Calling web services

I am trying to call a web service written in C# net using Wininet. The web service has been hosted in IIS. The web service url is /Trial/Service1.asmx and it has only the default HelloWorld method in it. I can access the web service via the browser by the url http://localhost/Trial/Service1.asmx . I can call the web service method HelloWorld using the Invoke button on the browser which we get on giving the url. But the app returns 400 ( Bad request ). If I use GET instead of POST I am getting 200 OK. But I need to use the POST method.


What could be wrong?

Here is the code I am using

//m_lpOutBuffer is a DWORD data member and initialized with 0.

Code:

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{   
   

    CString csSoapString;
    csSoapString = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>";
    csSoapString += "<soap:Envelope xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" ";
    csSoapString += "xmlns:xsd=\"http://www.w3.org/2001/XMLSchema \"";
    csSoapString += "xmlns:soap=\"http://schemas.xmlsoap.org/soap/envelope/\">";
    csSoapString += "<soap:Body>";
    csSoapString += "<HelloWorld xmlns:m=\"http://tempuri.org/\"/>";
    csSoapString += "</soap:Body>";
    csSoapString += "</soap:Envelope>";

    LPTSTR AcceptTypes[2] = {TEXT("text/xml"), NULL};

    DWORD dwFlags = INTERNET_FLAG_NO_CACHE_WRITE |INTERNET_FLAG_KEEP_CONNECTION;

    HINTERNET hNet = InternetOpen(L"", INTERNET_OPEN_TYPE_PRECONFIG,
                                        NULL, NULL, 0 );


    if (hNet)
    {
        HINTERNET hSession = InternetConnect(hNet, _T("localhost"),
                                              INTERNET_DEFAULT_HTTP_PORT,
                                            _T(""),
                                            _T(""), INTERNET_SERVICE_HTTP, 0, 0);

        if (hSession)
        {
            hRequest = HttpOpenRequest(hSession, _T("POST"),
                                      _T("/Trial/Service1.asmx"),
                                      _T("HTTP/1.1"),NULL,
                                        (LPCTSTR*)AcceptTypes, dwFlags, 0);

            if (hRequest)
            {
                int nContentLength = csSoapString.GetLength();
                CString csLength;
                csLength.Format( _T( "%d" ),nContentLength );
                CString csSoapAction;
               
                csSoapAction += _T("Content-Type: text/xml;charset=utf-8\r\n");
                csSoapAction += _T( "Content-Length: ");
                csSoapAction += csLength;
                csSoapAction += _T("SOAPAction: \"" );
                csSoapAction += _T("http://tempuri.org/HelloWorld");
                csSoapAction += _T("\"\0\r\n\r\n");   

                BOOL bSent = HttpSendRequest(hRequest, ( LPCTSTR )csSoapAction, csSoapAction.GetLength(), (LPVOID )(LPCTSTR)csSoapString, csSoapString.GetLength());

                DWORD dwBufferSize = 0;
                m_lpOutBuffer = 0;

              // read the reponse
                ReadQueryResponse ( HTTP_QUERY_RAW_HEADERS_CRLF, dwBufferSize );

                TCHAR* pLBuffer = (TCHAR* )m_lpOutBuffer;
                CString csStatusCode( pLBuffer, dwBufferSize + 1 );
                DWORD dwRetVal = _wtol((TCHAR*)(LPCTSTR)csStatusCode);
                int nReponseSize = _tcslen( pLBuffer );

                if( 0 == nReponseSize )
                {
                    return;
                }
                CString csResposeHeader( pLBuffer, nReponseSize );
                OutputDebugString( csResposeHeader ); // shows 400( bad request )
            }
        }
    }
}

bool CWinInet_ClientDlg::ReadQueryResponse( UINT uQueryLevel, DWORD& dwBufferSize )
{
    try
    {
        if( !HttpQueryInfo( hRequest, uQueryLevel,(LPVOID)m_lpOutBuffer, &dwBufferSize, 0 ))
        {
            DWORD dwErrorCode = GetLastError();
            // If buffer size is not sufficient, call QueryInfo() with the new buffer size.
            if( ERROR_INSUFFICIENT_BUFFER == dwErrorCode  )
            {
                if( 0 != m_lpOutBuffer )
                {
                    delete[] m_lpOutBuffer;
                    m_lpOutBuffer = 0;
                }
                m_lpOutBuffer = new char[dwBufferSize];
                if( 0 == m_lpOutBuffer )
                {

                    return false;
                }
                return ReadQueryResponse( uQueryLevel,dwBufferSize );
            }
            else if( dwErrorCode == ERROR_HTTP_HEADER_NOT_FOUND )
            {
                return false;
            }
        }
        return true;
    }
    catch( ... )
    {       
        return false;
    }
}

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Thanks in advance.

What platform do you need to support?
In Windows 7, it might be easier to use the Windows Web Services API (WWSAPI), see http://www.codeguru.com/cpp/com-tech...ices-C-API.htm .