XFN Attribute Model
In the XFN attribute model, a set of zero or more attributes can be associated with a named object. Each attribute in the set has a unique attribute identifier, an attribute syntax, and a set of zero or more distinct attribute values. Each attribute value has an opaque data type. The attribute identifier serves as a name for the attribute. The attribute syntax indicates how the attribute values are encoded.
The operations in the base attribute interface can be used to examine and modify the settings of attributes associated with existing named objects. These objects can be contexts or other types of objects. The attribute operations do not create names or remove names in contexts.
The range of support for attribute operations can vary widely. Some naming systems might not support any attribute operations. Other naming systems might support only read operations or operations on attributes whose identifiers are in some fixed set. A naming system might limit attributes to have single values or might require at least one value. Some naming systems might associate attributes only with context objects, while others might allow associating attributes with noncontext objects.
Typically, attributes of an object are manipulated through operations that operate on a single attribute, such as reading or updating a single attribute. Moreover, the client is typically expected to be able to read all attribute values of a single attribute in one call. However, sometimes there is a requirement to manipulate several attributes of a single object or to obtain individual attribute values of a single attribute from the name service. To address these requirements, two kinds of attribute operations are defined:
- © 2010, Oracle Corporation and/or its affiliates