Data Transformation Engine Type Designer Reference Guide

Type Designer Reference Guide
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Chapter 12 - Error Detection and
Recovery
This chapter explains how errors are detected in your data and how to recover
from these errors.
Error Detection
During map execution, the input data is compared to the data definition in the
type tree. If the data does not match the definition, it is invalid or "in error".
To validate a data object as belonging to a certain type, the data must be
matched to its type definition. For data to be valid, the following must be true:
♦ The data must have the properties defined in the Properties window.
♦ If the type is an item that has restrictions, the data object must match one of
the restrictions.
♦ If the type is a group, the components of the data object must match those
defined in the group window, and each component rule must evaluate to TRUE
at map execution time.
Ultimately, all data objects, no matter how complex, consists of items, because
items represent the smallest unit of data. When all of the items that collectively
comprise a component are found, the component has been "found."
When executing a map, invalid data is recorded in the trace file. You can decide
what you want the system to do when errors are encountered: you can map the
errors to an output and also have the system ignore invalid data. For methods on
ignoring invalid data, see the section Restart Attribute.
How Error Detection Works
When data is validated, the system may encounter data that does not match its
type definition. A combination of how that type is defined and what data shows up
determines what happens next. As data is validated, the system tracks valid data
objects, data objects that exist but are in error, and data that cannot be
recognized as belonging to any type.
If a data object is valid, the information is recorded, as needed, and validation
continues.