问题
The problem
I have a page with a silverlight object. It attempts to retrieve XML from another (external cross domain) page. But I am struggling with a security exception.
I have this code working brilliantly in WPF.
When using a website hosting a silverlight application with the same code, the user agent string of the HttpRequest object is null (and seemingly cannot be set). In fact there is no header information at all - this causes a security exception when attempting to make my asynchronous call.
The question
Why is the user-agent string (and header information) null in my silverlight 4 application when making an asynchronous call using HttpWebRequest?
Thanks in advance!
回答1:
sounds like you are might be hitting a cross domian issue does your external xml have a clientaccesspolicy file or a crossdomain file on the site? http://msdn.microsoft.com/en-us/library/cc197955(VS.95).aspx
Also what is the exception ? can you post.
Update:
OK, Have looked and run your code and yes it a crossdomian issue. The site "http://eu.wowarmory.com/" has a crossdomian file but only allow access from the sites listed in that file ? is you site one of those ? If not you are hitting crossdomain security. (WPF runs on the full CLR and so does not have these restrictions.)
There are options ... -Silverlight 4 running in elevated trust is one - but that is OOB
-Doing it in Javascript and the passing the data into Silverlight
-Get you server to do the work for you i.e. proxy
-Get them to change the crossdomain file !
There are others it really depends on what you are trying to achieve overall? can you explain more ?
来源：https://stackoverflow.com/questions/2908072/silverlight-4-httpwebrequest-user-agent-string-is-null