Openstack 的 RPC使用。

大家都已经很熟悉了RPC了。 比如说nfs就是采用的RPC通信。

尤其SUN RPC 已经成为了C语言开发的经典一种进程间调用机制。

 

openstack 的RPC 机制， 是基于AMQP 活着其他高级消息协议而实现得远程调用机制。

 

而oslo.messaging 在这些消息协议基础上实现了很nice的接口。developer 可以很方便的调用。 

oslo messaging wiki 

 

参考 openstack的developer手册，实现一个RPC 的server端。

http://docs.openstack.org/developer/oslo.messaging/server.html

call_server.py

 1 from oslo_config import cfg

 2 import oslo_messaging

 3 

 4 class ServerControlEndpoint(object):

 5 

 6     target = oslo_messaging.Target(namespace='control',

 7                                    version='2.0')

 8 

 9     def __init__(self, server):

10         print "this is ServerControlEndpoint"

11         self.server = server

12 

13     def stop(self, ctx):

14         if server:

15             self.server.stop()

16 

17 class TestEndpoint(object):

18 

19     def test(self, ctx, arg):

20         print "this is TestEndpoint test server"

21         return arg

22 

23 transport = oslo_messaging.get_transport(cfg.CONF)

24 

25 print "cfg.CONF: ", cfg.CONF

26 print "transport: ", transport

27 target = oslo_messaging.Target(topic='test', server='server1')

28 print "target: ", target

29 endpoints = [

30     ServerControlEndpoint(None),

31     TestEndpoint(),

32 ]

33 server = oslo_messaging.get_rpc_server(transport, target, endpoints,

34                                        executor='blocking')

35 print "server: ", server

36 server.start()

37 server.wait()

View Code

 执行, 等待client 调用。

$ python call_server.py

 

实现一个 RPC的client端

http://docs.openstack.org/developer/oslo.messaging/rpcclient.html

call_client.py

1 from oslo_config import cfg

2 import oslo_messaging as messaging

3 

4 transport = messaging.get_transport(cfg.CONF)

5 target = messaging.Target(topic='test') #, version='2.0')

6 client =  messaging.RPCClient(transport, target)

7 print client.call({}, 'test', arg="hello")

8 cctxt = client.prepare() # version='2.0')

9 print cctxt.call({}, 'test', arg="hello")

View Code

 执行，可以得到 server段的返回结果。 

$ python call_server.py

 

notifier.py

http://docs.openstack.org/developer/oslo.messaging/notifier.html 

 

notification_listener.py

http://docs.openstack.org/developer/oslo.messaging/notification_listener.html