How to execute some code before posting a form using classic ASP - forms

Question

Using classic ASP, I want to execute some code before submitting to a form, below is my code.
I am trying to store login credentials into cookies before posting the form to another page.
Please note that I am posting to an ASP.NET page that is held in a separate domain.
Another example, just to make this clearer. Let's say I want to validate fields before posting without using JavaScript.
<%
dim uname
uname= Request.Cookies("username")
%>
<FORM action="httppost_login.aspx" METHOD ="post" >
<br />Username: <INPUT NAME ="username" SIZE ="30" maxlength="15" value="<% if uname <>"" then response.write(uname) %>" />
<br />Password: <INPUT NAME ="password" SIZE ="30" type=password maxlength="20" />
<br />
<INPUT TYPE ="SUBMIT" value="Login" name="btnSubmit" />
<input type="checkbox" name="remember" value="Remember my username" <%if uname <> "" then Response.Write("checked")%> />Remember my username
</FORM>
<%
If Request.Form("btnSubmit") <> "" Then
uname=Request.Form("username")
dim rememberme
rememberme = request.form("remember")
if rememberme <> "" and uname <> "" then
Response.Cookies("username") = uname
Response.Cookies("username").Expires = Date() + 30
end if
end if
%>

Answer 1

You can't run code easilly after the submit button is pressed.
This comes down to design. Your form action is:
httppost_login.aspx
The 'standard' way of achieving what you want is by having code on that page which handles the cookies/anything else.
I would usually give the form action a querystring:
<FORM action="httppost_login.aspx?action=login" METHOD ="post" >
Then on that page, have:
Dim strPageAction
strPageAction = request.querystring("action")
if(strPageAction = "login" then
'Put your cookie code here, request.form("username") etc will still work!
end if

Answer 2

yes, a redirect page can post to a third party page using xmlhttp