I cant help much on the python or cpp bits, or rabbitmq, but on the general 'send string' subject I think it is probably that you'll want to use unicode strings to get the client sending AMQP strings on the wire. The AMQP strings are utf8 encoded, wheres I believe python str type is often used for raw bytes, and the client has no way of knowing whether thats the case or not and so sends an AMQP binary value containing the bytes instead.
Robbie On 30 March 2017 at 09:52, Daniel Pocock <[email protected]> wrote: > > > Hi all, > > I've recently been working on some projects involving qpid-proton (C++ > and Python variants) and rabbitmq servers and there are a couple of > issues I've observed, could anybody comment on these? > > Environment > ----------- > > I'm running Debian jessie / stable with the qpid-proton packages from > the Debian backports repository[1], currently version 0.14.0-4~bpo8+1 > and rabbitmq[2] version 3.3.5-1.1+deb8u1 > > When I install the rabbitmq-server package on a host, I run these > commands to enable AMQP 1.0 support: > > apt-get install rabbitmq-server > rabbitmq-plugins enable rabbitmq_amqp1_0 > systemctl restart rabbitmq-server > > > I've also tried installing a config file /etc/rabbitmq/rabbitmq.config > although if I understand correctly, it is not needed and in fact the > package doesn't install it there by default. > > > Sending to RabbitMQ with qpid-proton python > ------------------------------------------- > > I started with the simple_send.py[3] example and trimmed it down to send > a single string and then stop: > > def on_sendable(self, event): > if self.msg_body is not None: > print("on_sendable !") > print ("sending : %s" % (self.msg_body,)) > msg = Message(body=self.msg_body) > event.sender.send(msg) > self.msg_body = None > > I found that the connection to RabbitMQ would be dropped and an error > would appear in the RabbitMQ log. I tried changing the body type to a > dict containing a string, e.g. {'my_body':'foo'} and then it would > successfully pass the message to RabbitMQ but then the receiver would > complain that it was a map and not a string. > > I found that the problem could be fixed by adding "inferred=True" to the > Message constructor: > > msg = Message(body=self.msg_body, inferred=True) > > Below is a complete example of the error from the RabbitMQ log when > inferred=True is not present, the body in this case was the string "foo" > > > Receiving from RabbitMQ with qpid-proton C++ > -------------------------------------------- > > I looked at the receive example simple_recv.cpp[4] and other examples > and noticed code like this being used to access the message body as > std::string: > > proton::get<std::string>(m.body()) > > However, that didn't work for me, it threw a conversion_error exception > "unexpected type, want: string got: binary" complaining that the body > was binary. I had to use something like this to convert my message body > to a std::string: > > proton::binary __b = proton::get<proton::binary>(m.body()); > std::string _s = (std::string)__b; > > If I send a string from Python, should it appear as binary in the > receiver? What is the suggested way to write a receiver that can handle > any arbitrary message that started as a string and may arrive in some > other format, especially if the message broker or client is changed at > some arbitrary time in the future? > > I also observed similar issues receiving messages that had been sent > into RabbitMQ by Kamailio's kazoo module[5], it is linked with the > librabbitmq client library. > > Regards, > > Daniel > > > > > > 1. https://packages.qa.debian.org/q/qpid-proton.html > 2. https://packages.qa.debian.org/r/rabbitmq-server.html > 3. > https://qpid.apache.org/releases/qpid-proton-0.17.0/proton/python/examples/simple_send.py.html > 4. > https://qpid.apache.org/releases/qpid-proton-0.17.0/proton/cpp/examples/simple_recv.cpp.html > 5. http://www.kamailio.org/docs/modules/4.4.x/modules/kazoo.html > > > Error from RabbitMQ log: > > =INFO REPORT==== > accepting AMQP connection <0.891.0> (127.0.0.1:48410 -> 127.0.0.1:5672) > > =ERROR REPORT==== > ** Generic server <0.897.0> terminating > ** Last message in was {'$gen_cast', > {frame, > {{'v1_0.transfer', > {uint,0}, > {uint,0}, > {binary,<<"1">>}, > {uint,0}, > > false,false,undefined,undefined,undefined, > undefined,undefined}, > > <<0,83,112,208,0,0,0,11,0,0,0,5,66,80,4,64,66, > 82,0,0,83,115,208,0,0,0,34,0,0,0,13,64,64, > > 64,64,64,64,64,64,131,0,0,0,0,0,0,0,0,131,0, > > 0,0,0,0,0,0,0,64,82,0,64,0,83,119,160,3,102, > 111,111>>}, > <0.891.0>}} > ** When Server state == {state,<0.900.0>,<0.906.0>,unlimited,<0.891.0>, > <0.896.0>, > {[],[]}, > > {session,0,2147483647,2147483647,0,65535,65535,0, > 65535,65535,1,0, > {0,nil}, > {0,nil}}} > ** Reason for termination == > ** {function_clause, > [{rabbit_amqp1_0_framing,fill_from_binary, > [{'v1_0.amqp_value',undefined},<<"foo">>], > [{file,"rabbitmq-amqp1.0/src/rabbit_amqp1_0_framing.erl"}, > {line,56}]}, > {rabbit_amqp1_0_message,decode_section,1, > [{file,"rabbitmq-amqp1.0/src/rabbit_amqp1_0_message.erl"}, > {line,122}]}, > {rabbit_amqp1_0_message,assemble,4, > [{file,"rabbitmq-amqp1.0/src/rabbit_amqp1_0_message.erl"}, > {line,62}]}, > {rabbit_amqp1_0_message,assemble,1, > [{file,"rabbitmq-amqp1.0/src/rabbit_amqp1_0_message.erl"}, > {line,30}]}, > {rabbit_amqp1_0_incoming_link,transfer,4, > [{file,"rabbitmq-amqp1.0/src/rabbit_amqp1_0_incoming_link.erl"}, > {line,148}]}, > {rabbit_amqp1_0_session_process,handle_control,2, > > [{file,"rabbitmq-amqp1.0/src/rabbit_amqp1_0_session_process.erl"}, > {line,214}]}, > {rabbit_amqp1_0_session_process,handle_cast,2, > > [{file,"rabbitmq-amqp1.0/src/rabbit_amqp1_0_session_process.erl"}, > {line,134}]}, > {gen_server2,handle_msg,2, > [{file,"src/gen_server2.erl"},{line,1022}]}]} > > =ERROR REPORT==== > closing AMQP connection <0.891.0> (127.0.0.1:48410 -> 127.0.0.1:5672): > {handshake_error,running,<0.897.0>, > {{symbol,"amqp:internal-error"}, > "Session error: ~p~n~p~n", > [function_clause, > [{rabbit_amqp1_0_framing,fill_from_binary, > [{'v1_0.amqp_value',undefined},<<"foo">>], > [{file,"rabbitmq-amqp1.0/src/rabbit_amqp1_0_framing.erl"}, > {line,56}]}, > {rabbit_amqp1_0_message,decode_section,1, > [{file,"rabbitmq-amqp1.0/src/rabbit_amqp1_0_message.erl"}, > {line,122}]}, > {rabbit_amqp1_0_message,assemble,4, > [{file,"rabbitmq-amqp1.0/src/rabbit_amqp1_0_message.erl"}, > {line,62}]}, > {rabbit_amqp1_0_message,assemble,1, > [{file,"rabbitmq-amqp1.0/src/rabbit_amqp1_0_message.erl"}, > {line,30}]}, > {rabbit_amqp1_0_incoming_link,transfer,4, > [{file,"rabbitmq-amqp1.0/src/rabbit_amqp1_0_incoming_link.erl"}, > {line,148}]}, > {rabbit_amqp1_0_session_process,handle_control,2, > > [{file,"rabbitmq-amqp1.0/src/rabbit_amqp1_0_session_process.erl"}, > {line,214}]}, > {rabbit_amqp1_0_session_process,handle_cast,2, > > [{file,"rabbitmq-amqp1.0/src/rabbit_amqp1_0_session_process.erl"}, > {line,134}]}, > {gen_server2,handle_msg,2, > [{file,"src/gen_server2.erl"},{line,1022}]}]]}} > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [email protected] > For additional commands, e-mail: [email protected] > --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
