I was saddened by this proposal to make Web services portable, because it ignores our past. As Marcus Tullius Cicero put it, “a man without a knowledge of his people’s history . . . remains a child forever.”

The authors have renamed the universal computer-oriented language (UNCOL), an idea published almost 50 years ago [1], “xSL”: they note that there are a number (N) of languages for requesting Web services, and a number (M) of platforms implementing Web services. A naive approach therefore requires N×M implementations. By introducing a standard intermediate language (UNCOL, also known as xSL), this number is reduced to N+M.

This is often called the N×M translator problem, and is not as trivial as it may appear. For example, an appropriate intermediate representation is critical, and one of the most fundamental questions is whether it should be a union or an intersection language [2]. Although the authors present an overview of xSL, it is only five paragraphs long, and doesn’t address such issues. Thus, we are left with little hard data on the most important aspects of the idea.

The bulk of the paper is devoted to a reprise of the reasoning behind UNCOL, and the standard methods for implementing systems using intermediate languages. These points are well covered in the existing literature, and there is no need to repeat them here.