example).

otherwise, the first hAtom valid <h#> element to appear in an hAtom document is the Entry Title
otherwise, the Entry Title is the empty string

Atom does not allow for an entry not to have a title.

Entry Content

an Entry Content element is identified by class="content"
an Entry Content element represents the concept of an atom content
an Entry MAY have 0 or more Entry Content elements

We recognize this varies from the Atom spec: see the next rule.

the "logical Entry Content" of an Entry is the concatenation, in order of appearance, of all the Entry Contents within the Entry

Many weblogs split content into multiple sections with a "Read More" link and javascript tricks. This is also needed in cases where Entry Titles are coded inline and are considered part of the content.

the "logical Entry Content" MUST be complete; that is, contain the entire content of the Entry

Otherwise it should be marked as Entry Summary.

Entry Summary

an Entry Summary element is identified by class="excerpt"
an Entry Summary element represents the concept of an atom summary
an Entry MAY have 0 or more Entry Summary elements

We recognize this varies from the Atom spec: see the next rule.

the "logical Entry Summary" of an Entry is the concatenation, in order of appearance, of all the Entry Summarys within the Entry

Entry Permalink

an Entry Permalink element is identified by rel="bookmark"
an Entry Permalink element represents the concept of an atom link in an entry
Entry Permalinks SHOULD be absolute URIs
Entry Permalinks MUST be the same as the atom:link (or rss:link) used in syndication feeds

The intention of the previous two rules to gently force people to use strings that can be byte compared for equivalence. In general, the canonical URI should be the link used in an Atom entry.

if an Entry has multiple elements marked as the Entry Permalink, they MUST have exactly the same URI
an Entry SHOULD have an Entry Permalink
there can be at most 1 Entry in an XHTML document without an Entry Permalink; the Entry Permalink of this Entry is the URI of the page

This rule is needed for media pages (i.e. a news article on cnn.com). There is some ugliness of with this because the URI could be non-canonical.

Disambiguation

The first valid element in an Entry marked as an Entry Permalink is the Entry Permalink

Entry Published

an Entry Published element is identified by class="published"
a Entry Published element represents the concept of atom published
the machine readable datetime should be encoded with an <abbr> element using the datetime-design-pattern; the machine readable datetime should be complete, that is, specified to the second with the timezone included

This is to be consistent with the Atom Datetime Construct.

optionally, this can be specified by an HTML element with the ISO datetime in the text.

This is a little uglier for the reader, but it's possible.

Disambiguation

The first valid element in an Entry marked as an Entry Published is the Entry Published element

Entry Updated

an Entry Updated element is identified by class="updated"
a Entry Updated element represents the concept of atom updated
the machine readable datetime should be encoded with an <abbr> element using the datetime-design-pattern; the machine readable datetime should be complete, that is, specified to the second with the timezone included

This is to be consistent with the Atom Datetime Construct.

if there is no Entry Updated element, the value is assumed to be that of Entry Published

Entry Published is more often available in weblog templates, so we're going with that.

if there is no Entry Updated and Entry Published elements, transformation to Atom is problematic

This is because a published element is required. Suggestions would be appreciated here.

optionally, this can be specified by an HTML element with the ISO datetime in the text.

This is a little uglier for the reader, but it's possible.

Disambiguation

The first valid element in an Entry marked as an Entry Updated is the Entry Updated element

Entry Author

an Entry Author element is represented by class="author"
an Entry Author element SHOULD use an XHTML <address> element
an Entry Author element represents the concept of an atom author
an Entry Author element SHOULD contain an hCard

If it does not, just consider the text to effectively be the FN. hReview also considers a hCard to be a SHOULD, not a MUST.

an Entry MAY have 0 or more Entry Author elements
if an Entry has 0 Entry Author elements, the "logical Entry Author" is assumed to be the author of the XHTML page

Atom requires at least one Author

Categories and Tags

This section needs a lot more work.

Entry categories and tagging are represented by rel-tag
rel-tag elements may appear anywhere within a Entry, including Entry Content. This is the one case where we break opacity.

XMDP Profile

<dl class="profile">
 <dt>class</dt>
 <dd><p>
  <a rel="help" href="http://www.w3.org/TR/html401/struct/global.html#adef-class">
   HTML4 definition of the 'class' attribute.</a>
  This meta data profile defines some 'class' attribute values (class names) 
  and their meanings as suggested by a 
  <a href="http://www.w3.org/TR/WD-htmllink-970328#profile">
   draft of "Hypertext Links in HTML"</a>.
  <dl>
   <dt>hfeed</dt>
   <dd>
    The concept of atom:feed from 
    <a href="http://www.atomenabled.org/developers/syndication/atom-format-spec.php">The Atom Syndication Format</a>, 
    constrained and modified as per the <a href="http://microformats.org/wiki/hatom">hAtom microformat spec</a>.
   </dd>
   <dt>hentry</dt>
   <dd>
    The concept of atom:entry from 
    <a href="http://www.atomenabled.org/developers/syndication/atom-format-spec.php">The Atom Syndication Format</a>, 
    constrained and modified as per the <a href="http://microformats.org/wiki/hatom">hAtom microformat spec</a>.
   </dd>
   <dt>content</dt>
   <dd>
    The concept of atom:content from 
    <a href="http://www.atomenabled.org/developers/syndication/atom-format-spec.php">The Atom Syndication Format</a>, 
    constrained and modified as per the <a href="http://microformats.org/wiki/hatom">hAtom microformat spec</a>.
   </dd>
   <dt>excerpt</dt>
   <dd>
    The concept of atom:summary from 
    <a href="http://www.atomenabled.org/developers/syndication/atom-format-spec.php">The Atom Syndication Format</a>, 
    constrained and modified as per the <a href="http://microformats.org/wiki/hatom">hAtom microformat spec</a>.
   </dd>
   <dt>bookmark</dt>
   <dd>
    The concept of atom:link (without any "rel") with an atom:entry from 
    <a href="http://www.atomenabled.org/developers/syndication/atom-format-spec.php">The Atom Syndication Format</a>, 
    constrained and modified as per the <a href="http://microformats.org/wiki/hatom">hAtom microformat spec</a>.
   </dd>
   <dt>published</dt>
   <dd>
    The concept of atom:published from 
    <a href="http://www.atomenabled.org/developers/syndication/atom-format-spec.php">The Atom Syndication Format</a>, 
    constrained and modified as per the <a href="http://microformats.org/wiki/hatom">hAtom microformat spec</a>.
   </dd>
   <dt>updated</dt>
   <dd>
    The concept of atom:updatedfrom 
    <a href="http://www.atomenabled.org/developers/syndication/atom-format-spec.php">The Atom Syndication Format</a>, 
    constrained and modified as per the <a href="http://microformats.org/wiki/hatom">hAtom microformat spec</a>.
   </dd>
   <dt>author</dt>
   <dd>
    The concept of atom:author from 
    <a href="http://www.atomenabled.org/developers/syndication/atom-format-spec.php">The Atom Syndication Format</a>, 
    constrained and modified as per the <a href="http://microformats.org/wiki/hatom">hAtom microformat spec</a>.
   </dd>
  </dl>
 </dd>
</dl>

Examples

See hatom-examples.

Examples in the wild

This section is informative.

Ranting and Roaring (David Janes)
Second p0st (Phil Pearson)
Sound Advice (Benjamin Carlyle)
Sedna RSS (a feed aggregator based on SPIP, by Fil, IZO and others; GPLd sources are available at SPIP-Zone)

Implementations

This section is informative.

the Almost Universal Microformat Parser can extract hAtom content from webpages (example)
the microformat-action Greasemonkey script detects hAtom content on webpages and will call the Almost Universal Microformat Parser
the hAtom Template Rewriter converts Blogger, MovableType and Wordpress templates into hAtom compatible ones -- (hopefully) without presentation impact
An hAtom-2-Atom XSLT is available. (This version is currently broken but a working version is available)

References

Normative References

Informative References

Specifications That Use hAtom

Similar Work

Semantically-Interlinked Online Communities (SIOC) RDF Ontology

Work in progress

This specification is a work in progress. As additional aspects are discussed, understood, and written, they will be added. There is a separate document where we are keeping our brainstorms and other explorations relating to hAtom:

blog-post Brainstorming

Hints and Tips

CSS tips

HTML typically styles address as a block level element in an italic font. This will make it inline and plain within hAtom elements:

.entry address {
    display: inline;
    font-weight: normal;
    font-style: normal;
}

HTML typically puts a dotted line under <abbr> elements. This will put postage paid to that for Entry Updated and Entry Posted:

.entry abbr.updated, .entry abbr.posted {
  font-style: normal;
  border: none;
}

MovableType Template

A datetime encoded in an ABBR element can be produced with the following template code:

<abbr 
 class="posted" 
 title="<$MTEntryDate format="%Y%m%dT%H%M%S"$><$MTBlogTimezone
 no_colon="1"$>"><$MTEntryDate format="%X"$></abbr>

Discussions

See blogs discussing this page.

Q&A

If you have any questions about hAtom, check the hAtom FAQ, and if you don't find answers, add your questions!

Issues

Please add any issues with the specification to the separate hAtom issues document.

Recent Changes

Most recent at top please. This section will eventually be removed but should be helpful for people tracking changes during specing.

Entry Permalink now SHOULD (as opposed to MUST) be a complete URI
Entry Title now preferentially uses class="title"
Entry Author most explicitly be marked class="author"
using an <address around Entry Author and Entry Contributor is no longer required

@@ Line 347: / Line 347: @@
 </pre>
-=== Parsing Details ===
 == Examples ==

hatom: Difference between revisions

Revision as of 21:56, 3 February 2006

hAtom

Draft Specification

Editor/Author

Contributors

Copyright

Patents

Introduction

Semantic XHTML Design Principles

Format

In General

Schema

Nomenclature

Nesting Rules

hAtom Opaque

Cardinality

Logical Cardinality

Rules and Definitions

Feed

Entry

Entry Title

Disambiguation

Entry Content

Entry Summary

Entry Permalink

Disambiguation

Entry Published

Disambiguation

Entry Updated

Disambiguation

Entry Author

Categories and Tags

XMDP Profile

Examples

Examples in the wild

Implementations

References

Normative References

Informative References

Specifications That Use hAtom

Similar Work

Work in progress

Hints and Tips

CSS tips

MovableType Template

Discussions

Q&A

Issues

Recent Changes

See Also

Navigation menu

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