Data Transformation Engine Functions and Expressions Reference Guide

Functions and Expressions Reference Guide
228
Chapter 4 - Implementing a Library
EXIT Function
This chapter provides information on how to develop a function in a library that
will be executed from an
EXIT function.
EXIT Function’s Library Interface
Library functions are used within an EXIT function using information contained in
the
EXITPARAM structure. This method provides great flexibility for data passed to
and from a map. For example, the map can pass binary data containing nulls, and
there is no limitation on the length of the returned data. The method also allows
functions to report additional information by providing a return code and error
message.
Using the EXITPARAM Structure
The Function Prototype
The function to be executed must be a function in a library with the following
prototype:
void MyFunc(LPEXITPARAM lpep);
Definition of the EXITPARAM Structure
The definition of the EXITPARAM structure is as follows:
struct tagExitParamStruct
{
DWORD dwSize;
DWORD dwToLen;
DWORD dwFromLen;
DWORD dwMapInstance;
void FAR * lpv;
LPSTR lpszCmdLine;
BYTE HUGE * lpDataToApp;
BYTE HUGE * lpDataFromApp;
UINT uRetryCount;
UINT uRetryInterval;
BOOL bRollback;