The <PROCNAME> method accesses input and output parameters using two parameter arrays, and that each array element is of the TINFParam datatype. The TINFParam datatype is a C++ class that serves as a “variant” data structure that can hold any of the Informatica internal datatypes. The actual data in a parameter of type TINFParam* is accessed through member functions of the form Get<Type> and Set<Type>, where <Type> is one of the Informatica internal datatypes. TINFParam also has methods for getting and setting the indicator for each parameter.
You are responsible for checking these indicators on entry to the external procedure and for setting them on exit. On entry, the indicators of all output parameters are explicitly set to INF_SQL_DATA_NULL, so if you do not reset these indicators before returning from the external procedure, you will just get NULLs for all the output parameters. The TINFParam class also supports functions for obtaining the metadata for a particular parameter. For a complete description of all the member functions of the TINFParam class, see the infemdef.h include file in the tx/include directory.
One of the main advantages of Informatica external procedures over COM external procedures is that Informatica external procedures directly support indicator manipulation. That is, you can check an input parameter to see if it is NULL, and you can set an output parameter to NULL. COM provides no indicator support. Consequently, if a row entering a COM-style external procedure has any NULLs in it, the row cannot be processed. Use the default value facility in the Designer to overcome this shortcoming. However, it is not possible to pass NULLs out of a COM function.