RxEpics/cpp: ReactiveX-style recipes for EPICS/PVXS

["Khokhriakov, Igor via Tech-talk" <tech-talk at aps.anl.gov>]

Hi all,

I wanted to share a project that may be interesting to people working with EPICS, PVXS, acquisition scripts, or higher-level control-system automation.

The project is called rx-controls-suite:

https://urldefense.us/v3/__https://github.com/scientific-software-hub/rx-controls-suite__;!!G_uCfscf7eWS!dLLG5g5HnbbiJvQpn7Sq75aLLC5Lgx6AgUJF_Ccg4Z_wpdj6XUk9hDjeUcQ33aGbZtWw4kXOrNFbSDl6gMbOGm-wBtCFyqIQ$ 

The basic idea is to express common control-system tasks as reactive streams and reusable recipes.

For example:

poll or monitor a value;
combine several values into one snapshot;
react to fault conditions;
apply quality flags;
share one health stream with multiple consumers;
build acquisition or middleware logic as a pipeline.

The suite originally grew from Tango-related work, but the goal is explicitly cross-platform: the same ReactiveX-style operator vocabulary across different control systems and languages.

I have now added a C++ EPICS and Python subprojects:

RxEpics/cpp
RxEpics/python

It wraps EPICS/PVXS concepts as rxcpp::observable<T> streams, aligned with the existing Python design. There is also a corresponding RxTango/cpp side, because one of the long-term goals is to express cross-SCADA recipes using the same vocabulary on both sides.

The motivation is not to replace existing EPICS tools. It is to explore whether some recurring automation patterns can be made more explicit and reusable, instead of being reimplemented each time with custom loops, callbacks, buffers, timestamp matching, and error-handling glue.

I recently presented the broader idea at the Tango Users Group Meeting 2026, using a demo that combines a simulated Tango storage ring and an EPICS beamline in one Python process:

https://urldefense.us/v3/__https://www.youtube.com/watch?v=9CyGPIwJlxc__;!!G_uCfscf7eWS!dLLG5g5HnbbiJvQpn7Sq75aLLC5Lgx6AgUJF_Ccg4Z_wpdj6XUk9hDjeUcQ33aGbZtWw4kXOrNFbSDl6gMbOGm-wBjncTtBQ$ 

I would appreciate feedback from the EPICS community, especially around the C++/PVXS direction:

Does a ReactiveX-style layer around EPICS/PVXS sound useful?
Are there existing EPICS patterns or tools this should align with?
Which recurring EPICS automation recipe would be a good first serious example?

Best regards,
Igor Khokhriakov