2.3 The Current LISI Reference
A reference model is defined as a set of concepts, entities, interfaces, and diagrams that provides common ground for comparisons. A reference model is also a valuable tool for evaluating and comparing information systems. It does not provide a specific system design, but rather it defines a common set of services and interfaces for building specific designs. For example, the DoD Technical Reference Model (DoD TRM) was developed as a framework for evaluating technical implementations and for determining DoD systems characteristics. The Joint Technical Architecture (JTA) was developed from the DoD TRM to specify technical implementations when building a system. The TRM/JTA should allow systems to incorporate and exhibit the technical characteristics that were determined as important to DoD.
The LISI Reference Model is the foundation for a similar process that focuses on the interoperability of DoD systems. The LISI Reference Model, extended to include detailed definitions of capabilities, options, and implementation criteria, can support rigorous system interoperability evaluations and comparative assessments.
The current LISI Reference Model is shown in Figure D-3. The reference model provides a framework for understanding operational information interactions in context with the technologies and system interactions required for interoperability. It defines major thresholds of operational information interaction and provides direct translation at each level to a requisite suite of information system capabilities.
The current LISI Reference Model provides a baseline of capability thresholds, described in terms of the PAID attributes. The reference model provides the common vocabulary and framework needed to discuss interoperability between systems. At each level, a word or phrase highlights the most important aspect of PAID needed to achieve that level. For example, a system targeting interactions with other systems working at Level 3 (Integrated) must build toward the specific set of capabilities listed in the LISI Reference Model for Level 3. As stated earlier, the reference model can be extended to address specific PAID capabilities, characteristics, and implementation criteria.
Figure D-3 The Current LISI Reference Model