[Twisted-Python] AMP with a long-lived connection - results and deferred?

[Oon-Ee Ng]

Thanks David, but when I do something along the lines of:-

def mycall(in):
    print(in)
d = self.connection.boxReceiver.callRemote(Command, a='test')
d.addCallBack(mycall)

The print never actually happens. I'm not really sure why, it was one
of the first things I tried. I tried the most basic thing, modifying
the doMath() example, and mycall only triggers when the reactor stops
(even if I run doMath multiple times with delays).

On Thu, Oct 29, 2015 at 1:15 PM, David Ripton <dripton at ripton.net> wrote:
> On 10/28/2015 02:24 AM, Oon-Ee Ng wrote:
>> Working off the example ampserver.py and ampclient.py examples, I
>> wanted to build a client which maintains a single connection while
>> allowing the passing of messages back and forth. However I'm stuck at
>> one of the most basic steps, getting back the result (without
>> 'completing' the connection).
>>
>> The ampclient.py example simply connects, does a callRemote on the
>> resulting protocol, and adds callbacks to extract the result from a
>> dictionary and print it. The deferred being used in this case is
>> produced by connectProtocol.
>>
>> I'm trying to write a client (inheriting from amp.AMP) which is
>> embedded in a kivy GUI, something which is quite possible using the
>> _threadedselect reactor.
>>
>> On connection, I use the connectionMade method to save the 'self' (in
>> this case, the client inheriting from amp.AMP) in my kivy app. I can
>> then call a function which does a callRemote on this saved client,
>> which indeed triggers the server appropriately.
>>
>> The callRemote returns a deferred (from reading docs online, a remote
>> reference). I can't figure out what to do with it, specifically in
>> terms of getting the result ('total', when calling Sum from
>> ampserver.py).
>>
>> Assistance much appreciated.
>
> Basically, callRemote returns a deferred, that you can add callbacks and
> errbacks to, which will be called when the remote call succeeds or
> fails.  On success, the callback will receive an argument equal to the
> return value of the remote callable that you called.  On failure, the
> errback will receive an error argument.
>
> I have an old GUI (PyGTK, not Kivy) chat over AMP example at
> https://github.com/dripton/ampchat that might help you.  (Though I think
> all of my commands return boring responses.)
>
> --
> David Ripton    dripton at ripton.net
>
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