使用XMLHttpRequest从Javascript调用Soap Web服务功能

Question

Web服务中函数的参数：

POST /_vti_bin/******.ConnectorService.asmx HTTP/1.1
Host: www.*****.com
Content-Type: text/xml; charset=utf-8
Content-Length: length
SOAPAction: "http://www.*****.com/SaveFile"

<?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>
    <SaveFile xmlns="http://www.proged.tn">
      <urlSite>string</urlSite>
      <iListName>string</iListName>
      <iUpdateMode>NotVerified or FillEmpty or Replace or NotReplace</iUpdateMode>
      <iMetaData>xml</iMetaData>
      <iAttachments>xml</iAttachments>
      <iOverWrite>boolean</iOverWrite>
    </SaveFile>
  </soap:Body>
</soap:Envelope>

我的js代码：

function sendReq()
{
var my_title="title";
var c='<img alt="" src="data:image/png;base64,iVBORw0KGgoAAAANSUhE.....AAAElFTkSuQmCC" />';
    var b= false;
    var wsUrl = "http://www.proged.tn/sites/toyourbusiness/_vti_bin/PROGED.ConnectorService.asmx?op=UpdateListItem";
    var soapRequest ='<?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>'+
    '<SaveFile xmlns="http://www.*****.com">'+
      '<urlSite>http://www.*****.com/***/***</urlSite>'+
      '<iListName>{*****}</iListName>'+
      '<iUpdateMode>NotVerified</iUpdateMode>'+
      '<iMetaData><Fields><Field Name="Title" >'+my_title+'</Field></Fields></iMetaData>'+
      '<iAttachments><Attachments><Attachment Name="name of the file">'+c+'</Attachment></Attachments></iAttachments>'+
      '<iOverWrite>'+b+'</iOverWrite>'+
    '</SaveFile >'+
  '</soap:Body>'+
'</soap:Envelope>';
    var xmlhttp =  createXMLHttpRequest();

    xmlhttp.open("POST", wsUrl, true,"username","password");

    xmlhttp.setRequestHeader ("Post", "/_vti_bin/****.ConnectorService.asmx HTTP/1.1");
    xmlhttp.setRequestHeader ("Host", "www.****.com");
    xmlhttp.setRequestHeader("Access-Control-Allow-Origin", "*");
    xmlhttp.setRequestHeader ("Content-Type", "text/xml; charset=utf-8");
    xmlhttp.setRequestHeader("Content-Length", soapRequest.length);
    xmlhttp.setRequestHeader ("SOAPAction", "http://www.****.com/SaveFile");

    xmlhttp.onerror = function(e) {
        alert("Error ocurred. Error = " + e.message);
    }
    xmlhttp.ontimeout = function(e) {
        alert("Timeout error!");
    }
    xmlhttp.onreadystatechange  = function () { 
        alert(xmlhttp.readyState);

        if (xmlhttp.readyState==4)
        {
            alert(xmlhttp.responseText);
            alert(xmlhttp.status);
            // if "OK"
            if (xmlhttp.status==200 || xmlhttp.status==0)
            {
                alert(xmlhttp.responseXML);
            //[Get xmlhttp.responseXML.xml and do something with it]

            }
            else
            {
            //[Get xmlhttp.responseXML.xml and do something with it in the case of an error]
            }
        }
    }

    xmlhttp.send(soapRequest);
}

这会返回xmlhttp.responseXML = null，status = 0，有什么不对!!