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## note = This tutorials assumes that you have completed [[dynamic_reconfigure/Tutorials/SettingUpDynamicReconfigureForANode(python)| Setting up Dynamic Reconfigure for a Node(python)]] or [[dynamic_reconfigure/Tutorials/SettingUpDynamicReconfigureForANode(cpp)|(c++)]]
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## descriptive title for the tutorial
## title = Using the Dynamic Reconfigure Python Client
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## description = This tutorial cover basic setup and usage of the dynamic_reconfigure client.
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<<IncludeCSTemplate(TutorialCSHeaderTemplate)>>

<<TableOfContents(4)>>

= The Code =
Now that we have a node that we can reconfigure, we need to write a node to reconfigure it. Create a file called client.py in the nodes directory and add the following code to it:

{{{#!python
#!/usr/bin/env python

import rospy

import dynamic_reconfigure.client

def callback(config):
    rospy.loginfo("Config set to {int_param}, {double_param}, {str_param}, {bool_param}, {size}".format(**config))

if __name__ == "__main__":
    rospy.init_node("dynamic_client")

    client = dynamic_reconfigure.client.Client("dynamic_tutorials", timeout=30, config_callback=callback)

    r = rospy.Rate(0.1)
    x = 0
    b = False
    while not rospy.is_shutdown():
        x = x+1
        if x>10:
            x=0
        b = not b
        client.update_configuration({"int_param":x, "double_param":(1/(x+1)), "str_param":str(rospy.get_rostime()), "bool_param":b, "size":1})
        r.sleep()
}}}
= The Breakdown =
Writing a dynamic reconfigure client is very simple:

{{{#!python
#!/usr/bin/env python

import rospy

import dynamic_reconfigure.client
}}}
We first import rospy and dynamic_reconfigure.client.

{{{#!python
def callback(config):
    rospy.loginfo("Config set to {int_param}, {double_param}, {str_param}, {bool_param}, {size}".format(**config))
}}}
We then define a callback which will print the config returned by the server. There are two main differences between this callback and the servers, one it does not need to return an updated config object, two it does not have the "level" argument. This callback is optional.

{{{#!python
if __name__ == "__main__":
    rospy.init_node("dynamic_client")

    client = dynamic_reconfigure.client.Client("dynamic_tutorials", timeout=30, config_callback=callback)

    r = rospy.Rate(0.1)
    x = 0
    b = False
    while not rospy.is_shutdown():
        x = x+1
        if x>10:
            x=0
        b = not b
        client.update_configuration({"int_param":x, "double_param":(1/(x+1)), "str_param":str(rospy.get_rostime()), "bool_param":b, "size":1})
        r.sleep()
}}}
Lastly we initialize ROS and our Client. Our main loop runs once every ten seconds and simply calls {{{update_configuration}}} on the client every time. Note that you need not use a full configuration and could also pass in a dictionary with only one of the parameters as well.

= Run It! =
Once again make the node executable: {{{chmod +x nodes/client.py}}} Launch a core and your server node, and launch your new client node. If you've done everything correctly, both your client and server should begin to print out matching configurations every ten seconds.

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