I am new STEP and Express modeling. How can I convert XML data into STEP "p21" file using C++ bindings and CAA module? Where can I find a good tutorial for the EXPRESS modeling language? If I am missing something, suggest me to learn them. I would like someone to explain me the way we do it or show some guidelines to approach the problem.
You should definitively take a look at the CAA V5 Encyclopedia. The chapter about ENOVIA V5 contains several articles such as:
STEP Overview - Understanding STEP, Express, and SDAI
Building Components - How to build an Express schema
Generating the ENOV_DATAX Data Structure - How to migrate data to ENOVIA
... as well as a few use cases and quick API reference.
Since you must use the CAA, you also have the option take a course directly from Dassault Systèmes