The System.Web.UI.WebControls.ObjectDataSource control supports an optional expiration policy that is based on the System.Web.Caching.SqlCacheDependency object for the data cache (the service must be configured for the database server).

SQL Server supports two mechanisms for cache invalidation: polling and notification. Each mechanism has a different syntax for the System.Web.Caching.SqlCacheDependency object.

The System.Web.UI.WebControls.ObjectDataSource supports only polling. The System.Web.Caching.SqlCacheDependency string is used to create a System.Data.SqlClient.SqlDependency object that is passed to the System.Data.Common.DbCommand constructor before the ObjectDataSource.Select method is executed. The ObjectDataSource.SqlCacheDependency string identifies databases and tables according to the same format that is used by the @ Page directive, where the first part of the string is a connection string to a SQL Server database, followed by a colon delimiter, and finally the name of the database table (for example, "connectionstring1:table1"). If the ObjectDataSource.SqlCacheDependency property depends on more than one table, the connection string and table name pairs are separated by semicolons (for example, "connectionstring1:table1";connectionstring2:table2").

To support notification, you must write the cache logic in the implementation of your ObjectDataSource.SelectMethod property and handle the construction of the System.Web.Caching.SqlCacheDependency object in your code.