GOA and UOA: The split
Debarshi Ray printed in his blog an explainable article about the reasons of this split. Ubuntu is using the SSO of Meego while Gnome has written its very own from scratch. The reason that Gnome forced to build a new SSO was that Meego’s SSO has a DBus daemon written using Qt and the deamon had to be rewritten without Qt using GObject for it to be a part of GNOME.
“I do not know why Ubuntu decided not to use GNOME Online Accounts (GOA), because they decided to switch after GOA was born“.
Will GOA and UOA be merged?
This is more a question if Ubuntu will merge these two SSO in the upcoming releases, as Gnome definitely won’t. While UOA support plugins that can extend the functionality of SSO to support more accounts, at the present time UOA doesn’t work with some Gnome Apps like Documents.
That means that you have to make a double Gmail account, both in UOA and GOA to have a working Empathy and a working Documents. That applies in my case that I use Ubuntu Gnome and Gnome Control Center 3.6.
It is more likely in Ubuntu 13.04 to have a completely drop of GOA and a fully replacement with UOA and this has to do more with the systemd migration that might happen in Gnome, which Ubuntu is not willing to support as they successfully built their own Init Manager (Upstart). Don’t forget that Upstart is also used by Google’s Chrome OS, so it is a significant and important project for them (Canonical).
Ray says: “The SSO will closely tie in to the way we will do application bundles and sandboxing in GNOME, which in turn will depend on systemd. These things are still being hotly discussed within GNOME, so I do not know what the exact implementation will be neither do I know what Ubuntu plans to do, but it is possible that theirs will be different“.
UOA Current State
UOA in Gnome 12.10 is a huge improvement over the GOA as far it concerns the number of the different accounts that support, while this number can easily grow with the use of the plugins, something that GOA don’t want to use, at least for the present time, and the known reasons -”Third-party plugins lead to a kitchen sink. There is no way you can stop them from stepping on each others feet“.
While UOA seems impressive, in practice doesn’t work quite well. It can’t sync with Documents and other Gnome services, while it also has many bugs with Empathy. Of course that happens with GCC 3.6, but my guess the same issue applies for the GCC 3.4.2 that Ubuntu 12.10 ships.
GOA Current State
Gnome Online Accounts support just a limited number of Application right now, but it fully integrates with Gnome.
Also, I’am in favor with the way that GOA handles the different accounts. It makes more sense rather to pick applications (UOA) to switch on/off the services of each App, because in the end of the day, that is SSO for. A seamless authentication protocol, app agnostic.
Something that I have noticed, is that Gnome always tries to make the things right and select the optimal solutions (and this brings delays), where in Ubuntu mostly care about make the things work, without caring a lot about the technologies. It is kinda like, Gnome is building, Ubuntu is using.
The fact is that both of modules (GOA and UOA) are far from completed and we have to (again) wait for a six month development cycle to see how they will end up.