Designing workspace - session scope best?

Grails newbie - I'm building a simple Grails app where a user will be working on objects down the domain hierarchy within the scope of a top-level domain object - the "workspace". For example, if my domain objects are project-author (1-M) and author-comments (1-M), I only want the authors and comments for the currently selected project to be visible to the user (they can switch projects/workspaces though).

From a design princ开发者_StackOverflow社区iple, is storing the index of the current "workplace" best done in session scope, or as a persisted "user preferences" object? This would require quite a bit of rework on the controllers, so I'm hesitant to go down this route.

Security may become an issue, so I'm hesitant to parameterize all my URLs for each "workspace".

Any advice would be appreciated.

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Basically there are currently two ways to deal with this by using existing plugins:

1. Multi Tenant Core
2. Spring Security ACL