An XVCL approach to handling variants: a KWIC product line example

We developed XVCL (XML-based variant configuration language), a method and tool for product lines, to facilitate handling variants in reusable software assets (such as architecture, code components or UML models). XVCL is a newer version of Bassett´s frames (1997), a technology that has achieved substantial productivity improvements in large data processing product lines written in COBOL. Despite its simplicity, XVCL can effectively manage a wide range of product line variants from a compact base of meta-components, structured for effective reuse. We applied XVCL in two medium-size product line projects and a number of smaller case studies. We communicate XVCL´s capabilities to support product lines by means of a simple, but still interesting, example of the KWIC system introduced by Parnas in 1970´s. We show how we can handle functional variants, variant design decisions and implementation-level variants in a generic KWIC system.