auto-discovery – Joss Winn

Pimping your ride on the semantic web

Joss Winn / April 21, 2009August 30, 2009 / Fun, Identity, Standards & Specs, Tips, Web

Yesterday, I wrote about how I’d marked up my home page to create a semantic profile of myself that is both auto-discoverable and portable. A place where my identity on the web can be aggregated; not a hole I’ve dug for myself, but an identity that reaches out across the web but always leads back home.

While I enjoy polishing my text editor regularly and hand-crafting beautifully formed, structured data, we all know it’s a fool’s game and that the semantic web is about machines doing all the work for us. So here’s a quick and dirty run down of how to pimp your ride on the semantic web with WordPress and a few plugins.

You’ll need a self-hosted WordPress site that allows you to install plugins. I’ve got one on Dreamhost that costs me $6 a month. Next, you’ll want to install some plugins. I’ll explain what they do afterwards. One thing to note here is that I’m using plugins from the official plugin repository whenever possible. It means that you can install them from the WordPress Dashboard and you’ll get automatic updates (and they’re all GPL compatible). In no particular order…

I think that’s quite enough. All but the SIOC plugin are available from the official WordPress plugin repository. Here’s what they provide:

APML: Attention Profile Markup Language

APML (Attention Profiling Mark-up Language) is an XML-based format for capturing a person’s interests and dislikes. APML allows people to share their own personal attention profile in much the same way that OPML allows the exchange of reading lists between news readers.

The plugin creates an XML file like this one that marks up and weighs your WordPress tags as a measure of your interests. It also lists your blogroll/links and any embedded feeds.

Extended Profile

This plugin adds additional fields in your user profile which is encoded with hCard semantic microformat markup and can then be displayed in a page or as a sidebar widget. You can import hCard data, too. There might also be another use for this, too. (see below)

Micro Anywhere

Provides a couple of additional editor functions that allow you to create an hCard or hCalendar events page. Here’s an example.

OpenID

This plugin allows users to login to their local WordPress account using an OpenID, as well as enabling commenters to leave authenticated comments with OpenID. The plugin also includes an OpenID provider, enabling users to login to OpenID-enabled sites using their own personal WordPress account. XRDS-Simple is required for the OpenID Provider and some features of the OpenID Consumer.

This is key to your identity. You can use your blog URL as your OpenID or delegate a third-party service, such as MyOpenID or ClaimID. In fact, you’ve almost certainly got an OpenID already if you have a Yahoo!, Google, MySpace or AIM account. It’s up to you which one you choose to use as your persistent ID. Read more about OpenID here. It’s important and so are the issues it addresses.

XRDS-Simple

This is required to add further functionality to the OpenID plugin. It adds Attribute Exchange (AX) to your OpenID which basically means that certain profile information can be passed to third-party services (less form filling for you!) Like a lot of these plugins, install it and forget about it.

SIOC

Provides auto-discoverable SIOC metadata. “A SIOC profile describes the structure and contents of a weblog in a machine readable form.”

wp-RDFa

Provides an auto-discoverable FOAF (Friend of a Friend) profile, based on the members of your blog. I’ve been in touch with the author of this plugin and suggested that the extended profile information could also be pulled into the FOAF profile. This is largely dependent on the FOAF specification being finalised, but expect this plugin to do more as FOAF develops.

OAI-ORE Map

Provides an auto-discoverable OAI-ORE resource map of your blog. It conforms to version 0.9 of the specification, which recently made it to v1.0, so I imagine it will be updated in the near future. OAI-ORE metadata describes aggregated resources, so instead of seeing your blog post permalink as the single identifier for, say, a collection of text and multimedia, it creates a map of those resources and links them.

LinkedIn hResume

LinkedIn hResume for WordPress grabs the hResume microformat block from your LinkedIn public profile page allowing you to add it to any WordPress page and apply your own styles to it.

I like this plugin because you benefit from all the features of LinkedIn, but can bring your profile home. Ideal for students or anyone who wants to create a portfolio of work and offer their resume/CV on a single site. Depending on the theme you use, it does require some additional styling.

Get_OPML

This is a nice way to create an OPML file of your sidebar links. If, like on my personal blog, your links point to resources related to you, you can easily create an OPML file like this one. There’s a couple of things to note about this plugin though. The instructions mention a Technorati API key. I didn’t bother with this. When you create your links, just scroll down the page to the ‘advanced’ section and add the RSS feed there. Secondly, the plugin author has, for some stupid reason, hard-coded the feed to their own site into the plugin. Assuming you don’t want this spamming your personal OPML file, download a modified version from here or comment out line 101 in get-opml.php. I guess the plugin author thinks that you’ll be using this to import the OPML into a feed reader and from there, you can delete his feed. That’s no good to us though. Finally, you’ll want to make your OPML file auto-discoverable. You can do this by adding a line of html in your header, using the Header-Footer plugin below.

Header-Footer

This simply allows you to add code to the header and footer of your blog. In our case, you can use it to add an auto-discovery link to the header of every page of your blog.


<link rel="outline" type="text/xml+opml" title="ADD YOUR TITLE HERE" href="http://YOUR_BLOG_ADDRESS/opml.xml" />

WP Calais * + tagaroo

These three plugins use the OpenCalais API to examine your blog posts and return a bunch of semantic tags. I’ve written about this in more detail here (towards the end).

The Calais Web Service automatically creates rich semantic metadata for the content you submit – in well under a second. Using natural language processing, machine learning and other methods, Calais analyzes your document and finds the entities within it. But, Calais goes well beyond classic entity identification and returns the facts and events hidden within your text as well.

It’s an easy way to add relevant tags to your content and broadcast your content for indexing by OpenCalais. They place an additional link in your header that lists the tags for web crawlers and, I guess, improves the SEO for your site.

Extra Feed Links

I’ve written about this plugin previously, too. It adds additional autodiscovery links to your blog for author, category and tag feeds. WordPress feed functionality is very powerful and this plugin makes it especially easy to make those feeds visible.

Lifestream

This isn’t a semantic web plugin, but is a powerful way of aggregating all of your activity across the web into a single activity stream. See my example, here. It also produces a single RSS feed from your aggregated activity. Nice 😉

Wrapping things up

If you set all of this up, you’ll have a WordPress site that can act as your primary identity across the web, aggregates much of your activity on the web into a single site and also offers multiple ways for people to discover and read your site. You also get a ‘well-formed’ portfolio that is enriched with semantic markup and links you to the wider online community in a way that you control.

Bear in mind that some of these plugins might not appear to do anything at all. The semantic web is about machines being able to read and link data, right? If you look closely in the source of your home page, you’ll see a few lines that speak volumes about you in machine talk.


<link rel="meta" href="./wp-content/plugins/wp-rdfa/foaf.php"type="application/rdf+xml" title="FOAF"/>
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:dc="http://purl.org/dc/elements/1.1/">
<link rel="meta" type="text/xml" title="APML" href="http://blog.josswinn.org/apml/" />
<link rel="alternate" type="application/rss+xml" title="NoteStream RSS Feed" href="http://blog.josswinn.org/feed/" />
<link rel="resourcemap" type="application/atom+xml" href="http://blog.josswinn.org/wp-content/plugins/oai-ore/rem.php"/>

If you do want a way to view the data, I recommend the following Firefox add-ons

Operator: Auto-discovers any embedded microformats and provides useful ways to search for similar data via third-party services elsewhere on the web.

OPML Reader: Auto-discovers an OPML file if you have one linked in your header. Allows you to either download the file or read it on Grazr.

Semantic Radar: Auto-discovers embedded RDF data. Displays custom icons to indicate the presence of FOAF, SIOC, DOAP and RDFa formats.

The Tabulator Extension: Auto-discovers and provides a table-based display for RDF data on the Semantic Web. Makes RDF data readable to the average person and shows how data are linked together across different sites.

As always, please let me know how this overview could be improved or if you know of other ways to add semantic functionality to your WordPress blog. Thanks.

Addicted to feeds

Joss Winn / April 15, 2009February 24, 2010 / Data, Fun, Mashups, Standards & Specs

I’ve been a long time consumer of news feeds and spend a lot of time reading the web via 200+ feeds in Google Reader. More recently, and largely as a result of working on WriteToReply, I’ve become just as addicted to publishing feeds from any data end point I can find.

WordPress makes this quite easy for developers, providing a whole load of functions and template tags for feeds. For the rest of us, there’s also documentation which is useful is you’re wondering what kinds of feeds can be generated from a basic WordPress site.

All the examples below, assume you’re using ‘pretty URLs’. If your URLs are something like http://example.com/?p=123 then the same principles apply but you’ll use the format /?feed=feed_type i.e. http://example.com/?feed=rss2 The documentation shows full examples.

So, here are the basic content feeds. RSS is RSS version 0.92 and RDF is RSS version 1.0, if you were wondering.

http://example.com/feed/

http://example.com/feed/rss/

http://example.com/feed/rss2/

http://example.com/feed/rdf/

http://example.com/feed/atom/

It’s also pretty straightforward to create a feed from a category or tag

http://example.com/category/my_category/feed/

http://example.com/tag/my_tag/feed/

You can also create feeds from combined tags

http://example.com/tag/tag1+tag2+tag3/feed/

And we know that a feed is available for site comments

http://example.com/comments/feed/

and it’s simple to grab a feed of comments from a single post by appending /feed/ to the end of the post permalink.

http://example.com/2009/01/01/my-latest-post/feed

You can also create a feed of a single post itself, by appending '?withoutcomments=1' to the end of the URL

http://example.com/2009/01/01/my-latest-post/feed/?withoutcomments=1

There is a feed for each author of the blog

http://example.com/author/joss/feed

but alas, as far as I know, no feed for the comments by any particular person.

You can also do something fancy with dates

http://example.com/2009/feed

http://example.com/2009/01/feed

http://example.com/2009/01/15/feed

and one of my favourite types of feed is from a search

http://example.com/?s=search_term&feed=rss2

Now all of this is well and good, but how many readers are going to know or care about constructing the various types of feeds available? Fortunately, it’s possible to make many of these feeds auto-discoverable either by adding some simple code to your theme’s header.php or installing a plugin.

By default, two feeds are auto-discoverable on your WordPress site: An atom and rss2 feed of your posts.

By using the Extra Feed Links plugin, you can make your comments, category, tag, author and search feeds autodiscoverable.

It’s also got a useful template tag that allows you to show the feed links in your theme, making the discovery of feeds even easier. I created a simple widget for the plugin to display the feed and an RSS icon in the sidebar

Here’s the code. Let me know where it could be improved as I just hacked it together from looking at other widgets.

<?php
function widget_extrafeeds_register() {
function widget_extrafeeds($args) {
extract($args);
?>
<br />
<?php echo $before_widget;
echo $before_title;
echo $widget_name;
echo $after_title; ?>
<ul class="sidebarList">
<?php extra_feed_link(); ?> <?php extra_feed_link('http://path/to/your/feed/icon/feed.png'); ?>
</ul>
<?php echo $after_widget; ?>
<?php
}
register_sidebar_widget('Extra Feeds',
'widget_extrafeeds');
register_sidebar_widget('Extra Feeds','widget_extrafeeds');}
add_action('init', widget_extrafeeds_register);
?>

To get this to work with the plugin, you need to add this to the very bottom of the plugin’s main.php file

// widget support
require(dirname(__FILE__) . '/widget.php');

Like I said, if anyone can improve on this, do let me know. Also note that you’ll need to point the URL in the widget to a feed icon. A lot of themes include them in their /images/ directory, which makes it easy.

By using the widget or template tag, you can have these appearing on the relevant pages.

Try it by using http://writetoreply.org/tags 🙂

If you’re interested in how to add category and tag auto-discovery feeds to your theme’s source code, try adding this to your header.php

<?php if (is_category()) { ?>
<link rel="alternate" type="application/atom+xml" title="<?php bloginfo('name'); ?> &amp;raquo; <?php single_cat_title(''); ?> Atom Feed" href="<?php echo
get_category_feed_link(get_query_var('cat'), 'atom'); ?>" />
<?php } ?>

<?php if (is_tag()) { ?>
<link rel="alternate" type="application/atom+xml" title="<?php bloginfo('name'); ?> &amp;raquo; <?php single_tag_title(''); ?> Atom Feed" href="<?php echo
get_tag_feed_link(get_query_var('tag_id'), 'atom'); ?>" />
<?php } ?>

<?php if (is_category()) { ?>
<link rel="alternate" type="application/rss+xml" title="<?php bloginfo('name'); ?> &amp;raquo; <?php single_cat_title(''); ?> RSS2 Feed" href="<?php echo
get_category_feed_link(get_query_var('cat'), 'rss2'); ?>" />
<?php } ?>

<?php if (is_tag()) { ?>
<link rel="alternate" type="application/rss+xml" title="<?php bloginfo('name'); ?> &amp;raquo; <?php single_tag_title(''); ?> RSS2 Feed" href="<?php echo
get_tag_feed_link(get_query_var('tag_id'), 'rss2'); ?>" />
<?php } ?>

<?php if (is_category()) { ?>
<link rel="alternate" type="application/rdf+xml" title="<?php bloginfo('name'); ?> &amp;raquo; <?php single_cat_title(''); ?> as RDF data" href="<?php echo
get_category_feed_link(get_query_var('cat'), 'rdf'); ?>" />
<?php } ?>

<?php if (is_tag()) { ?>
<link rel="alternate" type="application/rdf+xml" title="<?php bloginfo('name'); ?> &amp;raquo; <?php single_tag_title(''); ?> as RDF data" href="<?php echo
get_tag_feed_link(get_query_var('tag_id'), 'rdf'); ?>" />
<?php } ?>

I learned this from the author of this related plugin, which is similar but not quite as powerful as the Extra Feed Links plugin.

Finally, if you use FeedBurner, beware that it breaks some of the above feeds. One fix for ensuring that tag and category feeds continue to work as they should is to modify the FeedBurnerFeedSmith plugin as noted here. Simply change the line

is_feed() &amp;&amp; $feed != 'comments-rss2' &amp;&amp; !is_single() &amp;&amp;

to read

is_feed() &amp;&amp; $feed != 'comments-rss2' &amp;&amp; !is_single() &amp;&amp; !is_tag() &amp;&amp;

That’ll do for now. I intend to learn more about the RSS and Atom specifications over the next few weeks and will post anything I think relevant here. If you can add anything to this post, please do leave a comment. Thanks.