RSS + OPML/ SSE = Really Simple Synchronization

Microsoft CTO Ray Ozzie is blogging about a new specification--SSE (Simple Sharing Extensions) for RSS and OPML--that Microsoft is proposing.  The SSE specification, which is an early draft, is being released under a Creative Commons license – Attribution-ShareAlike, and has input from RSS and OPML pioneer Dave Winer, who comments on SSE in his blog today.

Ozzie describes the problem as follows:

As an industry, we have simply not designed our calendaring and directory software and services for this “mesh” model.  The websites, services and servers we build seem to all want to be the “owner” and “publisher”; it’s really inconsistent with the model that made email so successful, and the loosely-coupled nature of the web.

RSS syndicatates information in a simple and straightforward way, but it's not bi-directional.  Ozzie's team created SSE to enable loosely-coupled applications to use RSS and OPML in a way that has bi-directional, asynchronous replication of new and changed items of two or more cross-subscribed feeds and outlines.

An FAQ on Microsoft's MSDN site gives the following description of the benefits of SSE:

For example, SSE could be used to share your work calendar with your spouse. If your calendar were published to an SSE feed, changes to your work calendar could be replicated to your spouse's calendar, and vice versa. As a result, your spouse could see your work schedule and add new appointments, such as a parent-teacher meeting at the school, or a doctor's appointment.

SSE allows you to replicate any set of independent items (for example, calendar entries, lists of contacts, list of favorites, blogrolls) using simple RSS semantics. If you can publish your data as an RSS feed, the simple addition of SSE will allow you to replicate your data to any other application that implements the SSE specification.

The new XML elements described in SSE enable feed readers and publishers to generate and process incoming item changes in a manner that enables consistency to be achieved. In order to accomplish this, SSE introduces concepts such as per-item change history (to manage item versions and update conflicts) and tombstones (to propagate deletions, and un-deletions).

It's progress when Microsoft, Winer, Creative Commons and simple scenarios for making the Web more useful converge. I called attention obsessed Steve Gillmor to get his take. "SSE is the doorway to attention," he pronounced. "Adding namespaces to RSS and OPML brings us to the era of the integration of the Web and the crown jewels of [Lotus] Notes [created by Ozzie while at Lotus and now part of IBM]: Replication. Replication creates the timestamp to close the loop on the fundamentals of attention--who (a feed), what (an item) and for how long (time). From those three things you can infer 99 percent of the data that makes attention valuable." 

The blogosphere is buzzing about what will turn out to be an important part of the formula for managing information and attention on the Web...