AntiPatterns identify mistakes committed in software development and offer the right solutions, writes Dr R Srinivasan

IN software development a single design occurrence is an event; two of them are a coincidence and three occurrences lead to a 'pattern'. We mentioned that if we do not study Design Patterns, we will not be able to improve them and hence it will be very difficult to come up with an improved version in future. However, Thomas Mowbray and Rapheal Malveau in their book, 'Software Architecture Bootcamp' point out that Design Patterns have more stringent requirements for documenting knowledge while they should represent proven solutions, not merely wishful thinking about how software development should be done. We may wonder about such comments particularly after describing the advantages of following the philosophy of pattern-oriented software design. The reason is that Patterns illustrate the cases only from successful projects where nothing is brought out on the cases of patterns of failures. As Jim Coplein says, it is useful and very important to show the presence of Patterns in unsuccessful systems also. Moreover, Design Patterns start with a lengthy discussion on the situation, context and forces that lead to a unique solution. We have mentioned in an earlier article that there is no steady state in software development and so no classroom lecture or seminar or books can define many variables that exist for any given time. In practice we find that the books on Software Engineering do not and cannot say, "What do I do when something goes wrong and how to avoid this problem in future". It is therefore essential that we should be able to track the results of negative solutions thereby making us aware of what does not work. The identification of what to avoid is a critical factor in successful software development. This is where another approach called AntiPatterns is introduced. AntiPatterns represent the latest concept in a series of revolutionary changes in software development.

AntiPatterns start with situations that occur in practice and highlight the potential consequences leading to intriguing situations instead of abstract forces as in the case of Patterns. AntiPatterns will lead us to identify mistakes committed in software development. By elaborating the symptoms and consequences of implementing the bad solution. AntiPatterns will offer a re-factored solution for the successful software development. To quote Brown, et. al from their book 'AntiPatterns - Refactoring Software, Architectures and Projects in Crisis', while Patterns help us to identify and implement procedures, designs and codes that work, AntiPatterns do the exact opposite; they let you zero in on the development detonators, architectural tripwires, and personality booby traps that can spell doom for the project. AntiPatterns will also be able to identify the so-called good solutions applied under the wrong context or situation. Thus AntiPatterns may be considered to be a fall out of Patterns, focussing on the wide and ever growing occurrence of repeated software failures in the effort to understand, prevent and recover from the failures. By making use of the proper tools in this new methodology, a welcome service to the software industry emanates because AntiPatterns will effectively describe measures to be deployed at every stage of software development like design, execution and management.

A question may arise in the minds of many software developers and project managers whether such topics and new methodologies like AntiPatterns are essential to take note of and follow. The answer is an absolute yes, because of the following reasons: in the real world we have been witnessing bad software designs, wrong decisions by the managers, inadequate test procedures, noncompliance to quality aspects, etc. Consistent reasons, common misunderstanding of the context and classic mistakes lead to bad designs and bad software. Through AntiPatterns we will be able to identify the reasons for such mistakes and failures on time to prevent serious consequences. It is possible to unearth the truth about deficiencies of commercial off the shelf methods that may be infected with defects, contradictions, and false promises. AntiPatterns will pave the way for explaining how a software project should be executed and warn against negative software practices with respect to change management, etc.

So to summarize, AntiPatterns will describe the proper measures to be taken in software development and like their design counterparts, they provide the industry vocabulary for the commonly occurring defective processes and implementations. Once an AntiPattern is correctly identified, we can derive refactored solution to make the project become successful. We will discuss different classifications of AntiPatterns in the next few issues.

(To be continued)

(The author is Chief Technology Officer, Internet Component Management Group, Bangalore and can be contacted at: r.srinivasan@iCMGworld.com)