Machine experiments often require the saving of a lagre amount of data to file. While an ASCII format is easy to implement and read later on for analysis purposes, it is time and disk space consuming. Especially timing concers lead to the decision, that FESA classes should write data to files in binary format. There are already standard libraries like HDF5 especially for C/C++. However, they are often large and hide the implementation / file format from the user. While this is in general good, it is required that the data written can be read by Java clients and recently also by Python scripts. As the requirements are simple, it was decided to implement a simple tagged file format in self writte libraries. Due to the applications the C++ library is best tested for writing and is currently the only library implementing writing. The Java and Python library currently only implement reading binary files.

The library source code for C++, Java and Python and a generic BDIO file explorer can be checked out from subversion: https://www-acc.gsi.de/svn/sd/bdio

• Initial design note (2012-04-24)
• Format of the binary files