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How To Send Soap Call Using Msxml Replace Stk

- 14 Jun 2007

I know… This is a simple thing, but there is no documentation on it so here it is:

UPDATE: You can now use Windows Webservica API (WWSAPI) to create native code WebService calls!

The SoapToolkit (STK) is out of support. So what if you need to make a SOAP call in VB 6 or scripting? Realizing that SOAP calls to web service are just a POST with some XML, you should be able to do this easily. You can get the format for this POST from a network sniffer such as Network Monitor (available from Microsoft) or from the WSDL of service definition.

Here is a simple definition of a web service that returns the length of a string:

GetStringLength

Test

The test form is only available for requests from the local machine.

SOAP 1.1

The following is a sample SOAP 1.1 request and response. The placeholders shown need to be replaced with actual values.

POST /HelloWS/service.asmx HTTP/1.1
Host: jsandersvm2003
Content-Type: text/xml; charset=utf-8
Content-Length: length
SOAPAction: "http://tempuri.org/GetStringLength"
<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
  <soap:Body>
    <GetStringLength xmlns="http://tempuri.org/">
      <theString>string</theString>
    </GetStringLength>
  </soap:Body>
</soap:Envelope>

HTTP/1.1 200 OK
Content-Type: text/xml; charset=utf-8
Content-Length: length
<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
  <soap:Body>
    <GetStringLengthResponse xmlns="http://tempuri.org/">
      <GetStringLengthResult>int</GetStringLengthResult>
    </GetStringLengthResponse>
  </soap:Body>
</soap:Envelope>

Here is one way to make this call in a simple VB form application. Reference MSXML3.0 in your project (beware of lines wrapping in your browser if you are a cut and past programmer).

Sub

Command2_Click()
 ‘How to send this using MSXML
 ‘POST /HelloWS/service.asmx HTTP/1.1
 ‘Host: jsandersvm2003
 ‘Content-Type: text/xml; charset=utf-8
 ‘Content -length: <>

‘SOAPAction: “http://tempuri.org/GetStringLength”

‘
 ‘<soap:Envelope xmlns:xsi=”http://www.w3.org/2001/XMLSchema-instance” xmlns:xsd=”http://www.w3.org/2001/XMLSchema” xmlns:soap=”http://schemas.xmlsoap.org/soap/envelope/”>
 ‘
 ‘ <GetStringLength xmlns=”http://tempuri.org/”>
 ‘ <></theString>
 ‘ </GetStringLength>
 ‘ </soap:Body>

‘</soap:Envelope>

Dim myXML As New

XMLHTTP30

    ‘ False means Synchronously
    myXML.open(“POST”, “http://jsandersvm2003/HelloWS/service.asmx”, False)
    myXML.setRequestHeader(“Content-Type”, “text/xml; charset=utf-8”)
    myXML.setRequestHeader(“SOAPAction:”, http://tempuri.org/GetStringLength)

‘ NOTE: You could do this… very brute force way to send it.
 ‘Dim theTxt As String
 ‘theTxt = “<soap:Envelope xmlns:xsi=” & Chr(34) & “http://www.w3.org/2001/XMLSchema-instance” & Chr(34) & ” xmlns:xsd=” & Chr(34) & “http://www.w3.org/2001/XMLSchema” & Chr(34) & ” xmlns:soap=” & Chr(34) & “http://schemas.xmlsoap.org/soap/envelope/” & Chr(34) & “><GetStringLength xmlns=” & Chr(34) & “http://tempuri.org/” & Chr(34) & “><theString xmlns=” & Chr(34) & “http://tempuri.org/” & Chr(34) & “>string</theString></GetStringLength></soap:Envelope>”

‘myXML.send theTxt

‘ NOTE: This allows you to leverage the XML DOM

    Dim node
    Dim xmlSrcDoc As New MSXML2.DOMDocument30
    xmlSrcDoc.async = False
    xmlSrcDoc.validateOnParse = False
    xmlSrcDoc.resolveExternals = False
    xmlSrcDoc.preserveWhiteSpace = True
    ‘ caveat for the createProcessingInstruction. the encoding string will be missing from the XML instruction line.
    ‘ so you could skip the createProcessingInstruction code, instead prepend the string to the XML you generate for the rest of the body ala
    ‘

“myXML.send “ ” & xmlSrcDoc.xml

    ‘ most servers will not care about that because the HTTP header already specifies the encoding
    ‘ Create a processing instruction targeted for xml.
    node = xmlSrcDoc.createProcessingInstruction(“xml”, “version=’1.0′”)
    ‘ issue: cannot do this: node.setAttribute “encoding”, “utf-8”
    xmlSrcDoc.appendChild(node)
    node = Nothing
    ‘ Create the Soap Envelope
    Dim soapEnvelope As IXMLDOMElement
    soapEnvelope = xmlSrcDoc.createElement(“soap:Envelope”)
    ‘ Create the attributes for it
    soapEnvelope.setAttribute(“xmlns:soap”, “http://schemas.xmlsoap.org/soap/envelope/”)
    soapEnvelope.setAttribute(“xmlns:xsi”, “http://www.w3.org/2001/XMLSchema-instance”)
    soapEnvelope.setAttribute(“xmlns:xsd”, “http://www.w3.org/2001/XMLSchema”)
    xmlSrcDoc.appendChild(soapEnvelope)
    ‘ Create the Soap Body
    Dim soapBody As IXMLDOMElement
    soapBody = xmlSrcDoc.createElement(“soap:Body”)
    soapEnvelope.appendChild(soapBody)
    ‘ Create the node for the call we are making
    Dim soapCall As IXMLDOMElement
    soapCall = xmlSrcDoc.createElement(“GetStringLength”)
    soapCall.setAttribute(“xmlns”, “http://tempuri.org/”)
    soapBody.appendChild(soapCall)
    ‘ finally add the argument(s)
    Dim soapArgs As Object
    soapArgs = xmlSrcDoc.createElement(“theString”)
    soapArgs.Text = “Jeff is cool”
    soapCall.appendChild(soapArgs)
    ‘ let it go!
    myXML.send(xmlSrcDoc.xml)
    ‘ myXML.send “ ” & xmlSrcDoc.xml
    Dim xmlDoc As MSXML2.DOMDocument30
    xmlDoc = myXML.responseXML
    ‘ This query will depend on what you expect back from the SOAP call

MsgBox(xmlDoc.Text)

    ‘ or this if you want to traverse the XML DOM
    ‘Dim oNode As Object
    ‘Set oNode = xmlDoc.documentElement.selectSingleNode(“//HelloWorldResult”)
    ‘If oNode Is Nothing Then
    ‘     MsgBox “Requested information not found.”
    ‘Else
    ‘     MsgBox oNode.Text

‘End If

End

Sub

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Jeff Sanders Technical Blog

I am a Microsoft employee that has worked on all aspects of the Web Stack for a long time. I hope these blogs are useful to you! Use this information at your own risk.

How To Send Soap Call Using Msxml Replace Stk

GetStringLength

Test

SOAP 1.1