The book currently in your hands touches on a wide range of topics in the area of software product line engineering and offers unique solutions to particular problems appearing in the whole development cycle. We show how to semi-automatically derive feature models from requirements documents, dive deeper in modelling variability with a domain-specific language tailored for this purpose, and propose methodologies to develop items in a product-driven as well as in a solution-driven style. We also introduce aspects into core asset development, track changes and decisions in the development process and deal with potential conflicts and uncertainties. However, there is one thread that runs as a common theme through all chapters of this book: all the techniques and methodologies are centred around what we will call conventional software product line engineering. That means that a certain domain is analysed, and a number of components are produced, tested and later on assembled to form actual products, much like in a design–develop–compile–assemble style. It is easy to imagine how software running on modern smart phones, for instance, is developed this way. Other examples following this style can easily be found by looking around. However, the software landscape in which we are living has changed a lot in recent years. Software is no longer produced only by compiling source code, burning the final application onto a CD-ROM and delivering it to a customer. The Internet has opened the door to different styles of product delivery and consumption. Whole applications can be called by clicking a single link and a plethora of web services stands ready for delivering a wide range of functionalities never seen before.

The way of creating an application by consuming and composing services offered by different providers changes the style of application development and, therefore, also affects what we earlier called ‘traditional’ software product line engineering. For this reason new challenges will arise for SPLE that cannot be tackled by traditional solutions.