Re: [EXTERNAL] PyDM Write Widgets Do Not Honor PVA ACF Permission Rules

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

>>value writing is still allowed on the PyDM GUI interface.

>Does this mean the widget is only "enabled" on the UI level, but the actual PV does not update if you try to write, or are you actually seeing the PV updating on a separate terminal?

The PVA protocol currently offers no access information.

The PVA server on the IOC, specifically the PVXS version (QSRV2), does honor the access security settings, https://github.com/epics-docs/epics-docs/blob/master/appdevguide/AccessSecurity.rst

With Channel Access, the client is updated about the current permissions, so widgets in a GUI can indicate if you have write access or not.

With PVA,  the client is currently clueless. Widgets in a GUI cannot indicate if you have write access or not. So you might think that you have write access, but when you then actually enter a value on the GUI, you get a write error, and the value on the IOC does not change.

The situation is absolutely safe but a little unfortunate.