| An object identifier. OIDs are normally used as object identifiers for
persistent objects that use data store identity. They're also used for
view objects, which actually use non-data store identity.
An OID is effectively a long containing a value in the range 0 to
260-1. The 60 bits encode three unsigned integer ID values; a
15-bit class ID value, a 30-bit object ID high value, and a 15-bit
object ID low value.
The object ID value is separated into two parts to facilitate the use of a
particular strategy for efficiently generating unique OID values, called the
high/low approach. In this approach, the high value is obtained
from a persistent store, and the low value is assigned locally by the
application. The advantage is performance; it avoids the bottleneck of
hitting the persistent store every time an ID needs to be generated.
author:
Mike Martin
version:
$Revision: 1.4 $
See Also: StoreManager |
