DIM, a portable, light weight package for information publishing, data transfer and inter-process communication

摘要

The real-time systems of HEP experiments are presently highly distributed, possibly on heterogeneous CPUs. In many applications, there is an important need to make information available to a large number of other processes in a transparent way. For this purpose the "PRC-like" systems are not suitable, since most of them rely on polling from the client and one-to-one connections. DIM is a very powerful alternative to those systems. It provides a named space for processes to publish information (Publishers) and a very simple API for processes willing to use this information (Subscribers). It fully handles error recovery at the Publisher and Subscriber level, without additional software in the application. DIM is available on a large variety of platforms and operating systems with C and C++ bindings. It is presently used in several HEP experiments, while it was developed in the DELPHI experiment and is maintained at CERN. We shall present its capabilities and examples of its use in HEP experiments in domains ranging from simple data publishing to event transfer, process control or communication layer for an Experiment Control Package (SMI++). We shall also present prospectives for using it as communications layer for future experiment's control systems.