Los mensajes normales son mensajes sin características especiales que proporciona ApsaraMQ for RocketMQ. Se diferencian de los mensajes con características especiales, como los programados, los diferidos, los ordenados y los transaccionales. En este tema se incluye código de ejemplo para enviar y recibir mensajes normales mediante el SDK de cliente HTTP para Python.
Requisitos previos
Antes de comenzar, compruebe que se completaron a continuación operaciones:
Instale el SDK for Python. Para obtener más información, consulte Prepare the Python SDK environment.
Cree en la consola de ApsaraMQ for RocketMQ los recursos que desea especificar en el código. Estos recursos incluyen instancias, topics y grupos de consumidores. Para obtener más información, consulte Create resources.
Obtenga el par de accesskey de su cuenta de Alibaba Cloud. Para obtener más información, consulte Create an AccessKey.
Envío de mensajes normales
A continuación se muestra un ejemplo de código para enviar mensajes normales mediante el SDK de cliente HTTP para Python:
import sys
from mq_http_sdk.mq_exception import MQExceptionBase
from mq_http_sdk.mq_producer import *
from mq_http_sdk.mq_client import *
import time
# Initialize the producer client.
mq_client = MQClient(
# The HTTP endpoint. You can obtain the endpoint in the HTTP Endpoint section of the Instance Details page in the ApsaraMQ for RocketMQ console.
"${HTTP_ENDPOINT}",
# Make sure that the environment variables ALIBABA_CLOUD_ACCESS_KEY_ID and ALIBABA_CLOUD_ACCESS_KEY_SECRET are configured.
# The AccessKey ID that is used for authentication.
os.environ['ALIBABA_CLOUD_ACCESS_KEY_ID'],
# The AccessKey secret that is used for authentication.
os.environ['ALIBABA_CLOUD_ACCESS_KEY_SECRET']
)
# The topic in which the message is produced. You must create the topic in the ApsaraMQ for RocketMQ console.
topic_name = "${TOPIC}"
# The ID of the instance to which the topic belongs. You must create the instance in the ApsaraMQ for RocketMQ console.
# If the instance has a namespace, the instance ID must be specified. If the instance does not have a namespace, set the instanceID parameter to an empty string. You can obtain the namespace of the instance on the Instance Details page in the ApsaraMQ for RocketMQ console.
instance_id = "${INSTANCE_ID}"
producer = mq_client.get_producer(instance_id, topic_name)
# Cyclically send four messages.
msg_count = 4
print("%sPublish Message To %s\nTopicName:%s\nMessageCount:%s\n" % (10 * "=", 10 * "=", topic_name, msg_count))
try:
for i in range(msg_count):
msg = TopicMessage(
# The message content.
"I am test message %s.hello" % i,
# The message tag.
"tag %s" % i
)
# The custom attributes of the message.
msg.put_property("a", i)
# The message key.
msg.set_message_key("MessageKey")
re_msg = producer.publish_message(msg)
print("Publish Message Succeed. MessageID:%s, BodyMD5:%s" % (re_msg.message_id, re_msg.message_body_md5))
except MQExceptionBase as e:
if e.type == "TopicNotExist":
print("Topic not exist, please create it.")
sys.exit(1)
print("Publish Message Fail. Exception:%s" % e)
Suscripción a mensajes normales
A continuación se muestra un ejemplo de código para suscribirse a mensajes normales mediante el SDK de cliente HTTP para Python:
from mq_http_sdk.mq_exception import MQExceptionBase
from mq_http_sdk.mq_consumer import *
from mq_http_sdk.mq_client import *
# Initialize the consumer client.
mq_client = MQClient(
# The HTTP endpoint. You can obtain the endpoint in the HTTP Endpoint section of the Instance Details page in the ApsaraMQ for RocketMQ console.
"${HTTP_ENDPOINT}",
# Make sure that the environment variables ALIBABA_CLOUD_ACCESS_KEY_ID and ALIBABA_CLOUD_ACCESS_KEY_SECRET are configured.
# The AccessKey ID that is used for authentication.
os.environ['ALIBABA_CLOUD_ACCESS_KEY_ID'],
# The AccessKey secret that is used for authentication.
os.environ['ALIBABA_CLOUD_ACCESS_KEY_SECRET']
)
# The topic in which the message is produced. You must create the topic in the ApsaraMQ for RocketMQ console.
topic_name = "${TOPIC}"
# The ID of the consumer group that you created in the ApsaraMQ for RocketMQ console.
group_id = "${GROUP_ID}"
# The ID of the instance to which the topic belongs. You must create the instance in the ApsaraMQ for RocketMQ console.
# If the instance has a namespace, the instance ID must be specified. If the instance does not have a namespace, set the instanceID parameter to an empty string. You can obtain the namespace of the instance on the Instance Details page in the ApsaraMQ for RocketMQ console.
instance_id = "${INSTANCE_ID}"
consumer = mq_client.get_consumer(instance_id, topic_name, group_id)
# In long polling mode, if no message in the topic is available for consumption, the request is suspended on the broker for the specified period of time. If a message becomes available for consumption within the specified period of time, a response is immediately sent to the consumer. In this example, the value is specified as 3 seconds.
# The long polling period. Unit: seconds. In this example, the value is specified as 3. The maximum value that you can specify is 30.
wait_seconds = 3
# The maximum number of messages that can be consumed at a time. In this example, the value is specified as 3. The maximum value that you can specify is 16.
batch = 3
print(("%sConsume And Ak Message From Topic%s\nTopicName:%s\nMQConsumer:%s\nWaitSeconds:%s\n" \
% (10 * "=", 10 * "=", topic_name, group_id, wait_seconds)))
while True:
try:
# Consume messages in long polling mode.
recv_msgs = consumer.consume_message(batch, wait_seconds)
for msg in recv_msgs:
print(("Receive, MessageId: %s\nMessageBodyMD5: %s \
\nMessageTag: %s\nConsumedTimes: %s \
\nPublishTime: %s\nBody: %s \
\nNextConsumeTime: %s \
\nReceiptHandle: %s \
\nProperties: %s\n" % \
(msg.message_id, msg.message_body_md5,
msg.message_tag, msg.consumed_times,
msg.publish_time, msg.message_body,
msg.next_consume_time, msg.receipt_handle, msg.properties)))
except MQExceptionBase as e:
# No message in the topic is available for consumption.
if e.type == "MessageNotExist":
print(("No new message! RequestId: %s" % e.req_id))
continue
print(("Consume Message Fail! Exception:%s\n" % e))
time.sleep(2)
continue
# If the broker fails to receive an acknowledgement (ACK) for a message from the consumer before the period of time specified by the msg.next_consume_time parameter elapses, the broker delivers the message for consumption again.
# A unique timestamp is specified for the handle of a message each time the message is consumed.
try:
receipt_handle_list = [msg.receipt_handle for msg in recv_msgs]
consumer.ack_message(receipt_handle_list)
print(("Ak %s Message Succeed.\n\n" % len(receipt_handle_list)))
except MQExceptionBase as e:
print(("\nAk Message Fail! Exception:%s" % e))
# If the handle of a message times out, the broker cannot receive an ACK for the message from the consumer.
if e.sub_errors:
for sub_error in e.sub_errors:
print(("\tErrorHandle:%s,ErrorCode:%s,ErrorMsg:%s" % \
(sub_error["ReceiptHandle"], sub_error["ErrorCode"], sub_error["ErrorMessage"])))