The Bloglines press release entitled New Bloglines Web Services Selected by FeedDemon, NetNewsWire and Blogbot to Eliminate RSS Bandwidth Bottleneck has this interesting bit of news

Redwood City, Calif.--September 28, 2004 -- Three leading desktop news feed and blog aggregators announced today that they have implemented new open application programming interfaces (API) and Web Services from Bloglines (www.bloglines.com) that connect their applications to Bloglines' free online service for searching, subscribing, publishing and sharing news feeds, blogs and rich web content. FeedDemon (www.bradsoft.com), NetNewsWire (www.ranchero.com), and Blogbot (www.blogbot.com) are the first desktop software applications to use the open Bloglines Web Services.

Bloglines Web Services address a key issue facing the growing RSS market by reducing the bandwidth demands on sites serving syndicated news feeds. Now, instead of thousands of individual desktop PCs independently scanning news sources, blogs and web sites for updated feeds, Bloglines will make low-bandwidth requests to each site on behalf of the universe of subscribers and cache any updates to its master web database. Bloglines will then redistribute the latest content to all the individuals subscribed to those feeds via the linked desktop applications -- FeedDemon, NetNewsWire or Blogbot -- or via Bloglines' free web service.
...
Bloglines Web Services Enable Synchronization for Desktop News Aggregators "Our customers have been looking for the ability to synchronize their feed subscriptions across multiple computers," said Nick Bradbury, founder of Bradbury Software and creator of FeedDemon, the leading RSS aggregator for Windows. "By partnering with Bloglines, we are now able to offer the rich desktop functionality FeedDemon customers have come to expect, with the flexible mobility and portability of a web service."

There are two aspects of this press release I'm skeptical about. The first is that having desktop aggregators fetch feeds from Bloglines versus the original sources of the feeds somehow "eliminates the RSS bandwidth bottleneck". It seems to me that the Bloglines proposal does the opposite. Instead of thousands of desktop aggregators fetching tens of thousands to hundreds of thousands of feeds from as many websites instead it is proposed that they all ping the Bloglines server. This seems to be creating a bottleneck to me, not the other way around.

The second aspect of the proposal is that I call into question is the Bloglines Sync API. The information on this API is quite straightforward

The Bloglines Sync API is used to access subscription information and to retrieve blog entries. The API currently consists of the following functions:

• listsubs - The listsubs function is used to retrieve subscription information for a given Bloglines account.
• getitems - The getitems function is used to retrieve blog entries for a given subscription.

All calls use HTTP Basic authentication. The username is the email address of the Bloglines account, and the password is the same password used to access the account through the Bloglines web site.

I was interested in using this API to round out the existing feed synchronization support in RSS Bandit. In current versions a user can designate a file share, WebDAV server or FTP server as the central location for synchronizing multiple instances of RSS Bandit. I investigated what it would take to add Bloglines as a fourth synchronization point after reading the aforementioned press release and came to the conclusion that the API provided by Bloglines falls short of providing the functionality that exists in RSS Bandit today with the other synchronization sources.  

The problems with the Bloglines Sync API include

1. The Bloglines Sync API only allows clients to retrieve the subscribed feeds. The user has to login to the Bloglines site to perform feed management tasks like adding, deleting or modifying the feeds to which they they are subscribed.
2. No granular mechanism to get or set the read/unread state of the items in the users feed list. 

These limitations don't make using the Bloglines Sync API a terribly useful way for synchronizing between two desktop aggregators. Instead, it primarily acts as a way for Bloglines to use various desktop aggregators as a UI for viewing a user's Bloglines subscriptions without the Bloglines team having to build a rich client application.

Thanks, but I think I'm going to pass.