This module discussed the various components of Oracle Net. Let us review how they fit together.
Remember, there are three "names" in Net that refer to remote databases:
The database name (for example, ORACLE_SID)
The service name (logged in the tnsnames.ora file)
The database link name (points to the service name)
The image below illustrates the complete process surrounding a remote connection.
You begin by issuing the distributed SQL, which produces the following:
The DBA_DB_LINKS view is interrogated (using the link name) to get the user ID and password.
The tnsnames.ora file uses the service name to look up:
Database SID name
The hosts file on the server then gathers the IP address (using the host name from tnsnames.ora) for the remote host.
At this point we have everything we need to connect successfully to the remote database. Net then establishes the network connection, and the remote listener creates a server process. The server process establishes the connection and signs on to Oracle with our user ID and password. The next module discusses how to configure a Net client and server, then examines Net's internal details.