BLISS – an integrated beamline control system

In December 2015, the ESRF embarked on the development of a new beamline experiment control system, to turn a page started more than 20 years ago with SPEC [1]. This new system aims to support the EBS upgrade – a monumental leap into the fourth generation of light sources, providing an X-ray beam with 100 times more brilliance and coherence – empowering beamline scientists and ESRF users with a modern, versatile, and easy-to-use experiment control system to fully capitalise on the advantages offered by the EBS.

The new beamline control system, called BeamLine Instrumentation Support Software, or BLISS, started operation on selected beamlines in August 2020, coinciding with the EBS launch. Subsequently, BLISS has been successfully deployed on over 30 beamlines out of a total of 45, and is projected to be implemented on all beamlines by 2025.

BLISS introduces several key improvements compared to SPEC:
1.    Programming Language: BLISS utilises Python as the programming language.
2.    Data Storage: Redis serves as an in-memory database for scan data.
3.    Scan Framework: The system features a continuous scan framework.
4.    Plotting Solution: Flint is integrated as the plotting solution.
5.    Data Format: NeXus/HDF5 is adopted as the data format.
6.    Data Management: BLISS incorporates FAIR data management principles.
7.    User Interface: Daiquiri serves as the Graphical User Interface (Figure 1).

Click on image to enlarge

Fig. 1: Schematic view of the BLISS software architecture.

The adoption of Python, recognised as the de-facto standard programming language for science and AI/ML, facilitates both code customisation by scientists and the integration of code from the extensive library of scientific algorithms in Python. The continuous scanning framework enhances data acquisition speed, reducing dead time to maximise utilisation of the EBS source. Rich plotting capabilities and a graphical web-based user interface provide experienced and novice users with tools to follow and interact with experiments. BLISS is fully integrated with EWOKS, the ESRF meta-workflow system. EWOKS relies on NeXus/HDF5 and rich metadata to fully automate data reduction and processing, delivering final results to users via the data portal.

The main impact of replacing SPEC with BLISS on beamlines is the enhanced capability to acquire data more rapidly, resulting in more efficient use of beamtime and opening up the possibility to perform more complex experiments. Users have expressed their satisfaction with the increased volume of data obtained within the same beamtime, the ability to implement more complex acquisition protocols and the option to invoke their own source code during experiments. An illustrative example highlighting the effectiveness of BLISS is the “Closing the Loop” experiment conducted on ID10, detailed in a previous Tech Talk.

The next phase in BLISS development for beamlines involves the creation and deployment of blissdata, which will implement seamless access to data during and after the acquisition for on-the-fly data processing. While BLISS is an unique feature of the ESRF, its open-source licensing makes it available for adoption by any facility interested in exploring its capabilities. Some software components, such as the NexusWriter, are currently being deployed at ALBA. Furthermore, BLISS is undergoing testing on a beamline at DESY, considering its potential as a viable option for the new source, Petra IV.

Principal publication and authors
A Marriage Made in BLISS – An Integrated Beamline Control System, M. Guijarro (a), L. Felix (a), W. De Nolf (a), J. Meyer (a), A. Götz (a), Synchrotron Radiat. News 36, 6, 12-19 (2023); https://doi.org/10.1080/08940886.2023.2277141
(a) ESRF