OSF DCE Application Development Guide--Core Components

OSF DCE Application Development Guide—Core Components
The ERA API provides the ability to define attribute types and to attach attribute
instances to registry objects. registry objects are nodes in the registry database, to which
access is controlled by an ACL manager type. The registry objects are
• principal
• group
• organization
• policy
• directory
• replist
• attr_schema
All registry objects and their accompanying ACL manager type are described in the .
The ERA API also provides a trigger interface that application servers use to integrate
their attribute services with ERA services.
28.1.1 Attribute Schema
The schema extensions are implemented in a single attribute schema that is essentially a
catalog of schema entries, each of which defines the format and function of an attribute
type. The schema can be dynamically updated to create, modify, or delete schema
entries.
The attribute schema is identified by the name xattrschema under the security junction
point (usually /.:/sec) in the CDS namespace. Access to the attribute schema (hereinafter
called simply schema) is controlled by an ACL on the schema object. The schema is
propagated from the master security server to replicas, like other registry data. Since the
attribute schema is local to a cell, it defines the types that can be used within the cell, but
not outside the cell (unless the type is also defined in another cell).
28.1.2 Attribute Types and Instances
Each attribute type definition in the schema consists of attribute type identifiers (UUID
and name) and semantics that control the instances of attributes of this type. In this
manual, schema entry refers to the registry entry that defines an attribute type.
An attribute instance is an attribute that is attached to an object and has a value (as
opposed to an attribute type, which has no values but simply defines the semantics to
which attribute instances of that attribute type must adhere). Attribute instances contain
the UUID of their attribute type.
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