Different name services are often embedded in different applications and services in a computing environment. Working with different name services presents significant difficulties to the application developer. Most applications are designed to use a single name service and have very limited access to objects in a distributed computing environment. Because different applications use different name services they expect names to be composed differently. They often use different names for what the user considers very similar objects. For example, you might be able to send mail to your friend Johanna using her name email@example.com, but be required to use another name, jsmith@altair, to access her calendar.
FNS, Sun's implementation of the XFN standard, allows you to name objects in a uniform way, yet still provide the functionality that applications and developers need.
XFN is X/Open Company, Ltd. Federated Naming standard. XFN is a standard actively supported by organizations such as Sun Microsystems, Inc., IBM, Hewlett-Packard, Digital Equipment Corpaoration, Siemens, and OSF. FNS, the Solaris operating environment implementation of XFN, is compliant with the X/Open Preliminary Specification for Federated Naming (July 1994). Applications that use FNS are portable across platforms because the interface exported by FNS is XFN, a public, open interface endorsed by other vendors and X/Open. The X/Open Co. Ltd. is an international standards organization committed to defining computing standards that are endorsed and adhered to by the major computer vendors.
FNS provides a method for federating multiple name services under a single, simple uniform interface for the basic naming operations. The service supports resolution of composite names--names that span multiple name systems-- through the naming interface. Each member of a federation has autonomy in its choice of naming conventions, administrative interfaces, and its particular set of operations other than name resolution.
In the Solaris environment, the FNS implementation consists of a set of enterprise-level name services (see "Solaris Enterprise-Level Naming Services") with specific policies and conventions for naming organizations, users, hosts, sites, and services as well as support for global name services (see "Global Naming Services") such as DNS and X.500.
FNS is useful for the following reasons:
A single uniform naming interface is provided to clients for accessing different name services. As a consequence, the addition of new name services does not require changes to applications or to existing member name services.
Names can be composed in a uniform way, and the resulting composite names can have any number of components.
Coherent naming is encouraged through the use of shared contexts and shared names.
In this manual it is important to distinguish between XFN and FNS. The FNS policies include some extensions to XFN policies, and these are explicitly defined with notes. Objects belonging to the XFN programming interface are designated as XFN objects to avoid confusion with other programming interfaces.