Many organizations have large values invested in computer software. The task of integrating these legacy systems with new technology and system architectures can often be formidable. The object-oriented approach we present in this chapter offers a convenient short-cut for integrating legacy systems into a security framework. The idea is to turn an existing application into an object that can interact with other objects in the architecture.
Figure 3.4: Encapsulation of legacy system
Figure 3.4 illustrates the principle for encapsulating a legacy system into an object. A wrapper software is written that outwardly has an object interface corresponding to the services offered by the legacy system. Internally, the wrapper object maps calls to the the object interface to the corresponding access to the legacy system. Output from the legacy system is likewise repackaged to fit the object-oriented paradigm. The main advantage of this approach is that the system being encapsulated needs not to be changed.