In order to create adapters that interact with a Domain Manager, it is necessary to understand how the Domain Manager is configured. The adapter creates, deletes, and interacts with instances of objects that are defined by using the MODEL language.

The MODEL language is an object-oriented language used to construct a correlation model to describe a managed domain. The language is used to define a set of classes and the attributes, relationships, and events that are associated with the classes.

Classes describe the objects that are modeled for use in a Domain Manager. Instances are specific occurrences of a class. For example, a class might describe a human and an instance of the class is someone named Bill.

Attributes describe a class and, for an instance of the class, include information about its present state. Examples of attributes include an element’s name and a counter that counts the number of packets traversing an interface.

Relationships define how instances are related to other instances. Relationships can be one-to-one, one-to-many, many-to-one, or many-to-many. When only a single instance can be related to another instance (or instances), it is a relationship. When multiple instances can be related to another instance (or instances), it is a relationshipset.

Events describe the failures that can occur for a class, the symptoms that these failures can cause, and the effect of failures.

Symptoms can be described a follows:

  • Local, meaning they are observed in the instance of the class.

  • Propagated, meaning they are observed in instances related to the failing instances.

    Once classes are specified, the model is loaded and run on a Domain Manager. Instances are created for each entity that is modeled. Each instance is associated with a class and has values for its attributes, relationships, and events.

    The models stored in a Domain Manager are static. Instances are dynamic and are stored in the repository, as shown in Domain Manager with a model and repository.

    Instances in a Domain Manager consist of a table entry and data. The table entry includes the name of each instance and its class. Each instance name must be unique. The table of names always contains an entry for the NULL object.

    The data associated with each instance includes properties such as attributes, operations, and the relationships between instances. The data also includes event information such as problems, symptoms, and events.

    The MODEL Reference Guide provides additional information about MODEL.

    Figure 1. Domain Manager with a model and repository