/// <summary>
/// Begins asynchronous ajax call handling
/// </summary>
/// <param name="context"></param>
/// <param name="callback"></param>
/// <param name="asyncState"></param>
/// <returns></returns>
public IAsyncResult BeginProcessRequest(HttpContext context, AsyncCallback callback, object asyncState)
{
AjaxTask task = null;
string ajaxCmd = context.Request["cmd"];
//Check for purchase restrictions
if (!string.IsNullOrEmpty(ajaxCmd))
{
task = CreateTask(ajaxCmd.ToLower());
}
if (task == null)
{
task = AjaxTask.NullTask;
}
//Assign task properties
task.HttpContext = context;
task.AsyncCallback = callback;
task.AsyncState = asyncState;
//Start the task
task.Begin();
//If task is not executing any async code then we need to call Finish() here
if (task.AsyncWaitHandle == null)
{
task.AsyncCallback(task);
}
return(task);
}
/// <summary>
/// Called automatically when an ajax task is done executing
/// NOTE: This function is called from the ThreadPool thread
/// </summary>
/// <param name="result"></param>
public void EndProcessRequest(IAsyncResult result)
{
//A task has finished executing
//Check Task.Status and proceed accordingly
AjaxTask task = result as AjaxTask;
task.Finish();
//If there is a URL to redirect to then clear the response and only write the redirect url
if (!string.IsNullOrEmpty(task.RedirectURL))
{
task.HttpContext.Response.Clear();
task.HttpContext.Response.Write(task.RedirectURL);
}
else // Add cache-control, pragma, and expires to prevent caching of Ajax content
{
task.HttpContext.Response.AppendHeader("Cache-Control", "no-cache, no-store, must-revalidate");
task.HttpContext.Response.AppendHeader("Pragma", "no-cache");
task.HttpContext.Response.AppendHeader("Expires", "0");
}
}
