MBO Or Odata Or A combination for my App

Hi Experts,

I am new to SAP Mobile app development and quite confused as to how to build my app with the below functionality:

1. Retrieve all the invoice document numbers from SAP

2. When user clicks one of the invoice documents - the invoice opens as pdf.

My dilemma is:

I do not want to hit SAP every time user logs onto the app. The list of invoices should be loaded only the first time and then only if new invoice is posted or existing invoice changed. Seems like MBO approach must be taken for data caching etc

Once the user clicks on the invoice, I wish to hit SAP database at the runtime, get the invoice and display as pdf. Seems like ODATA approach must be taken.

Can ODATA work for both these requirements?