CGNS/MLL - C and Fortran APIs for Applications

The Mid-Level Library (aka MLL) is an example implementation of the CGNS/HDF5 file mapping providing both a C and a Fortran API.

CGNS Mid-Level Library (MLL)

This document outlines a CGNS library designed to ease the implementation of CGNS by providing developers with a collection of handy I/O functions. Since knowledge of the database manager and file structure is not required to use this library, it greatly facilitates the task of interfacing with CGNS.

The CGNS Mid-Level Library (aka MLL) is based on the SIDS File Mapping. It allows reading and writing all of the information described in that manual, including grid coordinates, block interfaces, flow solutions, and boundary conditions. Using the mid-level library functions ensures efficient communication between the user application and the internal representation of the CGNS data.

It is assumed that the reader is familiar with the information in the CGNS Standard Interface Data Structures (SIDS), as well as SIDS File Mapping. The reader is also strongly encouraged to read the User’s Guide to CGNS, which contains coding examples using the Mid-Level Library to write and read simple files containing CGNS databases. The Mid-Level Library (aka MLL) is an example implementation of the CGNS/HDF5 file mapping providing both a C and a Fortran APIs.

CGNS Parallel Mid-Level Library

The Parallel Mid-level Library (aka PMLL) is an extension of the CGNS/MLL C and Fortran API that enables parallel-aware file mapping.

Special Thanks

Diane Poirier of ICEM CFD Engineering originally wrote this document for the CGNS Project Group.