Oracle proxy authentication and federated trusted contexts

Create a physical connection to the Oracle data source, and then switch the connection to a different user on the same connection.

Using Oracle proxy authentication and federated trusted contexts reduces the network overhead of creating a separate network connection from the federated server to the Oracle database for each user, while still positively asserting the identity of the connected user to the Oracle data source. The application can switch from user to user, as required, to process transactions on the behalf of the users.

To configure this scenario, you perform these tasks:

On the Oracle server, use the Oracle ALTER USER statement to register each proxy user. Here Mary, who is the proxy user, is granted permission to use the proxy named BOSS and gains the role CLERK for the duration of the connection:
```
ALTER USER MARY GRANT
CONNECT THROUGH BOSS
WITH ROLE CLERK
```

On the federated server, create the trusted context object:

CREATE TRUSTED CONTEXT MY_FED_TCX
BASED UPON CONNECTION USING SYSTEM AUTHID BOSS
ATTRIBUTES (ENCRYPTION 'NONE')
WITH USE FOR MARY WITHOUT AUTHENTICATION
ENABLE

With this configuration, the federated server can set up an end-to-end trusted connection from the client through the federated server to the Oracle data source. BOSS can establish a trusted connection, and MARY can reuse it.

To establish and reuse trusted connections, use the API that database provides.