How to determine what part of the application is to execute in a separate module?
If this part of the application, you can reusing and it does not depend on anything. Modules are necessary only for the issuance of a code that may be reused.
How to determine what part of the application need to make a separate controller?
No way. Read about thin controllers and fat models, or at worst solstice service layer. Reus controllers it is not noble.
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