SPIDER: a schema mapPIng DEbuggeR

A schema mapping is a high-level declarative specification of how data structured under one schema, called the source schema, is to be transformed into data structured under a possibly different schema, called the target schema. We demonstrate SPIDER, a prototype tool for debugging schema mappings, where the language for specifying schema mappings is based on a widely adopted formalism. We have built SPIDER on top of a data exchange system, Clio, from IBM Almaden Research Center. At the heart of SPIDER is a data-driven facility for understanding a schema mapping through the display of routes. A route essentially describes the relationship between source and target data with the schema mapping. In this demonstration, we showcase our route engine, where we can display one or all routes starting from either source or target data, as well as the intermediary data and schema elements involved. In addition, we demonstrate "standard" debugging features for schema mappings that we have also built, such as computing and exploring routes step-by-step, stopping or pausing the computation with breakpoints, performing "guided" computation of routes by taking human input into account, as well as tracking the state of the target instance during the process of computing routes.