Consuming JSON using Silverlight throws SecurityException - json

Question

I am trying to consume the JSON service from a Silverlight application on button click. But while reading the JSON service url, it throws the below exception.
System.Security.SecurityException ---> System.Security.SecurityException: Security error.
at System.Net.Browser.BrowserHttpWebRequest.InternalEndGetResponse(IAsyncResult asyncResult)
at System.Net.Browser.BrowserHttpWebRequest.<>c__DisplayClassa.<EndGetResponse>b__9(Object sendState)
at System.Net.Browser.AsyncHelper.<>c__DisplayClass4.<BeginOnUI>b__0(Object sendState)
--- End of inner exception stack trace ---
at System.Net.Browser.AsyncHelper.BeginOnUI(SendOrPostCallback beginMethod, Object state)
at System.Net.Browser.BrowserHttpWebRequest.EndGetResponse(IAsyncResult asyncResult)
at System.Net.WebClient.GetWebResponse(WebRequest request, IAsyncResult result)
at System.Net.WebClient.OpenReadAsyncCallback(IAsyncResult result)
Below is my code:
private void Button_Click(object sender, RoutedEventArgs e)
{
WebClient client = new WebClient();
client.OpenReadCompleted += new OpenReadCompletedEventHandler(client_OpenReadCompleted);
string url = "http://www.javascriptkit.com/dhtmltutors/javascriptkit.json";
client.OpenReadAsync(new Uri(url));
}
private void client_OpenReadCompleted(object sender, OpenReadCompletedEventArgs e)
{
StreamReader reader = new StreamReader(e.Result);
}
Please help me to fix it
I added clientaccesspolicy.xml in web folder. But when Fiddler is checked it says, "The requested URL /clientaccesspolicy.xml was not found on this server" . But I could access this xml from my url.
<?xml version="1.0" encoding="utf-8" ?>
<access-policy>
<cross-domain-access>
<policy>
<allow-from http-request-headers="*">
<domain uri="*"/>
<domain uri="http://*"/>
</allow-from>
<grant-to>
<resource path="/" include-subpaths="true"/>
</grant-to>
</policy>
</cross-domain-access>
</access-policy>

Answer 1

Before allowing a connection to a network resource, the Silverlight runtime will try to download a security policy file from the domain that hosts the network resource. There are two different methods used to download the security policy that depend on whether the connection request was from a WebClient or HTTP class or whether the connection request was from sockets.
If the connection request was from a WebClient or an HTTP class to a cross-domain site, the Silverlight runtime tries to download the security policy file using the HTTP protocol. The Silverlight runtime first tries to download a Silverlight policy file with a name of "clientaccesspolicy.xml" at the root of the requested target domain using the HTTP protocol.
If the "clientaccesspolicy.xml" is either not found (the web request returns a 404 status code), returned with an unexpected mime-type, is not valid XML, or has an invalid root node, then the Silverlight runtime will issue a request for the Flash policy file with a name of "crossdomain.xml" at the root of the requested target domain, using the HTTP protocol.
HTTP redirects for the policy file are not allowed. A redirect for a policy file will result in a SecurityException of access denied.