asp.net do a postback on page load

how do i code an aspx.page that does a post to an external site on pag开发者_如何学Goe load?

Example:

<form action="https://demo.demopage.net/" method="post">
   <input type="hidden" name="lang" value="de" />
</form>

My intention is to open opener.aspx in a target=_blank. Opener.aspx will do a postback to the above form.

thx for your help...

It's not a "postback" so much as it is a standard HTTP POST request. ASP.NET probably isn't necessary. How about something like this (using jQuery)...

<form id="someForm" action="https://demo.demopage.net/" method="post">
  ...
</form>

and

$(document)ready(function() {
  $('#someForm').submit();
});

You can use server side http post: HttpWebRequest, HttpWebResponse