Oracle Net Services provides enterprise-wide connectivity solutions in distributed,
heterogeneous computing environments. Oracle Net Services enables a network
session from a client application to an Oracle database.

Oracle Net Services uses the communication protocols or application programmatic
interfaces (APIs) supported by a wide range of networks to provide a distributed
database and distributed processing for Oracle.

■ A communication protocol is a set of rules that determine how applications access
the network and how data is subdivided into packets for transmission across the
network.
■ An API is a set of subroutines that provide, in the case of networks, a means to
establish remote process-to-process communication through a communication
protocol.

After a network session is established, Oracle Net Services acts as a data courier for the
client application and the database server. It is responsible for establishing and
maintaining the connection between the client application and database server, as well
as exchanging messages between them. Oracle Net Services is able to perform these
jobs because it is located on each computer in the network.

Oracle Net Services provides location transparency, centralized configuration and
management, and quick out-of-the-box installation and configuration. It also lets you
maximize system resources and improve performance. Oracle’s shared server
architecture increases the scalability of applications and the number of clients
simultaneously connected to the database.The Virtual Interface (VI) protocol places
most of the messaging burden on high-speed network hardware, freeing the CPU for
more important tasks.

Oracle网络服务
1. Oracle 网络服务可以在客户端应用程序与数据库服务器间建立网络会话
2. racle 网络服务利用通信协议或被各种网络支持的 API 来实现分布式数据库及分布式处理
3. 通信协议是定义了应用程序如何访问网络，以及数据如何被拆分为数据包以便在网络上传输
4. API 是一系列利用通信协议来实现进程到进程间通信的子程序