[rclpy_examples] QoS examples (#132)

* qos example

* add reliable/best_effort settings

rclpy_examples/listener_qos_py.py

@@ -0,0 +1,59 @@
+# Copyright 2016 Open Source Robotics Foundation, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import argparse
+import sys
+
+import rclpy
+from rclpy.qos import qos_profile_default, qos_profile_sensor_data
+
+from std_msgs.msg import String
+
+
+def chatter_callback(msg):
+    print('I heard: [%s]' % msg.data)
+
+
+def main(argv=sys.argv[1:]):
+    parser = argparse.ArgumentParser(formatter_class=argparse.ArgumentDefaultsHelpFormatter)
+    parser.add_argument(
+        '--reliable', dest='reliable', action='store_true',
+        help='set qos profile to reliable')
+    parser.set_defaults(reliable=False)
+    parser.add_argument(
+        '-n', '--number_of_cycles', type=int, default=20,
+        help='max number of spin_once iterations')
+    args = parser.parse_args(argv)
+    rclpy.init()
+
+    if args.reliable:
+        custom_qos_profile = qos_profile_default
+        print('Reliable listener')
+    else:
+        custom_qos_profile = qos_profile_sensor_data
+        print('Best effort listener')
+
+    node = rclpy.create_node('listener_qos')
+
+    sub = node.create_subscription(String, 'chatter_qos', chatter_callback, custom_qos_profile)
+
+    assert sub  # prevent unused warning
+
+    cycle_count = 0
+    while rclpy.ok() and cycle_count < args.number_of_cycles:
+        rclpy.spin_once(node)
+        cycle_count += 1
+
+if __name__ == '__main__':
+    main()

rclpy_examples/setup.py

@@ -4,7 +4,7 @@
     name='rclpy_examples',
     version='0.0.0',
     packages=[],
-    py_modules=['listener_py', 'talker_py'],
+    py_modules=['listener_py', 'talker_py', 'listener_qos_py', 'talker_qos_py'],
     install_requires=['setuptools'],
     author='Esteve Fernandez',
     author_email='[email protected]',
@@ -24,6 +24,8 @@
         'console_scripts': [
             'listener_py = listener_py:main',
             'talker_py = talker_py:main',
+            'listener_qos_py = listener_qos_py:main',
+            'talker_qos_py = talker_qos_py:main',
         ],
     },
 )

rclpy_examples/talker_qos_py.py

@@ -0,0 +1,59 @@
+# Copyright 2016 Open Source Robotics Foundation, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import argparse
+import sys
+from time import sleep
+
+import rclpy
+from rclpy.qos import qos_profile_default, qos_profile_sensor_data
+
+from std_msgs.msg import String
+
+
+def main(argv=sys.argv[1:]):
+    parser = argparse.ArgumentParser(formatter_class=argparse.ArgumentDefaultsHelpFormatter)
+    parser.add_argument(
+        '--reliable', dest='reliable', action='store_true',
+        help='set qos profile to reliable')
+    parser.set_defaults(reliable=False)
+    parser.add_argument(
+        '-n', '--number_of_cycles', type=int, default=20,
+        help='number of sending attempts')
+    args = parser.parse_args(argv)
+    rclpy.init()
+
+    if args.reliable:
+        custom_qos_profile = qos_profile_default
+        print('Reliable publisher')
+    else:
+        custom_qos_profile = qos_profile_sensor_data
+        print('Best effort publisher')
+
+    node = rclpy.create_node('talker_qos')
+
+    chatter_pub = node.create_publisher(String, 'chatter_qos', custom_qos_profile)
+
+    msg = String()
+
+    cycle_count = 0
+    while rclpy.ok() and cycle_count < args.number_of_cycles:
+        msg.data = 'Hello World: {0}'.format(cycle_count)
+        print('Publishing: "{0}"'.format(msg.data))
+        chatter_pub.publish(msg)
+        cycle_count += 1
+        sleep(1)
+
+if __name__ == '__main__':
+    main()