Revision as of 20:38, 18 April 2007

hCalendar

hCalendarはiCalendar (RFC2445)を基とした、シンプルでオープンなカレンダー・イベント情報配信用のmicroformatです。(X)HTMLやAtom, RSS, 任意のXMLなど、広範囲に適用可能なフォーマットとなっています。

hCalendarでイベント情報を配信するにはいくつかの方法があります。手っ取り早いのは、hCalendar creatorを使うこと。でももし、すでにイベントの情報を自分のblogやwikiなどに書いている場合はhCalendar authoring tipsを読み、hCalendarに沿うようマークアップをし直しましょう。

仕様

編者: Tantek Çelik (Technorati, Inc)
作者: Tantek Çelik, Technorati, Inc; Brian Suda

著作権

この仕様の著作権は、ページ編集に関わった人全てが保有しています。しかし、著者はこの仕様をGMPGやIETF、W3Cなどの標準化団体に提出することを考えています。この仕様に貢献したい場合は、これらの団体が持つ著作権に対する方針やポリシー（例:GMPG Principles）を読み、ライセンスに関する規定（例:CC-by 1.0や後のバージョン）を理解した上でお願いします。

特許方針

この仕様はロイヤリティーフリーの特許方針に帰属するものです。特許方針に関してはW3C Patent PolicyやRFC3667、RFC3668をご覧下さい。

謝辞

Thanks to:

Adam Bosworth for leading the FOO Camp 2004 HTML For Calendars presentation which brought together a critical mass of interested parties.

概要

iCalendar (RFC2445)はAppleのiCalなど、スケジュール管理用アプリケーションに広く採用され、また実装上の相互運用性も高いフォーマットになっています。

この広く使われているフォーマットを、blogで言及されるイベント情報に応用できないでしょうか。自分のblogにこれから行われるイベントであったり、この間参加したイベントについてエントリをおこすブロガーはたくさんいます。それらのイベント情報を少し構造化し、iCalendarとして出力可能にすれば、アプリケーションやWebサービスが自動的にその情報を利用できるようになります。

このhCalendarというう仕様は、XHTMLにてiCalendarを表現するフォーマットです。ブロガーはhCalendarを直接webページに埋め込んだり、またその情報をCSSでデザインすることが可能です。それだけではありません。アプリケーションはイベント情報を直接そのhCalendarから取ってくることができるようにります。イベントについて書かれたファイルを、webページとは別に用意する必要はもうありません。

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

For practical implementations, it should be noted that Internet Explorer's support for styling <abbr> elements is poor, and may require wrapper elements.

Format

In General

The iCalendar standard (RFC2445) forms the basis of hCalendar.

Note: the editor and authors of this specification are tracking the "iCal-Basic" effort and intend to base the core hCalendar profile on iCal-Basic. See references for a link to the current draft.

The basic format of hCalendar is to use iCalendar object/property names in lower-case for class names, and to map the nesting of iCalendar objects directly into nested XHTML.

More Semantic Equivalents

However, for some properties there is a more semantic equivalent, and therefore they get special treatment, e.g.:

URL in iCalendar becomes <a class="url" href="...">...</a> inside the element with class="vevent" in hCalendar.
ATTENDEE, CONTACT, and ORGANIZER in iCalendar may be represented by an hCard in hCalendar .
A named LOCATION (potentially with an address and/or geo) in iCalendar may be represented by a nested hCard in hCalendar. Similarly, an address LOCATION may be represented by an adr, and a geo (latitude and longitude) LOCATION may be represented by a geo.
UID in iCalendar simply becomes another semantic applied to a specific URL for an hCalendar event.

Singular vs. Plural Properties

For properties which are singular (e.g. "N" and "FN" from vCard), the first descendant element with that class should take effect, any others being ignored.

For properties which can be plural (e.g. "TEL" from vCard), each class instance should create a instance of that property. Plural properties with subtypes (e.g. TEL with WORK, HOME, CELL from vCard) can be optimized to share a common element for the property itself, with each instance of subtype being an appropriately classed descendant of the property element.

Plural Properties Singularized

Since plural property names become their singular equivalents, even if the original plural property permitted only a single value with multiple components, those multiple components are represented each with their own singularly named property and the the property is effectively multivalued and subject to the above treatment of multivalued properties.

Human vs. Machine readable

If an <abbr> element is used for a property, then the 'title' attribute of the <abbr> element is the value of the property, instead of the contents of the element, which instead provide a human presentable version of the value. This specification recommends that such <abbr> elements be used for the following iCalendar properties:

DTSTART, DTEND, DURATION, RDATE, RRULE

Example

Here is a sample event in an iCalendar:

BEGIN:VCALENDAR
PRODID:-//XYZproduct//EN
VERSION:2.0
BEGIN:VEVENT
URL:http://www.web2con.com/
DTSTART:20071005
DTEND:20071020
SUMMARY:Web 2.0 Conference
LOCATION:Argent Hotel\, San Francisco\, CA
END:VEVENT
END:VCALENDAR

and an equivalent event in hCalendar format with various elements optimized appropriately. See hcalendar-example1-steps for the derivation.

<div class="vevent">
 <a class="url" href="http://www.web2con.com/">http://www.web2con.com/</a>
  <span class="summary">Web 2.0 Conference</span>: 
  <abbr class="dtstart" title="2007-10-05">October 5</abbr>-
  <abbr class="dtend" title="2007-10-20">19</abbr>,
 at the <span class="location">Argent Hotel, San Francisco, CA</span>
 </div>

which could be displayed as:

http://www.web2con.com/ Web 2.0 Conference: October 5- 19, at the Argent Hotel, San Francisco, CA

Note that this is a live hCalendar microformat, which will be found on this page by parsers.

Example 2

The following example specifies a scheduled meeting that begins at 8:30 AM EST on March 12, 1998 and ends at 9:30 AM EST on March 12, 1998.

     BEGIN:VCALENDAR
     BEGIN:VEVENT
     UID:guid-1.host1.com
     DTSTAMP:19980309T231000Z
     DESCRIPTION:Project XYZ Review Meeting
     SUMMARY:XYZ Project Review
     DTSTART:19980312T133000Z
     DTEND:19980312T143000Z
     LOCATION:1CP Conference Room 4350
     END:VEVENT
     END:VCALENDAR

The equivalent in hCalendar:

<div class="vevent">
<h3 class="summary">XYZ Project Review</h3>
<p class="description">Project XYZ Review Meeting</p>
<p>To held on <abbr class="dtstart" title="1998-03-12T08:30:00-05:00">12 March 1998 from 8:30am EST</abbr> 
until <abbr class="dtend" title="1998-03-12T09:30:00-05:00">9:30am EST</abbr></p>
<p>Location: <span class="location">1CP Conference Room 4350</span></p>
<small>Booked by: <span class="uid">guid-1.host1.com</span> on 
<abbr class="dtstamp" title="19980309T231000Z">9 Mar 1998 6:00pm</abbr></small>
</div>

This could be displayed as:

XYZ Project Review

Project XYZ Review Meeting

To held on 12 March 1998 from 8:30am EST until 9:30am EST

Location: 1CP Conference Room 4350

Booked by: guid-1.host1.com on

9 Mar 1998 6:00pm

Note 1: The product information is not necessary since hCalendar is an interchange format. When transforming hCalendar back into iCalendar, the transforming engine should add its own product ID.

Note 2: A surrounding <span class="vcalendar"> element is optional, and is left out as such. It is optional since the context of a vcalendar is implied when a vevent is encountered. The implied context/scope is that of the document. Authors may explicitly use elements with class="vcalendar" to wrap sets of vevents that all belong to the same calendar, e.g. when publishing multiple calendars on the same page.

Note 3: The version information is unnecessary in hCalendar markup directly since the version will be defined by the profile of hCalendar that is used/referred to in the 'profile' attribute of the <head> element.

Note 4: ISO8601 dates (required by iCalendar) are not very human friendly. In addition, the year is often understood implicitly by humans from the context. Thus <abbr> elements are used to simultaneously provide a human friendly date and/or time in the visible contents of the element, while placing the respective machine parsable comprehensive ISO8601 datetime in the 'title' attribute. The notation YYYY-MM-DDThh:mm:ss should be used for better readability, following the format of RFC 3339.

Note 5: The difference between the DTEND ISO8601 date (2005-10-08) and the human readable date (7) is NOT a mistake. DTEND is exclusive, meaning, that the event ends just before the DTEND. Thus for events which start on one day and end on another day, the DTEND date must be specified as the day after the day that a human would say is the last day of the event.

Note 6: The location in this example contains implicit structure (venue name, city, state) which could be marked up explicitly as an hCard. See hCalendar brainstorming: hCard locations for a informative explanation of how to do this.

Buttons

Don't forget that you can add one of our buttons to the page, to indicate the presence of hCalendar microformats. For example: . If you can link it back to this page (or even page on your website, about your use of the microformat), so much the better!

More Examples

See hCalendar examples for more examples, including examples from iCalendar RFC 2445 converted into hCalendar.

Examples in the wild

This section is informative. The number of hCalendar examples in the wild has expanded far beyond the capacity of being kept inline in this specification. They have been moved to a separate page.

See hCalendar Examples in the wild.

Implementations

This section is informative. The number of hCalendar implementations has also expanded beyond the capacity of keeping them inline. They have been moved to a separate page.

See hCalendar Implementations.

References

Normative References

Informative References

Specifications That Use hCalendar

hReview

Similar Work

Related Pages

hCalendar - specification
hCalendar intro - plain English introduction
hCalendar authoring - learn how to add hCalendar markup to your existing events.
hCalendar creator (hCalendar creator feedback) - create your own hCalendar events.
hCalendar cheatsheet - hCalendar properties
hCalendar examples in the wild - an on-going list of websites which use hCalendars.
hCalendar implementations - websites or tools which either generate or parse hCalendars
hCalendar FAQ - If you have any questions about hCalendar, check here.
hCalendar parsing - normative details of how to parse hCalendar.
hCalendar profile - the XMDP profile for hCalendar
hCalendar singular properties - an explanation of the list of singular properties in hCalendar.
hCalendar tests - a wiki page with actual embedded hCalendar events to try parsing.
hCalendar "to do" - jobs to do
hCalendar advocacy - encourage others to use hCalendar.
iCalendar implementations

This specification is a work in progress. As additional aspects are discussed, understood, and written, they will be added. These thoughts, issues, and questions are kept in separate pages.

hCalendar Brainstorming - brainstorms and other explorations relating to hCalendar
hCalendar issues - issues with the specification

hcalendar-ja: Difference between revisions