Group, Service and Other Relationships

In addition to containment, other relationships between managed objects can be defined (e.g. IS-CONNECTED-TO, BACKS-UP, USES, etc.). Some may be symmetric, in that the relationship is the same from the viewpoint of either managed object. Others may be asymmetric where the roles of each managed object cannot be interchanged. Relationships are not limited to a pair of managed objects (one-to-one), but may also be one-to-many, many-to-one, or many-to-many. Group relationships are those that allow managed objects to be members of some particular set or grouping. That grouping may be for any management purpose, but must be defined as part of the managed object class definitions. One of the relationships mentioned above is the USES relationship. One managed object may make use of another managed object (on the same or a different OS) in order to provide its management or service providing capability. This relationship is known variously as a service relationship, a USES relationship, a client/server relationship, or a service user / service provider relationship. Service relationships are by nature asymmetric - one managed object is the service provider and the other is the service user. This gives rise to two different viewpoints on the relationship. The service user managed object knows only the characteristics of the managed object that provides the service, and not how the service is being provided (including whether the service provider in fact uses any other managed objects(s) to provide its service). On the other hand, the service provider knows hoe it is providing the service, but doesn't know about the service user, beyond its identity for security reasons. Rules for service relationships may be defined, but are limited to those aspects that are necessary for management. Other rules regarding service relationships are left up to the implementation of the underlying services.