OMA Reference Model

Application Interface	Domain Interfaces	Common Facilities	Object Services
Object Request Broker

Object Services are domain-independent interfaces that are used by many distributed object programs.
- Naming Service: find object based on name.
- Trading service: find object based on properties.
Common Facilities are end-user-oriented interfaces.
- Distributed Document Component Facility.
Domain Interfaces are application domain-oriented interfaces.
- Product Data Management Enablers: for manufacturing domain.
Application Interfaces are developed for specific applications. They are not standardized.