.. _Client ROS:

ROS Service Client 
======================

The Follow Along Examples:

- :ref:`Command ROS`
- :ref:`Server ROS`
- :ref:`Client ROS` <- you are here 

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    <div style="background: #C3F8FF" class="admonition note custom">
        <p style="background: light-blue" class="admonition-title">
            Follow along: ROS Topic Subscriber Example
        </p>
        <div class="line-block">
            <div class="line">The program launching process along with parameter settings are all simplified and set up on the Jupyter Notebook Environment.</div>
        </div>
        <ul>
            <li>Open the 02_01_ros_service_server.ipynb Jupyter Notebook</li>
            <li>Import the necessary python libraries and modules</li>
            <li>Follow and Execute the example codes</li>

        </ul>
        <div class="line">(The Jetson Board used for these examples are => Jetson Nano)</div>
        
    </div>


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    <hr>

Open the following jupyter notebook:

-   02_01_ros_service_server.ipynb
-   To run the cells within the notebook use Ctrl + Enter



.. thumbnail:: /_images/robot_control_move/comm10.webp

.. thumbnail:: /_images/robot_control_move/comm11.webp


-   Import print_function from `__future__` module for Python3 compatibility
-   Import AddTwoInts, AddTwoIntsResponse from rospy_tutorials.srv module
-   Import rospy modules


.. code-block:: python

    from __future__ import print_function
    from rospy_tutorials.srv import AddTwoInts,AddTwoIntsResponse
    import rospy


-   Create handle_add_two_ints() function
-   Output req.a, req.b, req.a + req.b
-   Return instances of req.a + req.b in AddTwoIntsResponse

.. code-block:: python

    def handle_add_two_ints(req):
        print("Returning [%s + %s = %s]"%(req.a, req.b, (req.a + req.b)))
        return AddTwoIntsResponse(req.a + req.b)

-   Create `add_two_ints_server()` function
-   Create add_two_ints_server Node
-   Create add_two_ints Service

.. code-block:: python

    def add_two_ints_server():
        rospy.init_node('add_two_ints_server')
        s = rospy.Service('add_two_ints', AddTwoInts, handle_add_two_ints)
        print("Ready to add two ints.")
        rospy.spin()

-   Execute the add_two_ints_server() function

.. code-block:: python

    add_two_ints_server()