Ungeek DaPo

I had an excellent conversation with Stephen Paul Weber, an active DiSo plugin developer, on his experience with the DiSo profile plugin. For those of you unfamiliar with this series of posts, the idea is to create blog-length interviews with various in the wild apps describing their processes and the technologies that they use with regards to data portability. The goal is to profile real use cases, solutions, and lessons learned when it comes to the current state of affairs for data portability technology. Note that these posts aren’t meant to recommend or not recommend certain technology, I leave that up to the developers/architects to decide based on their needs. If you have such an app and are interested in being interviewed, please leave me a comment on one of my posts and I will get in touch with you.

DiSo Project Background
Straight from the DiSo Google group About page

Social networks are becoming more open, more interconnected, and more distributed. Many of us in the web creation world are embracing and promoting web standards – both client-side and server-side. Microformats, standard apis, and open-source software are key building blocks of these technologies.

DiSo (dee • zoh) is an umbrella project for a group of open source implementations of these distributed social networking concepts. or as Chris Messina puts it:“to build a social network with its skin inside out”.

You can also listen to an interview by Chris Messina on Chris Messina about DiSo.

At this stage, DiSo plugins only work on self-hosted WordPress blogs which means if you have a blog on wordpress.com, you are out of luck. Also, all DiSo plugins currently are written in PHP, WordPress’s choice of language. Visit the WordPress site to get instructions on how to host your own WordPress blog and install plugins.

Application Overview
The DiSo WordPress profile plugin has the following main features

• When a user signs up for a WordPress account, the plugin makes it easier to import the user’s profile information via hCard and XFN (if available)
• Once a user has signed up for a WordPress account, the plugin makes it easier for the user (now blog owner) to publish their own profile with standards like hcard, XFN
• Supports permission features allowing blog owner to restrict access to his information based on predefined relationship, e.g., I can’t see his phone number but friends of him who login with their OpenID and are present on his authorized list of friends can see his phone number
• There is a sidebar widget that displays names/avatars of most recently logged in visitors

Technology
The key technical pieces are hCard, XFN (rel-me, rel-contact), PHP5, and standard WordPress plugin architecture. The plugin should work on WordPress 2.0 and above, and has been tested on 2.3 through 2.5. Currently the plugin mimics SGAPI functionality without the FOAF bit. Also, FOAF was considered but not implemented, another item for the future perhaps. He plans to add Google Social Graph API (SGAPI) support, but it wasn’t available when the plugin was written, so it is something to consider for the future – Steve Ivy wrote a PHP wrapper for SGAPI.

While the plugin works with OpenID, it does not require OpenID. There is a button to import profile and can fetch profile information if it is not an OpenID URL. OpenID profile extraction for XFN and hCard is automatic upon registeration and login. For OpenID feature to work, it needs the WP-OpenID plugin. No other libraries or plugins are required, in fact the import button works fine if the WP-OpenID is not installed. To display the user’s profile, the user needs to add a WordPress template tag. There is a page token for rendering on a WordPress page and a PHP function for addition directly to the template (documented on the plugin page). So far, most people don’t use it as a sidebar widget and instead display their profile information inline in the blog.

For an example of the plugin in action, check out Stephen’s blog, it powers the top half of his main page and the avatars of recent visitors in his sidebar.

Lessons learned
Some people have hCard on their OpenID pages via OpenID delegation usually or directly on the page. A large number of people have rel-me links going to their main profile somewhere else. In his opinion, the biggest hurdle is still HTML parsing in PHP which is surprsing to me since PHP is such a popular web development language. Event though PHP has excellent XML support but if the HTML is broken or incomplete as it is often the case in the world wild web, there is no library to handle that. An option is to fix it with HTML Tidy but most shared service providers (like DreamHost) do not have HTML Tidy installed. Without HTML Tidy, the plugin has to run the page through W3C remote tidy proxy which can be slow. Another option is to use HTML Purifier which is a re-implementation of HTML Tidy in PHP.

The current plugin user base is primarily DiSo developers and he has not gotten any feedback from non-DiSo developers. He noted that there is a goofy WordPress thing where the permissions model is based on the contacts list but WordPress only supports one blogroll list, so everyone on that list has the same permission. This is not a problem for most blogs but it could be a problem for multi-authors blog. There is no affiliation with WordPress other than it is a WordPress plugin.