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 Attribute Schema.
· 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.
More:
Defining an Attribute Trigger/Attribute Association
Access Control on Attributes with Triggers