This chapter's case study will look at some ways that we can find – and help the users fix – potential problems with the data or the application's computations. Both the data and the processing are possible sources of exceptional behavior. They aren't, however, equivalent; we can compare the two as follows:
- Exceptional data is the most common source of problems. The data may not follow the syntax rules and have an invalid physical format. Other, more minor errors may stem from data not having a recognized logical organization, for example wrong spelling of column names. Exceptions can also reflect users attempting to perform an unauthorized operation. We need to alert users and administrators of invalid data or invalid operations.
- Exceptional processing is what is commonly called a bug. An application shouldn't try to recover from these problems. While we prefer to find them as part of unit or integration...