Invoke restful webservice from windows mobile 6.5 compact framework

Question

I am trying to invoke a service from windows mobile 6.5 compact framework client. This gives me exception "Unable to read data from the transport connection".

The emulator I use is Windows mobile 6 professional emulator. Dotnet framework 3. Emulator connects to internet. I can open webpages from the internet. The same code runs fine if create a C# Windows Console application. Please guide.

        WebRequest Webrequest;
        HttpWebResponse response=null;

        Webrequest = WebRequest.Create("http://api.geonames.org/postalCodeSearchJSON?postalcode=9011&maxRows=10&username=demo");

        Webrequest.Method = "GET";
        Webrequest.ContentType = "html/xml";
        try
        {
            response = (HttpWebResponse)Webrequest.GetResponse();
        }catch(Exception exc){
            ShowErrorMessage("Ex : " + exc.Message);

            return;
        }

        Stream streamResponse = response.GetResponseStream();
        StreamReader streamReader = new StreamReader(streamResponse);
        string responseStr = streamReader.ReadToEnd();

Answer 1

I dod not know what exactly is wrong with your code. Possibly you have to set some properties before issuing the web request. Here is a snippet I used to get timezone information from a web service:

    /// <summary>
    /// This will call the webservice asynchronousely
    /// the call will immediately return
    /// The answer on the request is published to all event subscribers
    /// </summary>
    /// <param name="lat">decimal input for geographic Latitude</param>
    /// <param name="lng">decimal input for geographic Longitude</param>
    public void startRequest(string lat, string lng)
    {
        //tzInfos pTZinfos = new tzInfos();
        string myURL = @"http://ws.geonames.org/" + _webMethodName;
        //HttpWebRequest webRequest = (HttpWebRequest)HttpWebRequest.Create(myURL);
        //HttpWebResponse webResponse = (HttpWebResponse)webRequest.GetResponse();
        //string wsdl = "";
        _webServiceURI = myURL;
        try
        {
            _httpRequest = (HttpWebRequest)HttpWebRequest.Create(this._webServiceURI + "?lat=" + lat + "&lng=" + lng); // "?WSDL");
            _httpRequest.Method = "POST";
            _httpRequest.KeepAlive = false;
            _httpRequest.ContentType = "application/x-www-form-urlencoded";
            //httpRequest.ContentLength = requestData.Length;
            _httpRequest.Timeout = 30000;

            //async call
            IAsyncResult myAsycnCall = this._httpRequest.BeginGetResponse(new AsyncCallback(this.ResponseReceivedHandler), null);                
        }
        catch (WebException wx)
        {
            System.Diagnostics.Debug.WriteLine("Exception: " + wx.Message);
        }
        catch (Exception wx)
        {
            System.Diagnostics.Debug.WriteLine("Exception: " + wx.Message);
        }
    }
    /// <summary>
    /// This is the async method for the response to be get from the web service
    /// </summary>
    /// <param name="result"></param>
    private void ResponseReceivedHandler(IAsyncResult result)
    {
        string wsdl = "";
        geonamesTZfields pTZinfos = new geonamesTZfields();
        geonamesEventArgs tArg = new geonamesEventArgs();
        try
        {
            HttpWebResponse response = (HttpWebResponse)this._httpRequest.EndGetResponse(result);

            System.IO.Stream streamResponse = response.GetResponseStream();
            System.IO.StreamReader streamRead = new System.IO.StreamReader(streamResponse);
            wsdl = streamRead.ReadToEnd();
            System.Diagnostics.Debug.WriteLine("Response: " + wsdl);

            // Close the stream object
            streamResponse.Close();
            streamRead.Close();

            // Release the HttpWebResponse
            response.Close();
            if (wsdl.Length > 0)
            {
                StringBuilder sb = new StringBuilder(wsdl);
                pTZinfos.strCountryCode = xml_helper.xml_helper.getStrSetting(sb, "countryCode");
                pTZinfos.strCountryName = xml_helper.xml_helper.getStrSetting(sb, "countryName");
                pTZinfos.strTimezoneID = xml_helper.xml_helper.getStrSetting(sb, "timezoneId");
                pTZinfos.gmtOffset = xml_helper.xml_helper.getDecimalSetting(sb, "gmtOffset");
                pTZinfos.rawOffset = xml_helper.xml_helper.getDecimalSetting(sb, "rawOffset");
                pTZinfos.dstOffset = xml_helper.xml_helper.getDecimalSetting(sb, "dstOffset");
                pTZinfos.tzTime = xml_helper.xml_helper.getDateTimeSetting(sb, "time");
            }
            _tzFields = pTZinfos;
            //fire the event
            tArg.m_myEventArgumentdata = pTZinfos;
            tArg.m_myEventArgumentdata.DataIsValid = true;
            tArg.m_myEventArgumentdata.strLastError = "no error";
        }
        catch (WebException wx)
        {
            tArg.m_myEventArgumentdata.DataIsValid = false;
            tArg.m_myEventArgumentdata.strLastError = wx.Message;
        }
        catch (Exception ex)
        {
            tArg.m_myEventArgumentdata.DataIsValid = false;
            tArg.m_myEventArgumentdata.strLastError = ex.Message;
        }
        finally
        {
            this.onDataReceived(tArg); //notify all subscribers of new data arrived
        }
    }

You see I explicitely set some properties: _httpRequest.Method = "POST"; _httpRequest.KeepAlive = false; _httpRequest.ContentType = "application/x-www-form-urlencoded"; //httpRequest.ContentLength = requestData.Length; _httpRequest.Timeout = 30000; The full code is available by my article at: http://www.hjgode.de/wp/2010/03/04/using-ws-geonames-org-timezone-webservice-without-wsdl/. You may use that and change your web request and use the async call.

You may also try to simple open the web page: http://api.geonames.org/postalCodeSearchJSON?postalcode=9011&maxRows=10&username=demo in Internet Explorer Mobile on the device. You should get the answer back as:

{"postalCodes":[{"adminCode3":"3203","adminName2":"Wahlkreis St. Gallen","adminName3":"St. Gallen","adminCode2":"1721","adminCode1":"SG","postalCode":"9011","countryCode":"CH","lng":9.399845287638328,"placeName":"St. Gallen","lat":47.414775553450646,"adminName1":"Kanton St. Gallen"},{"adminCode1":"GS","postalCode":"9011","countryCode":"HU","lng":17.781944437499998,"placeName":"Győr","lat":47.607638900000005,"adminName1":"Győr-Moson-Sopron"},{"adminName2":"Tromsø","adminCode2":"1902","adminCode1":"19","postalCode":"9011","countryCode":"NO","lng":18.95508,"placeName":"Tromsø","ISO3166-2":"10","lat":69.6489,"adminName1":"Troms"},{"postalCode":"L-9011","countryCode":"LU","lng":6.1041667,"placeName":"Ettelbruck","lat":49.8475},{"adminCode1":"Z","postalCode":"9011","countryCode":"AR","lng":-67.5333333,"placeName":"CALETA OLIVIA","lat":-46.4333333,"adminName1":"SANTA CRUZ"},{"adminCode1":"Z","postalCode":"9011","countryCode":"AR","lng":-67.5333333,"placeName":"EL MANGRULLO","lat":-46.4333333,"adminName1":"SANTA CRUZ"},{"adminCode1":"Z","postalCode":"9011","countryCode":"AR","lng":-67.5333333,"placeName":"CAÑADON ESTHER","lat":-46.4333333,"adminName1":"SANTA CRUZ"},{"adminCode1":"Z","postalCode":"9011","countryCode":"AR","lng":-67.5333333,"placeName":"BAHIA LANGARA","lat":-46.4333333,"adminName1":"SANTA CRUZ"},{"postalCode":"9011","countryCode":"NZ","lng":170.47198,"placeName":"Mornington","lat":-45.87922},{"postalCode":"9011","countryCode":"PH","lng":124.7325,"placeName":"Balinguan","lat":9.050317457142857}]}

If that does not come in Internet Explorer Mobile, your connection is setup incorrectlyLook for WMDC connection settings adn 'This computer connects to'. Switching from Internet to Automatic may help. I assume you have docked the Emulator you use and WMDC or ActiveSync shows a connection with the emulator.

Answer 2

class ServiceConnection
{
    public string Url = "";

    private string postXml;

    public delegate void OnServerEndResponse(string response, int statusCode);
    public event OnServerEndResponse OnEndResponse;
    public ServiceConnection(string serviceName, string userName, string pwd)


    public void SendRequest(string requestXml)
    {
        postXml = requestXml;
        StartWebService();
    }

    public void StartWebService()
    {
        WebRequest request = WebRequest.Create(Url);
        request.Method = "GET";
        byte[] auth = Encoding.UTF8.GetBytes(UserName + ":" + Pwd);
        request.Headers["Authorization"] = "Basic " + System.Convert.ToBase64String(auth);
        request.BeginGetResponse(new AsyncCallback(GetResponseCallback), request);
    }

    void GetResponseCallback(IAsyncResult asynchronousResult)
    {
        HttpWebResponse response = null;
        HttpWebRequest webRequest = null;

        try
        {
            webRequest = (HttpWebRequest)asynchronousResult.AsyncState;
            response = (HttpWebResponse)webRequest.EndGetResponse(asynchronousResult);
            Stream streamResponse = response.GetResponseStream();
            StreamReader streamReader = new StreamReader(streamResponse);
            StringBuilder sb = new StringBuilder();
            sb.Append(streamReader.ReadToEnd());
            //string serverResponse = streamReader.ReadToEnd();
            streamResponse.Close();
            streamReader.Close();
            response.Close();


            OnEndResponse(sb.ToString(), Convert.ToInt32(response.StatusCode));
        }
        catch (Exception ex)
        {
            if (ex.Message == "The remote server returned an error: (401) Unauthorized.")
                OnEndResponse(ex.Message, 401);
            else if (ex.Message == "Unable to connect to the remote server")
                OnEndResponse(ex.Message, 4);
            else if (ex.Message == "Could not establish connection to network.")
                OnEndResponse(ex.Message, 10000);
            else
                OnEndResponse("Error in network", 10001);
        }
    }
}