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How do ros service responses work.

asked 2011-07-15 01:51:41 -0500

boy gravatar image

updated 2011-07-18 04:05:40 -0500

hello everyone,

I have the following problem:

When I can call a service"server node" to calculate something(for simplicity float_A/float_B), how can i use the response to do something in my client node(for instance make a dissension in my state_2). The code of the server node and client node is given below. (.srv file float32[] a ------- float32[] sum)

#client node
class State_2(smach.State):

def __init__(self):
    smach.State.__init__(self, outcomes=['outcome1','outcome2'])

self.check = False
self.subscriber = rospy.Subscriber("chatter",Array, self.callback)

def callback(self,data):
self.ranges_list = list(data.ranges)

def execute(self, userdata):
rospy.sleep(1.0)
rospy.wait_for_service('check_teammember_behind_turtle')

check_teammember_behind_turtle = rospy.ServiceProxy('check_teammember_behind_turtle', teammember)
check_teammember_behind_turtle(self.ranges_list[0:3])
## THINK I MISS HERE SOMETHING##
    ## MAYBE YOU CAN HELP ME##


rospy.loginfo('Executing state STATE_2')

if self.check: 
    return 'outcome1'
else:
    return 'outcome2'

## CODE SERVER ##
def handle_teammember(req):
list_teammember = list(req.a)
tx = list_teammember[0]/list_teammember[1]
ty = list_teammember[1]/list_teammember[2]
if (tx>ty):
tx_list = [tx]
print ("tx")
else:
tx_list = [ty]
print ("ty")

return teammemberResponse(tx_list)

def add_two_ints_server():
rospy.init_node('add_two_ints_server')
s = rospy.Service('check_teammember_behind_turtle', teammember, handle_teammember)
print "Ready to add two ints."
rospy.spin()
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Comments

Please try to make your head line informative next time. (I fixed this one)
Asomerville gravatar image Asomerville  ( 2011-07-18 04:06:32 -0500 )edit
I will do that, SORRY!
boy gravatar image boy  ( 2011-07-18 05:23:19 -0500 )edit

1 Answer

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answered 2011-07-15 02:37:27 -0500

dornhege gravatar image

updated 2011-07-17 21:32:04 -0500

The response is returned by the call. See this tutorial: http://www.ros.org/wiki/ROS/Tutorials/WritingServiceClient(python)

You need to adapt this code to yours:

rospy.wait_for_service('add_two_ints')
try:
    add_two_ints = rospy.ServiceProxy('add_two_ints', AddTwoInts)
    resp1 = add_two_ints(x, y)
    return resp1.sum
except rospy.ServiceException, e:
    print "Service call failed: %s"%e
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Comments

Thanks for the answer, but I still don't have it yet. Could you give me some hits or small example?? Reminder: I have to make a decision with the info obtained from server
boy gravatar image boy  ( 2011-07-17 20:47:54 -0500 )edit
thats what I thought too, but I cannot adapt the code without getting a lot of errors. Maybe It's my lack in experience in python and ROS. Could you give me some more hints??
boy gravatar image boy  ( 2011-07-17 22:32:48 -0500 )edit
If the code above runs, you just change one line to: resp = check_teammember_behind_turtle(self.ranges_list[0:3]) and then handle the response resp. Obviously the try/catch would be advisable, but to just get the information this should work.
dornhege gravatar image dornhege  ( 2011-07-17 23:06:01 -0500 )edit
I have it working :) Thanks
boy gravatar image boy  ( 2011-07-17 23:38:41 -0500 )edit
If it's working, accept the answer...karma karma karma!
Mac gravatar image Mac  ( 2011-07-20 06:28:22 -0500 )edit

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Asked: 2011-07-15 01:51:41 -0500

Seen: 3,318 times

Last updated: Jul 18 '11