Web macros give web browser users ways to "program" tedious tasks, allowing those tasks to be repeated more quickly and reliably than when performed by hand. Web macros face dependability problems of their own, however: changes in websites or failure on the part of end-user programmers to anticipate possible macro behaviors can cause macros to act incorrectly, often in ways that are difficult to detect. We would like to provide at least some of the benefits of software engineering methodologies to the creators of web macros. To do this we adapt assertions to web-macro programming scenarios. While assertions are well-known to professional software engineers, our web macro assertions are unique in their focus on website evolution, are generated automatically, and encode the expectations and assumptions of a rapidly growing group of users who often have limited formal programming expertise. We have integrated our techniques for assertion generation and evaluation into a web macro tool, and performed an empirical study investigating its use. Our results show that the assertions can help web macro users detect macro failures and correct macro faults.

Abstract

End-user programming tools offer no data types except "string" for many categories of data, such as person names and street addresses. Consequently, these tools cannot automatically validate or reformat these data. To address this problem, we have developed a userextensible model for string-like data. Each "tope" in this model is a user-defined abstraction that guides the interpretation of strings as a particular kind of data. Specifically, each tope implementation contains software functions for recognizing and reformatting instances of that tope's kind of data. This makes it possible at runtime to distinguish between invalid data, valid data, and questionable data that could be valid or invalid. Once identified, questionable and/or invalid data can be double-checked and possibly corrected, thereby increasing the overall reliability of the data. Valid data can be automatically reformatted to any of the formats appropriate for that kind of data. To show the general applicability of topes, we describe new features that topes have enabled us to provide in four tools.

No abstract

No abstract