OSF DCE Application Development Guide--Core Components

The Extended Attribute API

Note: Since attribute triggers cannot be associated with an attribute set instance,

this call provides no way to supply input data to a query attribute trigger.

28.3.3.4 The sec_rgy_attr_lookup_by_name() Call

The sec_rgy_attr_lookup_by_name() call reads a single attribute instance speciﬁed by

name for an object speciﬁed by name and domain. The call returns a sec_attr_t for the

speciﬁed attribute instance.

For multivalued attributes, the call returns the ﬁrst instance of the multivalued attribute.

(To retrieve every instance of a multivalued attribute, use the

sec_rgy_attr_lookup_by_id( ) call.)

For attribute sets, the call returns the attribute set instance, not the member instances. To

retrieve all members of the set, use the sec_rgy_attr_lookup_by_id( ) call.

Note: This call provides no way to supply input data to a query attribute trigger.

If the attribute to be read is associated with a query trigger that requires

input data, use the sec_rgy_attr_lookup_by_id( ) call.

28.4 The Attribute Trigger Facility

Some attribute types require the support of an outside server either to verify input

attribute values or to supply output attribute values when those values are stored in an

external database. Such a server could, for example, connect a legacy registry system to

the DCE registry. The attribute trigger facility provides for automatic calls to outside

DCE servers, known as attribute triggers.

Trigger servers, which are written by application developers, export the sec_attr_trig

interface. They are invoked automatically when an attribute that has been associated

with an attribute trigger (during schema entry creation) is queried or updated. The

attribute trigger facility consists of three components:

• The attribute schema trigger ﬁelds (trig_types and trig_binding) that associate an

attribute trigger and its binding information with an attribute type. These ﬁelds are

part of the standard creation of a schema entry that deﬁnes an attribute type. See

Section 28.1.1.

• The sec_attr_trig APIs that deﬁne the query and update trigger operations. The

APIs are provided in the sec_attr_trig_*()calls.

• The user-written attribute trigger servers are independent from DCE servers. The

trigger servers implement the trigger operations for the attribute types that require

attribute trigger processing. These servers are not provided as part of DCE, but must

be written by application developers.

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