Hybrid Cloud Architecture for Enterprise SAP Workloads: A Reference Model for Public-Sector Digital Transformation

Public-sector enterprises in the Kingdom of Saudi Arabia operate large SAP estates that act as systems of record for finance, human capital, supply chain, and reporting. These platforms carry sovereignty, data residency, audit, and continuity obligations that pure public-cloud and pure on-premises deployment models do not satisfy in isolation. Hybrid cloud, as defined by the National Institute of Standards and Technology, offers a defensible target state, but the literature lacks a consolidated reference model that maps SAP S/4HANA workloads, identity and integration services, and resilience tiers to a hybrid topology suitable for national-level public-sector use. This paper proposes a nine-layer hybrid cloud reference architecture for enterprise SAP workloads, anchored on SAP S/4HANA as the system of record and Amazon Web Services as the principal cloud plane, with on-premises and partner-managed components retained where residency, classification, or continuity constraints demand them. The model is synthesised from the AWS Well-Architected Framework and its SAP Lens, official SAP architectural documentation, the NIST cloud reference architecture, Saudi cybersecurity and cloud regulatory guidance, and patterns observed during sustained delivery on enterprise SAP platforms in the Kingdom. The paper presents the nine layers (network and connectivity; compute and platform; database; application; integration; identity and access; security and compliance; observability and operations; resilience and disaster recovery), discusses the operating model and governance envelope, and identifies open questions for future work. The model is mapped to the Cloud Computing Regulatory Framework issued by the Communications, Space and Technology Commission and to the Essential and Cloud Cybersecurity Controls issued by the National Cybersecurity Authority. The contribution is intended to support digital transformation programmes pursued under Saudi Vision 2030 and the National Strategy for Data and Artificial Intelligence, and to provide a vocabulary that architects, auditors, and programme sponsors can share when evaluating cloud target states for SAP. This is the first paper in a four-paper portfolio on cloud-era enterprise platforms for public-sector digital transformation in the Kingdom of Saudi Arabia. Companion papers address cloud migration strategy for SAP landscapes, cloud-native AI and big data integration in enterprise platforms, and workforce readiness for the cloud-era enterprise.