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... to the homepage of OCoN-Framework 2004.

State-based services appear in many of todays distributed environments. Interfaces of state-based services contain information about invokable methods, the possible states of implementations and the transitions between these states via method-invocations. Their description can be seen as an enhancement of interfaces known from broadly used programming languages like Java. Depending on the current state of a particular service not all methods are usable for its clients. Consequently it has to be ensured that a service is in a proper state before a client can invoke a method. Current middleware implementations cannot ensure that state-based services are used according to their specification. This can lead to faulty use of services and unexpected effects.

The OCoN-Framework provides an environment, with which a scheduling system for state-based services can be established. A system based on the framework ensures a high degree of fault-tolerance via replication of the internal components. Moreover it is self administrating by means of allocation of instantiation and destruction of components on dedicated hosts. Load balancing is adressed for the internal components by distribution of scheduling-workload to multiple nodes. For clients the framework schedules requests to services which meet their particular needs. The requirements of a client can be specified in addition to the pure interface desired. This leads to an abstraction from concrete instances of services.
For the development of services and clients the framework provides a Java-API which abstracts from the underlying middleware.

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Developers

• Jens Bruhn
• Sven Kaffille

If you are interested in copy of the software please contact the developers per e-mail.