<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div> Took a while to get back to this. Happened so far: I gave up on zeromq, since the sub client kept crashing every time. Rabbitmq/stomp examples worked over a public server with a guest user, so I set up a server of my own. Once a basic pub-sub messaging in place, I created a simple message handler, that can recognize racket expressions and evaluate them (or do what ever). I even got it to evaluate liitin expressions. I got really excited, since having thought about it a bit further, not only is it suitable for device or other service control, but one could even make it a generic way for messaging between liitin accounts. For example, since each liitin account has a protected namespace, this kind of messaging allows creating "pull-requests" to update liitin objects across namespaces. You can accept them either manually or automatically based on your message handler. But I'm only starting to get familiar with rabbitmq and stomp, and to achieve what I want, I need a full control of both client and server sides. I planning to use racket also for creating the needed server-side shell commands dynamically, and mix them with higher-level functionality. Now I'm stuck. As mentioned earlier, everything works nicely with the built-in "guest" user, but once trying to create a "messaging channel" for a new liitin account (user/device/service) I'm obviously missing something. I use the following shell commands on the server side: rabbitmqctl add_vhost /device5 rabbitmqctl add_user user device5 password rabbitmqctl set_permissions -p /device5 ".*" ".*" ".*" And based on the racket/stomp pub example, <a href="http://planet.racket-lang.org/package-source/tonyg/stomp.plt/2/1/planet-docs/manual/index.html" x-apple-data-detectors="true" x-apple-data-detectors-type="link" x-apple-data-detectors-result="0">http://planet.racket-lang.org/package-source/tonyg/stomp.plt/2/1/planet-docs/manual/index.html</a> chapter 2.2 ... I send a message (no error). But based on the sub example (chapter 2.3), when I try to receive it, a plain "error" is signaled highlighting "stomp-next-message s "my-subscription" I'm propably missing a level or two on top of the vhost, or the subscription definition on the client side is somehow invalid. Any idea what I'm doing wrong? Br, jukka <blockquote type="cite">On 18.11.2013, at 20.42, Jukka Tuominen <<a href="mailto:jukka.tuominen@finndesign.fi" x-apple-data-detectors="true" x-apple-data-detectors-type="link" x-apple-data-detectors-result="4">jukka.tuominen@finndesign.fi</a>></blockquote>wrote: <blockquote type="cite"> </blockquote><blockquote type="cite">Hi Tony, </blockquote><blockquote type="cite"> </blockquote><blockquote type="cite"> </blockquote><blockquote type="cite"><blockquote type="cite">On 18.11.2013, at 16.13, Tony Garnock-Jones <<a href="mailto:tonyg@ccs.neu.edu" x-apple-data-detectors="true" x-apple-data-detectors-type="link" x-apple-data-detectors-result="6">tonyg@ccs.neu.edu</a>> wrote: </blockquote></blockquote><blockquote type="cite"><blockquote type="cite"> </blockquote></blockquote><blockquote type="cite"><blockquote type="cite">Hi Jukka, </blockquote></blockquote><blockquote type="cite"><blockquote type="cite"> </blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">On 2013-11-16 1:48 AM, Jukka Tuominen wrote: </blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">I was happy to hear about the package Marketplace [...], and I wonder </blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">if it could be used as a starting point?</blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"> </blockquote></blockquote><blockquote type="cite"><blockquote type="cite">Marketplace is still in flux. It could be useful as a way of forcing </blockquote></blockquote><blockquote type="cite"><blockquote type="cite">yourself to really *commit* to the idea of pub/sub-all-the-way-down ;-) </blockquote></blockquote><blockquote type="cite"><blockquote type="cite">but it might not be the best choice to build a production system on top </blockquote></blockquote><blockquote type="cite"><blockquote type="cite">just yet.</blockquote></blockquote><blockquote type="cite"> </blockquote><blockquote type="cite">Ok, good to know. As far as I can see, an off-the-shelf pub-sub system</blockquote>is propably enough for this purpose, and I'm not really planning on studying the pub-sub itself, but rather how to utilize it. <blockquote type="cite">I'd very much like to choose a system that is robust and can scale up,</blockquote>eventhough at this phase and in my hands, a p-o-c is the level that I'm targetting. <blockquote type="cite"><blockquote type="cite"> </blockquote></blockquote><blockquote type="cite"><blockquote type="cite">Marketplace was inspired by, and can be seen as a generalization of, </blockquote></blockquote><blockquote type="cite"><blockquote type="cite">ordinary pub/sub and queueing middleware like STOMP servers and RabbitMQ. </blockquote></blockquote><blockquote type="cite"><blockquote type="cite"> </blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">Another option is to choose some generic open-source pub-sub server, </blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">and make the user and device ends speak racket.</blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"> </blockquote></blockquote><blockquote type="cite"><blockquote type="cite">I suggest looking into the STOMP protocol support for RabbitMQ. I wrote </blockquote></blockquote><blockquote type="cite"><blockquote type="cite">a Racket STOMP client [1, 2] a while back that might do what you need.</blockquote></blockquote><blockquote type="cite"> </blockquote><blockquote type="cite">I'll look into those, thanks! </blockquote><blockquote type="cite"> </blockquote><blockquote type="cite"><blockquote type="cite">One of the things I've been meaning to do is write a simple *server* in </blockquote></blockquote><blockquote type="cite"><blockquote type="cite">Racket to go along with it, but for now using RabbitMQ or similar is </blockquote></blockquote><blockquote type="cite"><blockquote type="cite">probably a good bet.</blockquote></blockquote><blockquote type="cite"> </blockquote><blockquote type="cite">I'm hoping to have the environment ready to use for a basic user, and</blockquote>familiar for a developer as if dealing with any software objects. I have a clear picture in my mind... <blockquote type="cite"><blockquote type="cite"> </blockquote></blockquote><blockquote type="cite"><blockquote type="cite">(Regarding Arduino: RabbitMQ also has experimental UDP support [3] which </blockquote></blockquote><blockquote type="cite"><blockquote type="cite">might be of interest in this connection.)</blockquote></blockquote><blockquote type="cite"> </blockquote><blockquote type="cite">Sounds very good! So far, I try to restrain myself from moving to even</blockquote>more foreign terrain until I get the architecture easy enough for me and others to use. <blockquote type="cite"> </blockquote><blockquote type="cite">Br, jukka </blockquote><blockquote type="cite"> </blockquote><blockquote type="cite"> </blockquote><blockquote type="cite"><blockquote type="cite"> </blockquote></blockquote><blockquote type="cite"><blockquote type="cite">Regards, </blockquote></blockquote><blockquote type="cite"><blockquote type="cite">Tony </blockquote></blockquote><blockquote type="cite"><blockquote type="cite"> </blockquote></blockquote><blockquote type="cite"><blockquote type="cite">[1] <a href="http://planet.racket-lang.org/display.ss?package=stomp.plt&owner=tonyg" x-apple-data-detectors="true" x-apple-data-detectors-type="link" x-apple-data-detectors-result="8">http://planet.racket-lang.org/display.ss?package=stomp.plt&owner=tonyg</a> </blockquote></blockquote><blockquote type="cite"><blockquote type="cite">[2]<a href="https://github.com/tonyg/racket-stomp" x-apple-data-detectors="true" x-apple-data-detectors-type="link" x-apple-data-detectors-result="9">https://github.com/tonyg/racket-stomp</a> </blockquote></blockquote><blockquote type="cite"><blockquote type="cite">[3] <a href="https://github.com/tonyg/udp-exchange" x-apple-data-detectors="true" x-apple-data-detectors-type="link" x-apple-data-detectors-result="10">https://github.com/tonyg/udp-exchange</a></blockquote></blockquote><blockquote type="cite"> </blockquote><blockquote type="cite">____________________ </blockquote><blockquote type="cite">Racket Users list: </blockquote><blockquote type="cite"><a href="http://lists.racket-lang.org/users" x-apple-data-detectors="true" x-apple-data-detectors-type="link" x-apple-data-detectors-result="11" style="-webkit-text-size-adjust: auto; background-color: rgba(255, 255, 255, 0);">http://lists.racket-lang.org/users</a></blockquote> </div></body></html>