How do I POST data to a remote URL in Classic ASP?

Question

I need to POST data to a url in the middle of a script.

1. User fills out form:
2. Form submits to process.asp: I need to PO

Answer 1

Most form action pages accept data as a POST.

Function postFormData(url, data)
    Dim xhr : Set xhr = Server.CreateObject("MSXML2.ServerXMLHTTP.3.0")
    xhr.open "POST", url, false
    xhr.setRequestHeader "Content-Type", "application/x-www-form-urlencoded"
    xhr.send Data
    If xhr.Status = 200 Then
       postFormData = xhr.ResponseText
    Else
        Err.Raise 1001, "postFormData", "Post to " & url & " failed with " & xhr.Status
    End If
End Function

When creating the data url encoding is needed on the data values. Since ASPs Server.URLEncode method only does path encoding and not component encoding you need to replace out / characters with %2F

Function URLEncodeComponent(value)
    URLEncodeComponent = Server.URLEncode(value)
    URLEncodeComponent = Replace(URLEncodeComponent, "/", "%2F")
End Function

Answer 2

OK all the answers were very complicated and I know you already selected a solution - but I feel like the simple Server.Transfer() command could have done exactly what you need.

At the end of your script instead of Response.Redirect(url) to the new page - just do a Server.Transfer(url) and it will pass your entire Request collection across to the next page.

Read about it here (support.microsoft.com).

There are some catches (i.e. it keeps the same URL on the browser so it can play tricks with the back button and such) but otherwise it's pretty simple.