Strategic research directions in object-oriented programming

This report is an overview of the eld of object oriented programming. It presents a brief historical perspective of the eld, then summarizes some major achievements. Four strategic research directions are then presented: technologiesintegration,software components, distributedprogramming, and open implementations. Object-oriented programming (OOP) is a technique for improving productivity, quality, and innovation in software development. Whereas procedures are sequences of statements that specify a transformation from inputs to outputs, objects are collections of operations sharing a state that provide persistent services over time. A procedure-oriented system consists of sequentially executed procedures, while an object-oriented system consists of a collection of interacting objects. Procedures express algorithms that implement computable functions, while objects express embedded systems that implement services over time, like banking or airline-reservation applications. Objects typically possess mutable state, operations that change their state, and operations that cause them to in turn invoke operations on other objects. Operations may be described through a well deened interface providing information about attributes and actions visible from clients. The implementation of each object is encapsulated { hidden from clients of the object. Object-oriented programming is about modeling, reusability, and integration: it provides modeling primitives, a framework for high-level reusability, and integrating mechanisms for organizing knowledge about application domains. |Modeling OOP reeects the structure of the application domain by the structure of the program, because there is a direct one-to-one correspondence between objects of the application domain and objects of the computational model. Its concepts of class, subclass, inheritance, and virtual function allow structure at the level of primitive components to be extended to structure at the level of concepts, classiication, and composition. If the application domain is the department of 1 The contributors to this report are