You have the wave protocol then XMPP server, which according the docs you have to use your own
Potentially you could store it in any way you see fit -- You received this message because you are subscribed to the Google Groups "Google Wave API" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/google-wave-api?hl=en.
