问题
I am new in Python/ ZeroMQ, so show forbearance if it is an easy question.
I try to run some examples, but it does not work really good.
Here is the hwserver/hwclient example of the ZeroMQ-Guide:
SERVER
# Hello World server in Python
# Binds REP socket to tcp://*:5555
# Expects b"Hello" from client, replies with b"World"
#
import time
import zmq
context = zmq.Context()
socket = context.socket(zmq.REP)
socket.bind("tcp://*:5555")
while True:
message = socket.recv() # Wait for next request from client
print("Received request: %s" % message)
time.sleep(1) # Do some 'work'
print( "teeest" )
socket.send(b"World") # Send reply back to client
CLIENT
# Hello World client in Python
# Connects REQ socket to tcp://localhost:5555
# Sends "Hello" to server, expects "World" back
#
import zmq
context = zmq.Context()
print("Connecting to hello world server…") # Socket to talk to server
socket = context.socket(zmq.REQ)
socket.connect("tcp://localhost:5555")
for request in range(10): # Do 10 requests,
# # waiting each time for a response
print("Sending request %s …" % request)
socket.send(b"Hello")
message = socket.recv() # Get the reply.
print("Received reply %s [ %s ]" % (request, message))
And I am getting this output:
Connecting to hello world server…
Sending request 0 …
Received reply 0 [ b'World' ]
Sending request 1 …
Received reply 1 [ b'World' ]
Sending request 2 …
Received reply 2 [ b'World' ]
Sending request 3 …
Received reply 3 [ b'World' ]
Sending request 4 …
Received reply 4 [ b'World' ]
Sending request 5 …
Received reply 5 [ b'World' ]
Sending request 6 …
Received reply 6 [ b'World' ]
Sending request 7 …
Received reply 7 [ b'World' ]
Sending request 8 …
Received reply 8 [ b'World' ]
Sending request 9 …
Received reply 9 [ b'World' ]
Process finished with exit code 0
Could somebody tell me why I dont get the prints of the server like "Received request" and "teeeest"?
Thank you!
回答1:
why I don't get the prints of the server like "Received request" and "teeeest"?
Well,
you actually do get 'em,
but because you do not look into the right ( both ) place(s) ( if reading also from Server-side PyCharm / Terminal window, you will see 'em -- that's a good news ).
Welcome to the distributed-computing. Having two "roles" dancing together ( as coded in the REQ/REP or other of the ZeroMQ Scalable Formal Communication Pattern Archetypes ), you have to check both sides of the distributed-dancing to see the whole picture.
Watching just one side leaves you without the full story.
To make this more easily visible, let's modify the code a bit:
SERVER MOD :
import time
import zmq
context = zmq.Context()
socket = context.socket( zmq.REP ); socket.bind( "tcp://*:5555" )
while True:
message = socket.recv() # Wait for next request from client
print( "TERMINAL[1]: SERVER has received request: %s" % message )
time.sleep(1) # Do some 'work'
print( "TERMINAL[1]: SERVER puts teeest......................." )
socket.send( b"World" ) # Send reply back to client
CLIENT MOD :
import zmq
context = zmq.Context()
print( "TERMINAL[2] CLIENT says Connecting to hello world server…" )
socket = context.socket( zmq.REQ ) # Socket to talk to server
socket.connect( "tcp://localhost:5555" )
for request in range( 10 ): # Do 10 requests,
# # waiting each time for a response
print( "TERMINAL[2] CLIENT Sending request %s …" % request )
socket.send( b"Hello" )
message = socket.recv() # Get the reply.
print( "TERMINAL[2] CLIENT Received reply %s [ %s ]" % ( request, message ) )
And this output you already "know":
TERMINAL[2] CLIENT says Connecting to hello world server…
TERMINAL[2] CLIENT Sending request 0 …
TERMINAL[2] CLIENT Received reply 0 [ b'World' ]
TERMINAL[2] CLIENT Sending request 1 …
TERMINAL[2] CLIENT Received reply 1 [ b'World' ]
TERMINAL[2] CLIENT Sending request 2 …
TERMINAL[2] CLIENT Received reply 2 [ b'World' ]
TERMINAL[2] CLIENT Sending request 3 …
TERMINAL[2] CLIENT Received reply 3 [ b'World' ]
TERMINAL[2] CLIENT Sending request 4 …
TERMINAL[2] CLIENT Received reply 4 [ b'World' ]
TERMINAL[2] CLIENT Sending request 5 …
TERMINAL[2] CLIENT Received reply 5 [ b'World' ]
TERMINAL[2] CLIENT Sending request 6 …
TERMINAL[2] CLIENT Received reply 6 [ b'World' ]
TERMINAL[2] CLIENT Sending request 7 …
TERMINAL[2] CLIENT Received reply 7 [ b'World' ]
TERMINAL[2] CLIENT Sending request 8 …
TERMINAL[2] CLIENT Received reply 8 [ b'World' ]
TERMINAL[2] CLIENT Sending request 9 …
TERMINAL[2] CLIENT Received reply 9 [ b'World' ]
So,
next just look into the other window / terminal,
where you will see all the intended SERVER-side print()-s:
TERMINAL[1]: SERVER has received request: b'Hello'
TERMINAL[1]: SERVER puts teeest.......................
TERMINAL[1]: SERVER has received request: b'Hello'
TERMINAL[1]: SERVER puts teeest.......................
TERMINAL[1]: SERVER has received request: b'Hello'
TERMINAL[1]: SERVER puts teeest.......................
TERMINAL[1]: SERVER has received request: b'Hello'
TERMINAL[1]: SERVER puts teeest.......................
TERMINAL[1]: SERVER has received request: b'Hello'
TERMINAL[1]: SERVER puts teeest.......................
TERMINAL[1]: SERVER has received request: b'Hello'
TERMINAL[1]: SERVER puts teeest.......................
...
Interested in mastering ZeroMQ as fast as possible ?
May enjoy a further 5-seconds read
about the main conceptual differences in [ ZeroMQ hierarchy in less than a five seconds ] or other posts and discussions here.
回答2:
It is not the client who should print the teeest but the server, because the print( "teeest" ) is instructed to be executed in the server file.
Your output shows the client's output but not the server's one.
来源：https://stackoverflow.com/questions/50692413/why-a-zeromq-example-does-not-work