[packagekit] Dynamic Groups in Packagekit

[Richard Hughes]

On Fri, 2008-09-26 at 12:33 +0200, Tim Lauridsen wrote:
> i have 2 new API method:
> GetCategories()         : Get collection categories from backend.
> GetCollections()        : Get collections from backend
> 
> And 2 new signals:
> Category:
>    cat_id       : category id (fx. apps)
>    name         : Category name
>    summary      : Category description
>    icon         : path to icon for category on locale system.
> 
> Collection:
>    grp_id       : group id with '@' prefix (ex. @kde-desktop)
>    cat_id       : category id (fx. apps)
>    name         : Translated collection name
>    summary      : Translated collection description
>    icon         : path to icon for collection on locale system.

I'm worried about the round trip time when a client requests the group
list. Think what happens when the client starts up:

GetCategories()
Category 1
Category 2
Category 3
Category 4
Category 5
Category 6
Category 7
Category 8
GetCollections(1)
Collection 1
Collection 2
Collection 3
Collection 4
Collection 5
GetCollections(2)
Collection 1
Collection 2
Collection 3
Collection 4
Collection 5
GetCollections(3)
Collection 1
Collection 2
Collection 3
Collection 4
Collection 5

etc.

If each RTT is about 50ms, and it's N squared complexity, it's a lot of
time. To approximate, if there are 10 categories, it'll take nearly a
second just to get the group list.

Why couldn't this be done using something like:

GetCategories()
Category (Applications)
Category (Applications/Tools)
Category (Applications/Games)
Category (Admin)
Category (Admin/Applications)

This would reduce getting the group list to one method, rather than the
number of catalogs.

Richard.