The NIST EXPRESS Toolkit - Lessons Learned
Don Libes, Steve Clark · 1992
In 1990, NIST released a software toolkit for building EXPRESS-related tools. The software was based on early drafts of EXPRESS and included a parser, a resolver, and a framework for producing schema-independent tools. During the past year, we have redesigned the toolkit with respect to user experience and the EXPRESS Draft International Standard. Our work will be of interest to implementors of EXPRESS tools and toolkits. This paper describes our work and the current state of the NIST EXPRESS toolkit. As well as describing our efforts in improving the toolkit performance, we will comment on: • the “hard ” parts of implementing the EXPRESS language, • things we did wrong, • several implementation-dependent extensions to EXPRESS, • sophisticated error and warning detection. We will also revisit our original ideas underlying the toolkit concept. We will discuss whether, in light of our experiences, the concepts still make sense, can be amended, or should be entirely scrapped.