An administrative procedure, which is merely a set of information that documents the way in which a task must be performed, may also be regarded as a procedural entity that may be encapsulated in an application object. Such an application object typically contains a small number of methods, and may possibly contain only one.
In the case of an object that contains only a single method and merely accepts data from a calling application object rather than possessing data objects of its own, the object may be regarded as simply a method rather than an application object in its own right. Where it is desirable to invoke the procedure from a number of applications, the procedure may be placed in a separate executable module and dynamically bound to its calling applications, thereby maintaining independence of the procedure from the applications.
A message is passed to the application object identifying the action to be performed and providing the necessary input data. The application object will then typically carry out a modal dialog (or possibly a series of dialogs) with the end user to obtain any further information, leading the user through the necessary steps in the required order. When the procedure has been completed, the application object terminates the dialog and possibly passes a message to its caller or to another application object, containing an acknowledgement of completion, or information collected during the procedure. Where completion of a method is mandatory to correct execution of the application, this acknowledgement of completion provides a useful mechanism for the caller to determine that the method has been successfully executed.
If such procedures are correctly defined at a generic level (for example, Enter the customer data), their application objects may be stored in a library and used by multiple applications. More complex procedures may be constructed within an application by invoking a number of such application objects in sequence. Acknowledgement messages from the application objects can be used to verify that the required steps have taken place.
Thus it can be seen that the object-oriented paradigm, when the definition of a data object is sufficiently expanded to include all types of logical entity, and when properly applied with correctly designed application objects obeying the aforementioned rules and guidelines, is generally applicable to almost all applications. A wide variety of applications may therefore achieve the modularization and reusability benefits afforded by an object-oriented design approach.