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Lesson 1

Oracle Net Services Architecture

This module adds more depth to our prior discussion of Oracle Net Services architecture. We will look at the Oracle Net components and at all of the parameter files, including the
  1. tnsnames.ora,
  2. listener.ora,
  3. protocol.ora, and
  4. sqlnet.ora files.
We will also see how the pieces fit together and how Net uses these files to establish database communications.

Learning Objectives

After completing this module, you will be able to:
  1. Describe the syntax and function of Net parameter files
  2. Define the components of Oracle network tools
  3. Describe the components and functions of the tnsnames.ora file
  4. Explain how the protocol.ora file operates
  5. Explain the purpose and uses of the sqlnet.ora file
  6. Establish Net communications at the process level
  7. Explain the purpose and syntax of Oracle database links
  8. Establish connections over database links
We will begin the module by looking at the syntax and function of the Net parameter files.

Oracle Names Legacy

Oracle Names is a product that stores connection information about all databases in a distributed environment in a single location. Any time an application issues a connection request, it consults the Oracle Names repository to determine the location of the database server. Oracle Names is primarily an administrative aid that makes the maintenance of this information easier. Its use is not required; the alternative is to provide local tnsnames.ora files on every client machine.

Oracle Names Upgrade

If you upgrade all or part of your network to Oracle9i, you should upgrade all the Oracle Names Servers in the region to version 9.
  1. Can my release 8.0 clients use Oracle Names version 9 to resolve service names?
  2. Can my release 8.0 clients then use the connect descriptor returned from Oracle Names version 9 to connect to an Oracle version 8 database?
    Yes, if the connect descriptor was specified correctly when it was entered into Oracle Names.
Oracle supplies three key components that interact to locate services, establish connections, transport data, and handle exceptions. They are:
  1. Oracle Net Services
  2. Transparent Network Substrate (TNS)
  3. Oracle Listener
While the interaction among these products does not generally require intervention beyond the initial installation, some customizations are often beneficial in an environment that is making heavy use of snapshots, symmetric replication, or other distributed functionality.

About Oracle Net Services

Oracle Net Services provides enterprise-wide connectivity solutions in distributed, heterogeneous computing environments. Oracle Net Services eases the complexities of network configuration and management, maximizes performance, and improves network diagnostic capabilities. This section introduces the basic networking concepts involved in a typical network configuration.

Understanding Connectivity

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