Windows phone开发之支持的通信方式

1. http协议
主要是由webclient或httpwebrequest两个类提供，直接封装http协议访问web站点。最常用的通信方式。
2. wcf
wcf作为ms大力的通信方案非常强大，但是到了wp7上就变成了太监，只支持简单的basichttpbinding而且还有非常多的限制。
3 socket
7.1sdk里新增的通信方式，支持tcp和udp但只能使用异步的socketasynceventargs事件方式，也有不少限制。
 
选择通信方式
因为同时需要考虑到服务器端的实现，在服务器端尽量精简，最好不要有什么iis之类大型依赖。
对应是服务器端实现方式如下：

 

http协议	httplistener
wcf	wcf应用程序宿主
socket	socket

 

由于我使用的是win7 httplistener和basichttpbinding在监听外网ip时都需要管理员身份验证，这点很不友好，我每次开程序都提示一下，不爽。所以决定使用socket。
 
socket协议选择
而socket分为tcp和udp，为了稳定选择了有重传功能和回复的tcp（其实udp也不是什么问题）。
tcp需要3次握手来维持链接，但是按照“偶尔连接”(occasionally connect)的设计准则，我不能让手机一直保持连接，而且断线检查也是个麻烦事。
所以决定采用http1.0类似的短链接方式，就是连上、发一条消息、然后断开的流程（暂时没有回复）
 
 
应用层消息报文设计
这个程序比较简单设计的报文也很简单，
因为内网传输不需要考虑身份验证，、完整性等，而且短链接不会遇到粘包和拆包之类的，真是太轻松了。
报文结构如下

 

length	长度	4字节int
action	动作	32字节utf8编码
context	内容	长度由length描述utf8编码

 
 

length表示context的长度，报文本身长度为length+4+32
action目前只有”tap”按键 一种
context表示按键的类型 有2种分类
一种是  keyboard 直接对应键盘的键名称
另一种是 media 媒体控制用 包括toggleplaypause（播放暂停）、forward（前进）、backward（后退）increasevolume（提高音量）等
表示方式是“media.toggleplaypause”

view code
namespace virtualkeyboard.contract
{
    public static class keymethods
    {
        public const string keyboardpackage = "keyboard";
        public const string mediapackage = "media";

        public static class keyboard
        {
            private const string keyboardpre = keyboardpackage + ".";

            /// <summary>
            /// enter
            /// </summary>
            public const string enter = keyboardpre + "enter";

            /// <summary>
            /// esc
            /// </summary>
            public const string esc = keyboardpre + "esc";
        }

        public static class media
        {
            private const string mediapre = mediapackage + ".";

            /// <summary>
            ///  切换播放暂停
            /// </summary>
            public const string toggleplaypause = mediapre + "toggleplaypause";

            /// <summary>
            /// 快进
            /// </summary>
            public const string fastforward = mediapre + "fastforward";

            /// <summary>
            /// 快退
            /// </summary>
            public const string fastbackward = mediapre + "fastbackward";

            /// <summary>
            /// 大步快进
            /// </summary>
            public const string veryfastforward = mediapre + "veryfastforward";

            /// <summary>
            /// 大步快退
            /// </summary>
            public const string veryfastbackward = mediapre + "veryfastbackward";

            /// <summary>
            /// 前进
            /// </summary>
            public const string forward = mediapre + "forward";

            /// <summary>
            /// 前退
            /// </summary>
            public const string backward = mediapre + "backward";

            /// <summary>
            /// 提高音量
            /// </summary>
            public const string increasevolume = mediapre + "increasevolume";

            /// <summary>
            /// 降低音量
            /// </summary>
            public const string decreasevolume = mediapre + "decreasevolume";

            /// <summary>
            /// 静音
            /// </summary>
            public const string mutevolume = mediapre + "mutevolume";

            /// <summary>
            /// 上一集
            /// </summary>
            public const string previoustrack = mediapre + "previoustrack";

            /// <summary>
            /// 下一集
            /// </summary>
            public const string nexttrack = mediapre + "nexttrack ";

            /// <summary>
            /// 停止
            /// </summary>
            public const string stop = mediapre + "stop";

            /// <summary>
            /// 全屏
            /// </summary>
            public const string fullscreen = mediapre + "fullscreen";
        }
    }
}
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客户端通信代码实现
view code
 public class sendcommandcompletedeventargs : eventargs
    {
        public bool success { get; internal set; }
        public string errmessage { get; internal set; }
    }

    public class client
    {
        const int actionsize = 32;
        const int buffersize = 1024;

        public event eventhandler<sendcommandcompletedeventargs> sendcommandcompleted;

        private void onsendcommandcompleted(sendcommandcompletedeventargs e)
        {
            eventhandler<sendcommandcompletedeventargs> handler = sendcommandcompleted;
            if (handler != null) handler(this, e);
        }

        public client()
        {

        }

        public void sendcommandasync(endpoint endpoint, string action, string command)
        {
            var actionbuffer = encoding.utf8.getbytes(action);
            var contextbuffer = encoding.utf8.getbytes(command);

            var buffersize = contextbuffer.length + actionsize + 4;
            var lengthbuffer = bitconverter.getbytes(contextbuffer.length);

            var buffer = new byte[buffersize];
            int offset = 0;
            array.copy(lengthbuffer, 0, buffer, offset, lengthbuffer.length);
            offset += 4;
            array.clear(buffer, offset, actionsize);
            array.copy(actionbuffer, 0, buffer, offset, actionbuffer.length);
            offset += actionsize;
            array.copy(contextbuffer, 0, buffer, offset, contextbuffer.length);

            var socketasynceventargs = new socketasynceventargs
                                           {
                                               usertoken =
                                                   new socket(addressfamily.internetwork, sockettype.stream,
                                                              protocoltype.tcp)
                                           };
            socketasynceventargs.completed += asynccompleted;
            socketasynceventargs.setbuffer(buffer, 0, buffersize);
            socketasynceventargs.remoteendpoint = endpoint;
            processconnect(socketasynceventargs);
        }

        #region private
        private void processconnect(socketasynceventargs e)
        {
            var socket = (socket)e.usertoken;
            bool willraiseevent = socket.connectasync(e);
            if (!willraiseevent)
            {
                connectcompleted(e);
            }
        }

        private void processsend(socketasynceventargs e)
        {
            var socket = (socket)e.usertoken;
            bool willraiseevent = socket.sendasync(e);
            if (!willraiseevent)
            {
                sendcompleted(e);
            }
        }

        private void asynccompleted(object sender, socketasynceventargs e)
        {
            switch (e.lastoperation)
            {
                case socketasyncoperation.connect:
                    connectcompleted(e);
                    break;
                case socketasyncoperation.send:
                    sendcompleted(e);
                    break;
                case socketasyncoperation.receive:
                    receivecompleted(e);
                    break;
                default:
                    return;
            }

        }

        private void receivecompleted(socketasynceventargs e)
        {
        }
        private void connectcompleted(socketasynceventargs e)
        {
            if (e.socketerror == socketerror.success)
            {
                processsend(e);
            }
            else
            {
                onsendcommandcompleted(new sendcommandcompletedeventargs { success = false, errmessage = "接收器无法连接" });
            }
        }

        private void sendcompleted(socketasynceventargs e)
        {
            var socket = (socket)e.usertoken;
            socket.close();
            if (e.socketerror == socketerror.success)
            {
                onsendcommandcompleted(new sendcommandcompletedeventargs { success = true });
            }
            else
            {
                onsendcommandcompleted(new sendcommandcompletedeventargs { success = false, errmessage = "发送命令失败" });
            }

        }
        #endregion

    }
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作者 fengyarongaa