How to send a HTTP POST from Classic ASP with a parameter to a WEB API?

Question

I am trying to create a call to a WEB API on the same machine on another port. It works fine and sends back the string and hits the .NET breakpoint but the parameter is never being passed..(it is null) .. Is there something I am missing in the classic ASP code to pass that string ? (DataToSend)

My calling code:

  <%
      Response.Buffer = True
      Dim xml
     ' Set xml = Server.CreateObject("Microsoft.XMLHTTP")
    Set xml = server.Createobject("MSXML2.XMLHTTP")

     DataToSend="<?xml version=""1.0"" encoding=""UTF-8""?><codes sku=""123123"" num-codes=""234234"" />"

      xml.Open "POST", _
          "http://localhost:1303/api/RegistrationCode", _
          False

      xml.setRequestHeader "Content-Type", "application/x-www-form-urlencoded"
      xml.setRequestHeader "X-VitalSource-API-Key", "xxx"

      xml.Send DataToSend

      'Display the HTML both as HTML and as text
      Response.Write "<h1>The HTML text</h1><xmp>"
      Response.Write xml.responseText
      Response.Write "</xmp><p><hr><p><h1>The HTML Output</h1>"
      Response.Write xml.responseText
      Set xml = Nothing
%>

WEB API code:

   public class RegistrationCodeController : ApiController
{
    string testXmlString = "<SomeValue>6</SomeValue>";



       public string Post([FromBody]string value)
    {
        return testXmlString;
    }

}

Solution

I ran into this issue as well. Late answer, but...

I had a case where I could not send the data in the URL because it was very large and exceeded the size limit, so I had to use POST, not GET. After some trial and error this is what I did:

In the classic ASP file

Public Function PostData(link, data)
    on error resume next

    if link<>"" then
        data = "{'Name': '" & data & "'}"
        data = Replace(data, "'", """")

        Dim oXMLHTTP
        Set oXMLHTTP = CreateObject("Msxml2.XMLHTTP.3.0")
        if oXMLHTTP is nothing then Set oXMLHTTP = CreateObject("Microsoft.XMLHTTP")

        oXMLHTTP.Open "POST", link, False
        oXMLHTTP.setRequestHeader "Content-Type", "application/json"
        oXMLHTTP.send data

        If oXMLHTTP.Status = 200 Then
            PostData = oXMLHTTP.responseText
        Else
            response.Write "Status: " & oXMLHTTP.Status & " | "
            response.Write oXMLHTTP.responseText
            response.end
        End If

    end if
End Function

In my WebAPI function:

public class PayLoad
{
    public string Name { get; set; }
}

[Route("api/Values/PostUnidataMethod")]
[HttpPost]
public string PostUnidataMethod([FromBody]PayLoad data)
{
    return data.Name;
}

I am not very familiar with ASP, but I found several examples that all used JSON to send the data to the Web API function, rather than just a string. So I created a simple DTO and then made the data into a JSON string. Remember to convert single-quotes to double-quotes. I like JSONLint to test the data to make sure.