For the "Comments to Indico event" PoC part, the discussion was about Access and References to these comments.
The CERN-Solid PoC by Jan will be implemented using NSS (MIT W3C, started in 2016).
His pod is on an NSS instance hosted in Germany, storage in https://www.digitalocean.com/).
NSS is also used by solidcommunity.net and this the recommended option. NSS is the Solid server that works best but will eventually get out-of-date,
CSS (open source re-write of NSS on Trellis) is not an alternative today. It doesn't exist operationally.
ESS is US-based, closed source, proprietary (inrupt.com), storage in AWS (Amazon Web Services). This won't be a popular option for CERN users' pods (US-based, proprietary).
php-SS (open source) is not ready.
The recommendation is to select solidcommunity.net from the pod providers' list on https://solidproject.org//users/get-a-pod#get-a-pod-from-a-pod-provider
User guide https://github.com/solid/userguide
About new users' possible confusion
I tried https://www.solidcommunity.net/common/popup.html and found the Olivier example (is it an example?) confusing. What is the difference between "solid community" and "www. solidcommunity.net" on page https://www.solidcommunity.net/common/popup.html
see HERE what I mean.
I went to https://solidcommunity.net/ and pressed "Log in". The popup now looks different.
See the difference.
About a CERN own server
Reading the Solid standard and implementing from scratch a Solid server to host CERN users' pods would be difficult to sell.
How to quantify the effort required?
How to ensure inter-operability with other servers = pod providers?
How to remain conformant, given the test-suite changes?
Why "self hosting" https://solidproject.org//self-hosting/nss only offers NSS?