Scope of components in atg

Question

hi everyone,
i just want to know the default scope and the recommended scope of
1) droplets
2) form-handlers
will the objects of the respective component be destroyed after the scope?

Answer 1

This is a broad question, but the general recommendation for scope of Nucleus components are (in order of preference):
1. Global: for everything that doesn't have per-request or per-session (including reference to the current Profile) state or references.
2. Request: for everything that has request or session references, but doesn't need state that lasts between requests. Note that ATG request scope does carry over after a form-handler redirect (kind of like "flash scope" in some other systems).
3. Session: for things that have state that needs to last across multiple requests or the entire length of the session (profile and shopping cart, for example). Session components can also be used to cache per-user data that is expensive to fetch or calculate.
You want to try to minimize session-scoped components, since they both lead to more per-user session memory usage, and session scoped components require extra configuration and thought to properly handle session fail-over.
However, if you are manually resolving request or session components in a globally scoped component, chances are good it should be request or session scoped itself (outside of a few special cases).
For FormHandlers, you should probably start out with request scope as the default, since they typically need access to the user's profile, shopping chart, or other per-user data.
For Droplets, you should probably start out with global scope as the default, unless they need a configured reference to a session or request-scoped components. Alternatively, a droplet can remain globalky scoped but can require that the caller pass in the profile (or whatever) as a required input parameter (a little more work for the caller, though).