lightweight kafka support

Change-Id: I1c124d7fbb64dd16990f18f677c2e61d18aa767e
Signed-off-by: gcalvino <guillermo.calvinosanchez@altran.com>

diff --git a/lcm/osm_common/msgkafka.py b/lcm/osm_common/msgkafka.py
new file mode 100644 (file)
index 0000000..7b294fc
--- /dev/null
+++ b/lcm/osm_common/msgkafka.py
@@ -0,0 +1,67 @@
+from aiokafka import AIOKafkaConsumer
+from aiokafka import AIOKafkaProducer
+from aiokafka.errors import KafkaError
+from msgbase import MsgBase, MsgException
+import asyncio
+import yaml
+#import json
+
+class msgKafka(MsgBase):
+    def __init__(self):
+        self.host = None
+        self.port = None
+        self.consumer = None
+        self.producer = None
+        # create a different file for each topic
+        #self.files = {}
+
+    def connect(self, config):
+        try:
+            self.host = config["host"]
+            self.port = config["port"]
+            self.topic_lst = []
+            self.loop = asyncio.get_event_loop()
+            self.broker = str(self.host) + ":" + str(self.port)
+
+        except Exception as e:  # TODO refine
+            raise MsgException(str(e))
+
+    def write(self, topic, msg, key):
+
+        try:
+            self.loop.run_until_complete(self.aiowrite(key, msg=yaml.safe_dump(msg, default_flow_style=True), topic=topic))
+
+        except Exception as e:
+            raise MsgException("Error writing {} topic: {}".format(topic, str(e)))
+
+    def read(self, topic):
+        self.topic_lst.append(topic)
+        try:
+            return self.loop.run_until_complete(self.aioread(self.topic_lst))
+        except Exception as e:
+            raise MsgException("Error reading {} topic: {}".format(topic, str(e)))
+
+    async def aiowrite(self, key, msg, topic):
+        try:
+            self.producer = AIOKafkaProducer(loop=self.loop, key_serializer=str.encode, value_serializer=str.encode,
+                                             bootstrap_servers=self.broker)
+            await self.producer.start()
+            await self.producer.send(topic=topic, key=key, value=msg)
+        except Exception as e:
+            raise MsgException("Error publishing to {} topic: {}".format(topic, str(e)))
+        finally:
+            await self.producer.stop()
+
+    async def aioread(self, topic):
+        self.consumer = AIOKafkaConsumer(loop=self.loop, bootstrap_servers=self.broker)
+        await self.consumer.start()
+        self.consumer.subscribe(topic)
+        try:
+            async for message in self.consumer:
+                return yaml.load(message.key), yaml.load(message.value)
+        except KafkaError as e:
+            raise MsgException(str(e))
+        finally:
+            await self.consumer.stop()
+
+