RSS : Java Glossary

Introduction

There are seven RDF variants, Atom and RSS. You probably want to use RSS version 2.0, or support multiple formats including Atom 3. Atom was designed after RSS, and is considered cleaner.

Websites called aggregators spider the various feeds and keep a central database of them, and redistribute the information in various ways.

RSS-2

Most of the fields are pretty obvious. You can learn details about the many optional fields.

Unlike ordinary XML, there is no DTD.

The ttl field means Time To Live in minutes, how long a copy of your feed could be cached before it should be considered stale.

The image is logo for your feed, by default 88 × 31 pixels.

The optional guid (not guide) stands for: globally unique identifier. It is a string that uniquely identifies the item. When present, software reading your feed can use this unique string to determine if an item is new. In my HTML Static macros implementatin, I created it by computing a MD5 digesh of the website, feed, link, title and publish date giving 16 bytes (256 bits) which I display display as a 32-digit hex number. You want a globally unique id, not just unique within the file, unique within the feed over time or unique over your entire website. It is not used to fetch the item. If you say:

<!-- example of a hash-style guid -->
<guid isPermaLink="false">2000220155</guid>

But if you say:

<!-- example of a url-style guid -->
<guid isPermaLink="true">http://mindprod.com/jgloss/yakshaving.html?123</guid>

The pubDate uses computer-unfriendly, English-only alphabetic month and day-of-week names of RFC 822 It won’t accept UTC, only GMT or UT. Java does not support UT. It supports only a subset of the Java TimeZone abbreviations, so it would be dangerous to use Locale default.

Two fields I would have expected are missing, the URL of the home page, and URL of the xxx.xml feed itself.

RDF

FeedBurner

Atom 3

Viewing Feeds

Advantages

Opera browser can manage your RSS feeds. Firefox supports RSS feeds calling them live bookmarks. Some sites refer to them as live feeds.

Because the date of each item is encoded in a standard way, it makes it possible to display just the new unviewed material no matter what the frequency of the automated visiting.

Setting Up a RSS Feed

• Use an ordinary text editor to compose an XML file. When the file gets too big, drop the oldest items.
• Use any of the tools mentioned below.
• You can use Rome to produce RSS feed in various formats. The library handles the differences between supported formats without impacting the developer. Once you have a servlet (or something similar) to produce a feed using Rome , you can hook it up with FeedBurner which will take care of HTML-ing the feed, as well as giving the users options to bookmark it on various social bookmarking sites, add the feed to various readers, provide statistics for the click-thru on the feed items, etc. You can also get a user-friendly URL by doing so. A example of this technique is at Techcrunch.
• Roll your own. RSS is not that complicated. In the simplest case, for each item you have a date, a title and a subject wrapped in boilerplate. It is not that difficult to write a program that formats the data is any RSS form and also in HTML ready to include as a side effect. You can hard code the data into a program you compile and run each time you update the feed, or you could put it an CSV file or one line per field. Or you might use HTML Static macros to publish the data both in HTML and RSS. You might find that easier than learning a third party package. That is how I do the Java Glossary RSS feed for my own website. I embed magic comments on my webpages that the HTML Static Macro engine finds, sorts, groups and compiles into RSS 2 feeds.

Aggregators

Once your feed in operational, you might want to register it with the following aggregators.

	Technorati
	JavaBlogs	Java only. Use a lower case userid and password.
	Google Blog Search	for both blogs and feeds
	FeedBurner

Books

	recommend book⇒Developing Feeds with RSS and Atom
		paperback
	ISBN13:	978-0-596-00881-9
	ISBN10:	0-596-00881-3
	publisher:	O’Reilly
	published:	2005-04-13
	by:	Ben Hammersley
Covers RSS-2 and Atom to create website update feeds, and website update consolidating feeds, especially for news websites.
abe books.co.uk abe books.ca amazon.co.uk amazon.ca abe books.de chapters.indigo.ca amazon.de abe books.com abe books.fr amazon.com amazon.fr barnes and noble.com abe books.it powells.com iberlibro.com o’reilly safari abe books anz