Software Specs?
Why Bother?
Tracy Volz

Dan Wallach, an assistant professor in the Department of Computer Science, and his colleagues made national headlines last year when they published a paper describing serious security flaws and poor software engineering in the Diebold AccuVote-TS voting system. According to Wallach, “Diebold’s software specs, such as they were, were terrible, making it no surprise that their code was riddled with design flaws.”

In addition to studying computer security, Wallach also teaches Rice’s COMP 314, a course about algorithms, data structures, and software engineering. COMP 314 has always required students to write software specs before writing any actual code, but the specs were never particularly detailed or insightful. Wallach wanted to change that: “I wanted to be able to say that my own students write better specs than Diebold.”

By learning to write good specs, students think through their design decisions in advance and have fewer bugs or other surprises waiting for them later. “The sooner you start writing code, the longer it will take,” warned Edsger Dijkstra, a famous computer scientist, and that became Wallach’s motto when redesigning the ways in which COMP 314 students write specs.

To support the course’s increased emphasis on writing, Wallach sought the Cain Project’s assistance. He and his staff of TAs and labbies worked with Tracy Volz to create a new spec template.
This group began by identifying the features of good specs. Based on that list of features and the project assignment, they created a spec template that also includes annotated examples. In addition, this group revised the grading rubric to match the criteria stated in the spec guidelines. Among other requirements, COMP 314 students must now keep their specs up to date as their implementation changes. “If your specs differ from your code, then both are wrong,” emphasized Wallach.

After the students’ first projects had been submitted, Wallach led a class discussion and asked for feedback about the project, in particular the usefulness of the new spec requirements. He was excited because students reported that, while the specs were difficult to write, they noticed it was far easier than they expected to finish the project. Said Wallach, “You could see the light bulbs turning on over my students’ heads.”

The students weren’t the only ones to find the new spec template helpful in streamlining their workload; the course TAs and labbies also remarked that grading the first project was much easier this year than it had been in the past. They described the improvement in students’ analysis, organization, and presentation of specs as “amazing” and “stunning.”

To view the spec template and revised grading rubric, visit:

http://www.owlnet.rice.edu/~comp314/05spring/Project1/specguide.html

http://www.owlnet.rice.edu/~comp314/05spring/project-grading.html

 

Tracy Volz, PhD, has worked with several faculty in Comp Sci over the course of five years to enhance their students’ communication skills.