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A naming method is a names resolution method that a client application uses to resolve a connect identifier to a connect descriptor when attempting to connect to a database service.
Users initiate a connection request to a database service by providing a connect string with the CONNECT command on the command line. A connect string includes a username and password, along with a connect identifier. A connect identifier can be the connect descriptor itself or a name that resolves to a connect descriptor. One of the most common connect identifiers is a net service name (a simple name for a database service). For example, the following connect string uses a complete connect descriptor as the connect identifier:
CONNECT scott/tiger@ (DESCRIPTION= (ADDRESS= (PROTOCOL=tcp) (HOST=sales-server1) (PORT=1521)) (CONNECT_DATA= (SERVICE_NAME=sales.us.acme.com)))
The following connect string uses the net service name sales as the connect identifier.
CONNECT scott/tiger@ sales
When the net service name sales is used as the connect identifier, connection processing takes place by first mapping sales to the connect descriptor. This mapped information is stored in one or more repositories of information that are accessed through naming methods.
The steps involved in the process for establishing a client session through a naming method are as follows:
The client initiates a connection request by providing a username and password, along with a connect identifier.
The connect identifier is resolved to a connect descriptor through a naming method. The information in the connect descriptor is returned to the client.
The client makes the connection request to the address provided in the connect descriptor.
A listener receives the request and directs it to the appropriate database server.
The connection is accepted by the database server.
Oracle Net supports the following naming methods for service names resolution:
Local Naming: In the local naming method, the connect identifiers (net service names and the corresponding connect descriptors) are stored in a localized configuration file named tnsnames.ora.
Directory Naming: In the directory naming method, the connect identifiers are stored in a centralized LDAP-compliant directory server.
Oracle Names: Oracle Names uses the Oracle proprietary software to store the names and addresses of all database services on a network. The clients wishing to connect to a database server direct their connection requests to an Oracle Names server. Oracle Names server resolves the name to a network address and returns that information to the client.
Host Naming: The host naming method enables users to connect to an Oracle database server by simply providing the server's host name or host name alias. Host names or host name aliases are mapped to a connect descriptor or the database server's global database name in an existing names resolution service, such as Domain Name System (DNS), Network Information Service (NIS), or a centrally maintained set of /etc/hosts files.
External Naming: In the external naming method, the net service names and the corresponding connect descriptors are stored in a non-Oracle naming service. These supported third-party services include NIS External Naming and Cell Directory Services (CDS).
