应用 - 流控 + 告警传递

告警协议（Session::sendAlarm），传递到对端时会变为异常

1、客户端

//::打开客户端会话
const clientSession = await SocketD.createClient("sd:ws://127.0.0.1:8602/?u=a&p=2")
        .open();

//发送并请求
clientSession.sendAndSubscribe("/demo", SocketD.newEntity().range(5,5)
        .metaPut("videoId", "42E056E1-B4B7-4EF4-AC4B-AEE77EDB0B86")).thenReply(r -> {
    if (r.dataSize() > 0) {
        console.info(r);
    }
}).thenError(err => {
    console.info(err);
});

2、服务端（以 java 为例）

public class Demo {
    public static void main(String[] args) throws Throwable {
        //::启动服务端
        SocketD.createServer("sd:ws")
                .config(c -> c.port(8602))
                .listen(new EventListener().doOn("/demo", (s, m) -> {
                    if (m.isSubscribe() == false) {
                        s.sendAlarm(m, "此事件只支持订阅模式");
                        return;
                    }

                    long videoId   = m.metaAsLong("videoId");
                    int rangeStart = m.rangeStart();
                    int rangeSize  = m.rangeSize();

                    if (videoId == 0 || rangeSize == 0) {
                        s.sendAlarm(m, "参数不合规");
                        return;
                    }

                    ByteBuffer[] fragments = new ByteBuffer[rangeSize];
                    for (int i = 0; i < rangeSize; i++) {
                        s.reply(m, new EntityDefault().dataSet(fragments[i]));
                    }
                    s.replyEnd(m, new EntityDefault());
                }))
                .start();
    }
}