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TDMQ for RocketMQ
DocumentationTDMQ for RocketMQRocketMQ 4.xSDK DocumentationAccess over TCPSDK for Python
SDK for Python
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Last updated: 2023-09-12 17:53:17
SDK for Python
Last updated: 2023-09-12 17:53:17
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Overview

This document describes how to use open-source SDK to send and receive messages by using the SDK for Python as an example and helps you better understand the message sending and receiving processes.

Prerequisites

You have created the required resources as instructed in Resource Creation and Preparation.
You have installed Python.
You have installed pip.
You have downloaded the demo.

Directions

Step 1. Prepare the environment

As RocketMQ-client Python is lightweight wrapper around rocketmq-client-cpp, you need to install librocketmq first.
Note
Currently, the Python client only supports Linux and macOS operating systems. It doesn't support Windows systems.
1. Install librocketmq 2.0.0 or later as instructed in Install librocketmq.
2. Run the following command to install rocketmq-client-python.
pip install rocketmq-client-python


Step 2. Produce messages

Create, compile, and run a message production program.
from rocketmq.client import Producer, Message

   # Initialize the producer and set the producer group information. Be sure to use the full name of the group, such as `rocketmq-xxx|namespace_python%group1`.
   producer = Producer(groupName)
   # Set the service address
   producer.set_name_server_address(nameserver)
   # Set permissions (role name and token)
   producer.set_session_credentials(
        accessKey,  # Role token
       secretKey,  # Role name
       ''
   )
   # Start the producer
   producer.start()

   # Assemble messages. The topic name can be copied on the **Topic** page in the console.   
   msg = Message(topicName)
   # Set keys
   msg.set_keys(TAGS)
   # Set tags
   msg.set_tags(KEYS)
   # Message content
   msg.set_body('This is a new message.')

   # Send messages in sync mode
   ret = producer.send_sync(msg)
   print(ret.status, ret.msg_id, ret.offset)
   # Release resources
   producer.shutdown()
Parameter
Description
groupName
Producer group name, which can be obtained under the Group tab on the cluster details page in the console.
nameserver
Cluster access address, which can be copied from Access Address in the Operation column on the Cluster page in the console. Namespace access addresses in new virtual or exclusive clusters can be copied from the Namespace list.

secretKey
Role name, which can be copied on the Role Management page.
accessKey
Role token, which can be copied in the Token column on the Role Management page.

topicName
Topic name, which can be copied on the Topic page in the console.
TAGS
A parameter used to set the message tag.
KEYS
A parameter used to set the message key.
There are certain defects in the message production of the open-source Python client, causing uneven load among different queues of the same Topic. For more information, see [RocketMQ document](https://github.com/apache/rocketmq-client-python/issues /128!cac28b204e4c02765f18ecd741ed1628).

Step 3. Consume messages

Create, compile, and run a message consumption program.
import time

   from rocketmq.client import PushConsumer, ConsumeStatus


   # Message processing callback
   def callback(msg):
       # Simulate the business processing logic
       print('Received message. messageId: ', msg.id, ' body: ', msg.body)
       # Return CONSUME_SUCCESS if the consumption is successful
       return ConsumeStatus.CONSUME_SUCCESS
       # Return the consumption status if the consumption is successful
       # return ConsumeStatus.RECONSUME_LATER


   # Initialize the consumer and set the consumer group information 
   consumer = PushConsumer(groupName)
   # Set the service address
   consumer.set_name_server_address(nameserver)
   # Set permissions (role name and token)
   consumer.set_session_credentials(
       accessKey,	 # Role token
       secretKey,   # Role name
       ''
   )
   # Subscribe to a topic
   consumer.subscribe(topicName, callback, TAGS)
   print(' [Consumer] Waiting for messages.')
   # Start the consumer
   consumer.start()

   while True:
       time.sleep(3600)
   # Release resources
   consumer.shutdown()
Parameter
Description
groupName
Consumer group name, which can be copied under the Group tab on the cluster details page.
nameserver
Cluster access address, which can be copied from Access Address in the Operation column on the Cluster page in the console. Namespace access addresses in new virtual or exclusive clusters can be copied from the Namespace list.

secretKey
Role name, which can be copied on the Role Management page.
accessKey
Role token, which can be copied in the Token column on the Role Management page.

topicName
Topic name, which can be copied on the Topic page in the console.
TAGS
A parameter used to set the tag of messages that are subscribed to. The default value is set to *, which means subscribing to all messages.

Step 4. View consumption details

Log in to the TDMQ console, go to the Cluster > Group page, and view the list of clients connected to the group. Click View Details in the Operation column to view consumer details.


Note
Above is a brief introduction to message publishing and subscription. For more information, see Demo or RocketMQ-Client-Python Sample.

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