[TYPO3-mvc] How to use an own storage backend / repository

[Stefano Kowalke]

Hey list,

I write an extbase extension were no database is needed. Actually its 
just an frontend for a webapi.

The extension consist of a searchform with a few filters and fires 
requests to the webapi (No SOAP, no Rest).

In the background its just put together the api url with an api token, 
the current timestamp and the search paramenters and get XML as response.

As far as I understand MVC this would be the job for an repository and 
and own storageBackend in Extbase.

How can I replace the current storageBackend with my custom 
storageBackend which talks with the api?

Thanks in advance

Stefano