DirectQuery Mode in SQL Server 2012 Analysis Services (SSAS) Tabular

Building a SQL Server 2012 Analysis Services Tabular model to support ad-hoc queries for a particular department within my organization. One of the requirements is that the database must always provide the most up-to-date data at all times. I know that the SSAS Multidimensional model supports a ROLAP storage mode which would meet my requirement but I want to use the SSAS Tabular model. How can I accomplish my task with the SSAS Tabular model?    More...