Topes: Reusable Abstractions for Validating Data

Programmers often omit input validation when inputs can appear

in many different formats or when validation criteria cannot be

precisely specified. To enable validation in these situations, we

present a new technique that puts valid inputs into a consistent

format and that identifies “questionable” inputs which might be

valid or invalid, so that these values can be double-checked by a

person or a program. Our technique relies on the concept of a

“tope”, which is an application-independent abstraction describing

how to recognize and transform values in a category of data.

We present our definition of topes and describe a development

environment that supports the implementation and use of topes.

Experiments with web application and spreadsheet data indicate

that using our technique improves the accuracy and reusability of

validation code and also improves the effectiveness of subsequent

data cleaning such as duplicate identification.