Vat on ebooks

My company recently engaged in selling eBooks online. The process involves:

1. Publishers upload eBooks (digital formats) to a central repository.
2. Central repository = Digital Warehouse + Distribution engine for encrypted eBooks
3. Retail eBookstore obtains its real-time inventory from the Central Repository to fulfill an eBook purchase by an end-user.

So, there are three entities -

1. Publisher/ Copyrights Holder;
2. Service Provider - Central Repository/ Digital Warehouse/ Distributor; and
3. Retailer who has a catalogue of eBooks and who is actually delivering the book to an end-user, however, receiving it in real-time from the Central Repository.

My questions are, thus,

1. if there is a Sales Tax/ VAT on eBooks/ Digital Books (which are not in the form of CDs/ DVDs)?;
2. If yes, then who pays it - Central Respository or the Retailer? 
3. What are the other taxes applicable in the process?

Any guidelines and advise is greatly appreciated.