Questions about dataengines and apologizes

[Aaron J. Seigo]

On Thursday, January 20, 2011, Matthieu Gallien wrote:
> I believe that some of the current solutions rely on encoding the address
> in the name of a requested source.

it often is, yes.

> I am not sure if a service could be used and how.

you could, yes, by implement serviceForSource and returning a Service object 
from there that is (internally) associated with that source. it could offer 
operations like "connect" with a string for the hostname and an optional int 
for the port. when called, that operation would then set some internal 
properties.

the way i usual recommend doing this is by subclassing DataContainer to do all 
the network stuff and when serviceForSource is called, passing the  
DataContainer subclass object to the Service subclass :) keeps everything 
nicely separated and clear in the code.

you could, of course, do the entire thing as a Service and not use a 
DataEngine at all. it probably quite depends on what sort of communication 
happens with the server; if it's a stateless "make a request, the server 
returns an answer" like http then a plan Service might be more 
straightforward. if there is ongoing communication with the server and/or the 
data ought to be shared between multiple widgets, then a DataEngine probably 
makes more sense.

> PS : by the way, I noticed that there is no techbase tutorial on writing
> services in a data engine. If the way it is done in the task engine is
> correct, I can try in the following month to make some text, but I will
> need a review from somebody.

yes, the task engine is a reasonable example :)

a simple example in kdeexamples/plasma/c++/dataengines/ would be nice, too, if 
you felt like it.

-- 
Aaron J. Seigo
humru othro a kohnu se
GPG Fingerprint: 8B8B 2209 0C6F 7C47 B1EA  EE75 D6B7 2EB1 A7F1 DB43

KDE core developer sponsored by Qt Development Frameworks
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