[Kde-pim] Push changes to Akonadi from inside a resource

[Dmitry Ivanov]

Hello there,

To make the RSS framework more flexible we decided to add a D-Bus interface
to the RSS resource to allow applications to manage feed list (i.e.
add/remove feeds) via D-Bus calls as well as the usual itemview
models. Resources are
supposed to be Akonadi-driven (at least I got such impression) and I need to
make the RSS resoure behave like an asynchronous resource.

While trying to tie D-Bus and the resource together (it turned out to be
quite easy) I discovered  that there are more than one way to _push_ the
changes to Akonadi from inside the resource.

1. When a new feed gets added via D-Bus I call synchronizeCollectionTree()
from inside the resource which leads to retrieveCollections() and finally to
collectionsRetrieved(). Akonadi syncs the collection tree and picks up the new
feed.

The advantage of this way is that the new collection (and its parent
collection) needs to have only the remoteID properly set (at least from what
I've seen so far).

The main disadvantage is that Akonadi has to refetch the entire collection
tree from the resource and then check if there are changes in it (if I
understand
it correctly).

2. When a new feed gets added via D-Bus I can use CollectionCreateJob to push
this feed to Akonadi. This triggers the collectionAdded() event which is also
invoked after adding a new collection via itemviews.

The advantage of this method is that the resource handles new feeds in
a unified way via collectionAdded() and Akonadi doesn't need to refetch the
entire collection tree, only the new collection.

The disadvantage is, the root resource collection has to have the ID properly
set. Otherwise CollectionCreateJob appends the new feed to the root Akonadi
collection (i.e. in case I pass a collection with id < 0 to CollectionCreateJob
as the parent collection). To meet this requirement I have to use
CollectionFetchJob to fetch the root resource collection after the user imports
his subscriptions via resource config dialog. (when the user imports
subscriptions
the resource builds the collection tree but the collections have invalid IDs,
obviously).
Probably I could create the root collection when the resource starts for
the first time and then fetch it from Akonadi after every restart. I
need to check
it.

So the question is, which method of pushing changes to Akonadi from a resource
is more appropriate (if they are correct at all)? Currently, I prefer
1) because it was
easier to implement. Maybe there are pitfalls I don't see?

Thanks in advance,

Dmitry

-- 
A: Because it destroys the flow of the conversation
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