Example 18.3. HTTP communication through the stream

// The _http variable is defined as class member variable since used in the callback function
class MyClass {
private:
    SFXHTTPConnection         _http;
    SFXAnsiStringStreamReader _reader;
    SFXAnsiString             _string;
public:
    Void Start(Void);
    XALLBACK_DECLARE_SFXHTTPCONNECTION(OnConnect)
    XALLBACK_DECLARE_SFXANSISTRINGSTREAMREADER(OnFetch)
};

Void MyClass::Start(Void)
{
    SFXAnsiStringStreamWriter writer;
    SFXAnsiString             message;
    SFCError error(SFERR_NO_ERROR);

    unused(environment);

    // HTTP connection using POST method
    if ((error = _http.Open()) == SFERR_NO_ERROR) {

        // message: content of HTTP request body to set
        message = "abcdefghijklmnopqrstuvwxyz";

        // get output stream for writing data into HTTP request body
        if ((error = _http.GetStreamWriter(message.GetLength(), &writer)) == SFERR_NO_ERROR) {

            // write data from the message variable into output stream buffer
            if ((error = writer.WriteSFXAnsiString(message)) == SFERR_NO_ERROR) {

                // write data from output stream buffer into http request body actually
                // data will not be written into http request body if Flush function is not called explicitly
                if ((error = writer.Flush()) == SFERR_NO_ERROR) {

                    // set request method to POST
                    if ((error = _http.SetMethod("POST")) == SFERR_NO_ERROR) {

                        // start to connect
#if 1
                        // in case of HTTP connection
                        // connect to the Web server
                        // * the connection result will be notified to the OnConnect function
                        if ((error = _http.Connect("http://www.example.com",
                            XALLBACK_INTERNAL(OnConnect))) == SFERR_NO_ERROR) {
#else
                        // in case of HTTPS connection
                        // set trust mode if necessary
                        _http.SetTrustMode(SSL_TRUST_MODE_FAIL);
                        // connect to the Web server
                        // * the connection result will be notified to the OnConnect function
                        if ((error = _http.Connect("https://www.example.com",
                            XALLBACK_INTERNAL(OnConnect))) == SFERR_NO_ERROR) {
#endif
                            TRACE("> connecting...");
                        }
                    }
                }
            }
        }
    }

    if (error != SFERR_NO_ERROR) {

        // if an error occurs
        // close the HTTP connection
        _http.Close();
    }
    return;
}

// callback function notified of the connection result
XALLBACK_IMPLEMENT_SFXHTTPCONNECTION(MyClass, OnConnect, error)
{
    TRACE("> connected... : %d", error);

    if (error == SFERR_NO_ERROR) {

        // examine response code
        TRACE("> result code : %d", _http.GetResultCode());

        if (_http.GetResultCode() == 200) {

            // get input stream for reading data from HTTP response body
            if ((error = _http.GetStreamReader(1024, &_reader)) == SFERR_NO_ERROR) {

                // read data from HTTP request body into input stream buffer
                // the fetch result will be notified to the OnFetch function
                if ((error = _reader.Fetch(XALLBACK_INTERNAL(OnFetch))) == SFERR_NO_ERROR) {

                    TRACE("> fetching...");
                }
            }
        }
        else {
            error = SFERR_INVALID_STATE;
        }
    }

    if (error != SFERR_NO_ERROR) {

        // if an error occurs
        // close the HTTP connection
        _http.Close();
    }
    return;
}

// callback function notified of the fetch result
XALLBACK_IMPLEMENT_SFXANSISTRINGSTREAMREADER(MyClass, OnFetch, error)
{
    SFXAnsiString string;

    TRACE("> fetched... : %d", error);

    if (error == SFERR_NO_ERROR) {

        // read data from input stream buffer into the string variable
        if ((error = _reader.ReadSFXAnsiString(&string)) == SFERR_NO_ERROR) {

            // add the string variable to the _string variable
            if ((error = _string.Add(string)) == SFERR_NO_ERROR) {

                // check whether or not data is still remaining
                if (_reader.Ends()) {

                    // since all data have been read, display them on BREW Output Window
                    TRACE("--------");
                    TRACE("%s", _string.GetCString());
                    TRACE("--------");

                    // release resources explicitly
                    // release input stream for reading data from HTTP response body
                    _reader.Release();
                    // close the HTTP connection
                    _http.Close();
                }
                else {

                    // read data from HTTP request body into input stream buffer
                    // the fetch result will be notified to the OnFetch function
                    error = _reader.Fetch(XALLBACK_INTERNAL(OnFetch));
                }
            }
        }
    }
	
    if (error != SFERR_NO_ERROR) {

        // if an error occurs
        // release input stream for reading data from HTTP response body
        _reader.Release();
        // close the HTTP connection
        _http.Close();
    }
    return;
}