An XMS object
can have attributes and properties, which are characteristics of the object.
Attributes and properties, however, are implemented in different ways.
- Attributes
- An attribute of an object is always present and occupies storage, even
if the attribute does not have a value. In this respect, an attribute is similar
in concept to a field in a fixed length data structure. Another distinguishing
feature is that each attribute has its own methods for setting and getting
its value.
- Properties
- A property of an object is present and occupies storage only after its
value is set. However, a property cannot be deleted, and the storage recovered,
after its value has been set, although you can change its value. Each individual
property does not have its own methods for setting and getting its value.
Instead, XMS provides
a set of generic methods for setting and getting the values of properties.