In this chapter we have presented an object-oriented architecture for a secure distributed system. Our high-level design shows how standardized or standard-based components can be used together to form a comprehensive system. The example also demonstrates to some extent the complexity inherent in the task of creating a secure and also usable distributed system architecture.
The object-oriented approach can be of great importance for existing applications. A common method for modernizing and adding new functionality to old and established applications, without the need for overly much modifying the base application itself, is to encapsulate the entire application into an object. The object interface can provide methods for all of the old functionality as well as for new additions. An application that has been encapsulated in this way can then be directly ``plugged in'' into the infrastructure architecture we have presented here.