General

The Directory standards specify a directory information shadowing service which DSAs may support in order to replicate Directory information. This shadowing service provides a standardized mechanism whereby shadowed information can be set up and maintained between cooperating DSAs. The information to be shadowed is specified in terms of a unit of replication.

This part of ISO/IEC ISP 15125 defines a number of functional shadowing subsets to which a DSA implementation may conform. Each functional subset requires a DSA to be capable of performing shadowing to a particular level, this level being based upon the degree of refinement permitted within the specification of a unit of replication. The functional subsets can be related to either a DSA implementation operating as a supplier of shadowed information or a DSA implementation acting as a consumer of shadowed information.

This part of ISO/IEC ISP 15125 identifies the capability to handle overlapping replicated areas specified within different units of replication as a separate, optional capability which a DSA implementation may combine with support for any of the functional shadowing subsets defined.

This part of ISO/IEC ISP 15125 does not specify any requirements related to the administration, management or protocol aspects of shadowing Directory information. However, this part of ISO/IEC ISP 15125 does mandate conformance to those parts of ISO/IEC ISP 15125 which do specify such requirements, specifically, ISO/IEC ISP 15125-14 (ADY62 - Establishment and Utilisation of Shadowing Agreements) and either part 10 (ADY51 -Shadowing using ROSE) or ISO/IEC ISP 15125-11 (ADY52 - Shadowing using RTSE).

Position within the taxonomy

This part of ISO/IEC ISP 15125 is identified in ISO/IEC TR 10000-2 as ADY53 “The Directory - Shadowing Capabilities - Shadowing Subsets”.

Scenario

In the Directory, replication of information between DSAs can be achieved by use of the standardized shadowing mechanism defined in ISO/IEC 9594-9: 1995 | ITU-T X.525: 1993. A subtree of the DIT which is to be replicated is the subject of a shadowing agreement between DSAs and specified in terms of a unit of replication. A DSA which provides a unit of replication is termed a 'shadow supplier'; a DSA which receives a unit of replication is termed a 'shadow consumer' (see Figure 1).