WLCG input for the first RCS-IT technical meeting. This is a list of topics that I believe are in the scope of the RCS-IT engagement process from the WLCG perspective. The list is not exclusive, not prioritized and probably overlaps with a lot of the input from the experiments. It will be the work of the next months to complement it, to harmonize it and to prioritize it.  

* WLCG Operations Coordination and generally support for WLCG core activities and functions: CERN IT has a role in supporting the WLCG collaboration beyond the scope of providing Tier-0 services. This role covers the coordination of the WLCG service and operations, the support for central services and tools such as CRIC, Hammercloud, the Experiment Test Framework, the MONIT infrastructure. It is important that enough effort is identified to continue those activities at least at the current level. In the case of tools and services, it is important to identify enough effort to maintain but also modernize them following the evolution of the technology and the WLCG needs. For the WLCG service and operations coordination, it is important organize across the RCS sector the structure to execute the plan in the WLCG roadmap for HL-LHC computing. The coordination of the future data challenges together with other institutes in WLCG is a clear example. 

* The EP and IT department have a leading role in the development and operations of the WLCG data management stack. Core components such as Rucio, FTS, EOS, CTA, GFAL are highly strategic for WLCG. So far, they have been developed independently (while collaboratively). An effort to harmonize and optimize the interactions between those components would be highly beneficial. WLCG partners participate to the development efforts for some those components and some WLCG sites run instances of those services. A collaborative effort together with those partners should be foreseen

* CERN today provides services for end user analysis, such as LXPLUS (interactive analysis), LXBATCH (batch analysis) and SWAN (notebook service). The HEP community is looking at alternatives for the future analysis facilities. CERN should investigate different options considering the specific needs of its community, the evolution of the computing models and the evolution of the technologies. This work would involve several teams in RCS (IT, EP-SFT and experiments)

* The migration from X509 proxies to tokens is strategic for WLCG and should conclude well in time for HL-LHC. There is a WLCG plan with milestones for the next years and that is reviewed periodically. Many of the components that will need to implement the full support for tokens are under the responsibility of groups in RCS (e.g. Dirac, Rucio, FTS, …) as well as the service granting tokens (IAM). The WLCG Authorization working groups has also a strong representation from RCS. The sector should work coherently towards the implementation of token support, understanding the interplay between services and proposing the most effective solution for some of the areas that are still under discussion 

* WLCG has a strategic interest building partnership with other HEP experiments and other sciences such as Astronomy/Astroparticle. Those experiments/sciences will share a large part of the infrastructure with WLCG and possibly many of the same services. The RCS sector is in the ideal position to foster this collaboration, leveraging European initiatives such as ESCAPE. 

* The modernization of the experiment software and common libraries is strategic to address the HL-LHC computing challenges. The IT department should work with EP-SFT and the experiments to facilitate the software development process. The software evolution for non-X86 architectures and hardware accelerators is a clear example of an activity that should be supported.