What does Microsoft imply when talking about the Business Intelligence Semantic Model (BISM)? Fundamentally, it is the Analysis Services storage engine in which you choose to store your analytical data. The solution may also include SharePoint, Reporting Services, Excel or a custom BI application.
SQL Server 2012 Analysis Services introduces a new Business Intelligence Semantic Model called tabular modeling. We will take a look at what this new model offers, as well as exploring the two existing models and how xVelocity fits in.
While we refer to these as "models", as does Microsoft in their documentation, it can be helpful to think of them as different types of Analysis Services storage engines. We recommend reading Analysis Services expert Chris Webb's excellent article "So, what is the BI Semantic Model?" at http://cwebbbi.wordpress.com/2012/02/14/so-what-is-the-bi-semantic-model.