Droplets Breaking Monolithic Applications Apart.pdfVIP

Page 1 Droplets: Breaking Monolithic Applications Apart Luca Deri, IBM Zurich Research Laboratory 1 Most current systems are built around a monolithic structure that integrates all the services offered. Such a paradigm has been used for many years and is now proving to have many limitations. This is partly because, with the advent of distributed systems, there is a need to distribute the intelligence and control among applications and network entities. Also due to heterogeneous data or systems that an application has to manage, it costs too much to rebuild the application every time a new service has to be supported. It would be better to add such services while the application is running. This paper attempts to show the benefits of a component-based application against a monolithic one and it introduces a new type of software components, called droplets based on dynamically loadable libraries. Droplets are used to implement selected application services and have the ability to be modified or added to the application while it is running, thus allowing to dynamically modify the application behavior or to extend its functionality at runtime. Finally the paper shows how to design and implement droplet-based applications and demonstrates how the droplet paradigm has been successfully integrated in an existing commercial application. Keywords: Software Components, Object-Oriented Programming (C++), Distributed Applications, Shared Libraries. 1. Introduction The traditional object-oriented (OO) programming vision is a bit vague on the subject of reuse. In a growing and changing world, our diverse and complex needs often vary from day to day, project to project, and role to role. Developers are supposed to write classes that may be reused in other applications, projects and platforms. Most object-oriented languages lack the means of packages that are containers for source files defining a certain entity such as a class, and often objects are distributed in binary form and