ECHOES Architecture for Data and Cloud Components (D6.3)

This deliverable defines the target architecture of the Cultural Heritage Cloud and establishes the M24 architectural baseline for data and cloud components. It addresses the challenge of operating the Cloud as a hybrid federated environment in which centrally governed platform capabilities coexist with provider-operated services, external repositories and domain-specific applications. The core architectural choice is a layered model that separates access and trust, platform control-plane responsibilities, execution, knowledge, storage, and applications and integration concerns. A common access boundary, built around the Cloud Web UI, Single Entry Point, Access Edge and shared AAI, provides a unified trust and entry context. Behind this boundary, the platform control plane coordinates policy resolution, knowledge-graph governance, binary asset handling, discoverability and managed platform operations. Vertical Applications are treated as partner-owned domain systems integrated through shared platform contracts, with platform governance remaining in the shared cloud core. The architecture separates authoritative sources of truth. Identity and entitlements remain governed by AAI, semantic ownership and governance metadata by the Administrative Repository, and storage targets and policy state by the Storage Registry / Data API. Platform services use this authoritative state to resolve effective operational context and avoid duplicated governance logic. The deliverable also clarifies the User Personal Space as a logical capability composed of a private semantic workspace and a private binary zone, resolved by platform policy instead of being hard-coded by applications. The Heritage Digital Twin is defined as a compound platform-managed object combining semantic representation, references to binary or non-semantic assets, governance metadata, operational state, persistent identity and publication state. This distinction supports consistent handling of VA-local preparation, platform-managed save and publication paths, snapshot-oriented versioning and explicit lifecycle transitions. Finally, observability, monitoring and operational continuity are treated as cross-cutting capabilities. Centrally operated services expose a full baseline of health, metrics, logs, traces and operation-state telemetry, while provider-operated or federated participants expose the diagnostic signals needed for conformance verification and operational governance. Together, these elements define the structural architecture and operational baseline for onboarding, execution, publication and federated participation across the ECHOES ecosystem.