ClientRuntimeContext.ExecutingWebRequest Event
SharePoint 2010
An event that is raised when the Web request is sent to the server.
Assemblies: Microsoft.SharePoint.Client.Runtime (in Microsoft.SharePoint.Client.Runtime.dll); Microsoft.SharePoint.Client.Silverlight.Runtime (in Microsoft.SharePoint.Client.Silverlight.Runtime.dll)
This event fires when the ExecuteQuery() method is executed.