Administering Analysis Services - Professional SQL Server Analysis Services 2005 with MDX - page 577

stored procedure accesses external resources and the current user
executing the stored procedure does not have permissions then exe-
cution of the stored procedure will not cause any ill effects. A use of
this impersonation mode is to define dynamic data security where
the current user's credential is need to access external resources.
▪ Use the service account: If you choose the Impersonate Service
Account, whenever the stored procedure is executed it will be ex-
ecuted under the credentials of service startup account for Analysis
Services. An example of a stored procedure that would need this im-
personation mode is an AMO stored procedure that does manage-
ment operations on the server.
▪ Use a specific username and password: If your business needs a
stored procedure to always be executed in the context of a specific
user, you need to choose this option. You need to specify a Windows
account name and password for this impersonation mode. A typical
example where you might use this options is when you access an
external source such as a data source or web service to retrieve data
with this account and utilize that value within the stored procedure for
computation.
To summarize, COM assemblies only support the credentials of the current
user impersonation, whereas .NET CLR assemblies support all the imperson-
ation modes. As an administrator of Analysis Services you need to choose
the right impersonation and permission that suits your business needs.
When you register an assembly with a specific Analysis Services database or
for the server using the Register Assembly dialog, Analysis Services 2005
Register Database Assembly dialog uses AMO to set up the correct proper-
ties. This, in turn, sends a Create command to the Analysis Services instance
as shown below.
<Create AllowOverwrite="true"
xmlns="http://schemas.microsoft.com/analysisservices/
2003/engine">
<ParentObject>
<DatabaseID>Adventure Works DW</DatabaseID>
</ParentObject>
<ObjectDefinition>