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Introducing Net8

This chapter covers the following topics:

Net8 Release 8.0 Overview

Net8 replaces SQL*Net as the networking services and connectivity component for Oracle8. Net8 has evolved considerably from SQL*Net, supporting application programming interfaces, Java-enabled Internet browsers and network services such as naming and security--hence the name change.

Net8 is the foundation of Oracle's family of networking products, allowing databases and their applications to reside on different computers and communicate as peer applications. Net8 allows clients to communicate with Oracle8 and Oracle7 servers through service names, which are easy to remember aliases for database addresses. Setting up Net8 primarily involves creating service names for clients so a simple connect string, such as CONNECT SCOTT/TIGER@SERVICE_NAME, can be used to make a connection from a client to a server.

Depending on your needs, service names can be stored in a variety of places, including the Domain Name System (DNS), configuration files on each client, a centrally located Oracle Names Server, or a non-Oracle naming service. Wherever you choose to store your service names, Net8 offers tools to easily configure service names.

Oracle Connectivity Overview

The main function of Net8 is to establish sessions and transfer data between a client and a server or between two servers. Once a session is established, Net8 acts as a data courier for the client and the server. The connection operation is initiated during any standard database login between the client application and the server, with information such as the client machine name and user name passed to the remote machine.

Sessions are established with the help of a network listener, located on the server. The network listener brokers the client request, handing off the request to the server. Every time a client (or server acting as a client) requests a session with a server, a network listener receives the actual request. The network listener determines the location of the server and enables the client to connect to the server. The network listener is a separate process whose responsibility is to listen for incoming client connection requests and manage the traffic to the server.

Client Request

The user requests a database connection from the server by supplying input (SQL command) through a client-side application such as SQL*Plus. The application sends the request to Net8 to be transported across the network to the server. After the connection request is accepted by the network listener on the server, the client application requests database information from the server.

Server Response to Client Request

The server runs the Oracle8 database software and a Net8 network listener program. The Net8 network listener, through an Oracle Protocol Adapter, accepts connections from client applications on the network.

Net8 on the server delivers the client data transfer request to the Oracle8 database. The database performs the function requested by the user on the client computer. Finally, Net8 transfers the results of the database functions to the client machine.

Architectural Overview

Net8, the networking layer formerly known as SQL*Net, uses the Transparent Network Substrate (TNS) and standard industry network protocols to connect a client to a server and establish an Oracle session. The following figure shows the basic connectivity architecture and process, with a connection request originating from a client side application. The database returns the queried information in the reverse direction.

The following is an overview of Oracle network connectivity components:

Net8

Net8 is a software layer that is required to communicate between Oracle clients and servers. The role of Net8 is to establish and maintain a connection between the client application and the server and exchange messages between them. It provides both client to server and server to server communications across any network. It enables client tools to access, modify, share, and store data on Oracle8 Servers over a network. The communication between client applications and servers takes place across one or more networks and is referred to as client/server communication.

Transparent Network Substrate (TNS)

The TNS is an underlying layer of Net8 that receives requests and settles all generic connectivity functions such as opening and closing a session or sending and receiving requests or responses. TNS then passes control to an Oracle Protocol Adapter to make the protocol-specific call.

Oracle Protocol Adapters

The Oracle Protocol Adapters are responsible for mapping TNS functionality to industry-standard protocols used in the client/server connection. Each adapter is responsible for mapping the equivalent functions between TNS and a specific protocol.

An Oracle Protocol Adapter translates (or adapts):

function calls of specific network protocols (such as TCP/IP) into equivalent function calls of the Oracle Transparent Network Substrate (TNS).
TNS generic function calls into specific function calls for the underlying network protocol.

Additional Information:

See:

the third-party network documentation that came with your protocol software for a detailed technical discussion of these protocols.
Chapter 2 Introducing Net8 Products, for a list of available protocol adapters.

Network-Specific Protocol Stack

The protocol stack (third party software) supplies a reliable means of communication across the network. All Oracle software in the client/server connection process requires an existing network protocol stack to make the machine-level connection between two machines. The network protocol is responsible only for getting the data from the client machine to the server machine, at which point the data is passed to the Oracle Protocol Adapter on the server side.

1 Introducing Net8