4 types of service in an SOA system.
- Business services
- Domain services
- Integration services
- Foundation / Utility services
Business Services
- Provide high-level functionality
- Provides abstraction of the interface
- Provides integration of the layers below
- Breaks the direct dependance between business processes and existing systems
- Provides a virtual implementation
- Provides business processes (e.g. customer profile) through groupings of related operations (e.g. search customer by email address)
- Provides a virtual implementation of related business operations that can be utilised across multiple systems
Domain Services
- Medium-grained functionality
- Services specific to a business domain are re-used across multiple systems
- Exposed outside the domain service
- Contains domain-specific functionality / operations
Integration Services
- Provide access and integration to existing applications
- Expose existing applications as services
- Involve a translation form whats available in the existing application and whats desired in the service
Foundation / Utility Services
- Least course-grained
- Contain domain-independant functionality (e.g security / logging)
- Used in the construction of higher-level services