The minimum to get up and going should be something like this:

1) In your component's install function:
from nox.coreapps.messenger.pymsgevent import JSONMsg_event
self.register_handler(JSONMsg_event.static_get_name(), myHandler)

2) Implement a handler:
def myHandler (e):
  import json
  print json.loads(e.jsonstring)
  e.reply(json.dumps({"msg":"Hello world"}))

3) Include jsonmessenger on the commandline or as a dependency

That may not be exactly correct -- it's adapted from a quick writeup I did in 
December about using the new Python support for the "regular" messenger (as 
opposed to the JSON messenger), which has not yet been pushed to the 
repository.  For reference, that post was:

(If using the new version of messenger that I linked to in that post, you 
remove the register_event_converter() call from step 1 and include 
pyjsonmessenger instead of jsonmessenger in step 3.)

Invoking the jsonmessenger component (on the commandline or by including it as 
a dependency in your app's meta.json) will create the server socket for you.

You absolutely do not have to use the class.  I'm removing it from 
that directory, because all it ever does is confuse people -- it really doesn't 
belong there. is a library for writing JSON messenger *clients* 
(external programs) in Python.  That may be useful to you, but you don't need 
it for the NOX side of things.

Hope that helps.

-- Murphy

On Jan 24, 2012, at 4:12 AM, Giorgio Mazza wrote:

> Thank you.
> I try to sum up the operations I need to perform, to see if I understood 
> correctly.
> Basically in my external application I have to set up a socket that sends 
> json messages and this would be quite simple.
> In my nox component, instead, I have to import the "JSONMsg_event" and, 
> within the "install()" instruction, to handle it with my specific method, 
> that, in my case, would only save these json messages into a dictionary, for 
> using them later, according to some conditions.
> Is that correct?
> A couple of things that I didn't understand:
> - I assume I also have to set up a server socket in my nox component, in 
> order to receive json messages and handle  JSONMsg_events. So, I think this 
> socket has to be already up and running when I handle the event. So, when do 
> I have to create it and how? Do I have to use channel class?
> - Second question, probably related to the first. I think to be pretty 
> confused about jsonmessenger: what are the jsonmessenger files I could look 
> into in order to understand fields and methods that I would need to use? Are 
> the and jsonmessenger.hh in nox/src/nox/coreapps/messenger? 
> And, if it is the case, how can I integrate them into a python component?
> Thanks again,
> Giorgio
> On 24/01/2012 12:28, Kyriakos Zarifis wrote:
>> Hi Giorgio,
>> yes, I think using jsonmessenger would be the best approach for this.
>> you need to implement a send/receive interface on the external application 
>> and in your nox component. For the external application, it's pretty 
>> straightforward - Connect to the jsonmessenger socket and send json strings. 
>> In your nox application you need to register for JSON messages, and handle 
>> them appropriately. 
>> The wiki explains the communication in a few steps (specifically for the 
>> GUI<->NOX, but it will be similar and simpler for any external app) here:
>> If you want to see a full example, the GUI and the monitoring component in 
>> destiny could be a place to look. I'm afraid it's much more complex than 
>> what you need, but the bits you need are in there if you dig in the code a 
>> bit.
>> On Tue, Jan 24, 2012 at 2:16 AM, Giorgio Mazza <> 
>> wrote:
>> Hi all!
>> I have written a simple component in python that works fine.
>> Now I would to improve it, making it to install flow entries depending on 
>> parameters received from an external application.
>> In particular I want to pass those parameters via json messages to my 
>> component, which, in my thougths, has to open a "permanent" socket listening 
>> for them, save those parameters in a dictionary and, as a consequence, 
>> decide the desired switch behaviour (whether install or not a flow entry for 
>> the received parameters).
>> In previous threads I found that I have to use jsonmessenger (even in 
>> python?) or to have a look to, but I am not sure to have 
>> understood what I have to do and where in order to realize such a behaviour.
>> Could anyone, please, help me?
>> Thank you in advance,
>> Giorgio Mazza
>> _______________________________________________
>> nox-dev mailing list
> _______________________________________________
> nox-dev mailing list

nox-dev mailing list

Reply via email to