May 2002

Regular Expressions: Lua Lights up Telecom Testing

by Cameron Laird and Kathryn Soraiz

The folks at Tollgrade Communications, Inc., "get" scripting. Support staffers do it; field engineers do it; even salesmen can do it. Developers certainly do it. Nearly everybody at this telecom specialist occasionally finds advantages in customizing the basic action of the company's products with a few extra executable lines.

That, of course, is one of the advantages available to those who embed scripting engines in their applications. Tollgrade develops test equipment for the telecommunications industry, particularly for testing telephone lines. As Tollgrade's Director of Software Development, Todd Wade, explains, Tollgrade's varied line generally bundles an embedded processor (a central processing unit and digital signal processor) with a specialized operating system and a specific application. In recent years, Wade and his colleagues have also made a point of exposing a scripting interface to the applications.

Their original motivation was the classic "software engineering" one: the proliferation of products spawned a parallel proliferation of software applications. Each had so much custom code that only the one or two original authors could effectively maintain the applications. Departure of one employee might lead to a crisis in management of all the products using software written by that employee. In Wade's words, "Thus began our search for techniques that would allow us to share more code between products and provide common development methodologies."

Domain-Specific Library Plus Scripting

The first step toward a solution was the creation of a toolkit, or library of abstract functionality, available on all platforms. This was largely achieved by late 1999 and unified peculiarities of memory management, process control, file-system organization, and so on.