table of Contents:
1. Python integration ActiveMQ
2. Packaging Services mq_service.py
3. The reception processing message mq_listener.py
4. Start the message listener service mq.py
The unit tests test_mq_serivce.py
6. Send Message function calls
7. Common Problems and Solutions
ActiveMQ is a very popular service middleware message queues, implements the JMS specification (port 61613) to support Python-based access STOMP protocol. Integrated Python ActiveMQ use stomp.py, simply arranged, this article further encapsulated in Django framework services mq_service.py
JMS：Java Message Service
STOMP: Simple (or Streaming) Text Orientated Messaging Protocol, Simple (Flow) text message oriented protocol
A typical system architecture diagram and message queues:
The timing is as follows:
Sample Code: https://github.com/rickding/HelloPython/tree/master/hello _activemq
├── settings.py
├── sq.m.
│ └── mq_service.py
│ └── mq_listener.py
├── tests
│ └── test_mq_service.py
├── management
│ └── commands
│ └── mq.py
一，Python集成ActiveMQ
代码文件 |
功能要点 |
|
Python集成ActiveMQ |
requirements.txt |
安装stomp.py： stomp.py >= 5.0.1 |
封装服务 |
mq_serivce.py |
封装ActiveMQ的消息发送和处理功能。在Django框架下，将地址等配置在settings.py中集中管理，注意端口为61613 |
接收处理消息 |
mq_listener.py |
增加消息接收处理类，继承stomp.ConnectionListener |
启动消息监听服务 |
mq.py |
在Django框架下，将启动服务代码封装成command，方便调用和维护。 |
单元测试 |
test_mq_serivce.py |
测试封装的功能函数 |
功能调用 |
views.py |
增加REST接口/chk/mq，调用mq_service发送消息 |
1. 新建Django项目，运行：django-admin startproject hello_activemq
2. 进到目录hello_activemq，增加应用：python manage.py startapp app
项目的目录文件结构如下：
3. 安装stomp.py，pip install stomp.py >= 5.0.1
二，封装服务mq_service.py，调用ActiveMQ发送消息
1. 增加mq_service.py：
import json
import logging
import stomp
from django.conf import settings
log = logging.getLogger(__name__)
def send_msg(msg_dict, queue_or_topic=settings.MQ_QUEUE):
conn = stomp.Connection10([(settings.MQ_URL, settings.MQ_PORT)])
conn.connect(settings.MQ_USER, settings.MQ_PASSWORD)
msg_str = json.dumps(msg_dict)
log.info('Send msg: %s, %s, %s' % (type(msg_dict), type(msg_str), msg_str))
conn.send(queue_or_topic, msg_str)
conn.disconnect()
2. 打开settings.py，配置ActiveMQ信息：
MQ_URL = '127.0.0.1'
MQ_PORT = 61613
MQ_USER = 'admin'
MQ_PASSWORD = 'admin'
MQ_QUEUE = '/queue/SampleQueue'
MQ_TOPIC = '/topic/SampleTopic'
3. 为了增加代码的兼容和容错能力，封装get_conn(), close_conn()等辅助函数，详见代码文件mq_service.py。
三，接收处理消息mq_listener.py
1. 增加mq_listener.py，声明消息处理类，继承stomp.ConnectionListener：
import json
import logging
import stomp
log = logging.getLogger(__name__)
class MqListener(stomp.ConnectionListener):
def on_message(self, headers, msg_str):
log.info('Receive msg: %s, %s, %s' % (type(msg_str), msg_str, headers))
msg_dict = None
try:
msg_dict = json.loads(msg_str)
except Exception as e:
log.warning('Exception when parse msg: %s' % str(e))
log.info('Parsed msg: {}, {}'.format(type(msg_dict), msg_dict))
def on_error(self, headers, msg_str):
log.info('Error msg: %s, %s, %s' % (type(msg_str), msg_str, headers))
2. 在on_message()函数中，将消息字符串解析为json，方便业务处理。
3. 声明on_error()函数处理错误信息。
四，启动消息监听服务mq.py
1. 将循环接收消息代码封装成函数consume_msg()，增加在服务中mq_serivce.py：
import logging
import time
import stomp
from django.conf import settings
log = logging.getLogger(__name__)
def consume_msg(listener, queue=settings.MQ_QUEUE, topic=settings.MQ_TOPIC):
conn = stomp.Connection10([(settings.MQ_URL, settings.MQ_PORT)])
conn.connect(settings.MQ_USER, settings.MQ_PASSWORD)
conn.set_listener('', listener)
conn.subscribe(queue)
conn.subscribe(topic)
while 1:
time.sleep(1000) # secs
conn.disconnect()
2. 调用set_listener()设置消息接收类实例，使用之前创建的MqListener
3. 调用subscribe()订阅消息，启动循环监听。
4. 我们将启动服务代码封装成command，在目录management/commands中增加mq.py
import logging
from django.core.management.base import BaseCommand
from hello_activemq.mq import mq_service as mq
from hello_activemq.mq.mq_listener import MqListener
log = logging.getLogger(__name__)
class Command(BaseCommand):
help = 'mq starts listener'
def handle(self, *args, **options):
log.info("mq starts")
return mq.consume_msg(MqListener())
5. 运行命令python manage.py mq，看到消息提示，启动监听服务成功。
五，单元测试test_mq_service.py
增加测试函数，发送消息：
import logging
from django.test import TestCase
from hello_activemq.mq import mq_service as mq
log = logging.getLogger(__name__)
class MQServiceTest(TestCase):
def test_send_msg(self):
msg_dict = {'content': 'test msg dict', 'msg': 'msg from python'}
mq.send_msg_to_queue(msg_dict)
mq.send_msg_to_topic({'msg': "test msg from python"})
运行python manage.py test，同时看到监听服务收到并处理消息：
六，发送消息功能调用
1. 在views.py中发送消息，调用mq_servcie.py
import json
from django.http import HttpResponse
from hello_activemq.mq import mq_service as mq
def chk_mq(req):
msg_dict = {
'url': req.get_raw_uri(),
'path': req.get_full_path(),
'host': req.get_host(),
}
mq.send_msg_to_queue(msg_dict)
mq.send_msg_to_topic(msg_dict)
return HttpResponse(json.dumps(msg_dict))
2. 在urls.py中配置路由
from django.urls import path
from app.views import chk_mq
urlpatterns = [
path('', chk_mq, name='chk'),
]
3. 运行命令启动服务：python manage.py runserver 0.0.0.0:8001
4. REST接口发送消息
七，常见问题和解决方法
1. 启动服务错误：[transport.py: 787, attempt_connection] Could not connect to host 127.0.0.1, port 61613
解决：检查ActiveMQ是否正常启动，特别注意是否开启STOMP协议端口61613
原因：Python连接ActiveMQ使用STOMP协议，端口默认61613
2. 接收到的消息内容不正确
Resolution: The message content is serialized to JSON, call json.dumps send () call json.loads () is received
Reason: the Python connection ActiveMQ STOMP protocol is used, as a simple text message format.
Note: the JMS specification class definition message 5:
String TextMessage,
Key-value pairs MapMessage,
Serialized object ObjectMessage
Byte stream BytesMessage
Data flow StreamMessage
ActiveMQ JMS messaging support Category 5, an increase of binary large file messages BlobMessage:
