Dave Johnson on open web technologies, social software and Java
Ive been meaning to write on this topic for a some time and to explain how Ive gone from being an advocate of RSS/Atom feeds, Atom Publishing Protocol and things bloggy to being a proponent of Linked Data (video), Semantic Web, RDF and other things that I previously considered to be nuisances. I've also got a new topic and blog series to announce, so here goes.
Once upon a time, I actually said the web is bloggy in conference presentations and without shame. It sounds silly and, for a blog server developer self-serving, but its true and its still true to this day. So much of what we do on the web can be made more useful via feeds. Thats because so many things can be usefully represented as a well formed log entry, i.e. a URL, title, date, description and a chunk of content. No matter whether your web application is Flickr, Twitter or IBM/Rational Team Concert, you can enable all sorts of interesting integrations and mashups by providing feeds.
Atom Publishing Protocol (APP) applied the feed concept to web APIs, using a feed to represent a collection of entries and allowing API callers to use HTTP to create, retrieve, update and delete entries. Entries could be anything of course. In the case of Googles APP-based GData Protocol, entries are Calendar Events, Picasa Photo uploads or YouTube videos. In the case of the IBM/Lotus Connections API, entries are Forum Posts, Social Network Profiles, File Uploads and more.
Im not going to argue that RSS is dead (or Atom) because I don't believe that, but the feeds approach only gets you so far. With feeds, we agree on a small set of common properties, e.g. URL, title, date, description and content. Not all resources on the web have those properties and many resources have a lot more. So in some cases applying Atom means forcing things to fit into the Atom model and in some cases it means inventing new properties for Atom, something that is supported by Atom format.
Im not going to argue that APP is dead or a failure either, but APP is an API approach and, for web integration, APIs only get you so far. Its definitely a good thing for developers when a web site or application provides an API, but if you have to integrate a set of N web sites and each has its own API and (even if theyre all based on APP) youre stuck doing N x N point-to-point integrations. APIs are not necessarily the best way, and certainly not the only way, to enable integrations on the web.
Linked Data (W3C page) is a different approach. Instead of forcing everything to fit the blog model, Linked Data gives us a way to define common vocabularies of properties about resources on the web and, most importantly, the links between them. Linked Data enables integration by allowing sites to weave their resources into the interlinked web of data that is the web.
These days, what's important to me at work is integration and in my mind, Feeds, APIs and Linked Data are different patterns for web-based integrations. They can be used in complementary ways. Just as we have defined and cataloged Enterprise Integration Patterns, I think it will be useful to do the same for Web Integration Patterns. I know I'll learn something in the process. In my next posts, I'll expand on this concept and after that, I'll start cataloging, in an informal and bloggy way, the patterns that I'm familiar with. More later...
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