Heterogeneous Services is a component within the Oracle9i database server that is necessary for accessing a non-Oracle database system.
The term "non-Oracle database system" refers to the following:
Any system accessed by PL/SQL procedures written in C (that is, by external procedures)
Any system accessed through SQL (that is, by Oracle Transparent Gateways and Generic Connectivity)
Any system accessed procedurally (that is, by procedural gateways)
Heterogeneous Services makes it possible for Oracle9i database server users to do the following:
Use Oracle SQL statements to retrieve data stored in non-Oracle systems.
Use Oracle procedure calls to access non-Oracle systems, services, or application programming interfaces (APIs) from within an Oracle distributed environment.
Heterogeneous Services is generally applied in one of two ways:
Users use an Oracle Transparent Gateway in conjunction with Heterogeneous Services to access a particular, vendor-specific, non-Oracle system for which an Oracle Transparent Gateways is designed. For example, you would use the Oracle Transparent Gateway for Sybase on Solaris to access a Sybase database system that was operating on a Sun Solaris platform.
Users use Heterogeneous Services' generic connectivity to access non-Oracle databases through ODBC or OLE DB interfaces.