A modeling toolset for the analysis and design of OSI network management objects - HP's OpenView GDMO Modeling Toolset network design software, Open System Interconnection - includes partial GDMO definition for a Unix password file - Product Information

Hewlett-Packard Journal, Oct, 1996 by Jacqueline A. Bray

Two useful features for cross-reference checking the object model are the Viewpoint and Inherited Characteristics options. Clicking the Viewpoint button, available on all template and Viewpoint windows, displays the viewpoint for a selected item. In the Viewpoint of Managed Object Class window in Fig. 4, the selected object is represented by the vertical bar, the templates on the left reference the selected object, and the templates on the right are referenced by the selected object The boxes on either side of the vertical bar contain the appropriate GDMO keywords. Above each template name is the template type (e.g., MOC (managed object class), PKG (package), etc.). The Viewpoint window is helpful when making changes to an object to verify that those changes will not adversely affect other objects that are dependent upon it.

Clicking Views and then the Inherited Characteristics button, available only on managed object class template windows, displays the window shown in Fig. 5. The characteristics available to a managed object class, whether specialized in that object class definition or inherited from an ancestor, can be displayed by selecting the characteristics of interest (Attributes, Notifications, etc.) from the row of buttons under Characteristics to Display and then clicking Compute. The scrolled window lists all of the inherited characteristics available and where they were referenced. Clicking on a characteristic and then the Details button displays its template.

The graphs available in the GDMO toolset represent three distinct and independent tree structures used in OSI system management. These graphs are the inheritance graph, the registration graph, and the name binding graph. The inheritance graph (Fig. 6) shows the inheritance hierarchy of all the managed object classes in a selected GDMO document, along with any superclasses derived from other documents. (All of the tool windows handle referencing across documents. When a template is referenced from another document, the template is prefaced with the document alias.) Object class nodes can also be added or deleted on this graph. GDMO and the GDMO toolset both support multiple inheritance, which allows classes to inherit properties from more than one superclass.

The registration graph (Fig. 7) shows part of the registration tree of object identifiers defined in ITU-T Recommendation X.721.4 An object identifier is a unique ASN.1 data type that is a sequence of nonnegative integers representing a particular object. GDMO describes the registration tree structure adopted in the OSI system management standards for allocating globally unique identifiers to components of managed object definitions.(5) Objects can be registered via the registration browser or the registration tree. Registration is typically done in the last phase of GDMO modeling, when document definitions are stable.

The name binding graph (Fig. 8) displays the containment relationships defined via the name binding template. The name binding template specifies a subordinate (contained) object and a superior (containing) object, along with an attribute of the subordinate object that will be used to name instances of that class. The name binding template also specifies whether object instances can be created and deleted via remote management, along with any limitations on those actions. For example, it may specify that an object instance can be deleted via remote management, but only if that object instance does not contain other objects. This containment hierarchy represents the structure of the Management Information Base (MIB). It shows the objects an agent contains and the hierarchy and containment of those objects, which are used not only to define the MIB structure but also as a means of unambiguously referencing object instances.(6)