[zeromq-dev] Notes from a hackathon

[Doron Somech]

So the new sockets are in the github master, you can take a loot at the
test to see how to use the new routing id field:

https://github.com/zeromq/libzmq/blob/master/tests/test_client_server.cpp

Few of the reasons I didn't like multi frames:
* I tried in the past to make both zeromq and NetMQ thread safe, think of
sending from multiple threads or receiving from multiple threads. we cannot
do that with Multipart.
* There are a lot of good transport that already implement message framing
(UDP, WebSockets, SCTP and even HTTP), but because zeromq required it is
own framing it was not easy to add them.
* Multipart, router usage (routing id frame) and not being thread safe make
the learning curve of zeromq hard to beginners. Without three of them
zeromq become much simpler.
* At least with NetMQ single part message is much faster than multipart.
* New stacks, multipart is complicated to implement, with the new API it
will much more easier to implement new stacks (like JSMQ) or any native
stack.

Pieter I'm looking forward to see how you expose the routing id in the czmq
API.
I also like the czmq API for sending mutlipart messages (the picture
feature) so maybe we can use that to generate single frame which is also
compatible with zproto.

About the implementation, none of new sockets support any option now.
server behave like mandatory router, so when router is not reachable or
highwater mark is reached an error will be returned.

As ZMTP 3.1 is still in raw status, what do you think of removing the
multipart from it? maybe the 3.1 will only support the new socket types.

Anyway I really excited about this change.





On Mon, Feb 2, 2015 at 4:17 PM, Thomas Rodgers <rodgert at twrodgers.com>
wrote:

> What we really want IMO is per-peer metadata, and an API to get/set
>> this. Using messages is a hack.
>
>
> Currently working on that :)
>
> Having two layers that both
>> carry per-message data is... wrong IMO.
>
>
> Protocols supporting 'out of band' data aren't exactly uncommon.
>
> However the key thing is, what's the problem. Then we can discuss
>> solutions to that.
>
>
> I don't have an immediate use-case justifying it. I noted it, mostly
> because it has come up a few times since I started paying attention.
>
> On Mon, Feb 2, 2015 at 7:55 AM, Pieter Hintjens <ph at imatix.com> wrote:
>
>> > It seems to me that in order to remove multi-part messages and
>> introduce new
>> > socket types (e.g. SERVER/CLIENT) that would
>> > necessitate a revision of the wire protocol. If we are going to do
>> that, it
>> > might be worth considering per-message
>> > metadata -
>>
>> We'd have to be very clear about the problem that per-message metadata
>> is aiming for. There is an elegance to delivering blobs and nothing
>> more. Metadata can be added on top using zproto.
>>
>> What we really want IMO is per-peer metadata, and an API to get/set
>> this. Using messages is a hack. If we are sending/receiving data on a
>> per-message basis, that is the message. Having two layers that both
>> carry per-message data is... wrong IMO.
>>
>> However the key thing is, what's the problem. Then we can discuss
>> solutions to that.
>>
>> -Pieter
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>> zeromq-dev at lists.zeromq.org
>> http://lists.zeromq.org/mailman/listinfo/zeromq-dev
>>
>
>
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