Gateway Process Flow

Figure 2-3 shows a typical gateway process flow. The steps explain the sequence of events that occur when a client application queries the non-Oracle database system database through the gateway.

Figure 2-3 Gateway Process Flow


Description of
Description of "Figure 2-3 Gateway Process Flow"

  1. The client application sends a query using Oracle Net to Oracle Database.

  2. Heterogeneous Services and the gateway converts the SQL statement into a SQL statement understood by the non-Oracle database system.

  3. Oracle Database sends the query to the gateway using Oracle Net.

  4. For the first transaction in a session, the gateway logs in to non-Oracle database system using a user name and password that is valid in the non-Oracle system.

  5. The gateway retrieves data using non-Oracle database system SQL statements.

  6. The gateway converts retrieved data into a format compatible with Oracle Database.

  7. The gateway returns query results to Oracle Database, again using Oracle Net Services.

  8. Oracle Database passes the query results to the client application using Oracle Net. The database link remains open until the gateway session is finished, or the database link is explicitly closed.