如何在Python中订阅NATS主题并不断接收消息？
如何在Python中订阅NATS主题并不断接收消息？
提问于 2020-09-11 19:41:49
我尝试了下面的例子(来自this页面)：
nc = NATS()
await nc.connect(servers=["nats://demo.nats.io:4222"])
future = asyncio.Future()
async def cb(msg):
nonlocal future
future.set_result(msg)
await nc.subscribe("updates", cb=cb)
await nc.publish("updates", b'All is Well')
await nc.flush()
# Wait for message to come in
msg = await asyncio.wait_for(future, 1)但这似乎只对接收一条消息有用。我如何订阅并继续接收消息？
我也见过the package example，但它似乎只是扮演对话双方的角色，然后退出。
回答 2
Stack Overflow用户
回答已采纳
发布于 2020-09-11 22:46:07
我不太了解python，但看起来您只是在等待一条消息和程序结束。您应该看看订阅者示例here。正如您所看到的，有一个循环将永远等待或等待SIGTERM信号。
Stack Overflow用户
发布于 2020-09-11 22:50:39
您还可以找到一个长时间运行的服务示例：https://github.com/nats-io/nats.py/blob/master/examples/service.py
import asyncio
from nats.aio.client import Client as NATS
async def run(loop):
nc = NATS()
async def disconnected_cb():
print("Got disconnected...")
async def reconnected_cb():
print("Got reconnected...")
await nc.connect("127.0.0.1",
reconnected_cb=reconnected_cb,
disconnected_cb=disconnected_cb,
max_reconnect_attempts=-1,
loop=loop)
async def help_request(msg):
subject = msg.subject
reply = msg.reply
data = msg.data.decode()
print("Received a message on '{subject} {reply}': {data}".format(
subject=subject, reply=reply, data=data))
await nc.publish(reply, b'I can help')
# Use queue named 'workers' for distributing requests
# among subscribers.
await nc.subscribe("help", "workers", help_request)
print("Listening for requests on 'help' subject...")
for i in range(1, 1000000):
await asyncio.sleep(1)
try:
response = await nc.request("help", b'hi')
print(response)
except Exception as e:
print("Error:", e)
if __name__ == '__main__':
loop = asyncio.get_event_loop()
loop.run_until_complete(run(loop))
loop.run_forever()
loop.close()页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/63846385
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