AptDaemon optionally is capable of providing the PackageKit system D-Bus
interface (see http://www.packagekit.org/gtk-doc/api-reference.html). The goal
is to provide the complete PackageKit API to run client applications smoothly.
There won't be any additions or changes to the original PackageKit API.


Unsupported or not fully covered methods:

 * org.freedesktop.PackageKit:

  - GetTimeSinceAction - could make use of the apt history
  - GetDaemonState - only reports that all is fine (used for debugging only)
  - SetProxy (should we change the apt config?)

 * org.freedesktop.PackageKit.Transaction:

  - GetOldTransaction
  - SetHints (cache_age doens't make any sense with APT, interactive and
    background/idle not yet implemented, locale and frontend_socket working)


Issues and shortcomings:

 - Messages are not used (possible candidates could be UNTRUSTED_PACKAGES,
   NEWER_PACKAGE_EXISTS, CONFIG_FILES_CHANGED, OTHER_UPDATES_HELD_BACK)
 - The post update hook (/etc/apt/apt.conf.d/20packagekit) cannot call
   StateHasChanged since caller and callee are the same process (aptd) and
   the call is blocking. So you see a time out warning in the apt logs.
 - Translations of package description don't work
 - RepoListChanged signal doesn't get emitted


Supported roles:

 - Get(Packages|Depends|Requires|Details)
 - (Download|Install|Remove|Update)Packages
 - InstallFiles (only one file at a time is supported)
 - GetUpdates
 - GetUpdateDetail
 - GetDistroUpgrades
 - WhatProvides (no builtin handling, only plugins)
 - RepoEnable (only enabling, not disabling)
 - InstallSignature
 - RepairSystem

Unsupported roles:

 - GetCategories: Curently groups are used, would be nice to reuse the
       categories from software-center or the Debian ones
 - GetRepoList: not implemented
 - RepoSetData: not implemented 

Roles we won't support at all because of missing infrastructure in APT:

 - AcceptEula: there isn't any equivalent mechanism in Debian/Ubuntu. Most
       packages mis-use debconf for this.

Supported filters:

 - (not)installed
 - (not)free
 - (not)gui
 - (not)devel
 - (not)collections
 - (not)supported
 - newest
 - (not)arch

Not yet supported filters:

 - (not)basename
 - (not)application
 - (not)source
 - (not)downloaded (0.8.9+)

Thanks to Richard Hughsie for his work on PackageKit!