Maybe my understanding of agile development isn't as good as it should be, but I'm curious how an agile developer would potentially use off-the-shelf (OTS) software when the requirements and knowledge of what the final system should be are changing as rapidly as I understand them to (often after each iteration of development).
I see two situations that are of particular interest to me:
(1) An OTS system meets the initial set of requirements with little to no modification, other than potential integration into an existing system. However, within a few iterations of development, this system no longer meets the needs without rewriting the core code. The developers must choose to either spend additional time learning the core code behind this OTS software or throw it away and build from scratch. Either would have a drastic impact on development time and project cost.
(2) The initial needs are not like any existing OTS system available, however, in the end when the customer accepts the product, it ends up being much like existing solutions due to requirement additions and subtractions. If the developers had more requirements and spent more time working on them up front, this solution could have been used instead of building again. The project was delivered, but later and at a higher cost than necessary.
As a software engineer, part of my responsibilities (as I have been taught), are to deliver high-quality software to the customer on time at the lowest possible cost (among other things). Agile development allows for high-quality software, but in some cases, it might not be apparent that there are better alternatives until it is too late and too much money has been spent.
My questions are:
This can occur regardless off the OTS nature of the component. Agile does not mean near-sighted.. you'd need to know the big chunks.. the framework bits and spend thinking time on it beforehand. That said, you can only build to what you know .. Delay only till the last responsible moment.Then you need to pick one of the alternatives and start on it. (I'd Avoid third party application unless the cost of developing it in-house is infeasible.. but that's just me). Prototype multiple solutions to check feasibility with list of known requirements. Keep things loosely coupled (replacable), easy to change and full tested. If you reach the fork of keep hacking or rewrite, you'd need to think of which has better value for the business and pick that option. It's comes down 'Now that we're here, what's the best we can do now?'
This can happen although the chances are slim compared to the team spending 2-3 months trying to get the requirements 'finalized' only to find that the market needs or customer minds have changed and 'Now we want it this way'. Once again, its a question of what is the point of time till which you are prepared to investigate and explore before committing on a path of action. Decide wisely with whatever information you have upto that point.. Hindsight is always 20-20 but the customers wont wait forever. You can't wait till the point of time where the requirements coalesce to fit a known OTS component :)
Agile says Do whatever makes sense and strip out the non-value-adding activities :) Agile is no magic bullet. just my 2 agile cents :)