High speed data exchange protocol for modern distributed data acquisition systems based on OPC XML-DA

The current work was inspired by the requirement to develop a data exchange protocol for the distributed data acquisition systems used for several long term experiments. These experiments have different requirements to the performance of the system, but compatibility with high level standards was a major goal for all of them. The primary objective of the project described here is to produce a universal middleware solution which can be used for almost any experiment independent of the data rates, real-time demands and metadata requirements. The opportunity to reuse software components made by scientists from different groups around the world is a great advantage of such high level design over legacy proprietary data acquisition systems. However, conformity with the high level standards, which are mainly based on XML technologies nowadays, makes it difficult to sustain high data rates required by certain installations. The paper proposes a data exchange protocol developed on top of the industry accepted OPC XML-DA and OPC complex data specifications, while acceptable performance is achieved by providing several extensions. The main attention was attended to the consistency with high level standards, multi-platform compatibility, interoperability in heterogeneous environments and high performance. The implementation of the protocol is mostly completed and first preliminary tests with benchmark results are introduced