This article describes a software update that enables the Microsoft Service for Distributed Relational Database Architecture (DRDA) to dynamically redirect the connection to an alternative SQL Server database. This process is performed by setting the SQL connection string argument to a different SQL Server database as returned by the RDBNAME field in the Windows Initiated Affiliate Application.
Software update information
A supported feature that changes the product's default behavior is now available from Microsoft Support. However, this feature is intended to change only the behavior that this article describes. Apply it only to systems that specifically require it.
This update is included in Cumulative Update 1 for Host Integration Server 2013.
After you apply this update, the Microsoft Service for DRDA is updated to support dynamic redirection of a connection to an alternative SQL Server database.
ESSO Windows-Initiated Affiliate Application
The windowsInitiatedAffiliateApplication attribute defines the Affiliate Application name that the DRDA Service should use with Microsoft Enterprise Single Sign-On (ESSO). In this situation, the DRDA Service maps the Windows Active Directory domain user to out-bound SQL Client credentials when the SQL Client uses SQL Server authentication. This optional property accepts a string value. The default value is an empty string that instructs the DRDA Service not to use Windows-initiated ESSO.
You can also specify a value of isRdbName to instruct the DRDA Service to retrieve SQL Server database connection information from the Windows-initiated Affiliate Application mapping records. For example, the mapping record may contain an Initial Catalog argument value pair, instructing the DRDA Service to dynamically redirect the connection to an alternative SQL Server database. By default, the DRDA Service connects to the SQL Server database by using the DRDA client-to-server connection information RDBNAM (Relational Database Name) field in the DRDA client-to-server ACCRDB (Access Relational Database) protocol flow. To use this feature, the ESSO Administrator creates a Windows-initiated Affiliate Application that has the same name as the expected in-bound DRDA RDBNAM value. Under these circumstances, the Affiliate Application contains a third field (User name, Password, "ConnectionString") and then includes in the user credential mapping the SQL Server connection string argument value pairs. In this example, the original RDBNAM value might be "SQL1," with the corresponding Affiliate Application named "SQL1." The user credential mapping for "USER1" might contain "MS$SAME" for the Username and Password fields and "Initial Catalog=”SQLALT1" for the ConnectionString field. This configuration instructs the DRDA Service to dynamically reroute connection requests from USER1 for database SQL1 to an alternative SQL Server database that's named SQLALT1.
Note When you use Windows-initiated ESSO, you must specify Integrated Security=false in the SQL Server connection string.
Affiliate applications are logical entities that represent a system or subsystem such as a host, a back-end system, or an IBM DB2 database client. Contact your SSO administrator for the SSO Affiliate Application name. For more information, see Understanding Enterprise Single Sign-On.
Example of the msdrdaservice configuration:
connectionString="Data Source=MyDataSource;Integrated Security=False; hostInitiatedAffiliateApplication="HostApp"