Security Roles are used in all versions of Microsoft SQL Servers. With Analysis Services (Multidimensional Data), Roles are used to manage security for objects and data (Analysis Services). The roles a database administrator defines manages these aforesaid objects and data.
Every user defined in a workstation or server has a SID. SIDs are security identifiers of these individual users (or even groups). In layman terms, SIDs are the DNA of the user. These identifiers, when attached to objects (all for specific access), are what defines permissions and rights. In other words, when you give 'John' access to read-only or full control, it's not just 'John', it's his SID which attaches (not visible to the administrator) to the object.
There are two primary roles that are provided with Analysis Services. The server role which is a fixed role that gives the administrator access to any instance of Analysis Services and the database role that are defined by the SQL administrator. The database role is the role assigned to a user (non-administrator) by the SQL server administrator.
Roles are groups of users who use the SQL server and data. Specific permissions for individual objects are given by the administrator. These members can be added or removed from specific roles depending on their individual need for database access. When roles are defined, SQL Server administrators are 'looking' at the needs (uses) of individual users.
