(A)synchronous DataEngines?

Bernhard Beschow bbeschow at cs.tu-berlin.de
Fri Mar 7 23:22:48 CET 2008


Hi all,

inside a data engine I'd like to request some data via http. There is the 
QHttp class I could use as well as KIO. Both of them seem to be asynchronous. 
Now I ran into trouble combining those with DataEngines for the following 
reason:

In my data engine, data is fetched asynchronously via QHttp each time 
updateSource gets called. After sending the request, the method returns false, 
while the QHttp object is waiting for a response. When new data is available, 
it is applied using setData, but the visualizations don't get updated until 
updateSource gets called next time. Even worse, this results in old data to 
be displayed. So I wonder what the proper way is to implement asynchronous 
data retrieval?

Of course, there is also synchronous data fetching. I'm not sure whether KIO 
can do this. I've seen code for this using a raw tcp socket, but I'd rather 
have high-level http access to the data. Anyway, blocking is probably not an 
option here since it blocks the whole applet (or even plasma), right?

Any hints are very welcome. Thanks in advance!

Best whishes,
Bernhard


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