The solution development is driven by the Design Phase at the beginning of the project. The Design Phase usually results into the following documents being produced
Integration Design Document
Indicating the data flow diagram between various component of the project
Mapping Specification
Specifying data mapping rules between two data format.
Exceptional Handling Document
Its always a good idea to have a separate Exceptional Handling Document capturing how the system should behave in case of any data or transactional error