III-C Necessary Platform- and CORBA-services

 

Management platforms available on the market (e.g., IBM NetView) usually contain the following key features:

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• Topology Management: Network nodes are dynamically discovered and polled for configuration information. This information is stored in a database and a graphical view of the network topology is presented at the platform's user interface. The database can be accessed through a programming interface by management applications which want to retrieve or supply topological information. In addition to the generic discovery and status polling applications for IP networks, the Generalized Topology Manager (GTM) application collects and maintains information about ``non-IP'' nodes.
• Event Management: The platform is able to receive and process network events via SNMP (traps) and CMIP or CMOT, respectively (event reports). The platform Event Management Services (EMS) receive, filter and store the events in log files that can then be accessed by users or by applications via a programming interface. Events can be presented on the graphical user interface. The platform allows to filter events by application-defined criteria and to forward them to registered applications. This allows automatic triggering of actions in case of pre-defined network situations.
• Performance Monitoring: Network administrators can define thresholds on the attributes of managed objects. An event is generated automatically when a previously defined threshold is exceeded so that an operator or an application can be informed e.g., whenever the QoS (Quality of Service) of a network resource falls below a critical level.
• Configuration Application: The platform contains a Browser for Management Information Bases (MIBs) that can be used to query a device's configuration by reading MIB information and to configure a device remotely by modifying its MIB variables.
• Monitoring the State of Resources: All network resources are periodically polled for state changes. A change of state is visualized through a colour change of the icon which represents the resource on the graphical user interface.
• Integration of Third-Party Applications: Although state-of-the-art platforms provide a number of basic services that are needed for network management, these services can be extended by integrating additional management applications that are tailored to specific needs. Many platforms also contain a set of APIs that allow the integration of user-written applications.

The services described above fulfil basic requirements for the management of networks and computer systems. For a platform that manages CORBA objects, these services must be enhanced to support the management of distributed applications and services in addition to network resources and computers. This is due to the fact that not only the amount of fine-grained managed objects representing the application components tends to be much higher than the number of networked devices but these managed objects are extremely dynamic: The installation of new applications must be monitored and the starting and stopping of application processes must be surveyed and controlled by the managing system. This poses high requirements w.r.t. scalability.

Our work focuses on the Event and Topology Services of the platform which provide a common basis for all kinds of management services. In addition, both access and maintain the platforms' Management Information Repository. Therefore, they are the main building blocks for the development of further CORBA management services like configuration applications. The handling of events is a major aspect of resource management, especially for detecting fault situations. Since the availability of CORBA-based applications and services depends on the functionality of computer systems and network components, the application and service management may not be separated from systems and network management. Therefore, interfaces have to be developed that allow CORBA events to be received and processed by the manager in the same way as SNMP traps; they will be described in section IV-A. Topology Services manage topological relationships between managed objects. In section IV-B we will show how these generic services can be used in a straightforward manner in order to visualize the relationships between CORBA objects.