Using XML with Legacy Business Applications

COM Classes and Data Types for C++

This is a brief list of the nonnative C++ COM data types and helper classes you are likely to have to deal with when using MSXML.

• VARIANT, encapsulated as a COM helper class in C++ as _variant_t: This data type is the most awkward. It's a structure with several fields. The first one is a VARTYPE that specifies the type of VARIANT, that is, the data type of the data stored in the VARIANT. The last one is a union of several field types that contains the value of the VARIANT. There are only a few DOM methods that use a VARIANT, and for each I show how to set up the VARIANT.

• BSTR Binary String data type, encapsulated as a COM helper class in C++ as _bstr_t: COM uses this in several places, but we mostly use it ...