def consume_data(topic, borker, group_id):
consumer = Consumer(brokers=[borker], group_id=group_id)
consumer.subscribe([topic, "thing-event"])
for msg in consumer:
try:
value = msg.value
print(value)
except Exception as err:
print(err)
continue
class Crawler:
MAX_URL = 10
def __init__(self):
self.url_counter = 1
self.document_client = DocumentClient()
self.indexing_client = IndexingClient()
self.pagerank_client = PagerankClient()
self.producer = Producer('url_queue')
self.consumer = Consumer('url_queue')
def run(self):
self.consumer.subscribe(self.run_for_url)
def run_for_url(self, ch, method, properties, body):
doc_url = body.decode("utf-8")
print("[Crawler] Received %r" % doc_url)
document_text = WebScraper.get_text(doc_url)
document_links = WebScraper.get_links(doc_url)
hash_object = hashlib.sha256(document_text.encode("utf-8"))
digest = hash_object.hexdigest()
doc_record = self.document_client.get_by_url(doc_url)
if "id" not in doc_record:
doc_record = self.document_client.create(doc_url, digest)
doc_indexed = self.indexing_client.get_by_id(doc_record["id"])
if "url" not in doc_indexed:
self.indexing_client.index(doc_record["id"], doc_url, document_text)
if doc_record["digest"] != digest:
self.document_client.update_digest(doc_record["id"], digest)
self.indexing_client.update_content(doc_record["id"], document_text)
for link in document_links:
if self.url_counter < Crawler.MAX_URL:
self.url_counter += 1
child_doc_record = self.document_client.get_by_url(link.geturl())
if "id" not in child_doc_record:
child_doc_record = self.document_client.create(link.geturl(), "digest")
self.document_client.create_link(doc_record["id"], child_doc_record["id"])
self.producer.publish(link.geturl())
self.pagerank_client.update(doc_record["id"])
class MessageBus:
def __init__(self,
broker_url='amqp://localhost',
queue_prefix=None,
exchange='messagebus'):
self.broker_url = broker_url
self.consumer = Consumer(self.broker_url, queue_prefix, exchange)
self._queue_prefix = queue_prefix
self.exchange = exchange
def publish(self, message, payload={}):
self._publish(message, payload)
def _publish(self, message, payload, correlation_id=None):
body = json.dumps(self._prepare_payload(payload), ensure_ascii=False)
connection = pika.BlockingConnection(
pika.URLParameters(self.broker_url))
channel = connection.channel()
properties = None
if correlation_id:
properties = pika.BasicProperties(correlation_id=correlation_id)
channel.basic_publish(exchange=self.exchange,
routing_key=message,
body=body,
properties=properties)
connection.close()
def _prepare_payload(self, payload):
def serialize(value):
if isinstance(value, datetime.datetime):
return value.isoformat()
return value
proc_payload = {k: serialize(v) for k, v in payload.items()}
if 'timestamp' not in proc_payload:
proc_payload['timestamp'] = datetime.datetime.utcnow().isoformat()
return proc_payload
def subscribe(self, message, callback):
self.consumer.subscribe(message, callback)
def subscribe_and_publish_response(self, message, callback):
def subscribe_callback(request_payload, **kwargs):
correlation_id = kwargs['properties'].correlation_id
response = callback(request_payload)
self._publish(message + '.answered', response, correlation_id)
self.consumer.subscribe(message,
subscribe_callback,
transient_queue=True)
def publish_and_get_response(self, message, payload, timeout_secs=5):
sent_correlation = str(uuid.uuid1())
consumer_ready = Event()
def on_consumer_ready():
consumer_ready.set()
consumer = Consumer(self.broker_url, self._queue_prefix, self.exchange)
consumer.on_connection_setup_finished = on_consumer_ready
response = {}
response_received = Event()
def response_callback(response_payload, **kwargs):
if not sent_correlation == kwargs['properties'].correlation_id:
return
response['payload'] = response_payload
response_received.set()
def wait_for_response():
consumer.subscribe(message + '.answered',
response_callback,
transient_queue=True)
consumer.start()
thread = Thread(target=wait_for_response)
thread.daemon = True
thread.start()
consumer_ready.wait(2)
self._publish(message, payload, correlation_id=sent_correlation)
timed_out = not response_received.wait(timeout_secs)
if timed_out:
raise MessageBusTimeoutError()
consumer.stop()
return response.get('payload')
def start(self):
self.consumer.start()
def stop(self):
self.consumer.stop()
