Using external websevice

class CampaignClients
{
}
public static server void getClient()
{
    COM     myXmlHttp;
    url     webServiceUrl;
    str     method;
    str     userName;
    str     password;
    str     strXML;
    str     strTxt;
    str     result;
    str     fileName;
    str     listValue;
    int     listLength;
    int     i;


    System.Exception netExcepn;
    InteropPermission permission;
    FileIOPermission    fileIOPerm;
    COM             receiveCom;
    XMLDocument     xmlDocu;
    XMLDocument     doc = XMLDOcument::newBlank();
    XMLElement      node;
    XMLNodeList     elemlist;
    str s_Json;
    ;

    try {

    permission = new InteropPermission(InteropKind::ComInterop);
    permission.assert();

    myXmlHttp = new COM('Microsoft.XMLHTTP'); // used ms xml http com object to communicate with the web service
    webServiceUrl   = strfmt("https://api.createsend.com/api/v3/clients.json");
    method          = "GET";
    fileName = "c:\\temp\\getRateFile.xml";
    xmlDocu = XmlDocument::newBlank('utf-8');

    CodeAccessPermission::revertAssert();
    fileIOPerm = new FileIOPermission(fileName, 'r');
    fileIOPerm.assert();

    xmlDocu.load(fileName);

    s_Json ='{"CompanyName": "Karya","Country": "India","TimeZone": "(GMT+10:00) Canberra, Melbourne, Sydney"}';

    CodeAccessPermission::revertAssert();
    permission = new InteropPermission(InteropKind::ComInterop);
    permission.assert();

    myXmlHttp.open(method,webServiceUrl,false,"2b4c0d6d781cbb43983e88674154cd39",password);
    myXmlHttp.setRequestHeader("content-type","text/xml"); //application/x-www-form-urlencoded
    myXmlHttp.send(s_Json);

    strTxt =strrtrim(myXMLHttp.responseText());
    info(strTxt);

    receiveCom  = myXMLHttp.responseXML();

    doc.loadXml(receiveCom.xml());
    elemList = doc.GetElementsByTagName("v3:Amount");
    listLength = elemList.length();

    for (i=0; i < elemList.length(); i++)
    {

        info(elemList.item(i).innerXml());
    }

    }
    catch (exception::CLRError)
    {
     netExcepn = CLRInterop::getLastException();
     info(netExcepn.ToString());
    }
    catch(exception::Error)
    {

     netExcepn = CLRInterop::getLastException();
     info(netExcepn.ToString());
    }
}