You can set up outbound syndication for your Web site and expose your content to the world in one afternoon using an XML technology called RSS. For anyone who ever wanted to increase audience and traffic while maintaining content and presentation control, RSS is the answer. Find out how to do it, step by step.
by Ladd Angelius
|n RSS XML feed is an extremely simple way to let external sites link to content on your Web site. If you’re looking for a fast, painless way to do outbound syndication and find a larger audience for your content, RSS is going to be worth your time.At its most basic, RSS generates a list of links, generated programmatically, to various resources on your site with a description of the content for each link. This XML feed is just a publicly accessible text file and therefore you can easily create your feed to automatically regenerate periodically. This way, new content updates are added to the list without any human effort. With RSS, your news feed can be as dynamic as you like.And, because it’s in XML, other sites can easily consume and display your content feed automatically, thereby driving traffic back to your site. This is a win-win situation for sites that want to increase their traffic while maintaining control of their content.In this article, you’ll learn what you need to create a feed, see a sample feed structure, walk through the code that creates the XML (in this case we’ve used ColdFusion). I’ll also discuss additional steps to take for validating and implementing syndication for your site.
What You Need
|A Sample RSS Feed
Once you have completed steps 1 and 2 on the previous page, it’s time to dynamically build the text file. This file will be formatted as XML and has two distinct sections. The top section contains basic information about your feed, such as the title and the time the file was generated. The bottom section has information on each specific piece of content that you wish to syndicate (an “item”).First, I’ll show an example feed, and then I’ll show how to generate and write out the file in ColdFusion. The example feed follows; bold items should be replaced with information for your site.
<?xml version="1.0" ?> <!-- RSS generated by DevX.com on Fri, 24 Jan 2003 12:38:45 PST ---> <rss version="0.91"> <channel> <!--- The 'channel' tag is the area where you specify general information about your feed---> <title>DevX Featured Content</title> <link>http://www.devx.com</link> <description>Latest DevX Content</description> <language>en-us</language> <copyright>Copyright 2003 DevX</copyright> <docs>http://backend.userland.com/rss</docs> <lastBuildDate>Fri, 24 Jan 2003 12:38:45 PST</lastBuildDate>
If you want to show an image with your content feed, use the optional image section below:
<image> <title>DevX</title> <url>http://www.devx.com/assets/devx/3182.gif</url> <link>http://www.DevX.com</link> </image>
The next section is where each piece of content is identified and described:
<item> <title>Attend to your future. </title> <description>A future where millions of users are waiting.</description> <link>http://www.devx.com/content/id/10559</link> <author> email@example.com </author> <pubDate>Wed, 22 Jan 2003 11:19:28 PST</pubDate> </item> <item> <title> etc </title> <description> etc </description> <link> etc </link> <pubDate> etc </pubDate> </item>
You can include as many items as you want. When you’re finished, close the channel and rss tags.
|Creating the File
To create the file, you first need to query the database to grab the content descriptions you want to syndicate. The SQL code below is a quick, simple method of doing this. You will need to modify it to fit your situation. The <cfquery> tags are specific to ColdFusion. The code in this section of the article is taken from the complete sample code, which is available for download here.
<cfset NumberOfFeedItems = 10> <cfquery name="getLatestPublishedArticles" datasource="yourDB"> SELECT TOP #numberOfFeedItems# * FROM yourContent ORDER BY PublishedDate DESC </cfquery>
Next, set a date variable.
<cfset theDatetime = "#dateformat(now(), "ddd, dd mmm yyyy")# #timeformat(now(), "HH:mm:ss")# PST">
Now, save the output to a variable. In my ColdFusion version I saved the output to a variable called “theXML.” It is a string that will contain all my XML.
<cfsetting enablecfoutputonly="yes"> <cfsavecontent variable="theXML">
Now write out the XML text. Here is the top portion of the file:
<cfoutput> <?xml version="1.0" encoding="ISO-8859-1" ?> <!-- RSS generated by DevX on #theDatetime# --> <rss version="2.0"> <channel> <title>DevX Featured Content</title> <link>http://www.devx.com</link> <description>Latest DevX Content</description> <language>en-us</language> <copyright>Copyright 2002 DevX</copyright> <docs>http://backend.userland.com/rss</docs> <lastBuildDate>#theDatetime#</lastBuildDate> <image> <title>DevX</title> <url>http://www.devx.com/assets/devx/3182.gif</url> <link>http://www.DevX.com</link> </image> </cfoutput>
The next step is to start adding content items that you want to syndicate. In ColdFusion, I did this with a simple loop. In other words, I loop over the values returned from the first query I did:
<cfloop from="1" to = "#numberOfFeedItems#" index="ctr">
Now set up variables with the data for each item. This is also a good place to “massage” the data so that you can avoid having any illegal characters or tags—you must have properly formatted XML. I used the “Replace” function to replace “<” signs with “& l t ;.” This gets around the problem of embedding HTML in your feed. If you might have HTML tags embedded in your XML, then the XML will not validate correctly unless you do this kind of replacement. Also, if you have URLs with URL parameters embedded in your fields, you must replace the “&” signs with “& a m p ;” so the XML will validate correctly. For example, in the URL http://www.aWebSite.com/index.htm?value1=one&value2=two, the “&” sign in the string will cause trouble.
<cfscript> title = replace(getContent.title[ctr], "<", "<", "ALL"); description = replace(getContent.abstract[ctr], "<", "<", "ALL"); description = replace(description, "&", "&", "ALL"); date = dateformat(getContent.dateFirstPublished[ctr], "ddd, dd mmm yyyy"); time = timeformat(getContent.dateFirstPublished[ctr], "HH:mm:ss") & " PST"; author = replace(getContent.author[ctr], "<", "<", "ALL"); pubDate = date & " " & time; </cfscript>
Then output the fields for each item:
<cfoutput> <item> <title>#title#</title> <description>#description#</description> <link>http://www.devx.com/content/id/#getContent.content_id[ctr]#</link> <author>#authors#</author> <pubDate>#pubDate#</pubDate> </item> </cfoutput>
Now close the loop, close the channel and rss tags, and close the cfsavecontent tag.
</cfloop> <cfoutput> </channel> </rss> </cfoutput> </cfsavecontent>
The XML is stored in “theXml” variable, and you can write it to a publicly accessible Web directory using this line:
<cffile action="write" file="c:devxsyndicationoutgoingdevxFeed.xml" output="#theXml#">
Finally, set the MIME type of the document so the browser knows the output is in XML. This is an optional step and simply allows you to see the XML you generate in a browser.
<cfcontent type="text/xml"> <cfoutput>#theXml#</cfoutput>
If you’ve done everything to this point, you now have a finished RSS file. You aren’t quite done though. These last few clean up items accomplish some important tasks:
Update the File at a Scheduled Time
Other methods might be using the cachedWithin attribute of the cfquery tag, creating a cron job (on a GNU/Linux system), using a Windows Scheduled Task, or setting a timestamp in the application and checking it each time the script is run.
Validate your RSS
http://feeds.archive.org/validator/check?url=<your RSS URL here>
All you do is go to the link with your RSS URL appended, like this:
If your RSS feed is valid, you’ll see this: Otherwise you see a detailed breakdown of your feed, with lines numbers, errors, and a help link to explain what the error is and how to fix it.
To do this just replace the top-most tag in your XML
<?xml version="1.0" ?>
with this line:
<?xml version="1.0" encoding="windows-1252" ?>
There are many character encoding settings you can use. This article has a good explanation of character encoding. Register Your Feed
On Syndic8.com, to add a feed you simply create a login and then suggest a valid feed URL. After suggesting a feed, it gets submitted for review by a human. Once a human has approved it, it gets added to the valid feed master list.
It’s a completely open and free process. When you sign up you will be asked to become one or all of the roles “Reviewer,” “Evangelist,” “Scraper,” or “Fixer” to help out with the community.
<channel> <title>DevX Featured Content</title> <link>http://www.devx.com</link> <description>Latest DevX Content</description> <category>Technical Articles</category> <category>Computer Programming</category> <category>ColdFusion</category> <item> <title> </title> <description> </description> <link> </link> <category>Java</category> <category>software engineering</category> </item>
You can create your own categories or you can use public taxonomies, where other folks have created standard categories. A couple of examples of public taxonomy sites are http://dmoz.org/ and http://www.superopendirectory.com/. To use a public taxonomy you provide a link to the taxonomy in the <category> tag like this:
Creating an RSS content feed is one of those projects that pays rich rewards for a very small upfront investment of time. For any Web site that wants to find painless ways to increase traffic while still controlling content, RSS is the right choice.Ladd Angelius is a Software Engineer at DevX. He can be reached at firstname.lastname@example.org.