Oracle Database gateways are the synchronous solution for operating in a heterogeneous environment. The common component of Oracle Database gateways is Heterogeneous Services. This chapter describes the architecture and functionality of the Heterogeneous Services component and its interaction with Oracle Database gateways.

• Heterogeneous Connectivity Process Architecture
  The Heterogeneous Services component in Oracle Database communicates with a Heterogeneous Services agent process which, in turn, communicates with the non-Oracle system.
• Heterogeneous Services Agents
  A Heterogeneous Services agent is the process through which Oracle Database connects to a non-Oracle system.
• Types of Heterogeneous Services Agents
  There are two types of Heterogeneous Services agents.
• Heterogeneous Services Components
  Heterogeneous Services in Oracle Database consists of a transaction service and a SQL service.
• Heterogeneous Services Configuration Information
  Heterogeneous Services components consist of generic code and must be configured to work with many different non-Oracle systems.
• Heterogeneous Services Data Dictionary
  The agent uploads configuration information to the Heterogeneous Services component immediately after establishing a connection.
• Process Flow for non-Oracle Database Queries
  There are a sequence of events that occur when a client application queries the non-Oracle database system through the gateway.