Continuously Align Software to Be Reusable

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The oft cited reason for not being able to build reusable software is the lack of time in the development process. Agility and refactoring are your friends for reuse. Take a pragmatic approach to the reuse effort and you will increase the odds of success considerably. The strategy that I have used with building reusable software is to pursue continuous alignment. What exactly is continuous alignment?

The idea of continuous alignment is very simple: Place value on making software assets reusable continuously. Pursue this across every iteration, every release, and every project. You may not make many assets reusable on day one, and that is perfectly okay. The key thing is to align software assets closer and closer to a reusable state using relentless refactoring and code reviews. Do this often and over a period of time you will transform your codebase.

You start by aligning requirements with reusable assets and do so across development iterations. Your iteration has tangible features that are being implemented. They become much more effective if they are aligned with your overall vision. This isn't meant to make every feature reusable or every iteration produce reusable assets. You want to do just the opposite. Continuous alignment accepts that building reusable software is hard, takes time, and is iterative. You can try to fight that and attempt to produce perfectly reusable software first time. But this will not only add needless complexity, it will also needlessly increase schedule risk for projects. Instead, align assets towards reuse slowly, on demand, and in alignment with business needs.

A simple example will make this approach more concrete. Say you have a piece of code that accesses a legacy database to fetch customer email addresses and send email messages. The logic for accessing the legacy database is interspersed with the code that sends emails. Say there is a new business requirement to display customer email data on a web application. Your initial implementation can't reuse existing code to access customer data from the legacy system. The refactoring effort required will be too high and there isn't enough time to pursue that option. In a subsequent iteration you can refactor the email code to create two new components: One that fetches customer data and another that sends email messages. This refactored customer data component is now available for reuse with the web application. This change can be made in one, two, or many iterations. If you cannot get it done, you can include it to on your list of known outstanding refactorings along with existing tasks. When the next project comes around and you get a requirement to access additional customer data from the web application, you can work on the outstanding refactoring.

This strategy can be used when refactoring existing code, wrapping legacy service capabilities, or building a new asset's features iteratively. The fundamental idea remains the same: Align project backlog and refactorings with reuse objectives. This won't always be possible and that is OK! Agile practices advocate exploration and alignment rather than prediction and certainty. Continuous alignment simply extends these ideas for implementing reusable assets.


by Vijay Narayanan

This work is licensed under a Creative Commons Attribution 3

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