[Zope3-Users] Periodically refresh RSS feeds

[Christian Theune]

Hi,

Florian Lindner wrote:
> Hello,
> I have the following situation:
> 
> An object represents an RSS feed. It should be updated like every 20 minutes. 
> If there is something new a Jabber message should be send out.
> 
> Currently I have it implemented with an scheduler loop that emits an 
> refreshRSSFeed event evey 20 minutes. My problem is that a handler for an 
> event must be a static function, but I want a handler function to be called 
> as a member of every instantiated RSS feed object.
> 
> Another idea I have:
> Implement an utility where the RSS feeds could register a function that is 
> called every 20 minutes.
> Another way would be that this utility takes an URL and monitors the URL for 
> changes and only notifies the RSS Feed object in case of a change.
>
> How would you do that?

So there's two problems here: scheduling and notifying persistent
objects about an event.

I don't have a good idea about the scheduling right now, except the hint
that using a 'zopectl run' script might be worthwhile.  I'm not sure
what a 'scheduler function is'.

About notifying persistent objects: There is a method
'getAllUtilitiesRegisteredFor(interface)' which might help you. Have a
look at zope/app/catalog/catalog.py beginning from line 150
(indexDocSubscriber) how the catalog handles events and dispatches them
to multiple catalogs. I think this pretty much matches your use case if
you make each RSS feed a (named) utility.

Of course you could also have a utility that maintains references to all
RSS feed objects and simply loops over them and calls a method for
refreshing.

Christian

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