Advanced Topics
Oracle Names
This chapter describes Oracle Names 2.0, including a general overview of the product and some of the key components. This chapter also discusses the new Dynamic Discovery Option, or DDO, which allows an administrator to install and use Oracle Names 2.0 with minimal configuration. Oracle Names 2.0 is included with the release of SQL*Net 2.3.
The difference between Oracle Names version 1.0 and version 2.0 is the Dynamic Discovery Option. If you choose not to use the Dynamic Discovery Option, then both versions are basically the same. Both are compatible with SQL*Net version 2.0 and later.
Attention: The Dynamic Discovery Option only works on nodes that use SQL*Net release 2.3. Services will not be automatically registered if SQL*Net release 2.3 is not used, and clients will not be able to find the well-known Names Server.
What Is Oracle Names?
Oracle Names version 2.0 is a supporting product for Oracle7 release 7.3 and SQL*Net release 2.3. Oracle Names makes network address and database link information available to all nodes throughout the network. Each database server's network address is stored with a name that is used to identify it. Client applications can then request a database connection with a simple name rather than a lengthy address.
What Is the Dynamic Discovery Option (DDO)?
Oracle Names 2.0 with the Dynamic Discovery Option enables configuration free networking while providing all the functionality of Oracle Names 1.0.
Note: The Dynamic Discovery Option is most appropriately used in a single community network. Oracle Corporation does not recommend using this option in complicated networks. For recommendations on when to use the Dynamic Discovery Option, see the section, "Choose Whether to Use the Dynamic Discovery Option" later in this chapter.
The new features of the Dynamic Discovery Option include:
A well-known Names Server is a server with an address that is hardcoded into the Oracle Names Server and its clients. The well-known Names Server is known, or available, at this address, so that clients do not need to be told, by way of configuration files, where to find the Names Server.
- Dynamic service registration
When a service starts up, it registers itself with the first well-known Names Server it locates. All listeners and databases are registered automatically with an Oracle Names Server at specific well-known name and address.
- Replication of service definitions
Well-known Names Servers continually reconcile the contents of their cache with those of other active well-known Names Servers on the network. Therefore, an object only has to register itself once with any Names Server for it to be registered across the network.
Choose Whether to Use the Dynamic Discovery Option
The new Dynamic Discovery Option in Oracle Names 2.0 is not for every network. There are several factors that you need to consider before using DDO on your network.
- If you are setting up a new network, using the Dynamic Discovery Option is a good choice. DDO enables all SQL*Net 2.3 services on the network to self-register with a well-known Names Server. This eliminates the need for any preconfiguration or maintenance on the part of the network administrator.
- If you have a simple existing network that is growing, the Dynamic Discovery Option is a good choice. Administrative changes can be made in a central location, and distributed to all the clients on the network.
- If you have multiple naming domains in your network, or expect to grow to the point of needing multiple naming domains, using the DDO is not a good choice. The DDO relies on the existence of a flat naming space. While a flat name space is convenient for small, local installations, it is not suitable for large, enterprise-scale networks.
- If you have a network that stays the same for long periods of time, whether large or small, converting the network to use the Dynamic Discovery Option may not be worth the effort. Static networks, especially small ones, are easy for an administrator to update or maintain manually.
- If you have networks which include gateways or MultiProtocol Interchanges, Oracle does not recommend the DDO for this type of network.
- Administrators of networks currently using Native Naming Adapters might find upgrading to DDO more troublesome than its benefits warrant.
See Chapter 2, "Introduction to the Dynamic Discovery Option"and Chapter 5, "Setting Up and Running Oracle Names with the Dynamic Discovery Option", for more information.
Note: Remember to plan for the migration before you begin. If you have a large or complex environment, you need to make sure that your migration plan will not isolate any existing users from accessing any data.
Compatibility Between Oracle Names versions 1.0 and 2.0
The Dynamic Discovery Option in Oracle Names version 2.0 is the only difference from Oracle Names version 1.0. If you choose not to use DDO, then Names Servers for Oracle Names version 1.0 and Oracle Names version 2.0 are basically the same.
Attention: DDO only works with nodes using SQL*Net 2.3. On all other versions of SQL*Net, service information must be entered into the network using Oracle Network Manager, and the clients need the appropriate configuration files. For more information on network configuration, see Chapter 5, "Setting Up and Running Oracle Names with the Dynamic Discovery Option", and Chapter 6, "Configuring Oracle Names".
Why Use Oracle Names?
There are many benefits to using Oracle Names including:
Such administrative advantages are critical to managing large distributed systems. In a production environment, it's important that users and applications be shielded from changes made to the network infrastructure. In the long run, this results in less work for the administrator and more reliability for the network.
Why Use Oracle Names with the Dynamic Discovery Option
The Dynamic Discovery Option enables network listeners and Oracle7 Servers to automatically register themselves with a well-known Names Server at a specific well-known address. Therefore the need for configuration files is significantly reduced. The only required configuration file is a LISTENER.ORA for each listener, which is created automatically during database installation.
Note: Other configuration files are required only if you want to have non-default values for some of your configuration parameters. See the section "Non-default Parameters"![[*]](jump.gif)
of this manual.
The DDO enables clients and services to find the well-known Names Server, automatically update Names Server addresses and database links as changes occur, and propagates these changes to other well-known Names Servers. This eliminates the need for extensive configuration files, and maintenance of those files.
What Is Stored in Oracle Names?
An Oracle Names Server stores names and addresses for network services such as databases or MultiProtocol Interchanges, database link definitions, and object aliases.
The Names Server stores the following types of objects, which are described below:
- MultiProtocol Interchange names and addresses
- Names Server names and addresses
After services have been defined in Oracle Names, users only need to refer to them by name to connect to a database or network service. The necessary exchange of details occurs between the requester and the Oracle Names Server.
With the Dynamic Discovery Option
There is no difference in what can be stored in Oracle Names version 1.0 and version 2.0 with the Dynamic Discovery Option. The only difference is that with the Dynamic Discovery Option, SQL*Net release 2.3 listeners register themselves and their databases automatically with an Oracle Names Server at a specific well-known address.
If you need to add services that are not automatically registered, such as Interchanges, aliases, and gateways, you will need to use Oracle Network Manager to configure what is stored in Oracle Names. See Oracle Network Manager Administrator's Guide for information on how to configure Oracle Names with Network Manager.
Who Uses Oracle Names?
Oracle Names has many users and one or more administrators.
The true user of Oracle Names is always either a client application in a client-server connection, or an Oracle server in a distributed database. Oracle Names is not visible to the user or the application programmer.
Oracle Names is administered by one or more people using the Oracle Network Manager and the Oracle Names Control Utility, or NAMESCTL. Oracle Names usually has at least one assigned administrator, although the data it stores may come from many sources.
System Requirements for Oracle Names
There are a small number of requirements for an Oracle Names Server. It must run on:
For specific information on memory and CPU requirements, refer to your Oracle operating system-specific manuals. They include installation instructions and other platform and operating system-specific information.
The memory required depends on the specific platform and the amount of data to be stored. In general, Oracle Names does not require a lot of memory, but if there is a large volume of data, more memory may be required.
Where to Go From Here
Deciding which migration strategy to use can be problematic. At the very least you should read the section "Choose Whether to Use the Dynamic Discovery Option" in this chapter. This section provides you with basic guidelines to help you decide whether using Oracle Names 2.0 with DDO is worthwhile for your network.
Once you have decided on a strategy, the following guidelines will help you determine which sections of this manual you need to read.
If you are setting up a new network and plan to use the DDO, read:
If you want to learn more details about the Oracle Names product, you may also be interested in reading Chapters 3 and 4.
If you have an existing network and plan to use the DDO, read:
If your network is more complicated than the scenarios presented, "Setting Up and Running Oracle Names with the Dynamic Discovery Option", see Appendix B, "Complex Network Issues and DDO" which provides guidelines for more complicated networks.
If you choose to run your network without using DDO, read:
Follow the procedures "Configuring Oracle Names", and Chapter 7 "Running and Managing Oracle Names" to configure Oracle Names 2.0 without DDO on your network.
