[TYPO3-mvc] Best Practice for Interaction between extbase Extensions?

[Tim Schoch | GSTALTIG]

Good morning List
 
I have a page selling some statistics, spread across different Blocks (like America, Europe etc.) A user can subscsribe to every Block by it's own. When he subscribes to one, additional Data is shown.
 
For obvious reasons I want to divide the functionallity into different extensions (one handling the Application, the other the subscription). How is the interaction done between two extensions?
I tried to set a link in the Block's *show-view* pointing to the Subscription's *new-view* passing the Block as an argument. This doen't work though. The UID of the Block is passed as a POST Argument but not substituted in the *new-view* oft he Subscription, therefor leaving me without a connection tot he first extension.
 
Has anyone done something similar until now?
 
Thank you
Tim
 
GSTALTIG GMBH / www.gstaltig.ch
Sonnenhofstr. 13 / 6020 Emmenbrücke
tim at gstaltig.ch / 076 488 24 97