Oracle in a Nutshell

Making the Connection

Oracle Net Services provides the transport of information to and from a server. Figure 5-1 illustrates this connection, with the components of Oracle Net Services and their associated configuration files.

Figure 5-1. Network communication and configuration

When a client creates a connection to a server, there are two basic steps in the process. In the first step, the client locates the appropriate server. The location can be accomplished through several means, including:

• Looking in the local TNSNAMES.ORA file.

• Getting the information from an external LDAP (Lightweight Directory Access Protocol) directory (new in Oracle8i) or an external naming service.

• Using a centralized naming service, such as Oracle Names (scheduled to be desupported after Oracle9i).

  Tip

  Oracle Names was designed to act as a centralized directory for network services. Unfortunately, it is a proprietary technology, whereas the new LDAP directories fulfill the same purpose and are open technologies. For this reason, Oracle has announced that Oracle Names will not be enhanced any more and has provided Oracle Names users with both a migration path to LDAP directories and a way to have Oracle Names servers act as proxy servers for LDAP directories.

• Directly connecting to the host using a TCP/IP or DNS identifier (new with Oracle8); this option does not give you all the services of Oracle Net Services, ...