Transformation of data items from data sources using a transformation script

Proactive validation of transformation scripts reduces the amount of computation that is used in transforming data sources into an object model using a transformation script that initially includes bugs.The semantics, or meanings, of the various components of the object model are defined by an ontology that categorizes objects, relationships, and/or properties according to various defined types such as: person, entity, or event. In one implementation, a method is provided that includes associating, with at least one processor, the transformation script with ontology parameters. The method also includes initiating a debugging operation of the transformation script having at least one condition and importing, from a data source, at least one data item for transformation. The method further includes determining, as part of the debugging operation, whether the at least one condition that uses the at least one data item is valid based on the ontology parameters and notifying a user, on a display device, of a result associated with the determination. Proactive debugging provides validation notifications as they arise during the debugging process.