Databases Reference
In-Depth Information
character-mode utility called Server Manager; since Oracle8
i
, you could use SQL*Plus.
The Oracle software installation media for earlier versions of the Oracle Database also
includes a sample script called
BUILD_DB.SQL
, described in the Oracle documentation.
Today, most users choose to create the database with the standard installer interface;
the command line method is actively discouraged for Oracle Database 12
c
Databases.
Oracle Net Services and Oracle Net
The overwhelming majority of applications that use an Oracle Database run on a dif‐
ferent machine and connect to the Oracle Database over a network. The software used
to transparently implement this connection process is known as Oracle Net Services.
Oracle Net Services handle interaction with underlying network protocols, such as TCP/
IP, and the coordination between client requests and the server processes that fulfill
them. Oracle Net Services include technology for clients to discover the appropriate
database instance, establish communication with that instance, and maintain an ongo‐
ing interaction between the client and the server.
Oracle Net is a layer of software that allows different physical machines to communicate
for the purpose of accessing an Oracle Database.
The term “Oracle Net Services” in Oracle refers to all the compo‐
nents of Oracle Net, including dispatchers, listeners, and shared
servers; these are explained later in this chapter.
A version of Oracle Net runs on the client machine and on the database server, and
allows clients and servers to communicate over a network using virtually any popular
network protocol. Oracle Net can also perform network protocol interchanges. For
example, it allows clients that are speaking LU 6.2 to interact with database servers that
are speaking TCP/IP.
Oracle Net also provides
location transparency
—that is, the client application does not
need to know the server's physical location. The Oracle Net layer handles the commu‐
nications, which means that you can move the database to another machine and simply
update the Oracle Net configuration details accordingly. The client applications will still
be able to reach the database, and no application changes will be required.
Oracle Net supports the notion of
service names
, or
aliases
. Clients provide a service
name or Oracle Net alias to specify which database they want to reach without having
to identify the actual machine or instance for the database. Oracle Net looks up the
actual machine and the Oracle instance, using the provided service name, and trans‐
parently routes the client to the appropriate database.
