The Basic Concepts

The Basic Concepts behind Nexus

This section gives an rough overview over the Nexus file format and how its components are mapped onto C++ classes. Clearly, this is not a full description of Nexus. For more detailed information see the Nexus web site.

Low level objects

Nexus organizes data in a tree like structure within a single file. The concept is pretty much the same as for HDF5. For those not familiar with HDF5 think about a file-system. Data is stored in fields which can be imagined as multidimensional arrays where all elements share the same data-type. In the file-system picture such a field would correspond to a file and in the HDF5 world it would be a dataset. The fields are organized within groups which can be imagined as directories (if you like file-systems) or - well - as a group from an HDF5 programmers point of view. It is possible to create symbolic links between objects within a single file or even between objects in different files.
Thus groups and fields are the most important objects in the Nexus world.
Attributes can be attached to these objects to store some metadata.

To be finished ...