異常代碼發生在第二句
HttpWebRequest request = result.AsyncState as HttpWebRequest;
WebResponse response = request.EndGetResponse(result);
提示信息：
System.Security.SecurityException ---> System.Security.SecurityException: 安全性錯誤。
位於 System.Net.Browser.BrowserHttpWebRequest.InternalEndGetResponse(IAsyncResult asyncResult)位於 System.Net.Browser.BrowserHttpWebRequest.<>c__DisplayClass5.<EndGetResponse>b__4(Object sendState)
位於 System.Net.Browser.AsyncHelper.<>c__DisplayClass2.<BeginOnUI>b__0(Object sendState)
--- 內部異常堆棧跟蹤的結尾 ---
位於 System.Net.Browser.AsyncHelper.BeginOnUI(SendOrPostCallback beginMethod, Object state)
位於 System.Net.Browser.BrowserHttpWebRequest.EndGetResponse(IAsyncResult asyncResult)
位於 SilverlightApplication2.MainPage.ResponseCallback(IAsyncResult result)
解決：
在\webapps\ROOT\下增加兩個文件：
crossdomain.xml和clientaccesspolicy.xml
------------------------------------------------------------------------
--crossdomain.xml--
------------------------------------------------------------------------
<?xml version="1.0"?>
<!DOCTYPE cross-domain-policy SYSTEM " http://www.adobe.com/xml/dtds/cross-domain-policy.dtd">
<cross-domain-policy>
<site-control permitted-cross-domain-policies="all" />
<allow-access-from domain="*"/>
<allow-http-request-headers-from domain="*" headers="*"/>
</cross-domain-policy>
------------------------------------------------------------------------
--clientaccesspolicy.xml--
------------------------------------------------------------------------
<?xml version="1.0" encoding="utf-8"?><access-policy>
<cross-domain-access>
<policy>
<allow-from http-request-headers="*">
<domain uri="*"/>
</allow-from>
<grant-to>
<resource path="/" include-subpaths="true"/>
</grant-to>
</policy>
</cross-domain-access>
</access-policy>