MSXML ServerXMLHTTP- Calling web service - vbscript

Question

Problem: I am getting the following error output from If Err.Number <> 0 Then check;
Err.Number :-1072954818
Err.Source :msxml6.dll
Err.Source :This method cannot be called until the open method has been called.
Code:
dim objHttpRequest
dim gw_menu_request
dim HTTPMethod
HTTPMethod="POST"
Set objHttpRequest = Server.CreateObject("MSXML2.ServerXMLHTTP.6.0")
gw_menu_request = "http://test.com?q=headerexpose/expose_headers/expose_json"
objHttpRequest.setRequestHeader "Content-Type", "application/x-www-form-urlencoded"
objHttpRequest.setRequestHeader "Content-Length", 0
objHttpRequest.open HTTPMethod, gw_menu_request, false
Response.write(objHttpRequest.ResponseXML)
If Err.Number <> 0 Then
Response.Write "Err.Number :" & Err.Number & "<br/>"
Response.Write "Err.Source :" & Err.Source & "<br/>"
Response.Write "Err.Source :" & Err.Description & "<br/>"
Response.Write "Err.File :" & Err.File & "<br/>"
End If
What am I missing here?

Answer 1

The issue is exactly as the described in the error, you are trying to set Request Headers without first calling Open(). You are also missing the Send() method to send the request before a response can be received.
Dim objHttpRequest
Dim gw_menu_request
Dim HTTPMethod
HTTPMethod="POST"
Set objHttpRequest = Server.CreateObject("MSXML2.ServerXMLHTTP.6.0")
gw_menu_request = "http://test.com?q=headerexpose/expose_headers/expose_json"
'Open request specifying method and URL to call
objHttpRequest.open HTTPMethod, gw_menu_request, False
'Set any HTTP headers needed before sending.
objHttpRequest.setRequestHeader "Content-Type", "application/x-www-form-urlencoded"
objHttpRequest.setRequestHeader "Content-Length", 0
'Send the request
objHttpRequest.Send
Response.write(objHttpRequest.ResponseXML.Xml)
If Err.Number <> 0 Then
Response.Write "Err.Number :" & Err.Number & "<br/>"
Response.Write "Err.Source :" & Err.Source & "<br/>"
Response.Write "Err.Source :" & Err.Description & "<br/>"
Response.Write "Err.File :" & Err.File & "<br/>"
End If
You also want ResponseXML.Xml or you will receive a
Microsoft VBScript runtime error: Type mismatch
because you are trying to output the object not the Xml property that contains the XML string representation.