rabbitmq消息发布
可靠投递
mandatory
当交换器无法路由消息,RabbitMQ将回发Basic.Return消息到发布者,同时回发完整消息。
Basic.Return是异步的,在消息发布后的任何时候都可能发生。
在rabbitpy库中,客户端自动接收Basic.Return,并触发异常
示例程序:发布失败
import datetime
import rabbitpy
# Connect to the default URL of amqp://guest:guest@localhost:15672/%2F
with rabbitpy.Connection() as connection:
with connection.channel() as channel:
# Create the message to send
body = 'server.cpu.utilization 25.5 1350884514'
message = rabbitpy.Message(channel,
body,
{'content_type': 'text/plain',
'timestamp': datetime.datetime.now(),
'message_type': 'graphite metric'})
# Publish the message to the exchange with the routing key
# "server-metrics" and make sure it is routed to the exchange
message.publish('chapter2-example', 'server-metrics', mandatory=True)
示例程序:异常捕获
import datetime
import rabbitpy
# Connect to the default URL of amqp://guest:guest@localhost:15672/%2F
connection = rabbitpy.Connection()
try:
with connection.channel() as channel:
properties = {'content_type': 'text/plain',
'timestamp': datetime.datetime.now(),
'message_type': 'graphite metric'}
body = 'server.cpu.utilization 25.5 1350884514'
message = rabbitpy.Message(channel, body, properties)
message.publish('chapter2-example',
'server-metrics',
mandatory=True)
except rabbitpy.exceptions.MessageReturnedException as error:
print('Publish failure: %s' % error)
发布者确认
发布者发送给RabbitMQ的每条消息,服务器发送一个确认(Basic.Ack)或者否认相应(Basic.Nack)。
示例程序:发布者确认
import rabbitpy
with rabbitpy.Connection() as connection:
with connection.channel() as channel:
exchange = rabbitpy.Exchange(channel, 'chapter4-example')
exchange.declare()
channel.enable_publisher_confirms()
message = rabbitpy.Message(channel,
'This is an important message',
{'content_type': 'text/plain',
'message_type': 'very important'})
if message.publish('chapter4-example', 'important.message'):
print('The message was confirmed')
rabbitpy中没有使用回调的方法,而是在确认收到之前会一直阻塞。
备用交换器
处理无法路由的消息。当不可路由的消息发布到已经定义了备用交换器的交换器中时,它将被路由到备用交换器。
示例程序:备用交换器
import rabbitpy
with rabbitpy.Connection() as connection:
with connection.channel() as channel:
my_ae = rabbitpy.Exchange(channel, 'my-ae',
exchange_type='fanout')
my_ae.declare()
args = {'alternate-exchange': my_ae.name}
exchange = rabbitpy.Exchange(channel,
'graphite',
exchange_type='topic',
arguments=args)
exchange.declare()
queue = rabbitpy.Queue(channel, 'unroutable-messages')
queue.declare()
if queue.bind(my_ae, '#'):
print('Queue bound to alternate-exchange')
基于事务的批量处理
确保消息投递成功。
import rabbitpy
with rabbitpy.Connection() as connection:
with connection.channel() as channel:
tx = rabbitpy.Tx(channel)
tx.select()
message = rabbitpy.Message(channel,
'This is an important message',
{'content_type': 'text/plain',
'delivery_mode': 2,
'message_type': 'important'})
message.publish('chapter4-example', 'important.message')
try:
if tx.commit():
print('Transaction committed')
except rabbitpy.exceptions.NoActiveTransactionError:
print('Tried to commit without active transaction')
由于错误无法路由消息时,将及时返回Basic.Return。发布者应发送TX.RollbackRPC请求并等待来自代理服务器的TX.Rollback相应,然后继续后续的工作。
HA队列
允许队列在多个服务器拥有冗余副本。
发布者发送消息到集群中的任何节点。RabbitMQ节点同步队列中消息的状态。发布的消息被放入队列,并存储在每台服务器上。
示例代码:HA队列声明
import rabbitpy
connection = rabbitpy.Connection()
try:
with connection.channel() as channel:
queue = rabbitpy.Queue(channel,
'my-ha-queue',
arguments={'x-ha-policy': 'all'})
if queue.declare():
print('Queue declared')
except rabbitpy.exceptions.RemoteClosedChannelException as error:
print('Queue declare failed: %s' % error)
示例代码:HA队列指定节点
import rabbitpy
connection = rabbitpy.Connection()
try:
with connection.channel() as channel:
arguments = {'x-ha-policy': 'nodes',
'x-ha-nodes': ['rabbit@node1',
'rabbit@node2',
'rabbit@node3']}
queue = rabbitpy.Queue(channel,
'my-2nd-ha-queue',
arguments=arguments)
if queue.declare():
print('Queue declared')
except rabbitpy.exceptions.RemoteClosedChannelException as error:
print('Queue declare failed: %s' % error)
消息持久化
delivery-mode=1,保存到内存;delivery-mode=2,保存到磁盘。服务器重启后,消息仍在队列中(队列必须声明为durable)。
如果rabbitmq经常等待操作系统响应读写请求,消息吞吐量将大大降低。
rabbitmq回推
发布者发布消息太快,RabbitMQ发送Channel.Flow RPC方法,阻塞发布者。发布者不能发送消息直到收到另一条Channel.Flow命令。
示例代码:检测连接状态
import rabbitpy
connection = rabbitpy.Connection()
print('Channel is Blocked? %s' % connection.blocked)
posted on 2020-10-13 21:47 hainingwyx 阅读(160) 评论(0) 编辑 收藏 举报