View source for xfolk



= xFolk (RC1) =

xFolk is a simple and open format for publishing collections of bookmarks. It better enables services for improving user experience and sharing data in web-based bookmarking software.  xFolk may be embedded in (X)HTML, Atom, RSS, and arbitrary XML. It is one of several open [[microformats|microformat]] standards.

__TOC__

== Draft Specification ==

=== Editor ===
[http://thecommunityengine.com/ Bud Gibson], [http://thecommunityengine.com The Community Engine]

=== Authors ===
* [http://thecommunityengine.com/ Bud Gibson], [http://thecommunityengine.com The Community Engine]

=== Copyright ===
{{MicroFormatCopyrightStatement2005}}

=== Patents ===
{{MicroFormatPatentStatement}}

=== Inspiration and Acknowledgments ===
Thanks to: [http://www.cnbc.cmu.edu/~plaut/ David Plaut] who introduced me to the idea that items may partially belong to many categories at once.  More recently, thanks to: [http://tantek.com/ Tantek Çelik], [http://epeus.blogspot.com/ Kevin Marks], [http://steve.osdir.com/ Steve Mallet], [http://hybernaut.com/ Brian DelVecchio], and [http://blogmarks.net François Hodierne] who have contributed to the development of xFolk with thoughtful critiques and implementations.

== Introduction ==
Social bookmarking services let users save and tag bookmarks to share with other users.  Over the past year, the number of these services has mushroomed to [http://en.wikipedia.org/wiki/Social_bookmarking over 20], with popular examples including: [http://del.icio.us del.icio.us], [http://furl.com furl], [http://de.lirio.us de.lirio.us], and [http://blogmarks.net blogmarks].  

Lack of an open, interoperable data standard is a major issue in using social bookmarking services.  An open standard would make it possible to easily collect social bookmark data and remix it to invent new services along the lines of  [http://gataga.com gataga]'s experimental bookmark search engine.  An open standard would also make it possible to write javascripts that work across services [http://johnvey.com/features/deliciousdirector/ as some currently do for del.icio.us], enabling across-the-board improvements in user experience.

xFolk is an open social bookmarking standard that aims to achieve both benefits.  Social bookmarking services that adopt xFolk will continue to differentiate themselves with data services.  But, the data itself will be easy to manipulate by third party scripts and easy to share.  As a result, bookmarking services will be able to offer a wider array of options to their users at low cost and focus on what truly differentiates them.  Individuals or groups operating standalone bookmark repositories will have access to a wider array of functionality than they can produce on their own.

== Semantic XHTML Design Principles ==
{{SemanticXHTMLDesignPrinciples}}

== Format ==
Extensive analysis of social bookmarking services and linkblogs, reported on [http://thecommunityengine.com/home/archives/xfolk elsewhere], reveals that the data published by both bookmarking services and '''many''' different linkblogs are described by the following implied schema:

* A bookmarked or tagged link.
* A title for the entry.
* Tags for the link.
* An extended description or summary of the link.

As demonstrated in early iterations of the xFolk standard, this general schema can be translated into markup by:

# creating a container element for each entry of class <code>xfolkentry</code>, 
# using an <a> element for the bookmarked or tagged link of class <code>taggedlink</code>, 
# using title attribute for the tagged link <a> element, if it exists, as the entry title, otherwise using the element value,
# using [[reltag|RelTag]] for the tags, and
# using a container element of class <code>description</code>, such as &lt;p>, for any extended description or summary.

A given xFolk entry will always contain a tagged link including a title with all other elements optional.  Entries may have more than one tag as well as more than one element of class <code>description</code>.  Multiple elements of class <code>description</code> are ordered by default document order. Semantic elements within xFolk entries may be nested at arbitray depths.

Many social bookmarking systems exist, each with its own markup conventions.  Further, many people are already publishing personal link blogs.  xFolk is designed with ease of adapting to these current practices as a primary goal.  Therefore, few assumptions are made as to the exact kinds of elements used for an xFolk entry.  Rather, the work of defining semantics is left entirely to the class and rel (in the case of [[reltag]]) attribute values.

It is expected that developers will use [http://www.w3.org/TR/xpath XPath] or equivalent syntax in accessing xFolk entry elements.  a requirement for XPath is that the (X)HTML document be well-formed but not necessarily valid.  Thus, while undesirable, it is possible to serviceably use xFolk in an (X)HTML document that does not validate.

=== XMDP Profile ===

See the [[xfolk-profile|xFolk profile]] for the [http://gmpg.org/xmdp XMDP] profile of xFolk.

== Example ==
Here is a sample bookmark as displayed in [http://del.icio.us del.icio.us]'s standard markup.  Lines where the value of elements' class attributes must change to conform to xFolk are marked with a comment at the end.
<pre>&lt;div class=“post”&gt; <!--will change-->
  &lt;div&gt;
    &lt;a class=“delLink” href=“http://www.sifry.com/alerts/archives/000306.html”&gt; <!--will change-->
      Sifry's Alerts: Technorati launches Related Tags
    &lt;/a&gt; 
  &lt;/div&gt;
  &lt;div class=“extended”&gt; <!--will change-->
    Ever wanted to see what posts are related to other posts, what tags 
    are related to others? Now you can! Just check under the Tag 
    description on most tag pages, like this one, or this one, and you'll
    see the patterns. Can you smell the emergence?
  &lt;/div&gt;
  &lt;div class=“meta”&gt;
    to
    &lt;a class=“delNav” href=“/fpgibson/folksonomy”&gt;folksonomy&lt;/a&gt; <!--will change-->
    &lt;a class=“delNav” href=“/fpgibson/technorati”&gt;technorati&lt;/a&gt; <!--will change-->
    ... &lt;a class=“delNav” href=“/url/cbcabf7de070fdb46598ee679367be49”&gt;
    and 1 other person
    &lt;/a&gt;
    ... on 2005-04-09
  &lt;/div&gt;
&lt;/div&gt;</pre>


The equivalent in xFolk is as follows.  Comments are placed at the end of lines where class attribute changes were required. 

<code><pre><nowiki>
&lt;div class=“xfolkentry”&gt; <!-- changed -->
  &lt;div&gt;
    &lt;a class=“taggedlink” href=“http://www.sifry.com/alerts/archives/000306.html”&gt; <!-- changed -->
      Sifry's Alerts: Technorati launches Related Tags
    &lt;/a&gt; 
  &lt;/div&gt;
  &lt;div class="description"&gt; <!-- changed -->
    Ever wanted to see what posts are related to other posts, what tags 
    are related to others? Now you can! Just check under the Tag 
    description on most tag pages, like this one, or this one, and you'll
    see the patterns. Can you smell the emergence?
  &lt;/div&gt;
  &lt;div class=“meta”&gt;
    to
    &lt;a rel=“tag” href=“/fpgibson/folksonomy”&gt;folksonomy&lt;/a&gt; <!-- changed -->
    &lt;a rel=“tag” href=“/fpgibson/technorati”&gt;technorati&lt;/a&gt; <!-- changed -->
    ... &lt;a class=“delNav” href=“/url/cbcabf7de070fdb46598ee679367be49”&gt;
    and 1 other person
    &lt;/a&gt;
    ... on 2005-04-09
  &lt;/div&gt;
&lt;/div&gt;
</nowiki></pre></code>

Converting markup to be conformant with xFolk is almost always this easy.  The advantage of xFolk is that it provides one set of class attributes that can be reused across all services and link blogs, almost always with no loss of granularity.  The next section presents several more examples to illustrate this point.

== Many more examples ==

We have numerous examples to help developers incorporate xFolk into their sites.

=== In the wild ===

These are real live examples of functioning systems that publish bookmarks in xFolk.  These are a great place to start for anyone looking for examples "in the wild" to try parsing, indexing, organizing etc.  If you publish using xFolk, feel free to add it to the top of this list.  Once the list grows too big, we'll make a separate wiki page.

* [http://de.lirio.us de.lirio.us] currently publishes its bookmarks using xFolk (with the deprecated class attribute <code>extended</code> in place of <code>description</code>, see [[xfolk-XMDP | the XMDP]]).
* [http://dev.blogmarks.net/wiki/BlogSync blogmarks] currently exports bookmarks to blogs in xFolk (scroll down to the export example on the page; the deprecated class attribute <code>extended</code> is used in place of <code>description</code>, see [[xfolk-XMDP | the XMDP]]).
* [http://thecommunityengine.com The Community Engine] uses xFolk (with the deprecated class attribute <code>extended</code> in place of <code>description</code>, see [[xfolk-XMDP | the XMDP]]) for its [http://thecommunityengine.com/home main entries] and for its [http://thecommunityengine.com/webcites republished bookmarks].

=== Additional social bookmarking services ===

This example illustrates how xFolk may be applied to one additional service:

* [[xfolk-scuttle | scuttle]]

=== Link blogs ===

Social bookmarking services are only the most recent examples of people publishing links.  Link blogs have been around almost since the beginning of blogging.  They represent somewhat more of a challenge for xFolk because their markup tends to be less semantic from the outset.  The following examples illustrate some particular challenges and how they can be overcome.

* [[xfolk-kottke | kottke]]
* [[xfolk-pollas | pollas]]
* [[xfolk-jacobian | jacobian]]
* [[xfolk-julian-bez | julian-bez]]

== Implementations ==

The following implementations have been developed which generate xFolk. If you have an xFolk implementation, feel free to add it to the top of this list. Once the list grows too big, we'll make a separate wiki page.

* [http://de.lirio.us de.lirio.us] currently publishes its bookmarks using xFolk 0.4 (the class attribute <code>extended</code> is used in place of description).
* [http://dev.blogmarks.net/wiki/BlogSync blogmarks] currently exports bookmarks to blogs in xFolk 0.4 (scroll down to the export example on the page; the class attribute <code>extended</code> is used in place of <code>description</code>).

== References ==
=== Normative References ===
* [http://www.w3.org/TR/2002/REC-xhtml1-20020801/ XHTML 1.0 SE]
* [[rel-tag|RelTag]]

=== Informative References ===
* [http://thecommunityengine.com/home/archives/xfolk articles about xFolk]
* [http://thecommunityengine.com/home/archives/tags/microformats articles about the business value of microformats]
* [http://gataga.com gataga social bookmark search engine]
* [http://johnvey.com/features/deliciousdirector/ an ajax based interface for del.icio.us]
* [http://en.wikipedia.org/wiki/Social_bookmarking social bookmarking defined at wikipedia]

=== Similar Work ===
* [[hreview | hReview]]

== Work in progress ==
Although this specification has recently begun to stabilize as indicated by the version RC1, it is still a work in progress.  If warranted, I am prepared to go through multiple release candidates to achieve the narrow purpose of making bookmark entries more genrally accessible with as with as light weight a format as possible.  All changes since the last iteration have been motivated by the implementation experience of developers attempting to achieve this narrow aim.  Further changes will also most likely be motivated by implementation concerns.  See "future directions" below for additional microformat possibilities.

=== Changes since xFolk 0.4 ===
The class attribute value <code>extended</code> was deprecated in favor <code>description</code> to better conform with other microformat usage and some requests during implementation.  The other change has been to allow use of multiple elements of class <code>extended</code> based on some use cases discovered in implementation.

=== Future directions ===
There are several extensions one might imagine for xFolk.  Frequently, these extensions are best achieved by combining xFolk with another microformat.  For instance, one might want to indicate his or her evaluation of the bookmarked item.  This might be achieved by using [[vote-links | Vote Links]] or [[hreview | hReview]] with xFolk.

One can also imagine extending xFolk to provide data conformant with various social bookmarking service APIs, for instance to provide all bookmarks by tag.  These APIs are currently too fluid for specification in any kind of standard.  The APIs and the functionality they provide represent one way social bookmarking services and meta services can differentiate themselves.

A companion format called "xFolk definition" is under development.  xFolk definition will provide a means of explicitly defining the tags used in social bookmarks.

== Discussions ==

=== Q&A ===
* If you have any questions about xFolk, check the [[xfolk-faq|xFolk FAQ]], and if you don't find answers, add your questions!

=== Issues ===
* Please add any issues with the specification to the separate [[xfolk-issues | xFolk issues]] document.