Establish a GPRS connection with TcpClient on Windows Mobile

Lagi nyari-nyari resource tentang TCP/IP programming di windows mobile, dapat artikel yang membahas GRPS connection. Lumayan, buat nambah referensi. Untuk memudahkan, saya tuliskan kembali disini.

NETCF’s HttpWebRequest secara otomatis akan men- sets up koneksi GPRS untuk koneksi web atau webservice jika wifi connection tidak tersedia. Therefore, ketika anda melakukan koneksi ke web, atau request ke webservice, developers tidak memerlukan coding khusus untuk menghandle koneksi GPRS. Tetapi ini tidak di support saat anda menggunakan level socket seperti class TcpClient and UdpClient. Dengan class tersebut, anda dapat menggunakan Connection Manager APIs untuk keperluan establish/release koneksi.

Berikut coding yang diperlukan untuk memanaged koneksi GPRS dengan menggunakan TcpClient:

    public class GPRSConnection
    {
        const int S_OK = 0;
        const uint CONNMGR_PARAM_GUIDDESTNET = 0x1;
        const uint CONNMGR_FLAG_PROXY_HTTP = 0x1;
        const uint CONNMGR_PRIORITY_USERINTERACTIVE = 0x08000;
        const uint INFINITE = 0xffffffff;
        const uint CONNMGR_STATUS_CONNECTED = 0x10;
        static Hashtable ht = new Hashtable();

        static GPRSConnection()
        {
            ManualResetEvent mre = new ManualResetEvent(false);
            mre.Handle = ConnMgrApiReadyEvent();
            mre.WaitOne();
            CloseHandle(mre.Handle);
        }

        ~GPRSConnection()
        {
            ReleaseAll();
        }

        public static bool Setup(Uri url)
        {
            return Setup(url.ToString());
        }

        public static bool Setup(string urlStr)
        {
            ConnectionInfo ci = new ConnectionInfo();
            IntPtr phConnection = IntPtr.Zero;
            uint status = 0;

            if (ht[urlStr] != null)
                return true;

            if (ConnMgrMapURL(urlStr, ref ci.guidDestNet, IntPtr.Zero) != S_OK)
                return false;
            
            ci.cbSize = (uint) Marshal.SizeOf(ci);
            ci.dwParams = CONNMGR_PARAM_GUIDDESTNET;
            ci.dwFlags = CONNMGR_FLAG_PROXY_HTTP;
            ci.dwPriority = CONNMGR_PRIORITY_USERINTERACTIVE;
            ci.bExclusive = 0;
            ci.bDisabled = 0;
            ci.hWnd = IntPtr.Zero;
            ci.uMsg = 0;
            ci.lParam = 0;

            if (ConnMgrEstablishConnectionSync(ref ci, ref phConnection, INFINITE, ref status) != S_OK &&
                status != CONNMGR_STATUS_CONNECTED)
                return false;

            ht[urlStr] = phConnection;
            return true;
        }

        public static bool Release(Uri url)
        {
            return Release(url.ToString());
        }

        public static bool Release(string urlStr)
        {
            return Release(urlStr, true);
        }

        private static bool Release(string urlStr, bool removeNode)
        {
            bool res = true;
            IntPtr ph = IntPtr.Zero;
            if (ht[urlStr] == null)
                return true;
            ph = (IntPtr)ht[urlStr];
            if (ConnMgrReleaseConnection(ph, 1) != S_OK)
                res = false;
            CloseHandle(ph);
            if (removeNode)
                ht.Remove(urlStr);
            return res;
        }

        public static void ReleaseAll()
        {
           foreach(DictionaryEntry de in ht)
           {
               Release((string)de.Key, false);
           }
           ht.Clear();
        }

        [StructLayout(LayoutKind.Sequential)]
        public struct ConnectionInfo
        {
            public uint cbSize;
            public uint dwParams;
            public uint dwFlags;
            public uint dwPriority;
            public int bExclusive;
            public int bDisabled;
            public Guid guidDestNet;
            public IntPtr hWnd;
            public uint uMsg;
            public uint lParam;
            public uint ulMaxCost;
            public uint ulMinRcvBw;
            public uint ulMaxConnLatency;
        }

        [DllImport("cellcore.dll")]
        private static extern int ConnMgrMapURL(string pwszURL, ref Guid pguid, IntPtr pdwIndex);

        [DllImport("cellcore.dll")]
        private static extern int ConnMgrEstablishConnectionSync(ref ConnectionInfo ci, ref IntPtr phConnection, uint dwTimeout, ref uint pdwStatus);

        [DllImport("cellcore.dll")]
        private static extern IntPtr ConnMgrApiReadyEvent();

        [DllImport("cellcore.dll")]
        private static extern int ConnMgrReleaseConnection(IntPtr hConnection, int bCache);

        [DllImport("coredll.dll")]
        private static extern int CloseHandle(IntPtr hObject);
    }

Untuk menggunakan class GPRSConnection diatas pada TcpClient, cukup dengan memanggil fungsi Setup pada class GPRSConnection. Berikut contohnya :

        public void DoTcpConnection()
        {
            string url = "www.msn.com";
            bool res = GPRSConnection.Setup("http://" + url + "/");
            if (res)
            {
                TcpClient tc = new TcpClient(url, 80);
                NetworkStream ns = tc.GetStream();
                byte[] buf = new byte[100];
                ns.Write(buf, 0, 100);
                tc.Client.Shutdown(SocketShutdown.Both);
                ns.Close();
                tc.Close();
                MessageBox.Show("Wrote 100 bytes");
            }
            else
            {
                MessageBox.Show("Connection establishment failed");
            }
        }

Happy GRPS Coding……:)

[Original Source : http://blogs.msdn.com/anthonywong/archive/2006/03/13/550686.aspx ]