Experimental Physics and
Industrial Control System

"Konrad, Martin" <[email protected]> · Wed, 16 Nov 2016 16:46:19 +0000

Hi Rod,
That's a tough one. There are at least two competing approaches:

A) Link everything statically or in it's more modern form use containers
(Docker or similar). This gives the application developer full control
over the versions of all his libraries.

B) Use shared libraries, often paired with packaging (e.g. Debian/RPM
packages) to simplify deployment and to handle dependencies.

Both approaches have their advantages: (A) gives the application
developer maximum control. (B) on the other hand makes it easier to fix
a bug in a library that is used by many applications. Consider applying
a fix to EPICS Base. You might need to rebuild hundreds of
IOCs/applications/containers if you go for (A). In case you go for (B)
you just need to rebuild Base, deploy the new package and restart the
applications which might save you a lot of time. Note that even though
packages might be upgraded on your Linux machines on a daily basis that
usually doesn't break functionality. Distributions generally only allow
bug fixes for their "stable" edition.

All large-scale Linux distributions are using (B) but more and more
software projects choose to provide containers. This is great since it
provides users with the latest code. On the other hand it can easily
introduces issues (e.g. security issues) due to out-of-date libraries
that might be shipped as part of these containers.

At FRIB we decided to go with approach (B), the same is true for
NSLS-II. AFAIK ESS' IOC Factory is going for something more along (A).

Regards,

Martin

-- 
Martin Konrad
Control System Engineer
Facility for Rare Isotope Beams
Michigan State University
640 South Shaw Lane
East Lansing, MI 48824-1321, USA
Tel. 517-908-7253
Email: [email protected]

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System