Ros.4 服务

多个节点间通讯 定义srv
与定义 msg类似
在功能包的根目录下 创建srv文件
sum.srv文件如下

int64 a
int64 b
---
int64 sum

catkin_make install

#!/usr/bin/env python
# service.py

from __future__ import print_function

from hrg.srv import sum,sumResponse
import rospy

def handle_add_two_ints(req):
    print("Returning [%s + %s = %s]"%(req.a, req.b, (req.a + req.b)))
    return sumResponse(req.a + req.b)
  
def add_two_ints_server():
    rospy.init_node('add_two_ints_server')
    s = rospy.Service('add_two_ints', sum, handle_add_two_ints)
    print("Ready to add two ints.")
    rospy.spin()

if __name__ == "__main__":
    add_two_ints_server()

#!/usr/bin/env python
# client.py

from __future__ import print_function

import sys
import rospy
from hrg.srv import *

def add_two_ints_client(x, y):
      rospy.wait_for_service('add_two_ints')
      try:
          add_two_ints = rospy.ServiceProxy('add_two_ints', sum)
          resp1 = add_two_ints(x, y)
          return resp1.sum
      except rospy.ServiceException as e:
          print("Service call failed: %s"%e)
  
def usage():
    return "%s [x y]"%sys.argv[0]

if __name__ == "__main__":
    if len(sys.argv) == 3:
        x = int(sys.argv[1])
        y = int(sys.argv[2])
    else:
        print(usage())
        sys.exit(1)
    print("Requesting %s+%s"%(x, y))
    print("%s + %s = %s"%(x, y, add_two_ints_client(x, y)))

rosrun hrg service.py
root@chxin-virtual-machine:~/catkin_ws# rosrun  hrg service.py
Ready to add two ints.
Returning [1 + 2 = 3]
#新cmd窗口
rossum hrg client.py 1 2 输出如下 
  root@chxin-virtual-machine:~/catkin_ws# rosrun hrg client.py 1 2
  Requesting 1+2
  1 + 2 = 3

其他的功能包也可使用 msg srv 共享的，是在整个python环境中的

image.png

注，新开cmd

#!/usr/bin/env python
# -*- coding: UTF-8 -*-
import rospy
from hrg.srv  import *
import sys

def _service():
    rospy.init_node("Service2")
    srv_server_handler = rospy.Service("add", sum, lambda req :sumResponse(req.a+req.b))
    rospy.spin()


def _client():
   add=rospy.ServiceProxy("add",sum)
   res=add(1,1)
   print(res)

if __name__ == "__main__":
     try:
        arg1=arg1=sys.argv[1]
        print(arg1)
        if("1"==arg1):
            _service()
        else:
            _client()
     except Exception as err:
         print(err)
         pass