(A)synchronous DataEngines?

[Aaron J. Seigo]

On Friday 07 March 2008, Christopher Blauvelt wrote:
> Don't implement updateSource(QString). 

you can do this, but then you'll never know when an update is actually wanted. 
only skip implementating updateSource if none of the data is requested on 
demand, otherwise you will break things such as, e.g., timed updates ("give 
me this web page evern 10 minutes)

> Create a timer in your engine that directs the HTTP data to be updated.  

if you ever need to create a timer in your engine, you're either doing 
something wrong or DataEngine needs fixing.

perhaps what you are looking for is setUpdateInterval?

however, this is usually controlled by the visualization (e.g. an applet) that 
is connecting to the data source by providing a number for how often it would 
like to get updated. 

for web data you probably want to pass a reasonable value to 
setMinimumUpdateInterval so the engine doesn't get update requests too often.

> Once it returns the data, set the 
> required information using setData.  Once everything is updated call
> checkForUpdates().

calling checkForUpdates should never be needed unless you are setting the data 
on the DataContainer* objects directly (you probably want to be using 
DataEngine::setData)

-- 
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 Trolltech
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