html5 udp socket

html5-udp-套接字

[草稿]

前 W3C Sysapps WG 提議的 UDP 套接字 API

注意：在此規範時，STREAM API 尚未最終確定。

參考：TCP UDP 套接字 API

如何使用

需要注意的事項：

1. 該實施仍只是一個正在進行中的草案。它至少需要完成Stream的readable和writable屬性的實作。
2. 預計將用作專用供應商的高層

它的目標是編寫供應商適配器，例如：

• Cordova 插件（Android/iOs/...）
• 反應本機 / NativeScript
• Chrome 應用程式
• 火狐操作系統
• WinJS
• Node.js / 瓦幹達
• CommonJS

非常歡迎任何人為這個項目做出貢獻;-)

使用範例

 //
// This example shows a simple implementation of UPnP-SSDP M-SEARCH
// discovery using a multicast UDPSocket
//

var address = '239.255.255.250' ,
    port = '1900' ,
    serviceType = 'upnp:rootdevice' ,
    rn = 'rn' ,
    search = '' ;

//  Request permission to send multicast messages to the address and
//  port reserved for SSDP
navigator . udpPermission . requestPermission ( { remoteAddress : "239.255.255.250" ,
                                           remotePort : 1900 } ) . then (
  ( ) => {
    // Permission was granted

    //  Create a new UDP client socket
    var mySocket = new UDPSocket ( ) ;

    // Build an SSDP M-SEARCH multicast message
    search += 'M-SEARCH * HTTP/1.1' + rn ;
    search += 'ST: ' + serviceType + rn ;
    search += 'MAN: "ssdp:discover"' + rn ;
    search += 'HOST: ' + address + ':' + port + rn ;
    search += 'MX: 10' ;


    // Receive and log SSDP M-SEARCH response messages
    function receiveMSearchResponses ( ) {
      mySocket . readable . getReader ( ) . read ( ) . then ( ( { value , done } ) => {
        if ( done ) return ;

        console . log ( 'Remote address: ' + value . remoteAddress +
                    'Remote port: ' + value . remotePort +
                    'Message: ' + ab2str ( value . data ) ) ;
        // ArrayBuffer to string conversion could also be done by piping
        // through a transform stream. To be updated when the Streams API
        // specification has been stabilized on this point.
      } ) ;
    }

    // Join SSDP multicast group
    mySocket . joinMulticast ( address ) ;

    // Send SSDP M-SEARCH multicast message
    mySocket . writeable . write (
      { data : str2ab ( search ) ,
       remoteAddress : address ,
       remotePort : port
      } ) . then (
        ( ) => {
          // Data sent sucessfully, wait for response
          console . log ( 'M-SEARCH Sent' ) ;
          receiveMSearchResponses ( ) ;
        } ,
        e => console . error ( "Sending error: " , e ) ;
    ) ;

    // Log result of UDP socket setup.
    mySocket . opened . then (
      ( ) => {
        console . log ( "UDP socket created sucessfully" ) ;
      } ,
      e => console . error ( "UDP socket setup failed due to error: " , e ) ;
    ) ;

    // Handle UDP socket closed, either as a result of the application
    // calling mySocket.close() or an error causing the socket to be
    // closed.
    mySocket . closed . then (
      ( ) => {
         console . log ( "Socket has been cleanly closed" ) ;
      } ,
      e => console . error ( "Socket closed due to error: " , e ) ;
    ) ;

  } ,
  e => console . error ( "Sending SSDP multicast messages was denied due to error: " , e ) ;
) ; 

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