An Overview of RSS


To understand RSS, you have to start with XML. XML stands for eXtensible Markup Language. In simplest terms, XML does for computers and software what HTML (Hypertext Markup Language) does for humansit provides a common, standardized way to present information. When you look at an XML file, you'll see something that looks a lot like an HTML file, with tags, descriptions, and text. The two look alike because they're related, both derived from SGML, the Standard Generalized Markup Language that is the granddaddy of many current markup languages. What you're seeing, though, is a description of data and how it's arranged. XML is the language that more and more applications and control systems use to pass data between one another, but we're most interested for its use in one type of application: RSS readers.

Now, as you begin to think about building an RSS feed ("feed" is what the RSS and its related content is called), you should be aware that there are several versions of RSS floating around. There are several reasons for the multiple versions, but you don't need to worry about them. You just need to know of two versions, and stick to one of them for your podcast.

A Bit of History

The first versions of RSS were published by Netscape and further developed by Dave Winer at UserLand. The initial version was designated RSS 0.90, which was followed by 0.91, 0.92, 0.93, and 0.94. The latest version of this branch of RSS development is RSS 2.0. The only early version still in common use is RSS 0.91. It has the advantage of being very simple, but it is very limited in terms of the information the RSS feed itself can carry. Most people who like Winer's way of building RSS have now moved to RSS 2.0, which has a much richer set of metadata options (that is, many more options for including information about the podcast, blog, or article that the RSS feed points to), but is still less "verbose" than the other major RSS specification, RSS 1.0. For a variety of reasons, most of the current crop of podcast aggregators (applications that find and download podcasts you've subscribed to) work with RSS 2.0you can experiment with RSS 1.0, but for compatibility with the majority of podcast listeners, you'll want to write your RSS using the 2.0 (or 0.91) specifications.

tip

If you want to write the smallest and simplest RSS file possible, use RSS 0.91; you can easily move to RSS 2.0 if you find that you need to include more information about your podcast. If conforming to standards is important (say, because your company has that as a part of their development standards), then learn about RSS 1.0 as a possible future direction.


RSS and Beyond

While UserLand was still working on early versions of its RSS, a working group affiliated with the W3C developed an RSS version that is compliant with RDF, the Resource Description Framework that the W3C designed to standardize the way people use metatags. RSS 1.0 is based on a set of standards developed and maintained by an independent group, rather than an individual, and so will be more attractive to some users. It is, on the other hand, rather more verbose than RSS 2.0, and offers little difference in the type of information it can carry.

In the meantime, the folks at UserLand have developed yet another standard that is being used by a growing number of directories and aggregators. OPML (Outline Processor Markup Language) is a specialized offshoot of XML that describes RSS feeds in an outline form and makes exchange of feed and directory information possible in a standard way. Let's take a look at a podcast in RSS 0.92 and the feed described in OPML.

Let's take a look at the same podcast described in the two different standards.

Listing 9.1. A Sample Feed in RSS 0.92
<?xml version="1.0"?> <rss version="0.92">   <channel>     <title>Absolute Beginner's Guide to Podcasting</title>     <link>http://ABG2Podcasting.com/</link>     <description>The Stuff You Need to Know</description>     <item>        <title>Second Beginner's Podcast</title>        <link>http://ABG2Podcasting_2.mp3</link>        <description>The Second Podcast</description>     </item>     <item>        <title>First Beginner's Podcast</title>        <link>http://ABG2Podcasting_1.mp3</link>     </item>   </channel> </rss> 

In Listing 9.1, you can see a simple feed developed in RSS 0.92. There are many features available in this version of RSS that aren't used here, because this is designed to be a minimal feedsomething that you could emulate to put a podcast in front of the public with minimal muss and fuss. Notice that there are a couple of lines at the top to tell the software reading the file what it's dealing with, then a brief description of the channel (that's the total collection of your podcasts) and the podcasts themselves.

Listing 9.2. A Sample Feed in OPML
<opml version="1.0">    -<head>       <title>playlist.xml</title>       <dateCreated>Mon, 01 Aug 2005 07:24:55 GMT</dateCreated>       <dateModified>Fri, 5 Aug 2005 09:24:39 GMT</dateModified>       <ownerName>Curtis Franklin, Jr.</ownerName>       <ownerEmail>curt.franklin@gmail.com</ownerEmail>       <expansionState>1,3,17</expansionState>       <vertScrollState>1</vertScrollState>       <windowTop>164</windowTop>       <windowLeft>50</windowLeft>       <windowBottom>672</windowBottom>       <windowRight>455</windowRight>    </head>    -<body>       -<outline text="Podcasts">          <outline text="Absolute Beginner's Guid to Podcasting Podcasts. "/>       </outline>       -<outline text="July Podcasts">         <outline text="First Beginner's Podcast" type="podcast"         f="http://ABG2Podcasting_2.mp3"/>         <outline text="Second Beginner's Podcast" type="podcast"         f="http://ABG2Podcasting_2.mp3"/>         <outline text="Third Beginner's Podcast" type="podcast"         f="http://ABG2Podcasting_3.mp3"/>       </outline>    </body> </opml> 

When you look at a feed for the same podcast in OPML, you first see that there are additional lines at the top of the file to describe information about the entire podcast collection and how certain elements are to be displayed. If you look more closely, you'll see that there are outlined items, and space to collect an entire group of items (or groups of groups) within the body of the document. Remember, as with so many other pieces of technology, OPML wasn't designed specifically for podcasting, but it has found growing use for this new purpose. More and more aggregators are accepting OPML, as are most of the podcast directories. Learning both RSS 0.92/2.0 and OPML will maximize your ability to connect your podcast with individual aggregators and directory listings.

There are a handful of things you need to keep in mind as you're building your RSS code. First, aim for a balance in the information you put into the various elements of the file. Titles, for example, should be just long enough to be unique. If you give your podcasts cryptic names in the title blocks of your RSS, it's quite possible that a confusing, cryptic name will be what your listeners see when they download the file. Using file descriptions that are too long, on the other hand, can crowd the screen when a potential listener looks at the information. Balance is key.

You should also be careful not to include special characters or formatting in the fields of your RSS feed. They will display inconsistently in the various RSS and podcast clients, and could cause formatting problems in the way information is shown.

Finally, you should be sure to use the elements provided in the specifications to move information into the RSS feed. RSS 2.0 allows for most types of information to be included in the feed; if you need to include more than the basic information then look at the specifications to be sure you're putting it in the right place.

tip

More information about, and the specifications for, the RSS standards can be found online. For RSS 1.0 information, go to http://purl.org/rss/1.0/. For RSS 2.0 information, go to http://rss.userland.com/. For OPML, go to http://www.opml.org.


After you have created your RSS feed, you can check it for validity and correctness by using one of the available online validators. Among the validators you can use to check your RSS feed are

  • Feed Validator

    http://feedvalidator.org/

  • Walidator.com

    http://www.walidator.com/

  • CZWeb.org

    http://validator.czweb.org/userland-rss.php

  • Redland Validator

    http://librdf.org/rss/

  • Allpodcasts.com

    http://www.allpodcasts.com/Tools/RSSValidator.aspx

Remember that the validators will tell you whether or not the code you've written is correct from an XML and RSS point of viewwhether your code complies with the standards and meets the rules of the language. They won't tell you whether your feed will workthat has to come from the combination of validation and testing.

Of course, if you would like to have a piece of software generate the RSS feed for you, several options are available. These programs will scan the pages you've written, including any podcasts, photos, or other materials, and generate the RSS to allow your readers or listeners to subscribe to the feed. Among the RSS feed generators available are

  • Podcastamatic

    http://bradley.chicago.il.us/projects/podcastamatic/

  • Podcast RSS Feed Generator

    http://www.tdscripts.com/webmaster_utilities/podcast-generator.php

  • DirCaster

    http://www.shadydentist.com/wordpress/software/dircaster

This list is far from exhaustive, since it's not terribly difficult to build an RSS generator and new ones are being released each month. You should look at two or three, try them with the code for your page, and see what sort of RSS code they deliver. Always remember to run the RSS generated by one of these programs through a validator before you place it on your siteprograms can write code that's just as bad as anything a human can create.

tip

If you want to have your podcast listed in Apple's iTunes podcast directory, you'll need to learn some new RSS tags. Most are similar to the RSS code you'll write for your usual podcast feed with slight differences. For a complete list of the tags and techniques you'll need, go to http://phobos.apple.com/static/iTunesRSS.html.


You can also generate good RSS code with the automatic features of many blog hosts used by podcasters. Blogger (www.blogger.com), Radio Userland (radio.userland.com), and WordPress (www.wordpress.org) are just three of the hosting services or server applications that can help build the RSS code for you when you use them to host a blog.

The final step in having the RSS feed on your site is to have a graphical "button" that visitors can click on to have their iPodder or other software read the RSS file. There are two widely used buttonsone labeled "XML", the other labeled "RSS"which you upload to your site (each is a small .GIF-format image), then display on your page with your RSS feed as the target when the user wants to copy the RSS to paste into their podcast aggregator. It's simple, and has become the standard way of displaying the fact that you have an RSS feed on your site.



Absolute Beginner's Guide to Podcasting
Absolute Beginners Guide to Podcasting.
ISBN: B001U8C03Q
EAN: N/A
Year: 2004
Pages: 167

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