http://wiki.ros.org/ROS/Tutorials/UnderstandingServicesParams

假设你的小乌龟仍旧在运行

ROS Services

service 是节点间进行通信的另一种方式。服务允许节点去发送一个请求和接收一个响应

使用rosservice

rosservide很容易附加在ROS的客户端/服务端上。rosservice也有很多命令可以用在服务上。
使用：

rosservice -h
Commands:
    rosservice args print service arguments
    rosservice call call the service with the provided args
    rosservice find find services by service type
    rosservice info print information about service
    rosservice list list active services
    rosservice type print service type
    rosservice uri  print service ROSRPC uri

1. rosservice list

$ rosservice list
/clear
/kill
/reset
/rosout/get_loggers
/rosout/set_logger_level
/spawn
/teleop_turtle/get_loggers
/teleop_turtle/set_logger_level
/turtle1/set_pen
/turtle1/teleport_absolute
/turtle1/teleport_relative
/turtlesim/get_loggers
/turtlesim/set_logger_level

这个命令展示给我们turtlesim node 提供了9个服务，另外有两个单独的服务：/rosout/get_loggers and /rosout/set_logger_level

2. rosservice type

$rosservice type /clear
std_srvs/Empty

这意味着我们call这个服务的时候不需要参数

3.roservice call

rosservice call [service] [args]
$rosservice call /clear

执行完之后，我们看到小乌龟的路径被清理了

使用rosparam

rosparam 允许我们存储并操作在ROS参数服务上的数据

 rosparam -h
rosparam is a command-line tool for getting, setting, and deleting parameters from the ROS Parameter Server.

Commands:
    rosparam set    set parameter
    rosparam get    get parameter
    rosparam load   load parameters from file
    rosparam dump   dump parameters to file
    rosparam delete delete parameter
    rosparam list   list parameter names

1. rosparam list
2. rosparam set 和 rosparam get
3. rosparam dump/load

rosparam dump [file_name] [namespace]
rosparam load [file_name] [namespace]