Web-based services (cloud services) is an important trend to innovate end-user services while optimising the service operational costs. CERN users are constantly proposing new approaches (inspired from services existing on the web, tools used in education or other science or based on their experience in using existing computing services). In addition, industry and open source communities have recently made available a large number of powerful and attractive tools and platforms that enable large scale data processing. “Big Data” software stacks notably provide solutions for scalable storage, distributed compute and data analysis engines, data streaming, web-based interfaces (notebooks). Some of those platforms and tools, typically available as open source products, are experiencing a very fast adoption in industry and science such that they are becoming “de facto” references in several areas of data engineering, data science and machine learning. In parallel to users' requests, WLCG is considering to consolidate its deployment model into a relatively reduced number of resource sites (while benefiting from potentially ephemeral resources like public cloud and large installations like experiment filter farms, HPC facilities, analysis centres). In this schema, analysis facilities could be provided as web-based services located in strategic WLCG centres or spawned on relatively short-lived farms.
