Parameters Used in the Interface

• "Composite Names"

• "References and Addresses"

• "Identifiers"

• "Strings"

• "Attributes and Attribute Values"

• "Attribute Sets"

• "Attribute-Modification Lists"

This section gives an overview of the types of parameters that are passed and returned by operations in the base context and attribute interfaces. Manipulation of these objects using their corresponding interfaces does not affect their representation in the underlying naming system.

Changes to objects in the underlying naming system can only be effected through the use of the interfaces described in "The Base Context Interface" and "Base Attribute Interface".

Composite Names

A composite name is represented by an object of type FN_composite_name_t. A composite name is a sequence of components, where each component is a string (of type FN_string_t) intended to contain a name from a single naming system. (See "Syntax" for a description of composite name syntax and structure.) Operations are provided to iterate over this sequence, modify it, and compare two composite names.

References and Addresses

A reference is represented by the type FN_ref_t. An object of this type contains a reference type and a list of addresses. The ordering in this list at the time of binding might not be preserved when the reference is returned upon lookup.

The reference type is represented by an object of type FN_identifier_t. The reference type is intended to identify the class of object referenced, but XFN does not dictate its precise use.

Each address in a reference is represented by an object of type FN_ref_addr_t. An address consists of an opaque data buffer and a type field, again of type FN_identifier_t. The address type is intended to identify the mechanism that should be used to reach the object using that address.

Multiple addresses in a single reference are intended to identify multiple communication endpoints for the same conceptual object. Multiple addresses can arise for various reasons; for example, because the object offers interfaces over more than one communication mechanism.

The client process must interpret the contents of the opaque buffers based on the type of the address and on the type of the reference. However, this interpretation is intended to occur below the application layer.

Most application developers should not be required to manipulate the contents of either address or reference objects themselves. These interfaces are generally used within service libraries.

Identifiers

Identifiers are used to identify reference types and address types in the reference and to identify attributes and their syntax in the attribute operations.

The FN_identifier_t type is used to represent an identifier. It consists of an unsigned integer, which determines the format of identifier, and the actual identifier, which is expressed as a sequence of octets.

XFN defines a small number of standard forms for identifiers, as shown in Table 2-4.

Table 2-4 XFN Identifier Formats

Identifier Format	Description
FN_ID_STRING	The identifier is an ASCII string (ISO 646).
FN_ID_DCE_UUID	The identifier is an OSF DCE UUID in string representation. See the X/Open DCE RPC (ISBN 1-872630-95-2).
FN_ID_ISO_OID_STRING	The identifier is an ISO OID in ASN.1 dot-separated integer list string format. See the ISO ASN.1 (ISO 8824).

Strings

The FN_string_t type represents character strings in the XFN interface. It provides a layer of insulation from specific string representations. The FN_string_t operations contain operations for string comparison, substring searches, and manipulation. The FN_string_t type supports multiple code sets. In Solaris 2.5, FNS supports ISO 646.

Attributes and Attribute Values

An attribute is represented by the FN_attribute_t type, and contains:

• An attribute identifier (of type FN_identifier_t)

• A syntax (of type FN_identifier_t)

• A set of distinct values (each value is a sequence of octets of type FN_attrvalue_t)

Various operations allow the construction, destruction, and manipulation of an attribute.

Attribute Sets

An attribute set is a set of attribute objects with distinct attribute identifiers. Attribute sets are represented by the FN_attrset_t type.

There are operations to allow the construction, destruction, and manipulation of an attribute set.

Attribute-Modification Lists

Use an attribute-modification list to specify multiple modification operations to be performed on the attributes associated with a single named object.

An attribute-modification list is represented by the FN_attrmodlist_t type. It consists of an ordered list of attribute-modification specifiers. Each specifier contains an operation and an attribute object. The attribute's identifier indicates the attribute that is to be operated upon. How the attribute's values are used depends on the operation.

The operation specifier is one of the values described in Table 2-1. The operations should be done in the order in which they appear in the list.