No plan survives contact with the enemy. This was made abundantly clear when Qunu was released as alpha for the public to abuse. As with any alpha there were countless problems that I dealt with on a daily basis. Clients insisting that a jid must have a node, xdata limitations in iq:register, double subscriptions, broken muc support, etc…
For some of these problems I was able to hack up a work around, such as email@example.com as a subscription proxy for quser.alpha.qunu.com. A few of them had no decent solution and I had to suggest other clients. The wiki page, http://qunu.com/wiki/index.php/Documentation, has a list of clients which have the bare minimum feature set.
The default gtalk client does not support muc or groupchat. Since a lot of people had a gmail account they naturally tried to use their gtalk clients. Making the brash assumption that gtalk behaved like every other xmpp server I directed them to the above list of working clients to try. After several confusing chats and some poking of my own I quickly discovered that gtalk is not xmpp.
That may sound rather harsh so let me qualify that. While google’s xmpp-like servers may follow the letter of the xmpp RFC‘s they most certainly do not follow the spirit. The reason I say this is that the gtalk servers will block any stanza which their default client will not understand regardless of which client you are actually using. This means that even if you wanted to get cool new features by using another jabber client, gtalk will block the stanzas before they get to your client. Not only do you have to get a different client, but you have to use a different server. *sigh*
The biggest issue, at least for qunu, is muc invites. GTalk silently drops them regardless of which client is on the other end. disco requests are reported assuming the default client. iq:version is always reported as not implemented, again ignoring the client.
Of course there is no bug/issue report system at google. Thus this blog post. Hopefully someone at gtalk will see this and file a bug. Of course, if you need further clarification, feel free test this yourself or ping me at firstname.lastname@example.org