Brainstorm organization of framework-supported IO packages

[makortel]

No description provided.

[makortel]

Presently

IOPool/Common (RootServiceChecker, getWrapperBasePtr(); edmProvDump, edmFileUtil etc executables)
IOPool/Input
IOPool/Output
IOPool/Provenance (for CommonProvenanceFiller.h that is used also in NanoAODOutputModule)
IOPool/SecondaryInput (only tests)
IOPool/Streamer (contains both input and output)
IOPool/TFileAdaptor

Utilities/DCacheAdaptor
Utilities/DavixAdaptor
Utilities/LStoreAdaptor
Utilities/StorageFactory
Utilities/XrdAdaptor

Notes

• TTree and RNTuple can be opened with bare ROOT, streamer not
  • In a way streamer using ROOT serialization can be thought as an implementation detail, that could change "at any time"
• Decided organization should naturally extend to hypothetical inclusion of other file formats (PDS, HDF5)
• Another consideration in addition to storage technology would be maintenance ownership (e.g. FWIO)
• DataFormats is a layering system (at least to some degree...)
• We could think of moving FWCore/{Integration,TestModules} outside of FWCore to reduce intertwining between FWCore and IOPool

[makortel]

Outcome

FWIO/Common (from IOPool/Common)

FWIO/PoolInput (from IOPool/Input and IOPool/SecondaryInput)
FWIO/PoolOutput (from IOPool/Output)
FWIO/TTreeProvenance (from IOPool/Provenance)

FWIO/RNTuple

FWIO/Streamer (from IOPool/Streamer)

# hypothetical extension
FWIO/HDF5
FWIO/PDS

FWStorage/TFileAdaptor (from IOPool/TFileAdaptor)
FWStorage/DCacheAdaptor (from Utilities/DCacheAdaptor)
FWStorage/LStoreAdaptor (from Utilities/LStoreAdaptor)
FWStorage/StorageFactory (from Utilies/StorageFactory)
FWStorage/XrdAdaptor (from Utilities/XrdAdaptor)

We probably want to split -lTree out from rootcore into a separate tool, and add similar tool for RNTuple.

[makortel]

cms-sw/cmssw#45349 suggested renaming IOPool to IOCore, and merging {Common,Input,Output} into TTree. Maybe we follow the result of our brainstorming above nevertheless. The PR moving things around should then close cms-sw/cmssw#45349.