A number of questions came up at the introductory Software Product Lines talk I gave at BCS SPA a couple of weeks ago. I’ve heard some of these before so perhaps it is worth recording them here:

Q1. What are the key issues in building a business case to migrate to a Software Product Line approach?

A. The Product Line Scope, i.e. what products and features your organisation will support in the Product Line, is a key decision that affects the viability and profitability of a Software Product Line. The scope decision should also be aligned to the business goals specified in the business case e.g. faster time-to-market, improved productivity etc.

Q2. How do you handle a case where refactoring a set of existing products to a Software Product Line causes a loss of capability for some customer?

A. This is a difficult situation that has to be handled sensitively. However, in a business context, the decision as to which products and features to support in the Software Product Line (the Scope), including those that are already present in existing products, should be an economic decision i.e. you should support the features that give the best return on investment (ROI).

Q3. How viable is it to continue to develop your existing products in a one-of-a-kind, isolated manner while developing your new Software Product Line?

A. It’s hard to generalise as this depends on many factors in the organisation in question, but it can be a very good approach. However, one thing you should have is a clear agreement about the conditions under which you will wind-down and eventually discontinue your one-of-a-kind development. This approach should not be used as a way of postponing or avoiding painful decisions about your organisation’s future business strategy. Deferring such discussions can be an indicator that key people have not bought into the Software Product Line approach.

Q4. Can these techniques be used where there are a hundred or so different components to be put together to build a product?

A. Yes, in fact, in the largest Software Product Lines, there are several hundred or even a thousand different components. In these cases the infrastructure and tools that underpin the Software Product Line will be highly developed.

Several more questions came up, but I didn’t have a chance to record them during the talk, so I’m afraid they are lost to posterity…