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Friday, October 10, 2014

What are some of the limitations / challenges of Adaptive Software Development (ASD)?

The Adaptive Software Development (ASD) culture is the result of efforts of Sam Bayer and Jim Highsmith in the field of rapid application development. The methodology aims at developing software that is capable of adapting continuously to the changes in the working environment. In ASD, in place of the waterfall approach, we have cycles of speculating, collaborating and learning. It is because of this dynamic cycle that the software is able to adapt to changing state of the requirements and learn through it. The cycle is very much tolerant to changes, driven by the risk, timeboxed and works in iterations.
Throughout the process the ASD life cycle remains focussed on the mission. Since adaptive software uses the information available from the environment for improving its working pattern, with the increasing complexities it becomes difficult for it to gather usable information. The effectiveness of the adaptive software development is reduced by the complexities of the environment. Today we expect more from the software and in such critical situations in which we never expected earlier. Thus complex environments pose a great challenge. There are three dimensions that contribute to this complexity:
> Increasing number of users: Now not only professionals, everyone uses software.
> Increasing number of systems: More number of systems means more number of interactions between them. Most of the system networks that we have now are heterogeneous. Maintaining homogeneous networks is easy.
> Increasing number of resources and goals: The most common trade off that programmers make is between time and space. Now there are several other things to worry about including security, bandwidth, money, quality, resolution and so on.

These three dimensions make it even hard for the designers to design a system. It is impossible to predict about these factors and therefore always right decisions can’t be made. This results in a product with a short lifetime. Every now and then upgrades will be required for modifying the software. Other factors related to complex environment that pose a challenge for adaptive software are:
> uncertainty
> hidden inputs
> non – deterministic
> unique
> continuity
> real world

Other things that put limitations on adaptive software development are following 4 myths:
> The traditional belief is that the specifications must be determined first. But this is not the case always. One specification can be taken at a time and refined in later stages. The aim should be combining several components together successfully and not developing a single app.
> People usually believe by maintenance that program code has degraded. The truth is that it remains the same while its environment changes. So maintenance involves evolution of the code to satisfy these changing needs. When programmers view this through a maintenance perspective, they tend to preserve the old program structure.
> It is undeniable that abstraction has an important role to play in the development process. But when we treat a process as a black box object we are actually ignoring the practical problem it faces of resource usage. In adaptive software development we take a new approach called open implementation. Here the modules have two interfaces – one for input/ output and the other checking performance. These two interfaces are perpendicular to each other. ADS also adds a feedback mechanism to this orthogonal interface system making it much better.
> While designing software we consider all the possible alternatives. The desired one is kept and the others are rejected. This means that once a requirement changes, we again have to see what alternatives are available and which one can be implemented. This might require changing all of the program structure. The best thing here to be done is programming the system such that it reconfigures itself.

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