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Consuming an RSS Feed with ASP.NET and XSLT

RSS is a web content syndication format defined using XML. It is used by many sites and blogs to allow their content to be presented and aggregated. For example, the list on the right of this page is produced from an RSS feed from BBC News. You can find out more about RSS here.

This example shows how an external RSS feed can be rendered on a web page (like the one shown here). The example uses a custom ASP.NET control (written in C#) to encapsulate the functionality and simplify its inclusion on any host page. The sample server control uses public properties to allow it to be easily customised by the host page. The control also uses ASP.NET page caching features to limit the requests made by the host page to the remote RSS feed.

View a simple sample page here and its source code here.

The host page needs to include a Register page directive to allow the control to be referenced.

<@% Register TagPrefix="RSSFeed" TagName="ArticleList" Src="rssfeed.ascx" %>

The host page then refers to the control using the TagPrefix and TagName. This reference can also include HTML style attribute settings. These attributes map onto the public properties of the control. In this case they allow the host page to define the RSS feed, the maximum number of items to display and the XSLT to be used to transform the RSS content.

<RSSFeed:ArticleList RSSFeedURL="http://sampleDomain/rssfeed.xml" MaxDisplayItems="10" XSLFile="localSampleTransform.xsl" runat="server" />

The code for the server control can be seen here

The control uses the OutputCache page directive. This means that the control will only request a copy of the RSS field at known intervals. This is important since some RSS Feeds will impose a quota on requests from the same source.

The XSLT uses "local-name()" to avoid namespaces prefix problems and allow a single XSLT to process the widest range of RSS versions. The XSLT also includes CSS Style names in the output HTML (using the Class attribute) to allow the look and feel of the content to be controlled. If a more elaborate style was required, this could be embedded in the XSLT.

A sample XSLT file can be seen here

Alternatives? An ASP.NET DataList control could have been used to render the RSS, with the data loaded from the original XML then into a DataTable. The DataList control could then be bound to the DataTable. This approach avoids the need for an XSLT, but it might be harder to support all the flavours of RSS.

BBC Logo
Clan 'behind Philippine massacre'
The first witness in the trial of a powerful clan accused of the Philippines' worst political massacre says the family plotted the killings over dinner.
'Many failures' caused BP spill
BP's internal investigation into the oil spill in the Gulf of Mexico finds that "a series of failures" was to blame.
Church defiant over Koran burning
A small US church says it will defy international condemnation and go ahead with plans to burn copies of the Koran on the 9/11 anniversary.
Sri Lanka leader seeks more power
Sri Lankan MPs are to vote on proposals allowing the president to seek a third term - a move critics say marks the country's slide to autocracy.
Castro chides Ahmadinejad 'anti-Semitism'
Cuba's Fidel Castro criticises Iranian President Mahmoud Ahmadinejad for what he called his anti-Semitic attitudes.
Kampusch releases book on ordeal
Natascha Kampusch, who was kidnapped and held in a cellar for more than eight years as a child, launches her autobiography in Vienna.
Six die in Pakistan drone strike
Six people have died in a US missile strike targeting militants in Pakistan's tribal district on the Afghan border, security officials say.
Australia, NZ top 'giving' index
Australia and New Zealand top the table in the largest ever study into global charitable behaviour, but some poor countries also scoring high.
Gunmen hit Honduras shoe factory
Men armed with automatic weapons burst into a shoe factory in northern Honduras, killing 18 people in suspected gang attack.
Row over Japan-China boat crash
A diplomatic row between China and Japan intensifies after collisions between two Japanese patrol boats and a Chinese trawler.
Wed, 08 Sep 2010 12:28:41 GMT