Calling a web service from an Android client
[ServiceContract]
    public interface ILoginService
    {

        [OperationContract]
        string Login(string username, string password);

        // TODO: Add your service operations here
    }

[OperationContract]
        [WebGet(ResponseFormat= WebMessageFormat.Json,
            UriTemplate="/LoginService/?username={username}&password={password}")]
        Response Login(string username, string password);

public LoginResponse RemoteLogin(String username, String password)
    {
        loginParameters = "/LoginService/username=" + username + "&password=" + password;


        HttpClient httpclient = new DefaultHttpClient();
        HttpGet httpget = new HttpGet(serviceAddress + loginParameters);

        HttpResponse response;

        LoginResponse loginResponse = null;

        try
        {
            response = httpclient.execute(httpget);

            HttpEntity entity = response.getEntity();

            if(entity != null)
            {
                InputStream instream = entity.getContent();
                String result = convertStreamToString(instream);
                JSONObject json = new JSONObject(result);

                // Parsing
                JSONArray nameArray = json.names();
                JSONArray valArray = json.toJSONArray(nameArray);

                loginResponse = new LoginResponse(valArray.getBoolean(1), valArray.getString(0), valArray.getString(2));


                instream.close();
            }

        }
        catch(Exception e)
        {
            loginResponse = new LoginResponse();
            String sDummy = e.toString();
        }
        return loginResponse;
    }