SharePoint XML Web Part and proxy setting at 11:24 AM

XML Web Part is quite useful when you want to collect data from other sites (e.g. RSS). Yesterday I wanted to display local weather information using Weather.com XML Data Feed. I followed these steps:

1. Registered to weather.com to download the SDK (to use weather images)
2. Copied SDK images to TEMPLATE\Images\weather\
3. Added XML Web Part to WSS site and set URL to

   http://xoap.weather.com/weather/local/(zipcode)?cc=*&prod=xoap
   &unit=e&par=null&key=(license key)

   [Update] Weather.com has changed the URL to

   http://xoap.weather.com/weather/local/[zipcode]?cc=*&dayf=5
   &link=xoap&prod=xoap&par=[PartnerID]&key=[LicenseKey]

4. Set up XSLT to display weather images

But I got errors on different WSS machines:

1. "Cannot retrieve the URL specified in the XML Link property"
2. "The web part has timed out"

The reason was my WSS sites were behind a proxy server. WSS XML Web Part need know proxy settings, otherwise it can not access the URL.

The first error happens when the WSS application pool does not use a domain account; the second error happens when a domain account is used.

After I added proxy settings in web.config, the problem was solved:

<!-- Proxy setting -->
<system.net>
  <defaultproxy useDefaultCredentials="true">
    <proxy usesystemdefault="false"
              proxyaddress="http://proxyServer:port"
              bypassonlocal="true">
    </proxy>
  </defaultproxy>
</system.net>