ubus是openwrt用来实现进程间通信的一种消息总线机制，其数据格式类似json。守护进程dbusd以server/client的方式统一管理进程间的通信，进程可以通过ubus向其他进程发送数据、调用服务,或则向dbus订阅特定消息。

1. ubus中每个对象都用路径(object path)的方式来表达, 命令ubus list 可以列出所有注册对象:

   root@Widora:/# ubus list
   dhcp
   iwinfo
   log
   network
   network.device
   network.interface
   network.interface.lan
   network.interface.loopback
   network.wireless
   rpc-sys
   service
   session
   system
   uci

2. 加上-v选项可以列出指定对象可调用的具体方法(method):

   root@Widora:/# ubus list network.interface.lan -v
   'network.interface.lan' @3fcd0eda
           "up":{}
           "down":{}
           "status":{}
           "prepare":{}
           "dump":{}
           "add_device":{"name":"String","link-ext":"Boolean"}
           "remove_device":{"name":"String","link-ext":"Boolean"}
           "notify_proto":{}
           "remove":{}
           "set_data":{}

3. 调用对象方法：通过ubus向特定对象发送方法名和参数, 对象接收到后会返回要求的状态数据或执行结果。

比如调用network.wireless对象status方法(无需参数), 会返回无线网络的状态： 

   root@Widora:/# ubus call network.wireless status
   {
        "radio0": {
                "up": true,
                "pending": false,
                "autostart": true,
                "disabled": false,
                "config": {
                        "variant": "mt7628",
                        "country": "CN",
                        "hwmode": "11bgn",
                        "htmode": "HT20",
                        "channel": "auto",
                        "disabled": false
                },
                "interfaces": [
                        {
                                "section": "ap",
                                "ifname": "ra0",
                                "config": {
                                        "mode": "ap",
                                        "ifname": "ra0",
                                        "ssid": "Widora-86D9",
     ... ...
   }