IE8/9原生是不支持WebSocket的，但是我们可以使用flash去模拟一个WebSocket接口出来。

这方面，https://github.com/gimite/web-socket-js 已经可以使用。

除了客户端之外，服务端需要做个flash安全策略设置。

这里的服务端是指WebSocet服务器所在的服务端。默认端口是843端口。

客户端使用flash模拟WebSocket时，会打开一个到服务端843端口的TCP链接。

并且发送数据：

<policy-file-request>.

服务端需要回应下面类似的内容

<?xml version="1.0"?>
<!DOCTYPE cross-domain-policy SYSTEM "/xml/dtds/cross-domain-policy.dtd">
<cross-domain-policy>
    <site-control permitted-cross-domain-policies="all"/>
    <allow-access-from domain="*" to-ports="*" secure="false"/>
    <allow-http-request-headers-from domain="*" headers="*"/>
</cross-domain-policy>

Node.js实现

• policy.js

  module.exports.policyFile =
  `<?xml version="1.0"?>
  <!DOCTYPE cross-domain-policy SYSTEM "/xml/dtds/cross-domain-policy.dtd">
  <cross-domain-policy>
    <site-control permitted-cross-domain-policies="all"/>
    <allow-access-from domain="*" to-ports="*" secure="false"/>
    <allow-http-request-headers-from domain="*" headers="*"/>
  </cross-domain-policy>`

• index.js

const Net = require('net')
const {policyFile} = require('./policy')
const port = 843
console.log(policyFile)
const server = new Net.Server()
server.listen(port, function() {
    console.log(`Server listening for connection requests on socket localhost:${port}`);
});
server.on('connection', function(socket) {
    console.log('A new connection has been established.');
    socket.end(policyFile)
    socket.on('data', function(chunk) {
        console.log(`Data received from client: ${chunk.toString()}`);
    });
    socket.on('end', function() {
        console.log('Closing connection with the client');
    });
    socket.on('error', function(err) {
        console.log(`Error: ${err}`);
    });
});