I have inherited and am working with a DNN application that has multiple modules that all work together. I am trying to optimize the code and arrange it so it is not repetitive and hard to follow. So I am working with Variables that need to be accessed from multiple modules throughout the app. I would like to set this up so I am using the "Norm" procedures. I could use some help to understand the best procedures for variable storage and access.

• I understand a Session variable is used for each user that logs on for their individual settings? 
• Application object can be used for what I would call Constants in VB6? These would be accessible to all users. 
• In the current modules there is a Declaration section that looks like it is used for declaring constant type variables. But a lot of them are repeated in all the modules. Is that a good practice? doesnt that leave me with multiple places to make code changes if a variable changes? Would that be better as an application object setting? Or could they all be declared one time in a file that is shared between multiple modules?

 I would appreciate any help or links to clear tutorials for this.
TIA 

Thanks for the reply.
The environment is a subscription based service that will be hosted on the web. There is a possibility that the app may be sold to an individual entity down the road but would then also be installed on a dedicated machine.

I can understand that a shared library could be used to track "Application Wide" type variables such as PortalID, actual address to specific pages on the server, last updated time stamps for tables and such but not for user specific information. 

Wouldn't module settings be confined to the specific module? I have modules that communicate with each other can those settings be accessed then?

When you speak of Cache, when does that get destroyed? how easy is it to access this in code?