ZeroMq IRC Log

Sunday September 4, 2011

[Time] Name	Message
[00:05] errordeveloper	hi
[00:05] errordeveloper	I would like to hear an opinion on this
[00:05] errordeveloper	interesting article btw http://www.imatix.com/articles:whats-wrong-with-amqp
[00:23] mikko	errordeveloper: opinion on what?
[00:44] errordeveloper	well they are critisizing AMQP in general ...
[00:45] errordeveloper	I wonder whether it really is so bad ?
[01:01] mikko	i don't understand AMQP well enough to answer that really
[01:37] strich	Afternoon
[01:39] strich	Quick question - I need to get the uuid out of a message, store it, and pass it back when I form a reply. Its not working, and I think its because I'm probably serializing it to char or string, and then back again in a bad format. Any tips/guides on how to do this in C++?
[01:39] strich	That is, the reply sends out, and the client doesn't get it. So I can only assume the uuid I'm replying to is wrong
[01:40] strich	I'm using ROUTER (server) and DEALER (client)
[01:41] errordeveloper	mikko: nevermind, I was mislead
[01:41] errordeveloper	someone told me that zmq is an implementation of amqp
[01:41] errordeveloper	and it's not :)
[01:42] errordeveloper	hm ... so there is no xml involved in zmq, right?
[01:43] strich	errordeveloper - As far as I know, no. But, you could still compose and serialize a XML structure into the zmq messages if you wanted to
[01:43] strich	The way I see it, zmq is your mail postage company. XML or google's protobuf or any number of other message structures are the contents of the letter itself.
[01:46] errordeveloper	sure
[01:46] errordeveloper	i'm all for zmq now :)
[01:47] strich	Aye i'm fairly new to it as well, but I'm loving it thus far
[01:47] strich	Even if the C++ part of it isn't that well done
[01:47] errordeveloper	though ... what about if my messages are time-sensetive ... i.e. they have to arrive in the same order ...
[01:48] errordeveloper	??
[01:48] strich	zmq takes care of that for you
[01:48] errordeveloper	kewl!!!
[01:48] errordeveloper	:)))
[01:48] strich	All you do as the developer is send the stuff and they'll arrive
[01:49] errordeveloper	I mean, I would like to use it for networked music perfomrance applications
[01:50] strich	music performance?
[01:50] strich	Like a concert?
[01:51] strich	You could stream music to subscribers using the PUBLISHER -> SUBSCRIBER concept, which multicasts out data (music) to clients
[02:07] mikko	strich: how are you serialising to char * ?
[02:08] strich	I've just rewritten my receive method, and it is currently untested with:
[02:08] strich	uuid.assign(static_cast<char*>(zmsg.data()));
[02:08] strich	uuid is a std::string
[02:09] mikko	i think you need to give size as well
[02:09] mikko	otherwise it will cut on first null char
[02:09] strich	You are correct. I didn't know if that would be ok or not
[02:09] mikko	std::string uuid (static_cast<char*>(zmsg.data()), zmsg.size());
[02:10] strich	Yep just added that. I think you just saved me some debugging Fun mikko, cheers :)
[02:11] mikko	another option is to use std::vector<unsigned char>
[02:11] strich	Any reason to, specifically?
[02:11] strich	My next question will be how I would drop my uuid string back into a reply. It seems most examples use memcpy
[02:12] mikko	it will work as expected as a string but conceptually when it's a vector you dont mishandle it as a string
[02:12] mikko	and expect .c_str() to be normal null terminated character array
[02:12] mikko	zmq::message_t reply(uuid.size()); memcpy (...
[02:13] strich	btw, do you have to supply .size for any message initialization? It seems theres a constructor that allows you to omit it
[02:14] mikko	yes, if you copy data to it
[02:14] mikko	the overloaded constructor with size will allocate storage for the message
[02:14] mikko	zmq::message_t msg; can be used when receiving
[02:14] mikko	where the engine calls init
[02:14] strich	ok np, I think I'm fucking it up there to. I'll rewrite my send method
[02:15] mikko	when you memcpy there has to be storage where to copy to
[02:18] strich	zmq::message_t zmsg(uuid.size()); memcpy(zmsg.data(), uuid.data(), uuid.size());
[02:26] strich	zmq::message_t zmsg(uuid.size()); memcpy(zmsg.data(), uuid.c_str(), uuid.size());
[02:26] strich	mikko - Which should I use of the above?
[02:27] mikko	i tend to use .c_str()
[02:27] mikko	just out of habbit
[02:27] mikko	i don't think there should be difference
[02:28] strich	ok np
[02:29] mikko	what is the issue?
[02:30] strich	Oh nothing, still just refactoring my methods. I just saw it in two examples and wanted to know if there was a diff
[06:40] Nitin	Hello everyone.. I have a question... I need to make a REST call to amazon web services.. Can I use zmq for that??..
[07:03] strich	mmm I don't think so Nitin
[07:04] strich	zmq requires zmq at both end-points
[07:04] strich	You'll need to write an interface between Amazon's API and an internal zmq network of your own
[07:21] Nitin	hmmm... ok.. so making a basic HTTP request is also not possible...
[07:54] sustrik	there's raw TCP under 0MQ, not HTTP
[07:54] strich	Even so, you wouldn't be able to communicate with a TCP socket unless its also under the control of zmq
[08:28] CIA-32	libzmq: 03Mikko Koppanen 07master * r9d0e122 10/ (acinclude.m4 configure.in): Added option to choose internal polling system ...
[11:10] errordeveloper	does anyone here know of PTP (IEEE 1588) ?
[11:21] strich	PTP?
[11:41] errordeveloper	strich: do you what it is ?
[11:41] errordeveloper	I mean, I do .. just wonder if PTP could be glued with 0MQ
[11:42] errordeveloper	I mean, if it could be done in somewhat semi-transparent fashion ....
[11:42] errordeveloper	I just posted this quesion to the list btw
[11:42] errordeveloper	my first post on 0mq
[11:43] errordeveloper	:()
[11:43] strich	You'd have to wrap it up at both end points I would think
[11:43] errordeveloper	strich: It would quite an interesting thing to do, wouldn't it ?
[11:43] strich	zmq is a carrier, using the TCP protocol
[11:43] strich	ANy other protocols would have to be wrapped out at both ends
[11:43] strich	*up
[11:44] errordeveloper	I suppose I need to read on 0mq architecture
[11:45] errordeveloper	hm .. I looked on github and there seem to be 3 release branches of 0mq
[11:45] errordeveloper	(at least)
[11:45] errordeveloper	is the protocol slightly different in all those version ?
[11:48] mikko	errordeveloper: yes, there are some modifications
[11:48] mikko	2.1 is not compatible with 3.0
[11:52] errordeveloper	ok .. but the API haven't changed, right ?
[11:53] mikko	errordeveloper: minor changes between 2.1 and 2.2
[11:53] mikko	ermm
[11:53] mikko	2.1 and 3.0
[11:53] errordeveloper	ok
[11:53] mikko	major version can break api
[11:53] errordeveloper	gentoo comes with 2.1 as I can see
[11:53] errordeveloper	I might stick to 2.1 for now then
[11:55] mikko	you usually only need 3.0 for subscription forwarding
[11:55] errordeveloper	ok
[11:56] mikko	pre 3.0 topic matching was done on client
[11:56] mikko	which causes extra network traffic
[12:03] michaelmi	Hi all ..
[12:03] michaelmi	This is my first zmq day, so please be patient ;-)
[12:04] michaelmi	I have set up a simple request-reply scenario with a client and a server application in C
[12:06] michaelmi	client: http://pastebin.com/nELBZ7Mf
[12:07] michaelmi	server: http://pastebin.com/t5M3dvak
[12:08] michaelmi	problem is: sometimes, the client seems to terminate before any data has been sent to the server
[12:08] michaelmi	a sleep before the exit seems to avoid this beavior or at least make it less probable
[12:09] michaelmi	is this intended? shouldn't zmq_close block until all data is delivered?
[12:09] mikko	michaelmi: that doesn't look correct
[12:10] michaelmi	mikko: I hoped so :-)
[12:10] mikko	char data[] = "hello world xxx"; sprintf (data, "hallo welt %d", i);
[12:10] mikko	doesn't the data get put to the text section?
[12:10] michaelmi	oh ..well .. yes . I think so
[12:11] michaelmi	or .. no .. mom
[12:11] michaelmi	I initialize an array on the stack .. it's not "char *data = "hello world";
[12:12] mikko	true
[12:13] mikko	you shouldnt send terminating null
[12:13] mikko	usually you send just the bytes
[12:13] mikko	and terminate on other side if needed
[12:13] michaelmi	ok
[12:13] mikko	what version of zeromq is this?
[12:14] michaelmi	libzmq-dev_2.0.10
[12:14] mikko	that explains
[12:14] mikko	if you upgrade it should be fine
[12:15] mikko	there is no linger option in 2.0.x
[12:15] mikko	linger sockopt behaves like SO_LINGER
[12:15] michaelmi	ah .. thx .. gonna check this out
[12:16] mikko	that code you have there is not deterministic with zeromq 2.0
[12:16] mikko	as the sleep might or might not be enough to send the message fully
[12:16] michaelmi	true .. I just wanted to get an indication that the exit() is part of the problem
[12:17] michaelmi	tcpdump seemed to point in that direction
[14:00] michaelmi	@mikko: just wanted to give feedback that with 2.1 the problem has vanished
[14:01] michaelmi	thx!! & bye
[15:51] strich	I've got a ROUTER/DEALER setup going nicely, but I'd like to cleanly shutdown and delete any associated content once a peer (DEALER) leaves after x seconds. How can I tell if a peer is no longer connected?
[16:02] strich	No one?
[17:06] count	strich: build another req/rep pipeline that heartbeats
[17:06] count	and poll
[17:06] count	?
[17:07] count	let me not use 'pipeline' there
[17:07] count	a req/rep connection
[17:07] count	:)
[17:07] strich	So 2 connections per peer?
[17:07] count	I guess, yes
[17:07] strich	That sounds a bit excessive
[17:08] strich	Can't I do it with router/dealer?
[17:09] count	I guess you could just interleave a heartbeat between each work message on your router/dealer
[17:10] strich	That is my plan currently
[17:10] strich	I was hoping zmq had a bit more in-built intelligence for this stuff

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Sunday September 4, 2011