ROS Service client

• Terminal 1

roscore

• Terminal 2

rosrun turtlesim turtlesim_node

• Terminal 3

rosservice list

/clear
/kill
/reset
/rosout/get_loggers
/spawn
/turtle1/set_pen
/turtle1/teleport_absolute
/turtle1/teleport_relative
/turtlesim/get_loggers

spawn service

Spawn another turtle with spawn service

• rosservice info <service name>

rosservice info /spawn

Node: /turtlesim
URI: rosrpc://user-N56VM:43083
Type: turtlesim/Spawn
Args: x y theta name

• rossrv info <service type>

float32 x
float32 y
float32 theta
string name
---
string name

call / execute

#left down corner: 0,0
rosservice call /spawn "x: 3.0
y: 3.0
theta: 0.0
name: 't1'"

service client

• rosservice info result show the the service implement in /turtlesim package

• most simple service client (without error handler)

#!/usr/bin/env python
import rospy
from turtlesim.srv import Spawn

def main():
    service = rospy.ServiceProxy('/spawn', Spawn)
    service(x=3.0, y=3.0, theta=0.0, name="t1")

if __name__ == "__main__":
    main()

Service client send Request and server answer with response

The service declare by service message that has tow parts request and response

request
---
response

• For example Spawn.srv file under turtlesim.srv folder

float32 x
float32 y
float32 theta
string name
---
string 

When compile the packaged catkin build and install class file that contains the class for example:

• Spawn
• SpawnRequest
• SpawnResponse

#!/usr/bin/env python
import rospy
from turtlesim.srv import Spawn, SpawnRequest

def main():
    service = rospy.ServiceProxy('/spawn', Spawn)
    req = SpawnRequest(x=3.0, y=3.0, theta=0.0, name="t1")
    res = service(req)
    print res.name

if __name__ == "__main__":
    main