add minimal module4 control example

module4/simple/api.py

@@ -0,0 +1,33 @@
+import rclpy
+from flask import Flask
+from geometry_msgs.msg import Twist
+
+app = Flask(__name__)
+
+rclpy.init()
+node = rclpy.create_node("web_api")
+publisher = node.create_publisher(Twist, "/RMC2/cmd_vel", 10)
+
+
+@app.after_request
+def cors(response):
+    response.headers["Access-Control-Allow-Origin"] = "*"
+    return response
+
+
+@app.post("/api/forward")
+def forward():
+    speed = Twist()
+    speed.linear.x = 0.1
+
+    for _ in range(40):
+        publisher.publish(speed)
+        rclpy.spin_once(node, timeout_sec=0.05)
+
+    for _ in range(5):
+        publisher.publish(Twist())
+        rclpy.spin_once(node, timeout_sec=0.05)
+
+    return "ok"
+
+app.run(host="0.0.0.0", port=8000, threaded=False)