Composite Registers

A register that is internally composed of two or more simple registers but acts as a single register. Each internal register may have its own namespace and governance processes.

What is a Composite Register?

Composite registers allow organizations to create unified views across multiple registers while maintaining separate governance, namespaces, or hosting environments for each component.

Composite register structure showing sub-registers within a unified register

A composite register presents a unified interface while internally delegating to sub-registers.

When to Use Composite Registers

Composite registers are useful when you need to:

Segregate Managerial Duty

Different teams or organizations manage different sub-registers while users access content through a single interface.

Facilitate Availability

Sub-registers can be hosted in different locations or on different schedules while maintaining a unified access point.

Limit Data Sovereignty

Each sub-register can maintain its own data governance policies while participating in the composite.

Scope Regulatory Concerns

Different jurisdictions or regulatory frameworks can apply to different sub-registers within the composite.

Topologies

ISO 19135:2026 Annex E describes three common topologies for composite registers. Each has different characteristics for governance, performance, and failure modes.

Hierarchical Structure

Hierarchical register topology with parent-child relationships

Sub-registers are organized under a parent register in a tree structure. The parent register coordinates access and may provide cross-cutting concerns like search across all sub-registers.

Characteristics

  • Clear authority flow from parent to children
  • Sub-registers inherit some governance from parent
  • Parent handles cross-register queries
  • Sub-register failure may affect availability

Examples

INSPIRE Registry, DGIWG Feature Concept Dictionary

Federated Structure

Federated register topology with peer-to-peer relationships

Independent registers that mutually recognize each other. There is no central authority; each register operates autonomously while agreeing to shared conventions.

Characteristics

  • Peer-to-peer relationships between registers
  • Each register maintains full autonomy
  • Shared conventions for interoperability
  • Failure of one register doesn't affect others

Examples

UN/FAO Land Cover Legend Registry

Hub and Spoke Structure

Hub and spoke register topology with central hub and specialized spokes

A central authoritative hub coordinates with specialized spoke registers. The hub provides core content and governance; spokes add domain-specific extensions.

Characteristics

  • Central hub is authoritative and required
  • Spokes extend hub with specialized content
  • Hub-spoke dependencies are explicit
  • Hub failure affects entire composite

Examples

UN/ISO 19114 MLE register

Governance Considerations

Composite registers introduce additional governance challenges beyond those of simple registers:

Conflict Resolution

How are conflicts between sub-registers resolved? Define clear precedence rules and escalation paths when sub-registers disagree on content or governance decisions.

Unified View Maintenance

Who maintains the unified view? The composite itself may need a dedicated manager or coordinating body to handle cross-register concerns.

Identifier Coordination

How are identifiers coordinated across sub-registers? Consider namespace prefixes, identifier delegation, and resolution services.

Sub-Register Availability

What happens when a sub-register is unavailable? Define fallback behaviors, caching strategies, and degraded service modes.

Related Topics