push-pull web service

config.ini

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+
+
+[server]
+server_host = 127.0.0.1
+server_port = 8081

main.py

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+import os
+import sys
+
+import cherrypy
+from cherrypy.lib.static import serve_file
+import socket
+
+import configparser
+
+from pubsub import pub
+import time
+
+PATH = os.path.dirname(os.path.abspath(__file__))
+
+config = configparser.ConfigParser()
+config.read("config.ini")
+TIMEOUT = 60 #sec
+
+
+class MainApp:
+
+    def __init__(self):
+        self.received_data = None
+
+    @cherrypy.expose
+    def submit(self, topic, data):
+        """
+        This is where publisher can submit data
+        """
+        pub.sendMessage(topic, data=data)
+        return "Published data to {}".format(topic)
+    
+    def msg_listener(self, data):
+        self.received_data = data
+        
+
+    @cherrypy.expose
+    def poll(self, topic):
+        """
+        Subscribers wait here for changes
+        """
+        
+        pub.subscribe(self.msg_listener, topic)
+
+        # wait for the data to come
+        rcv_data = self.received_data
+        s = time.time()
+        while not rcv_data and (time.time() - s) < TIMEOUT:
+            rcv_data = self.received_data
+        
+        if (time.time() - s) > TIMEOUT:
+            raise cherrypy.HTTPError(408, "Timeout Error. Publisher did not publish any data")
+        
+        self.received_data = None
+        pub.unsubscribe(self.msg_listener, topic)
+        return rcv_data
+
+
+ROOT = MainApp()
+
+if __name__ == "__main__":
+    cherrypy.server.socket_host = config["server"].get("server_host", "127.0.0.1")
+    cherrypy.server.socket_port = config["server"].getint("server_port", 8081)
+    ENGINE = cherrypy.engine
+
+    cherrypy.tree.mount(ROOT)
+    if hasattr(ENGINE, "signal_handler"):
+        ENGINE.signal_handler.subscribe()
+    if hasattr(ENGINE, "console_control_handler"):
+        ENGINE.console_control_handler.subscribe()
+    try:
+        ENGINE.start()
+    except Exception:
+        sys.exit(1)
+    else:
+        ENGINE.block()