Everything I need to know about RSS and XML Viewer Web Part (WP)
Firstly, I’d like to thank some great persons who share IT knowledge and experience with community. Secondly, I always tried to test some Web parts and standard functionality. So It’s time to share this knowledge with you.
Of cource, there is desclaimer
Everything you meet here is just my suggestions according my Sharepoint experience and my point of view on problems and all it’s may not be the ultimate truth
Purpose
RSS and XML view Web part are used for representation of XML data. RSS Web part provides us ability to work with RSS format (subformat of XML), while XML Web Part is used to show XML in your own HTML-page.
All this web parts may use custom XSL-transformations to customize data view. Common behavior of WPs is same: you define source link for xml-file and define necessary XSL-transformation, but in same cases we can get different error messages.
RSS Viewer WP is available just in Sharepoint Server edition, but not in Sharepoint Foundation (WSS). But you may do similar things with more common XML Viewer WP (http://weblogs.asp.net/gunnarpeipman/archive/2008/01/02/sharepoint-how-to-display-blog-feed-using-xml-web-part.aspx)
Connect to sources and proxy-services.
I suppose we will use the WPs with external sources, e.g. news sites. As you understand It can not be so simple if you are inside corparate network: beetween your Sharepoint farm and Internet stands firewall or proxy-servers.
Error
In following situation your RSS Viewer WP may show following error message:
The webpart has timed out
Resolution
Edit your web.config file with following code snippet for you web-application:
<!—… –>
<system.net>
<defaultProxy>
<proxy usesystemdefault="False" proxyaddress="http://proxyserver:proxyport"
bypassonlocal="True" />
</defaultProxy>
</system.net><!—… –>
Check the account under application pool is running. It has proper permissions to get access to source link.
Or increase the value of the Timeout attribute for WebPartWorkItem from the default 5000 milliseconds to a higher value.
You may use following URL to test your RSS Viewer WP:
http://feeds.bbci.co.uk/news/system/latest_published_content/rss.xml
Anonymous sessions problems
As I discovered all this web parts are used to communicate with another side not providing any authentication information. That’s why it very important to know about some assumptions i discovered.
Reason
XML and RSS Web part works only with anonymous access to sources.
Errors:
RSS Viewer WP doesn’t support authenticated sources and the following error is self-explained:
"The RSS webpart does not support authenticated feeds”
As for XML Viewer WP we see unodinary error, but the reason mey be the same:
Cannot retrieve the URL specified in the XML Link property. For more assisstance, contact your site administrator
Resolution
Discovering Internet you may meet following links that can resolve you access problems :
To get access to SharePoint Web Service – owssrv.dll, lists.asmx, feed.rss
- You need to provide rights for app pool account and anonymous access to objects:
- Provide anonymous access for the web application and list & libraries section at the site collection
- Web application pool account should be a part of WSS_WPG, ISS_WPG and WSS_ADMIN_WPG
- Get full description here: http://sharepointknowledgebase.blogspot.ru/2011/11/cannot-retrieve-url-specified-in-xml.html
Don’t try to get access to SharePoint getdata.svc Web Service
I spent a lot of time trying to get access to this useful REST web-service, but it can’t work with anonymous sessions used by WPs. You can look through all this service limitations : http://allthatjs.com/2012/07/20/limitations-of-sharepoint-listdata-svc/
I spent a lot of time but always got this error:
XML Viewer The Web Part has timed out.
Some useful links:
- SharePoint: How to display blog feed using XML Web Part (http://weblogs.asp.net/gunnarpeipman/archive/2008/01/02/sharepoint-how-to-display-blog-feed-using-xml-web-part.aspx)
- Do it Yourself RSS Aggregator in Windows SharePoint Services (http://blogs.officezealot.com/reinhart/archive/2005/01/18/3886.aspx)
- Error while referring “/_vti_bin/ListData.svc” (http://sharepoint.stackexchange.com/questions/14718/error-while-referring-vti-bin-listdata-svc)
- RSS Feeds using RSS WebPart and Proxy settings ( http://blog.mattsampson.net/index.php/rss-feeds-using-rss-webpart?blog=1 )
