The 3.0 API breaks the existing 2.0 APIs in order to provide a number of improvements.
Collections and Scopes are introduced.
The Document class and structure has been completely removed from the API, and the returned value is now Result.
Retry behaviour is more proactive, and lazy bootstrapping moves all error handling to a single place.
Individual behavior changes across services are explained here.
6.5@sdk:shared:partial$migration.adoc
6.5@sdk:shared:partial$migration.adoc
6.5@sdk:shared:partial$migration.adoc
6.5@sdk:shared:partial$migration.adoc
Information on the new API is to be found in the libcouchbase API pages.