Software Evolution [HOT]

Software evolution is the continual development of a piece of software after its initial release to address changing stakeholder and/or market requirements. Software evolution is important because organizations invest large amounts of money in their software and are completely dependent on this software. Software evolution helps software adapt to changing businesses requirements, fix defects, and integrate with other changing systems in a software system environment.

Software Evolution

Fred Brooks, in his key book The Mythical Man-Month,[1] states that over 90% of the costs of a typical system arise in the maintenance phase, and that any successful piece of software will inevitably be maintained.

Software technologies will continue to develop. These changes will require new laws and theories to be created and justified. Some models as well would require additional aspects in developing future programs. Innovations and improvements do increase unexpected form of software development. The maintenance issues also would probably change as to adapt to the evolution of the future software. Software processes are themselves evolving, after going through learning and refinements, it is always improve their efficiency and effectiveness.[2]

The need for software evolution comes from the fact that no one is able to predict how user requirements will evolve a priori .[3] In other words, the existing systems are never complete and continue to evolve.[4] As they evolve, the complexity of the systems will grow unless there is a better solution available to solve these issues. The main objectives of software evolution are ensuring functional relevance, reliability and flexibility of the system. Software evolution can be fully manual (based on changes by software engineers), partially automated (e.g. using refactoring tools) or fully automated.

E.B. Swanson initially identified the three categories of maintenance: corrective, adaptive, and perfective. Four categories of software were then catalogued by Lientz and Swanson (1980).[5]These have since been updated and normalized internationally in the ISO/IEC 14764:2006:[6]

Current trends and practices are projected forward using a new model of software evolution called the staged model.[14] Staged model was introduced to replace conventional analysis which is less suitable for modern software development is rapid changing due to its difficulties of hard to contribute in software evolution. There are five distinct stages contribute in simple staged model (Initial development, Evolution, Servicing, Phase-out, and Close-down).

Prof. Meir M. Lehman, who worked at Imperial College London from 1972 to 2002, and his colleagues have identified a set of behaviours in the evolution of proprietary software. These behaviours (or observations) are known as Lehman's Laws. He refers to E-type systems as ones that arewritten to perform some real-world activity. The behavior of such systems is strongly linked to the environment in which it runs, and such a system needs to adapt to varying requirements and circumstances in that environment. The eight laws are:

The laws predict that the need for functional change in a software system is inevitable, and not a consequence of incomplete or incorrect analysis of requirements or bad programming. They state that there are limits to what a software development team can achieve in terms of safely implementing changes and new functionality.

The "global process" that is made by the many stakeholders (e.g. developers, users, their managers) has many feedback loops. The evolution speed is a function of the feedback loop structure and other characteristics of the global system. Process simulation techniques, such as system dynamics can be useful in understanding and managing such global process.

Software evolution is not likely to be Darwinian, Lamarckian or Baldwinian, but an important phenomenon on its own. Given the increasing dependence on software at all levels of society and economy, the successful evolution of software is becoming increasingly critical. This is an important topic of research that hasn't received much attention.

Software Evolution is a term which refers to the process of developing software initially, then timely updating it for various reasons, i.e., to add new features or to remove obsolete functionalities etc. The evolution process includes fundamental activities of change analysis, release planning, system implementation and releasing a system to customers.

The cost and impact of these changes are accessed to see how much system is affected by the change and how much it might cost to implement the change. If the proposed changes are accepted, a new release of the software system is planned. During release planning, all the proposed changes (fault repair, adaptation, and new functionality) are considered.

b) Environment change: As the working environment changes the things(tools) that enable us to work in that environment also changes proportionally same happens in the software world as the working environment changes then, the organizations need reintroduction of old software with updated features and functionality to adapt the new environment.

c) Errors and bugs: As the age of the deployed software within an organization increases their preciseness or impeccability decrease and the efficiency to bear the increasing complexity workload also continually degrades. So, in that case, it becomes necessary to avoid use of obsolete and aged software. All such obsolete Softwares need to undergo the evolution process in order to become robust as per the workload complexity of the current environment.

e) For having new functionality and features: In order to increase the performance and fast data processing and other functionalities, an organization need to continuously evolute the software throughout its life cycle so that stakeholders & clients of the product could work efficiently.

Software is more than just a program code. A program is an executable code, which serves some computational purpose. Software is considered to be collection of executable programming code, associated libraries and documentations. Software, when made for a specific requirement is called software product.

Software engineering is an engineering branch associated with development of software product using well-defined scientific principles, methods and procedures. The outcome of software engineering is an efficient and reliable software product.

The process of developing a software product using software engineering principles and methods is referred to as software evolution. This includes the initial development of software and its maintenance and updates, till desired software product is developed, which satisfies the expected requirements.

Evolution starts from the requirement gathering process. After which developers create a prototype of the intended software and show it to the users to get their feedback at the early stage of software product development. The users suggest changes, on which several consecutive updates and maintenance keep on changing too. This process changes to the original software, till the desired software is accomplished.

Even after the user has desired software in hand, the advancing technology and the changing requirements force the software product to change accordingly. Re-creating software from scratch and to go one-on-one with requirement is not feasible. The only feasible and economical solution is to update the existing software so that it matches the latest requirements.

Software paradigms refer to the methods and steps, which are taken while designing the software. There are many methods proposed and are in work today, but we need to see where in the software engineering these paradigms stand. These can be combined into various categories, though each of them is contained in one another:

Software has become omnipresent and vital in our information-based society, so all software producers should assume responsibility for its reliability. While "reliable" originally assumed implementations that were effective and mainly error-free, additional issues like adaptability and maintainability have gained equal importance recently. For example, the 2004 ACM/IEEE Software Engineering Curriculum Guidelines list software evolution as one of ten key areas of software engineering education.

Combining all these features, this book is the indispensable source for researchers and professionals looking for an introduction and comprehensive overview of the state of the art. In addition, it is an ideal basis for an advanced course on software evolution.

"I liked this book very much. The editors have done an excellent job of gathering well written chapters from leading researchers in the field of software evolution, and editing them into a coherent volume that is timely and valuable. The topics are well chosen to cover a range of both established and novel research ideas. The organization is intelligent, allowing readers to pick and choose topics of particular interest to them. I especially like how accessible the material is to non-experts: ideas are carefully explained before being expounded upon (see, for example, the chapter on aspect-oriented software development). I certainly learned a lot reading this book, and I look forward to using it the next time I teach a graduate seminar in software evolution." - Michael Godfrey, University of Waterloo, Waterloo, ON, Canada

"Software evolution is an important field for both software engineering practitioners and researchers. This book gives an excellent overview of what is happening in software evolution research and where the practice of software evolution is heading. The authors addressed several research challenges that software evolution presents and described the state-of-the-art in their solution. I am convinced that both the researchers and practitioners will find this volume very insightful and useful." - Václav Rajlich, Wayne State University, Detroit, MI, USA 041b061a72