Environmental Models

  Simple instantiated Service Dependency Graph  [r]

Figure shows a directed graph expressing the dependencies of the objects in the scenario as described in the introduction. Its main components are the web server, both web clients, the DNS server and a generalizing object for the common communication infrastructure. The edges in the graph represent the dependencies. In the following, such models are called environmental models to stress their capability to reflect information specific to real objects in the managed IT-environment (in contrast to the abstract models explained further down). Each node represents one single or alternatively a group of real objects. Information attached to them reflects the content of traditional object related management variables. The (directed) edges represent dependencies between the nodes. For some applications of the models, undirected graphs are sufficient. For others it is useful to attach further management relevant attributes, e.g.:

If DNS in our example fails, web clients in principal are still useable by typing IP addresses. This restriction in the quality of service could be denoted as an attribute of the dependency between the clients and the DNS server.