(5) End-User Aggregation

• Users often have a small number of preferred Web sites
  • news can be tracked by subscribing to their feeds
  • this requires an feed-aware client (Firefox is not a good feed reader)
• Ajax-based feeds could be implemented as a client-side application
  • retrieve the feed, transform it to HTML, and render the result
  • but the security restriction of XMLHttpRequest gets into the way
  • Google Reader [http://www.google.com/reader/view/] accesses Google's own copy of the feed (FeedBurner [FeedBurner (1)])
• How can users find a feed?
  • feeds have URIs (they are Web resources) and can be referenced from within HTML

<link rel="alternate" type="application/rdf+xml" title="…" href="…" />
<link rel="alternate" type="application/rss+xml" title="…" href="…" />

<link rel="alternate" type="application/atom+xml" title="…" href="…" />

(6) Aggregation Intermediaries

• RSS is a frequently used format between content providers
  • news agencies want to distribute news items as easy as possible
  • by using a single format, producers and consumers can more easily interoperate
• Multiple RSS versions caused publishers to look for something better
  • RSS History [Content Syndication; RSS History (1)] had a head start and still is widely used
  • Atom History [Content Syndication; Atom History (1)] is a much better format and will eventually replace RSS
• User-configured portals are the merger between both scenarios
  1. users select a number of feeds as their preferred information sources
  2. the feeds are presented on a single personalized Web page [http://www.google.com/reader/view/]
  3. by sharing [http://www.google.com/reader/shared/16601496766743088901] and re-publishing [http://www.google.com/reader/public/atom/user/16601496766743088901/state/com.google/broadcast] items, users are becoming aggregation intermediaries

(14) Using Feeds for Data Management

• Delicious tags are available as feeds
• Creating a joint tag feed is as simple as aggregating feeds
  1. identify all tag feeds
  2. add all feeds to a feed aggregation platform
  3. republish the aggregate information as one feed
  4. use that feed for the aggregate information for all tags

(15) Delicious Tags as Feeds

(16) Google Reader Feeds

(17) Google Reader Widgets

        <table>
            <thead>
                <tr>
                    <th>Feed Roll</th>
                    <th>Feed Items</th>
                </tr>
            </thead>
            <tbody>
                <tr>
                    <td valign="top">
                        <script type="text/javascript" src="http://www.google.com/reader/ui/publisher-en.js"></script>
      <script type="text/javascript" src="http://www.google.com/reader/public/javascript-sub/user/16601496766743088901/label/delicious REST?callback=GRC_p(%7Bc%3A%22gray%22%2Ct%3A%22My%20%5C%22delicious%20REST%5C%22%20Feed%20Roll%22%2Cb%3A%22true%22%7D)%3Bnew%20GRC"></script>
                </td>
                    <td valign="top">
                        <script type="text/javascript" src="http://www.google.com/reader/ui/publisher-en.js"></script>
                        <script type="text/javascript" src="http://www.google.com/reader/public/javascript/user/16601496766743088901/label/delicious REST?n=10&callback=GRC_p(%7Bc%3A%22gray%22%2Ct%3A%22%5C%22delicious%20REST%5C%22%20via%20dret%22%2Cs%3A%22true%22%2Cb%3A%22false%22%7D)%3Bnew%20GRC"></script>                </td>
                </tr>
            </thead>
        </table>

(18) Explaining Delays