Using the Common Information Model for Building Semantic Services
One of the requirements for a successful SOA implementation is semantic interoperability of the service’s messages. This typically requires basing service messaging/interfaces on the industry-specific Common Information Model (CIM). Because the CIM is abstract, in the majority of cases this CIM has to be extended for various reasons from necessity to include additional data elements for integration reasons to adding elements required for carrying out business logics by the Service component. A new DeveloperWorks article by Gandhi Sivakumar introduces 3 typical CIM layers and describes the property of each one.
According to authors the foundation is a core CIM layer, which
... comprises of the raw industry published models such as the TeleManagement Forum's Shared Information Data model (SID) in telecommunication industry and the IBM financial services model names the IFW in finance industry which contains the abstract entities with attributes and relationships.
This layer is typically predefined, but can be slightly customized to add missing data definitions, relationships and unique name identifiers. This layer is usually contained in its own namespace(s) to allow service specification generation tools to maintain it as a separate base layer decoupled from additional CIM layers.
The core CIM layer is extended by a weaker CIM layer, which:
... encompasses the extended CIM entities which convey pure business meaning for existence ... the modeler needs to always visualize the manifestation of these elements in the Service interface and not include unless otherwise warranted from business perspective, further represent them through a well abstracted terminology.
The weaker CIM is an extension of the core CIM layer providing additional attributes, objects, relationships and interfaces. This layer contains the majority of business specific entities required for service implementation but missing in the core CIM. This layer is typically the most dynamic one and keeps growing as more functionality is added to services
Finally, the weakest CIM layer
... includes objects, attributes, interfaces, and methods which are required purely for integration purposes. For example the message header related entities, entities which are required for controlling the results, connecting the service operations and the weaker/core CIM layers. Note that this final layer must always co-exists with the lower weaker and core CIM layers, but are connected through the service operations.
The purpose of this layer is purely to support entities required for the implementation of integration and control functionality.
The article provides a very well defined multi-layered approach to adopting industry specific CIM models to SOA implementations. Proposed clear separation of core, service specific and integration specific extensions promotes a better overall maintainability of the semantic SOA model.